Merge pull request #571 from emersion/output-damage

Output damage tracking

backend/backend.c

@@ -37,7 +37,6 @@ void wlr_backend_destroy(struct wlr_backend *backend) {
 		return;
 	}
 
-	wl_signal_emit(&backend->events.destroy, backend);
 	if (backend->impl && backend->impl->destroy) {
 		backend->impl->destroy(backend);
 	} else {

backend/drm/backend.c

@@ -34,6 +34,8 @@ static void wlr_drm_backend_destroy(struct wlr_backend *backend) {
 		wlr_output_destroy(&conn->output);
 	}
 
+	wl_signal_emit(&backend->events.destroy, backend);
+
 	wl_list_remove(&drm->display_destroy.link);
 	wl_list_remove(&drm->session_signal.link);
 	wl_list_remove(&drm->drm_invalidated.link);
@@ -89,6 +91,8 @@ static void session_signal(struct wl_listener *listener, void *data) {
 			struct wlr_drm_plane *plane = conn->crtc->cursor;
 			drm->iface->crtc_set_cursor(drm, conn->crtc,
 				(plane && plane->cursor_enabled) ? plane->cursor_bo : NULL);
+			drm->iface->crtc_move_cursor(drm, conn->crtc, conn->cursor_x,
+				conn->cursor_y);
 		}
 	} else {
 		wlr_log(L_INFO, "DRM fd paused");

backend/drm/drm.c

@@ -184,18 +184,22 @@ void wlr_drm_resources_free(struct wlr_drm_backend *drm) {
 	free(drm->planes);
 }
 
-static void wlr_drm_connector_make_current(struct wlr_output *output) {
+static bool wlr_drm_connector_make_current(struct wlr_output *output,
+		int *buffer_age) {
 	struct wlr_drm_connector *conn = (struct wlr_drm_connector *)output;
-	wlr_drm_surface_make_current(&conn->crtc->primary->surf);
+	return wlr_drm_surface_make_current(&conn->crtc->primary->surf, buffer_age);
 }
 
-static void wlr_drm_connector_swap_buffers(struct wlr_output *output) {
+static bool wlr_drm_connector_swap_buffers(struct wlr_output *output) {
 	struct wlr_drm_connector *conn = (struct wlr_drm_connector *)output;
 	struct wlr_drm_backend *drm = (struct wlr_drm_backend *)output->backend;
+	if (!drm->session->active) {
+		return false;
+	}
 
 	struct wlr_drm_crtc *crtc = conn->crtc;
 	if (!crtc) {
-		return;
+		return false;
 	}
 	struct wlr_drm_plane *plane = crtc->primary;
 
@@ -203,16 +207,20 @@ static void wlr_drm_connector_swap_buffers(struct wlr_output *output) {
 	if (drm->parent) {
 		bo = wlr_drm_surface_mgpu_copy(&plane->mgpu_surf, bo);
 	}
-
 	uint32_t fb_id = get_fb_for_bo(bo);
 
-	if (drm->iface->crtc_pageflip(drm, conn, crtc, fb_id, NULL)) {
+	if (conn->pageflip_pending) {
-		conn->pageflip_pending = true;
+		wlr_log(L_ERROR, "Skipping pageflip");
-		wlr_output_update_enabled(output, true);
+		return false;
-	} else {
+	}
-		wl_event_source_timer_update(conn->retry_pageflip,
+
-			1000.0f / conn->output.current_mode->refresh);
+	if (!drm->iface->crtc_pageflip(drm, conn, crtc, fb_id, NULL)) {
+		return false;
 	}
+
+	conn->pageflip_pending = true;
+	wlr_output_update_enabled(output, true);
+	return true;
 }
 
 static void wlr_drm_connector_set_gamma(struct wlr_output *output,
@@ -250,7 +258,7 @@ void wlr_drm_connector_start_renderer(struct wlr_drm_connector *conn) {
 		wlr_output_update_enabled(&conn->output, true);
 	} else {
 		wl_event_source_timer_update(conn->retry_pageflip,
-			1000.0f / conn->output.current_mode->refresh);
+			1000000.0f / conn->output.current_mode->refresh);
 	}
 }
 
@@ -531,6 +539,9 @@ static bool wlr_drm_connector_set_cursor(struct wlr_output *output,
 	if (!buf && update_pixels) {
 		// Hide the cursor
 		plane->cursor_enabled = false;
+		if (!drm->session->active) {
+			return true;
+		}
 		return drm->iface->crtc_set_cursor(drm, crtc, NULL);
 	}
 	plane->cursor_enabled = true;
@@ -577,17 +588,15 @@ static bool wlr_drm_connector_set_cursor(struct wlr_output *output,
 	}
 
 	struct wlr_box hotspot = {
-		.width = plane->surf.width,
-		.height = plane->surf.height,
 		.x = hotspot_x,
 		.y = hotspot_y,
 	};
 	enum wl_output_transform transform =
 		wlr_output_transform_invert(output->transform);
-	struct wlr_box transformed_hotspot;
+	wlr_box_transform(&hotspot, transform,
-	wlr_box_transform(&hotspot, transform, &transformed_hotspot);
+		plane->surf.width, plane->surf.height, &hotspot);
-	plane->cursor_hotspot_x = transformed_hotspot.x;
+	plane->cursor_hotspot_x = hotspot.x;
-	plane->cursor_hotspot_y = transformed_hotspot.y;
+	plane->cursor_hotspot_y = hotspot.y;
 
 	if (!update_pixels) {
 		// Only update the cursor hotspot
@@ -606,7 +615,7 @@ static bool wlr_drm_connector_set_cursor(struct wlr_output *output,
 		return false;
 	}
 
-	wlr_drm_surface_make_current(&plane->surf);
+	wlr_drm_surface_make_current(&plane->surf, NULL);
 
 	wlr_texture_upload_pixels(plane->wlr_tex, WL_SHM_FORMAT_ARGB8888,
 		stride, width, height, buf);
@@ -630,35 +639,52 @@ static bool wlr_drm_connector_set_cursor(struct wlr_output *output,
 
 	gbm_bo_unmap(bo, bo_data);
 
-	return drm->iface->crtc_set_cursor(drm, crtc, bo);
+	if (!drm->session->active) {
+		return true;
+	}
+
+	bool ok = drm->iface->crtc_set_cursor(drm, crtc, bo);
+	if (ok) {
+		wlr_output_update_needs_swap(output);
+	}
+	return ok;
 }
 
 static bool wlr_drm_connector_move_cursor(struct wlr_output *output,
 		int x, int y) {
 	struct wlr_drm_connector *conn = (struct wlr_drm_connector *)output;
 	struct wlr_drm_backend *drm = (struct wlr_drm_backend *)output->backend;
-	if (!conn || !conn->crtc) {
+	if (!conn->crtc) {
 		return false;
 	}
 	struct wlr_drm_plane *plane = conn->crtc->cursor;
 
-	struct wlr_box box;
+	struct wlr_box box = { .x = x, .y = y };
-	box.x = x;
+
-	box.y = y;
+	int width, height;
-	wlr_output_effective_resolution(output, &box.width, &box.height);
+	wlr_output_transformed_resolution(output, &width, &height);
 
 	enum wl_output_transform transform =
 		wlr_output_transform_invert(output->transform);
-	struct wlr_box transformed_box;
+	wlr_box_transform(&box, transform, width, height, &box);
-	wlr_box_transform(&box, transform, &transformed_box);
 
 	if (plane != NULL) {
-		transformed_box.x -= plane->cursor_hotspot_x;
+		box.x -= plane->cursor_hotspot_x;
-		transformed_box.y -= plane->cursor_hotspot_y;
+		box.y -= plane->cursor_hotspot_y;
+	}
+
+	conn->cursor_x = box.x;
+	conn->cursor_y = box.y;
+
+	if (!drm->session->active) {
+		return true;
 	}
 
-	return drm->iface->crtc_move_cursor(drm, conn->crtc, transformed_box.x,
+	bool ok = drm->iface->crtc_move_cursor(drm, conn->crtc, box.x, box.y);
-		transformed_box.y);
+	if (ok) {
+		wlr_output_update_needs_swap(output);
+	}
+	return ok;
 }
 
 static void wlr_drm_connector_destroy(struct wlr_output *output) {
@@ -874,7 +900,7 @@ static void page_flip_handler(int fd, unsigned seq,
 	}
 
 	if (drm->session->active) {
-		wl_signal_emit(&conn->output.events.frame, &conn->output);
+		wlr_output_send_frame(&conn->output);
 	}
 }
 

backend/drm/renderer.c

@@ -128,9 +128,9 @@ void wlr_drm_surface_finish(struct wlr_drm_surface *surf) {
 	memset(surf, 0, sizeof(*surf));
 }
 
-void wlr_drm_surface_make_current(struct wlr_drm_surface *surf) {
+bool wlr_drm_surface_make_current(struct wlr_drm_surface *surf,
-	eglMakeCurrent(surf->renderer->egl.display, surf->egl, surf->egl,
+		int *buffer_damage) {
-		surf->renderer->egl.context);
+	return wlr_egl_make_current(&surf->renderer->egl, surf->egl, buffer_damage);
 }
 
 struct gbm_bo *wlr_drm_surface_swap_buffers(struct wlr_drm_surface *surf) {
@@ -138,7 +138,9 @@ struct gbm_bo *wlr_drm_surface_swap_buffers(struct wlr_drm_surface *surf) {
 		gbm_surface_release_buffer(surf->gbm, surf->front);
 	}
 
-	eglSwapBuffers(surf->renderer->egl.display, surf->egl);
+	if (!eglSwapBuffers(surf->renderer->egl.display, surf->egl)) {
+		wlr_log(L_ERROR, "eglSwapBuffers failed");
+	}
 
 	surf->front = surf->back;
 	surf->back = gbm_surface_lock_front_buffer(surf->gbm);
@@ -150,7 +152,7 @@ struct gbm_bo *wlr_drm_surface_get_front(struct wlr_drm_surface *surf) {
 		return surf->front;
 	}
 
-	wlr_drm_surface_make_current(surf);
+	wlr_drm_surface_make_current(surf, NULL);
 	glViewport(0, 0, surf->width, surf->height);
 	glClearColor(0.0, 0.0, 0.0, 1.0);
 	glClear(GL_COLOR_BUFFER_BIT);
@@ -222,8 +224,9 @@ static struct wlr_texture *get_tex_for_bo(struct wlr_drm_renderer *renderer, str
 	return tex->tex;
 }
 
-struct gbm_bo *wlr_drm_surface_mgpu_copy(struct wlr_drm_surface *dest, struct gbm_bo *src) {
+struct gbm_bo *wlr_drm_surface_mgpu_copy(struct wlr_drm_surface *dest,
-	wlr_drm_surface_make_current(dest);
+		struct gbm_bo *src) {
+	wlr_drm_surface_make_current(dest, NULL);
 
 	struct wlr_texture *tex = get_tex_for_bo(dest->renderer, src);
 

backend/headless/backend.c

@@ -51,6 +51,8 @@ static void backend_destroy(struct wlr_backend *wlr_backend) {
 		wlr_input_device_destroy(&input_device->wlr_input_device);
 	}
 
+	wl_signal_emit(&wlr_backend->events.destroy, backend);
+
 	wlr_egl_finish(&backend->egl);
 	free(backend);
 }

backend/headless/output.c

@@ -48,25 +48,20 @@ static void output_transform(struct wlr_output *wlr_output,
 	output->wlr_output.transform = transform;
 }
 
-static void output_make_current(struct wlr_output *wlr_output) {
+static bool output_make_current(struct wlr_output *wlr_output, int *buffer_age) {
 	struct wlr_headless_output *output =
 		(struct wlr_headless_output *)wlr_output;
-	if (!eglMakeCurrent(output->backend->egl.display,
+	return wlr_egl_make_current(&output->backend->egl, output->egl_surface,
-		output->egl_surface, output->egl_surface,
+		buffer_age);
-		output->backend->egl.context)) {
-		wlr_log(L_ERROR, "eglMakeCurrent failed: %s", egl_error());
-	}
 }
 
-static void output_swap_buffers(struct wlr_output *wlr_output) {
+static bool output_swap_buffers(struct wlr_output *wlr_output) {
-	// No-op
+	return true; // No-op
 }
 
 static void output_destroy(struct wlr_output *wlr_output) {
 	struct wlr_headless_output *output =
 		(struct wlr_headless_output *)wlr_output;
-	wl_signal_emit(&output->backend->backend.events.output_remove,
-		&output->wlr_output);
 
 	wl_list_remove(&output->link);
 
@@ -88,7 +83,7 @@ bool wlr_output_is_headless(struct wlr_output *wlr_output) {
 
 static int signal_frame(void *data) {
 	struct wlr_headless_output *output = data;
-	wl_signal_emit(&output->wlr_output.events.frame, &output->wlr_output);
+	wlr_output_send_frame(&output->wlr_output);
 	wl_event_source_timer_update(output->frame_timer, output->frame_delay);
 	return 0;
 }

backend/libinput/backend.c

@@ -95,12 +95,12 @@ static bool wlr_libinput_backend_start(struct wlr_backend *_backend) {
 	return true;
 }
 
-static void wlr_libinput_backend_destroy(struct wlr_backend *_backend) {
+static void wlr_libinput_backend_destroy(struct wlr_backend *wlr_backend) {
-	if (!_backend) {
+	if (!wlr_backend) {
 		return;
 	}
 	struct wlr_libinput_backend *backend =
-		(struct wlr_libinput_backend *)_backend;
+		(struct wlr_libinput_backend *)wlr_backend;
 
 	for (size_t i = 0; i < backend->wlr_device_lists.length; i++) {
 		struct wl_list *wlr_devices = backend->wlr_device_lists.items[i];
@@ -112,6 +112,8 @@ static void wlr_libinput_backend_destroy(struct wlr_backend *_backend) {
 		free(wlr_devices);
 	}
 
+	wl_signal_emit(&wlr_backend->events.destroy, wlr_backend);
+
 	wl_list_remove(&backend->display_destroy.link);
 	wl_list_remove(&backend->session_signal.link);
 

backend/meson.build

@@ -45,5 +45,16 @@ lib_wlr_backend = static_library(
 	'wlr_backend',
 	backend_files,
 	include_directories: wlr_inc,
-	dependencies: [wayland_server, egl, gbm, libinput, systemd, elogind, wlr_render, wlr_protos, drm],
+	dependencies: [
+		wayland_server,
+		egl,
+		gbm,
+		libinput,
+		systemd,
+		elogind,
+		wlr_render,
+		wlr_protos,
+		drm,
+		pixman,
+	],
 )

backend/multi/backend.c

@@ -42,11 +42,16 @@ static void subbackend_state_destroy(struct subbackend_state *sub) {
 
 static void multi_backend_destroy(struct wlr_backend *wlr_backend) {
 	struct wlr_multi_backend *backend = (struct wlr_multi_backend *)wlr_backend;
+
 	wl_list_remove(&backend->display_destroy.link);
+
 	struct subbackend_state *sub, *next;
 	wl_list_for_each_safe(sub, next, &backend->backends, link) {
 		wlr_backend_destroy(sub->backend);
 	}
+
+	// Destroy this backend only after removing all sub-backends
+	wl_signal_emit(&wlr_backend->events.destroy, backend);
 	free(backend);
 }
 

backend/wayland/backend.c

@@ -64,9 +64,9 @@ static bool wlr_wl_backend_start(struct wlr_backend *_backend) {
 	return true;
 }
 
-static void wlr_wl_backend_destroy(struct wlr_backend *_backend) {
+static void wlr_wl_backend_destroy(struct wlr_backend *wlr_backend) {
-	struct wlr_wl_backend *backend = (struct wlr_wl_backend *)_backend;
+	struct wlr_wl_backend *backend = (struct wlr_wl_backend *)wlr_backend;
-	if (!_backend) {
+	if (backend == NULL) {
 		return;
 	}
 
@@ -80,6 +80,8 @@ static void wlr_wl_backend_destroy(struct wlr_backend *_backend) {
 		wlr_input_device_destroy(input_device);
 	}
 
+	wl_signal_emit(&wlr_backend->events.destroy, wlr_backend);
+
 	wl_list_remove(&backend->local_display_destroy.link);
 
 	free(backend->seat_name);

backend/wayland/output.c

@@ -17,11 +17,14 @@ int os_create_anonymous_file(off_t size);
 
 static struct wl_callback_listener frame_listener;
 
-static void surface_frame_callback(void *data, struct wl_callback *cb, uint32_t time) {
+static void surface_frame_callback(void *data, struct wl_callback *cb,
-	struct wlr_output *wlr_output = data;
+		uint32_t time) {
-	assert(wlr_output);
+	struct wlr_wl_backend_output *output = data;
-	wl_signal_emit(&wlr_output->events.frame, wlr_output);
+	assert(output);
 	wl_callback_destroy(cb);
+	output->frame_callback = NULL;
+
+	wlr_output_send_frame(&output->wlr_output);
 }
 
 static struct wl_callback_listener frame_listener = {
@@ -36,22 +39,32 @@ static bool wlr_wl_output_set_custom_mode(struct wlr_output *_output,
 	return true;
 }
 
-static void wlr_wl_output_make_current(struct wlr_output *_output) {
+static bool wlr_wl_output_make_current(struct wlr_output *wlr_output,
-	struct wlr_wl_backend_output *output = (struct wlr_wl_backend_output *)_output;
+		int *buffer_age) {
-	if (!eglMakeCurrent(output->backend->egl.display,
+	struct wlr_wl_backend_output *output =
-		output->egl_surface, output->egl_surface,
+		(struct wlr_wl_backend_output *)wlr_output;
-		output->backend->egl.context)) {
+	return wlr_egl_make_current(&output->backend->egl, output->egl_surface,
-		wlr_log(L_ERROR, "eglMakeCurrent failed: %s", egl_error());
+		buffer_age);
-	}
 }
 
-static void wlr_wl_output_swap_buffers(struct wlr_output *_output) {
+static bool wlr_wl_output_swap_buffers(struct wlr_output *wlr_output) {
-	struct wlr_wl_backend_output *output = (struct wlr_wl_backend_output *)_output;
+	struct wlr_wl_backend_output *output =
+		(struct wlr_wl_backend_output *)wlr_output;
+
+	if (output->frame_callback != NULL) {
+		wlr_log(L_ERROR, "Skipping buffer swap");
+		return false;
+	}
+
 	output->frame_callback = wl_surface_frame(output->surface);
 	wl_callback_add_listener(output->frame_callback, &frame_listener, output);
+
 	if (!eglSwapBuffers(output->backend->egl.display, output->egl_surface)) {
 		wlr_log(L_ERROR, "eglSwapBuffers failed: %s", egl_error());
+		return false;
 	}
+
+	return true;
 }
 
 static void wlr_wl_output_transform(struct wlr_output *_output,
@@ -148,11 +161,12 @@ static bool wlr_wl_output_set_cursor(struct wlr_output *_output,
 	return true;
 }
 
-static void wlr_wl_output_destroy(struct wlr_output *_output) {
+static void wlr_wl_output_destroy(struct wlr_output *wlr_output) {
 	struct wlr_wl_backend_output *output =
-		(struct wlr_wl_backend_output *)_output;
+		(struct wlr_wl_backend_output *)wlr_output;
-	wl_signal_emit(&output->backend->backend.events.output_remove,
+	if (output == NULL) {
-		&output->wlr_output);
+		return;
+	}
 
 	wl_list_remove(&output->link);
 

backend/wayland/wl_seat.c

@@ -54,14 +54,16 @@ static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
 
 	struct wlr_output *wlr_output = &wlr_wl_pointer->current_output->wlr_output;
 
-	struct wlr_box box;
+	int width, height;
 	wl_egl_window_get_attached_size(wlr_wl_pointer->current_output->egl_window,
-		&box.width, &box.height);
+		&width, &height);
-	box.x = wl_fixed_to_int(surface_x);
-	box.y = wl_fixed_to_int(surface_y);
 
+	struct wlr_box box = {
+		.x = wl_fixed_to_int(surface_x),
+		.y = wl_fixed_to_int(surface_y),
+	};
 	struct wlr_box transformed;
-	wlr_box_transform(&box, wlr_output->transform, &transformed);
+	wlr_box_transform(&box, wlr_output->transform, width, height, &transformed);
 	transformed.x /= wlr_output->scale;
 	transformed.y /= wlr_output->scale;
 

backend/x11/backend.c

@@ -45,7 +45,7 @@ static bool handle_x11_event(struct wlr_x11_backend *x11, xcb_generic_event_t *e
 
 	switch (event->response_type) {
 	case XCB_EXPOSE: {
-		wl_signal_emit(&output->wlr_output.events.frame, output);
+		wlr_output_send_frame(&output->wlr_output);
 		break;
 	}
 	case XCB_KEY_PRESS:
@@ -175,7 +175,7 @@ static int x11_event(int fd, uint32_t mask, void *data) {
 
 static int signal_frame(void *data) {
 	struct wlr_x11_backend *x11 = data;
-	wl_signal_emit(&x11->output.wlr_output.events.frame, &x11->output);
+	wlr_output_send_frame(&x11->output.wlr_output);
 	wl_event_source_timer_update(x11->frame_timer, 16);
 	return 0;
 }
@@ -259,6 +259,8 @@ static void wlr_x11_backend_destroy(struct wlr_backend *backend) {
 		xkb_state_unref(x11->keyboard_dev.keyboard->xkb_state);
 	}
 
+	wl_signal_emit(&backend->events.destroy, backend);
+
 	wl_list_remove(&x11->display_destroy.link);
 
 	wl_event_source_remove(x11->frame_timer);
@@ -392,22 +394,23 @@ static void output_destroy(struct wlr_output *wlr_output) {
 	// output has been allocated on the stack, do not free it
 }
 
-static void output_make_current(struct wlr_output *wlr_output) {
+static bool output_make_current(struct wlr_output *wlr_output, int *buffer_age) {
 	struct wlr_x11_output *output = (struct wlr_x11_output *)wlr_output;
 	struct wlr_x11_backend *x11 = output->x11;
 
-	if (!eglMakeCurrent(x11->egl.display, output->surf, output->surf, x11->egl.context)) {
+	return wlr_egl_make_current(&x11->egl, output->surf, buffer_age);
-		wlr_log(L_ERROR, "eglMakeCurrent failed: %s", egl_error());
-	}
 }
 
-static void output_swap_buffers(struct wlr_output *wlr_output) {
+static bool output_swap_buffers(struct wlr_output *wlr_output) {
 	struct wlr_x11_output *output = (struct wlr_x11_output *)wlr_output;
 	struct wlr_x11_backend *x11 = output->x11;
 
 	if (!eglSwapBuffers(x11->egl.display, output->surf)) {
 		wlr_log(L_ERROR, "eglSwapBuffers failed: %s", egl_error());
+		return false;
 	}
+
+	return true;
 }
 
 static struct wlr_output_impl output_impl = {

examples/multi-pointer.c

@@ -56,13 +56,13 @@ static void handle_output_frame(struct output_state *output,
 	struct sample_state *sample = state->data;
 	struct wlr_output *wlr_output = output->output;
 
-	wlr_output_make_current(wlr_output);
+	wlr_output_make_current(wlr_output, NULL);
 
 	glClearColor(sample->clear_color[0], sample->clear_color[1],
 		sample->clear_color[2], sample->clear_color[3]);
 	glClear(GL_COLOR_BUFFER_BIT);
 
-	wlr_output_swap_buffers(wlr_output);
+	wlr_output_swap_buffers(wlr_output, NULL, NULL);
 }
 
 static void handle_output_add(struct output_state *ostate) {

examples/output-layout.c

@@ -100,8 +100,9 @@ static void handle_output_frame(struct output_state *output,
 	struct sample_state *sample = state->data;
 	struct wlr_output *wlr_output = output->output;
 
-	wlr_output_make_current(wlr_output);
+	wlr_output_make_current(wlr_output, NULL);
 	wlr_renderer_begin(sample->renderer, wlr_output);
+	wlr_renderer_clear(sample->renderer, &(float[]){0.25f, 0.25f, 0.25f, 1});
 
 	animate_cat(sample, output->output);
 
@@ -125,7 +126,7 @@ static void handle_output_frame(struct output_state *output,
 	}
 
 	wlr_renderer_end(sample->renderer);
-	wlr_output_swap_buffers(wlr_output);
+	wlr_output_swap_buffers(wlr_output, NULL, NULL);
 }
 
 static void handle_output_add(struct output_state *ostate) {

examples/pointer.c

@@ -85,13 +85,13 @@ static void handle_output_frame(struct output_state *output,
 	struct sample_state *sample = state->data;
 	struct wlr_output *wlr_output = output->output;
 
-	wlr_output_make_current(wlr_output);
+	wlr_output_make_current(wlr_output, NULL);
 
 	glClearColor(sample->clear_color[0], sample->clear_color[1],
 		sample->clear_color[2], sample->clear_color[3]);
 	glClear(GL_COLOR_BUFFER_BIT);
 
-	wlr_output_swap_buffers(wlr_output);
+	wlr_output_swap_buffers(wlr_output, NULL, NULL);
 }
 
 static void handle_output_add(struct output_state *ostate) {

examples/rotation.c

@@ -42,8 +42,9 @@ static void handle_output_frame(struct output_state *output, struct timespec *ts
 	int32_t width, height;
 	wlr_output_effective_resolution(wlr_output, &width, &height);
 
-	wlr_output_make_current(wlr_output);
+	wlr_output_make_current(wlr_output, NULL);
 	wlr_renderer_begin(sample->renderer, wlr_output);
+	wlr_renderer_clear(sample->renderer, &(float[]){0.25f, 0.25f, 0.25f, 1});
 
 	float matrix[16];
 	for (int y = -128 + (int)odata->y_offs; y < height; y += 128) {
@@ -56,7 +57,7 @@ static void handle_output_frame(struct output_state *output, struct timespec *ts
 	}
 
 	wlr_renderer_end(sample->renderer);
-	wlr_output_swap_buffers(wlr_output);
+	wlr_output_swap_buffers(wlr_output, NULL, NULL);
 
 	long ms = (ts->tv_sec - output->last_frame.tv_sec) * 1000 +
 		(ts->tv_nsec - output->last_frame.tv_nsec) / 1000000;

examples/simple.c

@@ -35,12 +35,12 @@ void handle_output_frame(struct output_state *output, struct timespec *ts) {
 		sample->dec = inc;
 	}
 
-	wlr_output_make_current(output->output);
+	wlr_output_make_current(output->output, NULL);
 
 	glClearColor(sample->color[0], sample->color[1], sample->color[2], 1.0);
 	glClear(GL_COLOR_BUFFER_BIT);
 
-	wlr_output_swap_buffers(output->output);
+	wlr_output_swap_buffers(output->output, NULL, NULL);
 }
 
 int main() {

examples/tablet.c

@@ -42,8 +42,9 @@ static void handle_output_frame(struct output_state *output, struct timespec *ts
 	int32_t width, height;
 	wlr_output_effective_resolution(wlr_output, &width, &height);
 
-	wlr_output_make_current(wlr_output);
+	wlr_output_make_current(wlr_output, NULL);
 	wlr_renderer_begin(sample->renderer, wlr_output);
+	wlr_renderer_clear(sample->renderer, &(float[]){0.25f, 0.25f, 0.25f, 1});
 
 	float matrix[16], view[16];
 	float distance = 0.8f * (1 - sample->distance);
@@ -76,7 +77,7 @@ static void handle_output_frame(struct output_state *output, struct timespec *ts
 	}
 
 	wlr_renderer_end(sample->renderer);
-	wlr_output_swap_buffers(wlr_output);
+	wlr_output_swap_buffers(wlr_output, NULL, NULL);
 }
 
 static void handle_tool_axis(struct tablet_tool_state *tstate,

examples/touch.c

@@ -41,8 +41,9 @@ static void handle_output_frame(struct output_state *output, struct timespec *ts
 	int32_t width, height;
 	wlr_output_effective_resolution(wlr_output, &width, &height);
 
-	wlr_output_make_current(wlr_output);
+	wlr_output_make_current(wlr_output, NULL);
 	wlr_renderer_begin(sample->renderer, wlr_output);
+	wlr_renderer_clear(sample->renderer, &(float[]){0.25f, 0.25f, 0.25f, 1});
 
 	float matrix[16];
 	struct touch_point *p;
@@ -56,7 +57,7 @@ static void handle_output_frame(struct output_state *output, struct timespec *ts
 	}
 
 	wlr_renderer_end(sample->renderer);
-	wlr_output_swap_buffers(wlr_output);
+	wlr_output_swap_buffers(wlr_output, NULL, NULL);
 }
 
 static void handle_touch_down(struct touch_state *tstate, int32_t touch_id,

include/backend/drm/drm.h

@@ -123,8 +123,8 @@ struct wlr_drm_connector {
 
 	union wlr_drm_connector_props props;
 
-	uint32_t width;
+	uint32_t width, height;
-	uint32_t height;
+	int32_t cursor_x, cursor_y;
 
 	drmModeCrtc *old_crtc;
 

include/backend/drm/renderer.h

@@ -45,7 +45,7 @@ bool wlr_drm_plane_surfaces_init(struct wlr_drm_plane *plane, struct wlr_drm_bac
 		int32_t width, uint32_t height, uint32_t format);
 
 void wlr_drm_surface_finish(struct wlr_drm_surface *surf);
-void wlr_drm_surface_make_current(struct wlr_drm_surface *surf);
+bool wlr_drm_surface_make_current(struct wlr_drm_surface *surf, int *buffer_age);
 struct gbm_bo *wlr_drm_surface_swap_buffers(struct wlr_drm_surface *surf);
 struct gbm_bo *wlr_drm_surface_get_front(struct wlr_drm_surface *surf);
 void wlr_drm_surface_post(struct wlr_drm_surface *surf);

include/rootston/desktop.h

@@ -16,15 +16,7 @@
 #include <wlr/types/wlr_idle.h>
 #include "rootston/view.h"
 #include "rootston/config.h"
-
+#include "rootston/output.h"
-struct roots_output {
-	struct roots_desktop *desktop;
-	struct wlr_output *wlr_output;
-	struct wl_listener frame;
-	struct timespec last_frame;
-	struct wl_list link; // roots_desktop:outputs
-	struct roots_view *fullscreen_view;
-};
 
 struct roots_desktop {
 	struct wl_list views; // roots_view::link
@@ -64,7 +56,7 @@ struct roots_desktop {
 struct roots_server;
 
 struct roots_desktop *desktop_create(struct roots_server *server,
-		struct roots_config *config);
+	struct roots_config *config);
 void desktop_destroy(struct roots_desktop *desktop);
 struct roots_output *desktop_output_from_wlr_output(
 	struct roots_desktop *desktop, struct wlr_output *output);
@@ -72,11 +64,12 @@ struct roots_view *desktop_view_at(struct roots_desktop *desktop, double lx,
 	double ly, struct wlr_surface **surface, double *sx, double *sy);
 
 void view_init(struct roots_view *view, struct roots_desktop *desktop);
-void view_destroy(struct roots_view *view);
+void view_finish(struct roots_view *view);
 void view_activate(struct roots_view *view, bool activate);
-
+void view_apply_damage(struct roots_view *view);
-void output_add_notify(struct wl_listener *listener, void *data);
+void view_damage_whole(struct roots_view *view);
-void output_remove_notify(struct wl_listener *listener, void *data);
+void view_update_position(struct roots_view *view, double x, double y);
+void view_update_size(struct roots_view *view, uint32_t width, uint32_t height);
 
 void handle_xdg_shell_v6_surface(struct wl_listener *listener, void *data);
 void handle_wl_shell_surface(struct wl_listener *listener, void *data);

include/rootston/output.h

@@ -0,0 +1,50 @@
+#ifndef _ROOTSTON_OUTPUT_H
+#define _ROOTSTON_OUTPUT_H
+
+#include <time.h>
+#include <pixman.h>
+#include <wayland-server.h>
+
+/**
+ * Damage tracking requires to keep track of previous frames' damage. To allow
+ * damage tracking to work with triple buffering, a history of two frames is
+ * required.
+ */
+#define ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN 2
+
+struct roots_desktop;
+
+struct roots_output {
+	struct roots_desktop *desktop;
+	struct wlr_output *wlr_output;
+	struct wl_list link; // roots_desktop:outputs
+
+	struct roots_view *fullscreen_view;
+
+	struct timespec last_frame;
+	pixman_region32_t damage; // in ouput-local coordinates
+
+	// circular queue for previous damage
+	pixman_region32_t previous_damage[ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN];
+	size_t previous_damage_idx;
+
+	struct wl_listener frame;
+	struct wl_listener mode;
+	struct wl_listener needs_swap;
+};
+
+void output_add_notify(struct wl_listener *listener, void *data);
+void output_remove_notify(struct wl_listener *listener, void *data);
+
+struct roots_view;
+struct roots_drag_icon;
+
+void output_damage_whole(struct roots_output *output);
+void output_damage_whole_view(struct roots_output *output,
+	struct roots_view *view);
+void output_damage_from_view(struct roots_output *output,
+	struct roots_view *view);
+void output_damage_whole_drag_icon(struct roots_output *output,
+	struct roots_drag_icon *icon);
+
+#endif

include/rootston/seat.h

@@ -17,12 +17,15 @@ struct roots_seat {
 	struct wl_list views; // roots_seat_view::link
 	bool has_focus;
 
+	struct wl_list drag_icons; // roots_drag_icon::link
+
 	struct wl_list keyboards;
 	struct wl_list pointers;
 	struct wl_list touch;
 	struct wl_list tablet_tools;
 
-	struct wl_listener seat_destroy;
+	struct wl_listener new_drag_icon;
+	struct wl_listener destroy;
 };
 
 struct roots_seat_view {
@@ -38,6 +41,18 @@ struct roots_seat_view {
 	struct wl_listener view_destroy;
 };
 
+struct roots_drag_icon {
+	struct roots_seat *seat;
+	struct wlr_drag_icon *wlr_drag_icon;
+	struct wl_list link;
+
+	double x, y;
+
+	struct wl_listener surface_commit;
+	struct wl_listener map;
+	struct wl_listener destroy;
+};
+
 struct roots_pointer {
 	struct roots_seat *seat;
 	struct wlr_input_device *device;
@@ -92,6 +107,10 @@ void roots_seat_begin_rotate(struct roots_seat *seat, struct roots_view *view);
 void roots_seat_end_compositor_grab(struct roots_seat *seat);
 
 struct roots_seat_view *roots_seat_view_from_view( struct roots_seat *seat,
-		struct roots_view *view);
+	struct roots_view *view);
+
+void roots_drag_icon_update_position(struct roots_drag_icon *icon);
+
+void roots_drag_icon_damage_whole(struct roots_drag_icon *icon);
 
 #endif

include/rootston/view.h

@@ -11,6 +11,7 @@ struct roots_wl_shell_surface {
 	struct roots_view *view;
 
 	struct wl_listener destroy;
+	struct wl_listener new_popup;
 	struct wl_listener request_move;
 	struct wl_listener request_resize;
 	struct wl_listener request_maximize;
@@ -23,13 +24,15 @@ struct roots_wl_shell_surface {
 struct roots_xdg_surface_v6 {
 	struct roots_view *view;
 
-	struct wl_listener commit;
 	struct wl_listener destroy;
+	struct wl_listener new_popup;
 	struct wl_listener request_move;
 	struct wl_listener request_resize;
 	struct wl_listener request_maximize;
 	struct wl_listener request_fullscreen;
 
+	struct wl_listener surface_commit;
+
 	uint32_t pending_move_resize_configure_serial;
 };
 
@@ -61,6 +64,7 @@ struct roots_view {
 	struct wl_list link; // roots_desktop::views
 
 	double x, y;
+	uint32_t width, height;
 	float rotation;
 
 	bool decorated;
@@ -97,17 +101,17 @@ struct roots_view {
 		struct roots_xwayland_surface *roots_xwayland_surface;
 #endif
 	};
+
 	struct wlr_surface *wlr_surface;
+	struct wl_list children; // roots_view_child::link
+
+	struct wl_listener new_subsurface;
 
 	struct {
 		struct wl_signal destroy;
 	} events;
 
-	// TODO: This would probably be better as a field that's updated on a
+	// TODO: this should follow the typical type/impl pattern we use elsewhere
-	// configure event from the xdg_shell
-	// If not then this should follow the typical type/impl pattern we use
-	// elsewhere
-	void (*get_size)(const struct roots_view *view, struct wlr_box *box);
 	void (*activate)(struct roots_view *view, bool active);
 	void (*move)(struct roots_view *view, double x, double y);
 	void (*resize)(struct roots_view *view, uint32_t width, uint32_t height);
@@ -118,6 +122,38 @@ struct roots_view {
 	void (*close)(struct roots_view *view);
 };
 
+struct roots_view_child {
+	struct roots_view *view;
+	struct wlr_surface *wlr_surface;
+	struct wl_list link;
+
+	struct wl_listener commit;
+	struct wl_listener new_subsurface;
+
+	void (*destroy)(struct roots_view_child *child);
+};
+
+struct roots_subsurface {
+	struct roots_view_child view_child;
+	struct wlr_subsurface *wlr_subsurface;
+	struct wl_listener destroy;
+};
+
+struct roots_wl_shell_popup {
+	struct roots_view_child view_child;
+	struct wlr_wl_shell_surface *wlr_wl_shell_surface;
+	struct wl_listener destroy;
+	struct wl_listener set_state;
+	struct wl_listener new_popup;
+};
+
+struct roots_xdg_popup_v6 {
+	struct roots_view_child view_child;
+	struct wlr_xdg_popup_v6 *wlr_popup;
+	struct wl_listener destroy;
+	struct wl_listener new_popup;
+};
+
 void view_get_box(const struct roots_view *view, struct wlr_box *box);
 void view_activate(struct roots_view *view, bool active);
 void view_move(struct roots_view *view, double x, double y);
@@ -127,6 +163,7 @@ void view_move_resize(struct roots_view *view, double x, double y,
 void view_maximize(struct roots_view *view, bool maximized);
 void view_set_fullscreen(struct roots_view *view, bool fullscreen,
 	struct wlr_output *output);
+void view_rotate(struct roots_view *view, float rotation);
 void view_close(struct roots_view *view);
 bool view_center(struct roots_view *view);
 void view_setup(struct roots_view *view);
@@ -145,4 +182,11 @@ enum roots_deco_part {
 
 enum roots_deco_part view_get_deco_part(struct roots_view *view, double sx, double sy);
 
+void view_child_init(struct roots_view_child *child, struct roots_view *view,
+	struct wlr_surface *wlr_surface);
+void view_child_finish(struct roots_view_child *child);
+
+struct roots_subsurface *subsurface_create(struct roots_view *view,
+	struct wlr_subsurface *wlr_subsurface);
+
 #endif

include/wlr/interfaces/wlr_output.h

@@ -18,8 +18,8 @@ struct wlr_output_impl {
 		int32_t hotspot_x, int32_t hotspot_y, bool update_pixels);
 	bool (*move_cursor)(struct wlr_output *output, int x, int y);
 	void (*destroy)(struct wlr_output *output);
-	void (*make_current)(struct wlr_output *output);
+	bool (*make_current)(struct wlr_output *output, int *buffer_age);
-	void (*swap_buffers)(struct wlr_output *output);
+	bool (*swap_buffers)(struct wlr_output *output);
 	void (*set_gamma)(struct wlr_output *output,
 		uint32_t size, uint16_t *r, uint16_t *g, uint16_t *b);
 	uint32_t (*get_gamma_size)(struct wlr_output *output);
@@ -32,5 +32,7 @@ void wlr_output_update_mode(struct wlr_output *output,
 void wlr_output_update_custom_mode(struct wlr_output *output, int32_t width,
 	int32_t height, int32_t refresh);
 void wlr_output_update_enabled(struct wlr_output *output, bool enabled);
+void wlr_output_update_needs_swap(struct wlr_output *output);
+void wlr_output_send_frame(struct wlr_output *output);
 
 #endif

include/wlr/render.h

@@ -5,6 +5,7 @@
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 #include <wayland-server-protocol.h>
+#include <wlr/types/wlr_box.h>
 #include <wlr/types/wlr_output.h>
 
 struct wlr_texture;
@@ -12,6 +13,13 @@ struct wlr_renderer;
 
 void wlr_renderer_begin(struct wlr_renderer *r, struct wlr_output *output);
 void wlr_renderer_end(struct wlr_renderer *r);
+void wlr_renderer_clear(struct wlr_renderer *r, const float (*color)[4]);
+/**
+ * Defines a scissor box. Only pixels that lie within the scissor box can be
+ * modified by drawing functions. Providing a NULL `box` disables the scissor
+ * box.
+ */
+void wlr_renderer_scissor(struct wlr_renderer *r, struct wlr_box *box);
 /**
  * Requests a texture handle from this renderer.
  */

include/wlr/render/egl.h

@@ -11,8 +11,12 @@ struct wlr_egl {
 	EGLConfig config;
 	EGLContext context;
 
-	const char *egl_exts;
+	const char *egl_exts_str;
-	const char *gl_exts;
+	const char *gl_exts_str;
+
+	struct {
+		bool buffer_age;
+	} egl_exts;
 
 	struct wl_display *wl_display;
 };
@@ -65,4 +69,7 @@ bool wlr_egl_destroy_image(struct wlr_egl *egl, EGLImageKHR image);
  */
 const char *egl_error(void);
 
+bool wlr_egl_make_current(struct wlr_egl *egl, EGLSurface surface,
+	int *buffer_age);
+
 #endif

include/wlr/render/interface.h

@@ -6,6 +6,7 @@
 #include <EGL/eglext.h>
 #include <stdbool.h>
 #include <wlr/render.h>
+#include <wlr/types/wlr_box.h>
 #include <wlr/types/wlr_output.h>
 
 struct wlr_renderer_impl;
@@ -17,6 +18,8 @@ struct wlr_renderer {
 struct wlr_renderer_impl {
 	void (*begin)(struct wlr_renderer *renderer, struct wlr_output *output);
 	void (*end)(struct wlr_renderer *renderer);
+	void (*clear)(struct wlr_renderer *renderer, const float (*color)[4]);
+	void (*scissor)(struct wlr_renderer *renderer, struct wlr_box *box);
 	struct wlr_texture *(*texture_create)(struct wlr_renderer *renderer);
 	bool (*render_with_matrix)(struct wlr_renderer *renderer,
 		struct wlr_texture *texture, const float (*matrix)[16]);

include/wlr/types/wlr_box.h

@@ -2,6 +2,7 @@
 #define WLR_TYPES_WLR_BOX_H
 
 #include <stdbool.h>
+#include <wayland-server.h>
 
 struct wlr_box {
 	int x, y;
@@ -18,8 +19,17 @@ bool wlr_box_contains_point(const struct wlr_box *box, double x, double y);
 
 bool wlr_box_empty(const struct wlr_box *box);
 
-enum wl_output_transform;
+/**
+ * Transforms a box inside a `width` x `height` box.
+ */
 void wlr_box_transform(const struct wlr_box *box,
-	enum wl_output_transform transform, struct wlr_box *dest);
+	enum wl_output_transform transform, int width, int height,
+	struct wlr_box *dest);
+
+/**
+ * Creates the smallest box that contains a rotated box.
+ */
+void wlr_box_rotated_bounds(const struct wlr_box *box, float rotation,
+	struct wlr_box *dest);
 
 #endif

include/wlr/types/wlr_compositor.h

@@ -13,7 +13,7 @@ struct wlr_compositor {
 	struct wl_listener display_destroy;
 
 	struct {
-		struct wl_signal create_surface;
+		struct wl_signal new_surface;
 	} events;
 };
 

include/wlr/types/wlr_data_device.h

@@ -71,10 +71,10 @@ struct wlr_drag_icon {
 	bool is_pointer;
 	int32_t touch_id;
 
-	int32_t sx;
+	int32_t sx, sy;
-	int32_t sy;
 
 	struct {
+		struct wl_signal map; // emitted when mapped or unmapped
 		struct wl_signal destroy;
 	} events;
 

include/wlr/types/wlr_output.h

@@ -2,6 +2,8 @@
 #define WLR_TYPES_WLR_OUTPUT_H
 
 #include <stdbool.h>
+#include <time.h>
+#include <pixman.h>
 #include <wayland-util.h>
 #include <wayland-server.h>
 
@@ -22,7 +24,6 @@ struct wlr_output_cursor {
 	struct wl_list link;
 
 	// only when using a software cursor without a surface
-	struct wlr_renderer *renderer;
 	struct wlr_texture *texture;
 
 	// only when using a cursor surface
@@ -51,22 +52,26 @@ struct wlr_output {
 	char serial[16];
 	int32_t phys_width, phys_height; // mm
 
+	// Note: some backends may have zero modes
+	struct wl_list modes;
+	struct wlr_output_mode *current_mode;
+	int32_t width, height;
+	int32_t refresh; // mHz, may be zero
+
 	bool enabled;
 	float scale;
 	enum wl_output_subpixel subpixel;
 	enum wl_output_transform transform;
-	bool needs_swap;
 
+	bool needs_swap;
+	// damage for cursors and fullscreen surface, in output-local coordinates
+	pixman_region32_t damage;
+	bool frame_pending;
 	float transform_matrix[16];
 
-	// Note: some backends may have zero modes
-	struct wl_list modes;
-	struct wlr_output_mode *current_mode;
-	int32_t width, height;
-	int32_t refresh; // mHz
-
 	struct {
 		struct wl_signal frame;
+		struct wl_signal needs_swap;
 		struct wl_signal swap_buffers;
 		struct wl_signal enable;
 		struct wl_signal mode;
@@ -75,9 +80,12 @@ struct wlr_output {
 		struct wl_signal destroy;
 	} events;
 
+	struct wl_event_source *idle_frame;
+
 	struct wlr_surface *fullscreen_surface;
 	struct wl_listener fullscreen_surface_commit;
 	struct wl_listener fullscreen_surface_destroy;
+	int fullscreen_width, fullscreen_height;
 
 	struct wl_list cursors; // wlr_output_cursor::link
 	struct wlr_output_cursor *hardware_cursor;
@@ -104,16 +112,44 @@ void wlr_output_set_transform(struct wlr_output *output,
 void wlr_output_set_position(struct wlr_output *output, int32_t lx, int32_t ly);
 void wlr_output_set_scale(struct wlr_output *output, float scale);
 void wlr_output_destroy(struct wlr_output *output);
+/**
+ * Computes the transformed output resolution.
+ */
+void wlr_output_transformed_resolution(struct wlr_output *output,
+	int *width, int *height);
+/**
+ * Computes the transformed and scaled output resolution.
+ */
 void wlr_output_effective_resolution(struct wlr_output *output,
 	int *width, int *height);
-void wlr_output_make_current(struct wlr_output *output);
+/**
-void wlr_output_swap_buffers(struct wlr_output *output);
+ * Makes the output rendering context current.
+ *
+ * `buffer_age` is set to the drawing buffer age in number of frames or -1 if
+ * unknown. This is useful for damage tracking.
+ */
+bool wlr_output_make_current(struct wlr_output *output, int *buffer_age);
+/**
+ * Swaps the output buffers. If the time of the frame isn't known, set `when` to
+ * NULL. If the compositor doesn't support damage tracking, set `damage` to
+ * NULL.
+ *
+ * Swapping buffers schedules a `frame` event.
+ */
+bool wlr_output_swap_buffers(struct wlr_output *output, struct timespec *when,
+	pixman_region32_t *damage);
+/**
+ * Manually schedules a `frame` event. If a `frame` event is already pending,
+ * it is a no-op.
+ */
+void wlr_output_schedule_frame(struct wlr_output *output);
 void wlr_output_set_gamma(struct wlr_output *output,
 	uint32_t size, uint16_t *r, uint16_t *g, uint16_t *b);
 uint32_t wlr_output_get_gamma_size(struct wlr_output *output);
 void wlr_output_set_fullscreen_surface(struct wlr_output *output,
 	struct wlr_surface *surface);
 
+
 struct wlr_output_cursor *wlr_output_cursor_create(struct wlr_output *output);
 /**
  * Sets the cursor image. The image must be already scaled for the output.

include/wlr/types/wlr_seat.h

@@ -209,6 +209,8 @@ struct wlr_seat {
 		struct wl_signal selection;
 		struct wl_signal primary_selection;
 
+		struct wl_signal new_drag_icon;
+
 		struct wl_signal destroy;
 	} events;
 

include/wlr/types/wlr_surface.h

@@ -56,6 +56,10 @@ struct wlr_subsurface {
 	struct wl_list parent_pending_link;
 
 	struct wl_listener parent_destroy_listener;
+
+	struct {
+		struct wl_signal destroy;
+	} events;
 };
 
 struct wlr_surface {
@@ -70,6 +74,7 @@ struct wlr_surface {
 
 	struct {
 		struct wl_signal commit;
+		struct wl_signal new_subsurface;
 		struct wl_signal destroy;
 	} events;
 

include/wlr/types/wlr_wl_shell.h

@@ -79,6 +79,7 @@ struct wlr_wl_shell_surface {
 	struct {
 		struct wl_signal destroy;
 		struct wl_signal ping_timeout;
+		struct wl_signal new_popup;
 
 		struct wl_signal request_move;
 		struct wl_signal request_resize;

include/wlr/types/wlr_xdg_shell_v6.h

@@ -34,6 +34,7 @@ struct wlr_xdg_client_v6 {
 
 struct wlr_xdg_popup_v6 {
 	struct wlr_xdg_surface_v6 *base;
+	struct wl_list link;
 
 	struct wl_resource *resource;
 	bool committed;
@@ -104,8 +105,7 @@ struct wlr_xdg_surface_v6 {
 		struct wlr_xdg_popup_v6 *popup_state;
 	};
 
-	struct wl_list popups;
+	struct wl_list popups; // wlr_xdg_popup_v6::link
-	struct wl_list popup_link;
 
 	bool configured;
 	bool added;
@@ -126,6 +126,7 @@ struct wlr_xdg_surface_v6 {
 	struct {
 		struct wl_signal destroy;
 		struct wl_signal ping_timeout;
+		struct wl_signal new_popup;
 
 		struct wl_signal request_maximize;
 		struct wl_signal request_fullscreen;

include/wlr/util/region.h

@@ -0,0 +1,29 @@
+#ifndef WLR_UTIL_REGION_H
+#define WLR_UTIL_REGION_H
+
+#include <pixman.h>
+#include <wayland-server.h>
+
+/**
+ * Scales a region, ie. multiplies all its coordinates by `scale`.
+ *
+ * The resulting coordinates are rounded up or down so that the new region is
+ * at least as big as the original one.
+ */
+void wlr_region_scale(pixman_region32_t *dst, pixman_region32_t *src,
+	float scale);
+
+/**
+ * Applies a transform to a region inside a box of size `width` x `height`.
+ */
+void wlr_region_transform(pixman_region32_t *dst, pixman_region32_t *src,
+	enum wl_output_transform transform, int width, int height);
+
+/**
+ * Expands the region of `distance`. If `distance` is negative, it shrinks the
+ * region.
+ */
+void wlr_region_expand(pixman_region32_t *dst, pixman_region32_t *src,
+	int distance);
+
+#endif

render/egl.c

@@ -127,18 +127,23 @@ bool wlr_egl_init(struct wlr_egl *egl, EGLenum platform, void *remote_display,
 	}
 
 	eglMakeCurrent(egl->display, EGL_NO_SURFACE, EGL_NO_SURFACE, egl->context);
-	egl->egl_exts = eglQueryString(egl->display, EGL_EXTENSIONS);
+	egl->egl_exts_str = eglQueryString(egl->display, EGL_EXTENSIONS);
-	if (strstr(egl->egl_exts, "EGL_WL_bind_wayland_display") == NULL ||
+	egl->gl_exts_str = (const char*) glGetString(GL_EXTENSIONS);
-			strstr(egl->egl_exts, "EGL_KHR_image_base") == NULL) {
+
+	wlr_log(L_INFO, "Using EGL %d.%d", (int)major, (int)minor);
+	wlr_log(L_INFO, "Supported EGL extensions: %s", egl->egl_exts_str);
+	wlr_log(L_INFO, "Using %s", glGetString(GL_VERSION));
+	wlr_log(L_INFO, "Supported OpenGL ES extensions: %s", egl->gl_exts_str);
+
+	if (strstr(egl->egl_exts_str, "EGL_WL_bind_wayland_display") == NULL ||
+			strstr(egl->egl_exts_str, "EGL_KHR_image_base") == NULL) {
 		wlr_log(L_ERROR, "Required egl extensions not supported");
 		goto error;
 	}
 
-	egl->gl_exts = (const char*) glGetString(GL_EXTENSIONS);
+	egl->egl_exts.buffer_age =
-	wlr_log(L_INFO, "Using EGL %d.%d", (int)major, (int)minor);
+		strstr(egl->egl_exts_str, "EGL_EXT_buffer_age") != NULL;
-	wlr_log(L_INFO, "Supported EGL extensions: %s", egl->egl_exts);
+
-	wlr_log(L_INFO, "Using %s", glGetString(GL_VERSION));
-	wlr_log(L_INFO, "Supported OpenGL ES extensions: %s", egl->gl_exts);
 	return true;
 
 error:
@@ -208,3 +213,32 @@ EGLSurface wlr_egl_create_surface(struct wlr_egl *egl, void *window) {
 	}
 	return surf;
 }
+
+int wlr_egl_get_buffer_age(struct wlr_egl *egl, EGLSurface surface) {
+	if (!egl->egl_exts.buffer_age) {
+		return -1;
+	}
+
+	EGLint buffer_age;
+	EGLBoolean ok = eglQuerySurface(egl->display, surface,
+		EGL_BUFFER_AGE_EXT, &buffer_age);
+	if (!ok) {
+		wlr_log(L_ERROR, "Failed to get EGL surface buffer age: %s", egl_error());
+		return -1;
+	}
+
+	return buffer_age;
+}
+
+bool wlr_egl_make_current(struct wlr_egl *egl, EGLSurface surface,
+		int *buffer_age) {
+	if (!eglMakeCurrent(egl->display, surface, surface, egl->context)) {
+		wlr_log(L_ERROR, "eglMakeCurrent failed: %s", egl_error());
+		return false;
+	}
+
+	if (buffer_age != NULL) {
+		*buffer_age = wlr_egl_get_buffer_age(egl, surface);
+	}
+	return true;
+}

render/gles2/renderer.c

@@ -105,14 +105,9 @@ static void init_globals() {
 	init_default_shaders();
 }
 
-static void wlr_gles2_begin(struct wlr_renderer *_renderer,
+static void wlr_gles2_begin(struct wlr_renderer *wlr_renderer,
 		struct wlr_output *output) {
-	// TODO: let users customize the clear color?
+	GL_CALL(glViewport(0, 0, output->width, output->height));
-	GL_CALL(glClearColor(0.25f, 0.25f, 0.25f, 1));
-	GL_CALL(glClear(GL_COLOR_BUFFER_BIT));
-	int32_t width = output->width;
-	int32_t height = output->height;
-	GL_CALL(glViewport(0, 0, width, height));
 
 	// enable transparency
 	GL_CALL(glEnable(GL_BLEND));
@@ -122,14 +117,30 @@ static void wlr_gles2_begin(struct wlr_renderer *_renderer,
 	// for users to sling matricies themselves
 }
 
-static void wlr_gles2_end(struct wlr_renderer *renderer) {
+static void wlr_gles2_end(struct wlr_renderer *wlr_renderer) {
 	// no-op
 }
 
+static void wlr_gles2_clear(struct wlr_renderer *wlr_renderer,
+		const float (*color)[4]) {
+	glClearColor((*color)[0], (*color)[1], (*color)[2], (*color)[3]);
+	glClear(GL_COLOR_BUFFER_BIT);
+}
+
+static void wlr_gles2_scissor(struct wlr_renderer *wlr_renderer,
+		struct wlr_box *box) {
+	if (box != NULL) {
+		glScissor(box->x, box->y, box->width, box->height);
+		glEnable(GL_SCISSOR_TEST);
+	} else {
+		glDisable(GL_SCISSOR_TEST);
+	}
+}
+
 static struct wlr_texture *wlr_gles2_texture_create(
-		struct wlr_renderer *_renderer) {
+		struct wlr_renderer *wlr_renderer) {
 	struct wlr_gles2_renderer *renderer =
-		(struct wlr_gles2_renderer *)_renderer;
+		(struct wlr_gles2_renderer *)wlr_renderer;
 	return gles2_texture_create(renderer->egl);
 }
 
@@ -159,7 +170,7 @@ static void draw_quad() {
 	GL_CALL(glDisableVertexAttribArray(1));
 }
 
-static bool wlr_gles2_render_texture(struct wlr_renderer *_renderer,
+static bool wlr_gles2_render_texture(struct wlr_renderer *wlr_renderer,
 		struct wlr_texture *texture, const float (*matrix)[16]) {
 	if (!texture || !texture->valid) {
 		wlr_log(L_ERROR, "attempt to render invalid texture");
@@ -174,7 +185,7 @@ static bool wlr_gles2_render_texture(struct wlr_renderer *_renderer,
 	return true;
 }
 
-static void wlr_gles2_render_quad(struct wlr_renderer *renderer,
+static void wlr_gles2_render_quad(struct wlr_renderer *wlr_renderer,
 		const float (*color)[4], const float (*matrix)[16]) {
 	GL_CALL(glUseProgram(shaders.quad));
 	GL_CALL(glUniformMatrix4fv(0, 1, GL_FALSE, *matrix));
@@ -182,7 +193,7 @@ static void wlr_gles2_render_quad(struct wlr_renderer *renderer,
 	draw_quad();
 }
 
-static void wlr_gles2_render_ellipse(struct wlr_renderer *renderer,
+static void wlr_gles2_render_ellipse(struct wlr_renderer *wlr_renderer,
 		const float (*color)[4], const float (*matrix)[16]) {
 	GL_CALL(glUseProgram(shaders.ellipse));
 	GL_CALL(glUniformMatrix4fv(0, 1, GL_TRUE, *matrix));
@@ -202,10 +213,10 @@ static const enum wl_shm_format *wlr_gles2_formats(
 	return formats;
 }
 
-static bool wlr_gles2_buffer_is_drm(struct wlr_renderer *_renderer,
+static bool wlr_gles2_buffer_is_drm(struct wlr_renderer *wlr_renderer,
 		struct wl_resource *buffer) {
 	struct wlr_gles2_renderer *renderer =
-		(struct wlr_gles2_renderer *)_renderer;
+		(struct wlr_gles2_renderer *)wlr_renderer;
 	EGLint format;
 	return wlr_egl_query_buffer(renderer->egl, buffer,
 		EGL_TEXTURE_FORMAT, &format);
@@ -243,6 +254,8 @@ static bool wlr_gles2_format_supported(struct wlr_renderer *r,
 static struct wlr_renderer_impl wlr_renderer_impl = {
 	.begin = wlr_gles2_begin,
 	.end = wlr_gles2_end,
+	.clear = wlr_gles2_clear,
+	.scissor = wlr_gles2_scissor,
 	.texture_create = wlr_gles2_texture_create,
 	.render_with_matrix = wlr_gles2_render_texture,
 	.render_quad = wlr_gles2_render_quad,

render/matrix.c

@@ -169,22 +169,26 @@ void wlr_matrix_project_box(float (*mat)[16], struct wlr_box *box,
 	int width = box->width;
 	int height = box->height;
 
-	float translate_center[16];
+	wlr_matrix_translate(mat, x, y, 0);
-	wlr_matrix_translate(&translate_center,
-			(int)x + width / 2, (int)y + height / 2, 0);
 
-	float rotate[16];
+	if (rotation != 0) {
-	wlr_matrix_rotate(&rotate, rotation);
+		float translate_center[16];
+		wlr_matrix_translate(&translate_center, width/2, height/2, 0);
 
-	float translate_origin[16];
+		float rotate[16];
-	wlr_matrix_translate(&translate_origin, -width / 2,
+		wlr_matrix_rotate(&rotate, rotation);
-			-height / 2, 0);
+
+		float translate_origin[16];
+		wlr_matrix_translate(&translate_origin, -width/2, -height/2, 0);
+
+		wlr_matrix_mul(mat, &translate_center, mat);
+		wlr_matrix_mul(mat, &rotate, mat);
+		wlr_matrix_mul(mat, &translate_origin, mat);
+	}
 
 	float scale[16];
 	wlr_matrix_scale(&scale, width, height, 1);
 
-	wlr_matrix_mul(&translate_center, &rotate, mat);
-	wlr_matrix_mul(mat, &translate_origin, mat);
 	wlr_matrix_mul(mat, &scale, mat);
 
 	if (transform != WL_OUTPUT_TRANSFORM_NORMAL) {
@@ -192,17 +196,14 @@ void wlr_matrix_project_box(float (*mat)[16], struct wlr_box *box,
 		wlr_matrix_translate(&surface_translate_center, 0.5, 0.5, 0);
 
 		float surface_transform[16];
-		wlr_matrix_transform(surface_transform,
+		wlr_matrix_transform(surface_transform, transform);
-				wlr_output_transform_invert(transform));
 
 		float surface_translate_origin[16];
 		wlr_matrix_translate(&surface_translate_origin, -0.5, -0.5, 0);
 
-		wlr_matrix_mul(mat, &surface_translate_center,
+		wlr_matrix_mul(mat, &surface_translate_center, mat);
-				mat);
 		wlr_matrix_mul(mat, &surface_transform, mat);
-		wlr_matrix_mul(mat, &surface_translate_origin,
+		wlr_matrix_mul(mat, &surface_translate_origin, mat);
-			mat);
 	}
 
 	wlr_matrix_mul(projection, mat, mat);

render/meson.build

@@ -22,7 +22,7 @@ lib_wlr_render = static_library(
 	glapi[0],
 	glapi[1],
 	include_directories: wlr_inc,
-	dependencies: [glesv2, egl],
+	dependencies: [glesv2, egl, pixman],
 )
 
 wlr_render = declare_dependency(

render/wlr_renderer.c

@@ -23,6 +23,14 @@ void wlr_renderer_end(struct wlr_renderer *r) {
 	r->impl->end(r);
 }
 
+void wlr_renderer_clear(struct wlr_renderer *r, const float (*color)[4]) {
+	r->impl->clear(r, color);
+}
+
+void wlr_renderer_scissor(struct wlr_renderer *r, struct wlr_box *box) {
+	r->impl->scissor(r, box);
+}
+
 struct wlr_texture *wlr_render_texture_create(struct wlr_renderer *r) {
 	return r->impl->texture_create(r);
 }

rootston/cursor.c

@@ -138,6 +138,11 @@ static void roots_cursor_update_position(struct roots_cursor *cursor,
 		} else {
 			wlr_seat_pointer_clear_focus(seat->seat);
 		}
+
+		struct roots_drag_icon *drag_icon;
+		wl_list_for_each(drag_icon, &seat->drag_icons, link) {
+			roots_drag_icon_update_position(drag_icon);
+		}
 		break;
 	case ROOTS_CURSOR_MOVE:
 		view = roots_seat_get_focus(seat);
@@ -198,7 +203,7 @@ static void roots_cursor_update_position(struct roots_cursor *cursor,
 			float angle = atan2(vx*uy - vy*ux, vx*ux + vy*uy);
 			int steps = 12;
 			angle = round(angle/M_PI*steps) / (steps/M_PI);
-			view->rotation = cursor->view_rotation + angle;
+			view_rotate(view, cursor->view_rotation + angle);
 		}
 		break;
 	}

rootston/desktop.c

@@ -24,12 +24,8 @@
 void view_get_box(const struct roots_view *view, struct wlr_box *box) {
 	box->x = view->x;
 	box->y = view->y;
-	if (view->get_size) {
+	box->width = view->width;
-		view->get_size(view, box);
+	box->height = view->height;
-	} else {
-		box->width = view->wlr_surface->current->width;
-		box->height = view->wlr_surface->current->height;
-	}
 }
 
 void view_get_deco_box(const struct roots_view *view, struct wlr_box *box) {
@@ -111,8 +107,7 @@ void view_move(struct roots_view *view, double x, double y) {
 	if (view->move) {
 		view->move(view, x, y);
 	} else {
-		view->x = x;
+		view_update_position(view, x, y);
-		view->y = y;
 	}
 	view_update_output(view, &before);
 }
@@ -195,7 +190,7 @@ void view_maximize(struct roots_view *view, bool maximized) {
 
 		view_move_resize(view, output_box->x, output_box->y, output_box->width,
 			output_box->height);
-		view->rotation = 0;
+		view_rotate(view, 0);
 	}
 
 	if (view->maximized && !maximized) {
@@ -203,7 +198,7 @@ void view_maximize(struct roots_view *view, bool maximized) {
 
 		view_move_resize(view, view->saved.x, view->saved.y, view->saved.width,
 			view->saved.height);
-		view->rotation = view->saved.rotation;
+		view_rotate(view, view->saved.rotation);
 	}
 }
 
@@ -244,22 +239,34 @@ void view_set_fullscreen(struct roots_view *view, bool fullscreen,
 			wlr_output_layout_get_box(view->desktop->layout, output);
 		view_move_resize(view, output_box->x, output_box->y, output_box->width,
 			output_box->height);
-		view->rotation = 0;
+		view_rotate(view, 0);
 
 		roots_output->fullscreen_view = view;
 		view->fullscreen_output = roots_output;
+		output_damage_whole(roots_output);
 	}
 
 	if (was_fullscreen && !fullscreen) {
 		view_move_resize(view, view->saved.x, view->saved.y, view->saved.width,
 			view->saved.height);
-		view->rotation = view->saved.rotation;
+		view_rotate(view, view->saved.rotation);
 
+		output_damage_whole(view->fullscreen_output);
 		view->fullscreen_output->fullscreen_view = NULL;
 		view->fullscreen_output = NULL;
 	}
 }
 
+void view_rotate(struct roots_view *view, float rotation) {
+	if (view->rotation == rotation) {
+		return;
+	}
+
+	view_damage_whole(view);
+	view->rotation = rotation;
+	view_damage_whole(view);
+}
+
 void view_close(struct roots_view *view) {
 	if (view->close) {
 		view->close(view);
@@ -305,19 +312,116 @@ bool view_center(struct roots_view *view) {
 	return true;
 }
 
-void view_destroy(struct roots_view *view) {
+void view_child_finish(struct roots_view_child *child) {
+	if (child == NULL) {
+		return;
+	}
+	view_damage_whole(child->view);
+	wl_list_remove(&child->link);
+	wl_list_remove(&child->commit.link);
+	wl_list_remove(&child->new_subsurface.link);
+}
+
+static void view_child_handle_commit(struct wl_listener *listener,
+		void *data) {
+	struct roots_view_child *child = wl_container_of(listener, child, commit);
+	view_apply_damage(child->view);
+}
+
+static void view_child_handle_new_subsurface(struct wl_listener *listener,
+		void *data) {
+	struct roots_view_child *child =
+		wl_container_of(listener, child, new_subsurface);
+	struct wlr_subsurface *wlr_subsurface = data;
+	subsurface_create(child->view, wlr_subsurface);
+}
+
+void view_child_init(struct roots_view_child *child, struct roots_view *view,
+		struct wlr_surface *wlr_surface) {
+	assert(child->destroy);
+	child->view = view;
+	child->wlr_surface = wlr_surface;
+	child->commit.notify = view_child_handle_commit;
+	wl_signal_add(&wlr_surface->events.commit, &child->commit);
+	child->new_subsurface.notify = view_child_handle_new_subsurface;
+	wl_signal_add(&wlr_surface->events.new_subsurface, &child->new_subsurface);
+	wl_list_insert(&view->children, &child->link);
+}
+
+static void subsurface_destroy(struct roots_view_child *child) {
+	assert(child->destroy == subsurface_destroy);
+	struct roots_subsurface *subsurface = (struct roots_subsurface *)child;
+	if (subsurface == NULL) {
+		return;
+	}
+	wl_list_remove(&subsurface->destroy.link);
+	view_child_finish(&subsurface->view_child);
+	free(subsurface);
+}
+
+static void subsurface_handle_destroy(struct wl_listener *listener,
+		void *data) {
+	struct roots_subsurface *subsurface =
+		wl_container_of(listener, subsurface, destroy);
+	subsurface_destroy((struct roots_view_child *)subsurface);
+}
+
+struct roots_subsurface *subsurface_create(struct roots_view *view,
+		struct wlr_subsurface *wlr_subsurface) {
+	struct roots_subsurface *subsurface =
+		calloc(1, sizeof(struct roots_subsurface));
+	if (subsurface == NULL) {
+		return NULL;
+	}
+	subsurface->wlr_subsurface = wlr_subsurface;
+	subsurface->view_child.destroy = subsurface_destroy;
+	view_child_init(&subsurface->view_child, view, wlr_subsurface->surface);
+	subsurface->destroy.notify = subsurface_handle_destroy;
+	wl_signal_add(&wlr_subsurface->events.destroy, &subsurface->destroy);
+	return subsurface;
+}
+
+void view_finish(struct roots_view *view) {
+	view_damage_whole(view);
 	wl_signal_emit(&view->events.destroy, view);
 
+	wl_list_remove(&view->new_subsurface.link);
+
+	struct roots_view_child *child, *tmp;
+	wl_list_for_each_safe(child, tmp, &view->children, link) {
+		child->destroy(child);
+	}
+
 	if (view->fullscreen_output) {
 		view->fullscreen_output->fullscreen_view = NULL;
 	}
+}
 
-	free(view);
+static void view_handle_new_subsurface(struct wl_listener *listener,
+		void *data) {
+	struct roots_view *view = wl_container_of(listener, view, new_subsurface);
+	struct wlr_subsurface *wlr_subsurface = data;
+	subsurface_create(view, wlr_subsurface);
 }
 
 void view_init(struct roots_view *view, struct roots_desktop *desktop) {
+	assert(view->wlr_surface);
+
 	view->desktop = desktop;
 	wl_signal_init(&view->events.destroy);
+	wl_list_init(&view->children);
+
+	struct wlr_subsurface *subsurface;
+	wl_list_for_each(subsurface, &view->wlr_surface->subsurface_list,
+			parent_link) {
+		subsurface_create(view, subsurface);
+	}
+
+	view->new_subsurface.notify = view_handle_new_subsurface;
+	wl_signal_add(&view->wlr_surface->events.new_subsurface,
+		&view->new_subsurface);
+
+	view_damage_whole(view);
 }
 
 void view_setup(struct roots_view *view) {
@@ -332,6 +436,42 @@ void view_setup(struct roots_view *view) {
 	view_update_output(view, NULL);
 }
 
+void view_apply_damage(struct roots_view *view) {
+	struct roots_output *output;
+	wl_list_for_each(output, &view->desktop->outputs, link) {
+		output_damage_from_view(output, view);
+	}
+}
+
+void view_damage_whole(struct roots_view *view) {
+	struct roots_output *output;
+	wl_list_for_each(output, &view->desktop->outputs, link) {
+		output_damage_whole_view(output, view);
+	}
+}
+
+void view_update_position(struct roots_view *view, double x, double y) {
+	if (view->x == x && view->y == y) {
+		return;
+	}
+
+	view_damage_whole(view);
+	view->x = x;
+	view->y = y;
+	view_damage_whole(view);
+}
+
+void view_update_size(struct roots_view *view, uint32_t width, uint32_t height) {
+	if (view->width == width && view->height == height) {
+		return;
+	}
+
+	view_damage_whole(view);
+	view->width = width;
+	view->height = height;
+	view_damage_whole(view);
+}
+
 static bool view_at(struct roots_view *view, double lx, double ly,
 		struct wlr_surface **surface, double *sx, double *sy) {
 	if (view->type == ROOTS_WL_SHELL_VIEW &&
@@ -569,11 +709,11 @@ void desktop_destroy(struct roots_desktop *desktop) {
 }
 
 struct roots_output *desktop_output_from_wlr_output(
-		struct roots_desktop *desktop, struct wlr_output *output) {
+		struct roots_desktop *desktop, struct wlr_output *wlr_output) {
-	struct roots_output *roots_output;
+	struct roots_output *output;
-	wl_list_for_each(roots_output, &desktop->outputs, link) {
+	wl_list_for_each(output, &desktop->outputs, link) {
-		if (roots_output->wlr_output == output) {
+		if (output->wlr_output == wlr_output) {
-			return roots_output;
+			return output;
 		}
 	}
 	return NULL;

rootston/meson.build

@@ -15,5 +15,5 @@ if get_option('enable_xwayland')
 	sources += ['xwayland.c']
 endif
 executable(
-	'rootston', sources, dependencies: [wlroots, wlr_protos]
+	'rootston', sources, dependencies: [wlroots, wlr_protos, pixman]
 )

rootston/output.c

@@ -2,17 +2,21 @@
 #include <time.h>
 #include <stdlib.h>
 #include <stdbool.h>
-#include <GLES2/gl2.h>
+#include <assert.h>
 #include <wlr/types/wlr_output_layout.h>
 #include <wlr/types/wlr_compositor.h>
 #include <wlr/types/wlr_wl_shell.h>
 #include <wlr/types/wlr_xdg_shell_v6.h>
 #include <wlr/render/matrix.h>
 #include <wlr/util/log.h>
+#include <wlr/util/region.h>
 #include "rootston/server.h"
-#include "rootston/desktop.h"
+#include "rootston/output.h"
 #include "rootston/config.h"
 
+typedef void (*surface_iterator_func_t)(struct wlr_surface *surface,
+	double lx, double ly, float rotation, void *data);
+
 /**
  * Rotate a child's position relative to a parent. The parent size is (pw, ph),
  * the child position is (*sx, *sy) and its size is (sw, sh).
@@ -31,66 +35,33 @@ static void rotate_child_position(double *sx, double *sy, double sw, double sh,
 	}
 }
 
-static void render_surface(struct wlr_surface *surface,
+static void surface_for_each_surface(struct wlr_surface *surface, double lx,
-		struct roots_desktop *desktop, struct wlr_output *wlr_output,
+		double ly, float rotation, surface_iterator_func_t iterator,
-		struct timespec *when, double lx, double ly, float rotation) {
+		void *user_data) {
-	if (!wlr_surface_has_buffer(surface)) {
+	iterator(surface, lx, ly, rotation, user_data);
-		return;
-	}
-
-	int width = surface->current->width;
-	int height = surface->current->height;
-	int render_width = width * wlr_output->scale;
-	int render_height = height * wlr_output->scale;
-	double ox = lx, oy = ly;
-	wlr_output_layout_output_coords(desktop->layout, wlr_output, &ox, &oy);
-	ox *= wlr_output->scale;
-	oy *= wlr_output->scale;
-
-	struct wlr_box render_box = {
-		.x = lx, .y = ly,
-		.width = render_width, .height = render_height,
-	};
-	if (wlr_output_layout_intersects(desktop->layout, wlr_output, &render_box)) {
-		struct wlr_box project_box = {
-			.x = ox,
-			.y = oy,
-			.width = render_width,
-			.height = render_height,
-		};
-		float matrix[16];
-		wlr_matrix_project_box(&matrix, &project_box, surface->current->transform,
-			rotation, &wlr_output->transform_matrix);
-		wlr_render_with_matrix(desktop->server->renderer, surface->texture,
-			&matrix);
-
-		wlr_surface_send_frame_done(surface, when);
-	}
 
 	struct wlr_subsurface *subsurface;
 	wl_list_for_each(subsurface, &surface->subsurface_list, parent_link) {
 		struct wlr_surface_state *state = subsurface->surface->current;
 		double sx = state->subsurface_position.x;
 		double sy = state->subsurface_position.y;
-		double sw = state->buffer_width / state->scale;
+		rotate_child_position(&sx, &sy, state->width, state->height,
-		double sh = state->buffer_height / state->scale;
+			surface->current->width, surface->current->height, rotation);
-		rotate_child_position(&sx, &sy, sw, sh, width, height, rotation);
 
-		render_surface(subsurface->surface, desktop, wlr_output, when,
+		surface_for_each_surface(subsurface->surface, lx + sx, ly + sy,
-			lx + sx,
+			rotation, iterator, user_data);
-			ly + sy,
-			rotation);
 	}
 }
 
-static void render_xdg_v6_popups(struct wlr_xdg_surface_v6 *surface,
+static void xdg_surface_v6_for_each_surface(struct wlr_xdg_surface_v6 *surface,
-		struct roots_desktop *desktop, struct wlr_output *wlr_output,
+		double base_x, double base_y, float rotation,
-		struct timespec *when, double base_x, double base_y, float rotation) {
+		surface_iterator_func_t iterator, void *user_data) {
 	double width = surface->surface->current->width;
 	double height = surface->surface->current->height;
 
-	struct wlr_xdg_surface_v6 *popup;
+	struct wlr_xdg_popup_v6 *popup_state;
-	wl_list_for_each(popup, &surface->popups, popup_link) {
+	wl_list_for_each(popup_state, &surface->popups, link) {
+		struct wlr_xdg_surface_v6 *popup = popup_state->base;
 		if (!popup->configured) {
 			continue;
 		}
@@ -103,20 +74,20 @@ static void render_xdg_v6_popups(struct wlr_xdg_surface_v6 *surface,
 		rotate_child_position(&popup_sx, &popup_sy, popup_width, popup_height,
 			width, height, rotation);
 
-		render_surface(popup->surface, desktop, wlr_output, when,
+		surface_for_each_surface(popup->surface, base_x + popup_sx,
-			base_x + popup_sx, base_y + popup_sy, rotation);
+			base_y + popup_sy, rotation, iterator, user_data);
-		render_xdg_v6_popups(popup, desktop, wlr_output, when,
+		xdg_surface_v6_for_each_surface(popup, base_x + popup_sx,
-			base_x + popup_sx, base_y + popup_sy, rotation);
+			base_y + popup_sy, rotation, iterator, user_data);
 	}
 }
 
-static void render_wl_shell_surface(struct wlr_wl_shell_surface *surface,
+static void wl_shell_surface_for_each_surface(
-		struct roots_desktop *desktop, struct wlr_output *wlr_output,
+		struct wlr_wl_shell_surface *surface, double lx, double ly,
-		struct timespec *when, double lx, double ly, float rotation,
+		float rotation, bool is_child, surface_iterator_func_t iterator,
-		bool is_child) {
+		void *user_data) {
 	if (is_child || surface->state != WLR_WL_SHELL_SURFACE_STATE_POPUP) {
-		render_surface(surface->surface, desktop, wlr_output, when,
+		surface_for_each_surface(surface->surface, lx, ly, rotation, iterator,
-			lx, ly, rotation);
+			user_data);
 
 		double width = surface->surface->current->width;
 		double height = surface->surface->current->height;
@@ -131,32 +102,160 @@ static void render_wl_shell_surface(struct wlr_wl_shell_surface *surface,
 			rotate_child_position(&popup_x, &popup_y, popup_width, popup_height,
 				width, height, rotation);
 
-			render_wl_shell_surface(popup, desktop, wlr_output, when,
+			wl_shell_surface_for_each_surface(popup, lx + popup_x, ly + popup_y,
-				lx + popup_x, ly + popup_y, rotation, true);
+				rotation, true, iterator, user_data);
 		}
 	}
 }
 
+static void view_for_each_surface(struct roots_view *view,
+		surface_iterator_func_t iterator, void *user_data) {
+	switch (view->type) {
+	case ROOTS_XDG_SHELL_V6_VIEW:
+		surface_for_each_surface(view->wlr_surface, view->x, view->y,
+			view->rotation, iterator, user_data);
+		xdg_surface_v6_for_each_surface(view->xdg_surface_v6, view->x, view->y,
+			view->rotation, iterator, user_data);
+		break;
+	case ROOTS_WL_SHELL_VIEW:
+		wl_shell_surface_for_each_surface(view->wl_shell_surface, view->x,
+			view->y, view->rotation, false, iterator, user_data);
+		break;
+#ifdef WLR_HAS_XWAYLAND
+	case ROOTS_XWAYLAND_VIEW:
+		if (view->wlr_surface != NULL) {
+			surface_for_each_surface(view->wlr_surface, view->x, view->y,
+				view->rotation, iterator, user_data);
+		}
+		break;
+#endif
+	}
+}
+
 #ifdef WLR_HAS_XWAYLAND
-static void render_xwayland_children(struct wlr_xwayland_surface *surface,
+static void xwayland_children_for_each_surface(
-		struct roots_desktop *desktop, struct wlr_output *wlr_output,
+		struct wlr_xwayland_surface *surface,
-		struct timespec *when) {
+		surface_iterator_func_t iterator, void *user_data) {
 	struct wlr_xwayland_surface *child;
 	wl_list_for_each(child, &surface->children, parent_link) {
 		if (child->surface != NULL && child->added) {
-			render_surface(child->surface, desktop, wlr_output, when,
+			surface_for_each_surface(child->surface, child->x, child->y, 0,
-				child->x, child->y, 0);
+				iterator, user_data);
 		}
-		render_xwayland_children(child, desktop, wlr_output, when);
+		xwayland_children_for_each_surface(child, iterator, user_data);
 	}
 }
 #endif
 
-static void render_decorations(struct roots_view *view,
+
-		struct roots_desktop *desktop, struct wlr_output *output) {
+struct render_data {
-	if (!view->decorated) {
+	struct roots_output *output;
+	struct timespec *when;
+	pixman_region32_t *damage;
+};
+
+/**
+ * Checks whether a surface at (lx, ly) intersects an output. Sets `box` to the
+ * surface box in the output, in output-local coordinates.
+ */
+static bool surface_intersect_output(struct wlr_surface *surface,
+		struct wlr_output_layout *output_layout, struct wlr_output *wlr_output,
+		double lx, double ly, float rotation, struct wlr_box *box) {
+	double ox = lx, oy = ly;
+	wlr_output_layout_output_coords(output_layout, wlr_output, &ox, &oy);
+	box->x = ox * wlr_output->scale;
+	box->y = oy * wlr_output->scale;
+	box->width = surface->current->width * wlr_output->scale;
+	box->height = surface->current->height * wlr_output->scale;
+
+	struct wlr_box layout_box = {
+		.x = lx, .y = ly,
+		.width = surface->current->width, .height = surface->current->height,
+	};
+	wlr_box_rotated_bounds(&layout_box, -rotation, &layout_box);
+	return wlr_output_layout_intersects(output_layout, wlr_output, &layout_box);
+}
+
+static void scissor_output(struct roots_output *output, pixman_box32_t *rect) {
+	struct wlr_output *wlr_output = output->wlr_output;
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(wlr_output->backend);
+	assert(renderer);
+
+	struct wlr_box box = {
+		.x = rect->x1,
+		.y = rect->y1,
+		.width = rect->x2 - rect->x1,
+		.height = rect->y2 - rect->y1,
+	};
+
+	int ow, oh;
+	wlr_output_transformed_resolution(output->wlr_output, &ow, &oh);
+
+	// Scissor is in renderer coordinates, ie. upside down
+	enum wl_output_transform transform = wlr_output_transform_compose(
+		wlr_output_transform_invert(wlr_output->transform),
+		WL_OUTPUT_TRANSFORM_FLIPPED_180);
+	wlr_box_transform(&box, transform, ow, oh, &box);
+
+	wlr_renderer_scissor(renderer, &box);
+}
+
+static void render_surface(struct wlr_surface *surface, double lx, double ly,
+		float rotation, void *_data) {
+	struct render_data *data = _data;
+	struct roots_output *output = data->output;
+	struct timespec *when = data->when;
+	struct wlr_renderer *renderer =
+		wlr_backend_get_renderer(output->wlr_output->backend);
+	assert(renderer);
+
+	if (!wlr_surface_has_buffer(surface)) {
+		return;
+	}
+
+	struct wlr_box box;
+	bool intersects = surface_intersect_output(surface, output->desktop->layout,
+		output->wlr_output, lx, ly, rotation, &box);
+	if (!intersects) {
 		return;
 	}
+
+	struct wlr_box rotated;
+	wlr_box_rotated_bounds(&box, -rotation, &rotated);
+
+	pixman_region32_t damage;
+	pixman_region32_init(&damage);
+	pixman_region32_union_rect(&damage, &damage, rotated.x, rotated.y,
+		rotated.width, rotated.height);
+	pixman_region32_intersect(&damage, &damage, data->damage);
+	bool damaged = pixman_region32_not_empty(&damage);
+	if (!damaged) {
+		goto damage_finish;
+	}
+
+	float matrix[16];
+	enum wl_output_transform transform =
+		wlr_output_transform_invert(surface->current->transform);
+	wlr_matrix_project_box(&matrix, &box, transform, rotation,
+		&output->wlr_output->transform_matrix);
+
+	int nrects;
+	pixman_box32_t *rects = pixman_region32_rectangles(&damage, &nrects);
+	for (int i = 0; i < nrects; ++i) {
+		scissor_output(output, &rects[i]);
+		wlr_render_with_matrix(renderer, surface->texture, &matrix);
+	}
+
+	wlr_surface_send_frame_done(surface, when);
+
+damage_finish:
+	pixman_region32_fini(&damage);
+}
+
+static void get_decoration_box(struct roots_view *view,
+		struct roots_output *output, struct wlr_box *box) {
+	struct wlr_output *wlr_output = output->wlr_output;
+
 	struct wlr_box deco_box;
 	view_get_deco_box(view, &deco_box);
 	double sx = deco_box.x - view->x;
@@ -164,49 +263,70 @@ static void render_decorations(struct roots_view *view,
 	rotate_child_position(&sx, &sy, deco_box.width, deco_box.height,
 		view->wlr_surface->current->width,
 		view->wlr_surface->current->height, view->rotation);
-	double ox = sx + view->x;
+	double x = sx + view->x;
-	double oy = sy + view->y;
+	double y = sy + view->y;
-
-	wlr_output_layout_output_coords(desktop->layout, output, &ox, &oy);
-	ox *= output->scale;
-	oy *= output->scale;
-
-	struct wlr_box project_box = {
-		.x = ox,
-		.y = oy,
-		.width = deco_box.width,
-		.height = deco_box.height,
-	};
 
-	float matrix[16];
+	wlr_output_layout_output_coords(output->desktop->layout, wlr_output, &x, &y);
-	wlr_matrix_project_box(&matrix, &project_box, WL_OUTPUT_TRANSFORM_NORMAL,
+
-		view->rotation, &output->transform_matrix);
+	box->x = x * wlr_output->scale;
-	float color[4] = { 0.2, 0.2, 0.2, 1 };
+	box->y = y * wlr_output->scale;
-	wlr_render_colored_quad(desktop->server->renderer, &color, &matrix);
+	box->width = deco_box.width * wlr_output->scale;
+	box->height = deco_box.height * wlr_output->scale;
 }
 
-static void render_view(struct roots_view *view, struct roots_desktop *desktop,
+static void render_decorations(struct roots_view *view,
-		struct wlr_output *wlr_output, struct timespec *when) {
+		struct render_data *data) {
-	render_decorations(view, desktop, wlr_output);
+	if (!view->decorated || view->wlr_surface == NULL) {
+		return;
+	}
 
-	switch (view->type) {
+	struct roots_output *output = data->output;
-	case ROOTS_XDG_SHELL_V6_VIEW:
+	struct wlr_renderer *renderer =
-		render_surface(view->wlr_surface, desktop, wlr_output, when,
+		wlr_backend_get_renderer(output->wlr_output->backend);
-			view->x, view->y, view->rotation);
+	assert(renderer);
-		render_xdg_v6_popups(view->xdg_surface_v6, desktop, wlr_output,
+
-			when, view->x, view->y, view->rotation);
+	struct wlr_box box;
-		break;
+	get_decoration_box(view, output, &box);
-	case ROOTS_WL_SHELL_VIEW:
+
-		render_wl_shell_surface(view->wl_shell_surface, desktop, wlr_output,
+	struct wlr_box rotated;
-			when, view->x, view->y, view->rotation, false);
+	wlr_box_rotated_bounds(&box, -view->rotation, &rotated);
-		break;
+
-#ifdef WLR_HAS_XWAYLAND
+	pixman_region32_t damage;
-	case ROOTS_XWAYLAND_VIEW:
+	pixman_region32_init(&damage);
-		render_surface(view->wlr_surface, desktop, wlr_output, when,
+	pixman_region32_union_rect(&damage, &damage, rotated.x, rotated.y,
-			view->x, view->y, view->rotation);
+		rotated.width, rotated.height);
-		break;
+	pixman_region32_intersect(&damage, &damage, data->damage);
-#endif
+	bool damaged = pixman_region32_not_empty(&damage);
+	if (!damaged) {
+		goto damage_finish;
+	}
+
+	float matrix[16];
+	wlr_matrix_project_box(&matrix, &box, WL_OUTPUT_TRANSFORM_NORMAL,
+		view->rotation, &output->wlr_output->transform_matrix);
+	float color[] = { 0.2, 0.2, 0.2, 1 };
+
+	int nrects;
+	pixman_box32_t *rects =
+		pixman_region32_rectangles(&damage, &nrects);
+	for (int i = 0; i < nrects; ++i) {
+		scissor_output(output, &rects[i]);
+		wlr_render_colored_quad(renderer, &color, &matrix);
+	}
+
+damage_finish:
+	pixman_region32_fini(&damage);
+}
+
+static void render_view(struct roots_view *view, struct render_data *data) {
+	// Do not render views fullscreened on other outputs
+	if (view->fullscreen_output != NULL &&
+			view->fullscreen_output != data->output) {
+		return;
 	}
+
+	render_decorations(view, data);
+	view_for_each_surface(view, render_surface, data);
 }
 
 static bool has_standalone_surface(struct roots_view *view) {
@@ -227,11 +347,12 @@ static bool has_standalone_surface(struct roots_view *view) {
 	return true;
 }
 
-static void output_frame_notify(struct wl_listener *listener, void *data) {
+static void render_output(struct roots_output *output) {
-	struct wlr_output *wlr_output = data;
+	struct wlr_output *wlr_output = output->wlr_output;
-	struct roots_output *output = wl_container_of(listener, output, frame);
 	struct roots_desktop *desktop = output->desktop;
 	struct roots_server *server = desktop->server;
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(wlr_output->backend);
+	assert(renderer);
 
 	if (!wlr_output->enabled) {
 		return;
@@ -240,9 +361,9 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 	struct timespec now;
 	clock_gettime(CLOCK_MONOTONIC, &now);
 
-	wlr_output_make_current(wlr_output);
+	float clear_color[] = {0.25f, 0.25f, 0.25f, 1.0f};
-	wlr_renderer_begin(server->renderer, wlr_output);
 
+	// Check if we can delegate the fullscreen surface to the output
 	if (output->fullscreen_view != NULL) {
 		struct roots_view *view = output->fullscreen_view;
 
@@ -261,65 +382,292 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 			wlr_output_set_fullscreen_surface(wlr_output, view->wlr_surface);
 		} else {
 			wlr_output_set_fullscreen_surface(wlr_output, NULL);
+		}
+
+		// Fullscreen views are rendered on a black background
+		clear_color[0] = clear_color[1] = clear_color[2] = 0;
+	} else {
+		wlr_output_set_fullscreen_surface(wlr_output, NULL);
+	}
+
+	int buffer_age = -1;
+	if (!wlr_output_make_current(wlr_output, &buffer_age)) {
+		return;
+	}
+
+	int width, height;
+	wlr_output_transformed_resolution(output->wlr_output, &width, &height);
 
-			glClearColor(0, 0, 0, 0);
+	// Check if we can use damage tracking
-			glClear(GL_COLOR_BUFFER_BIT);
+	pixman_region32_t damage;
+	pixman_region32_init(&damage);
+	if (buffer_age <= 0 || buffer_age - 1 > ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN) {
+		// Buffer new or too old, damage the whole output
+		pixman_region32_union_rect(&damage, &damage, 0, 0, width, height);
+	} else {
+		pixman_region32_copy(&damage, &output->damage);
 
-			render_view(view, desktop, wlr_output, &now);
+		// Accumulate damage from old buffers
+		size_t idx = output->previous_damage_idx;
+		for (int i = 0; i < buffer_age - 1; ++i) {
+			int j = (idx + i) % ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN;
+			pixman_region32_union(&damage, &damage, &output->previous_damage[j]);
+		}
+	}
+	pixman_region32_intersect_rect(&damage, &damage, 0, 0, width, height);
 
-			// During normal rendering the xwayland window tree isn't traversed
+	if (!pixman_region32_not_empty(&damage) && !wlr_output->needs_swap) {
-			// because all windows are rendered. Here we only want to render
+		// Output doesn't need swap and isn't damaged, skip rendering completely
-			// the fullscreen window's children so we have to traverse the tree.
+		goto damage_finish;
+	}
+
+	struct render_data data = {
+		.output = output,
+		.when = &now,
+		.damage = &damage,
+	};
+
+	wlr_renderer_begin(renderer, wlr_output);
+
+	if (!pixman_region32_not_empty(&damage)) {
+		// Output isn't damaged but needs buffer swap
+		goto renderer_end;
+	}
+
+	int nrects;
+	pixman_box32_t *rects = pixman_region32_rectangles(&damage, &nrects);
+	for (int i = 0; i < nrects; ++i) {
+		scissor_output(output, &rects[i]);
+		wlr_renderer_clear(renderer, &clear_color);
+	}
+
+	// If a view is fullscreen on this output, render it
+	if (output->fullscreen_view != NULL) {
+		struct roots_view *view = output->fullscreen_view;
+
+		if (wlr_output->fullscreen_surface == view->wlr_surface) {
+			// The output will render the fullscreen view
+			goto renderer_end;
+		}
+
+		view_for_each_surface(view, render_surface, &data);
+
+		// During normal rendering the xwayland window tree isn't traversed
+		// because all windows are rendered. Here we only want to render
+		// the fullscreen window's children so we have to traverse the tree.
 #ifdef WLR_HAS_XWAYLAND
-			if (view->type == ROOTS_XWAYLAND_VIEW) {
+		if (view->type == ROOTS_XWAYLAND_VIEW) {
-				render_xwayland_children(view->xwayland_surface, desktop,
+			xwayland_children_for_each_surface(view->xwayland_surface,
-					wlr_output, &now);
+				render_surface, &data);
-			}
-#endif
 		}
-		wlr_renderer_end(server->renderer);
+#endif
-		wlr_output_swap_buffers(wlr_output);
+
-		output->last_frame = desktop->last_frame = now;
+		goto renderer_end;
-		return;
-	} else {
-		wlr_output_set_fullscreen_surface(wlr_output, NULL);
 	}
 
+	// Render all views
 	struct roots_view *view;
 	wl_list_for_each_reverse(view, &desktop->views, link) {
-		render_view(view, desktop, wlr_output, &now);
+		render_view(view, &data);
 	}
 
-	struct wlr_drag_icon *drag_icon = NULL;
+	// Render drag icons
+	struct roots_drag_icon *drag_icon = NULL;
 	struct roots_seat *seat = NULL;
 	wl_list_for_each(seat, &server->input->seats, link) {
-		wl_list_for_each(drag_icon, &seat->seat->drag_icons, link) {
+		wl_list_for_each(drag_icon, &seat->drag_icons, link) {
-			if (!drag_icon->mapped) {
+			if (!drag_icon->wlr_drag_icon->mapped) {
 				continue;
 			}
-			struct wlr_surface *icon = drag_icon->surface;
+			render_surface(drag_icon->wlr_drag_icon->surface,
-			struct wlr_cursor *cursor = seat->cursor->cursor;
+				drag_icon->x, drag_icon->y, 0, &data);
-			double icon_x = 0, icon_y = 0;
+		}
-			if (drag_icon->is_pointer) {
+	}
-				icon_x = cursor->x + drag_icon->sx;
+
-				icon_y = cursor->y + drag_icon->sy;
+renderer_end:
-				render_surface(icon, desktop, wlr_output, &now, icon_x, icon_y, 0);
+	wlr_renderer_scissor(renderer, NULL);
-			} else {
+	wlr_renderer_end(renderer);
-				struct wlr_touch_point *point =
+	if (!wlr_output_swap_buffers(wlr_output, &now, &damage)) {
-					wlr_seat_touch_get_point(seat->seat, drag_icon->touch_id);
+		goto damage_finish;
-				if (point) {
+	}
-					icon_x = seat->touch_x + drag_icon->sx;
+	// same as decrementing, but works on unsigned integers
-					icon_y = seat->touch_y + drag_icon->sy;
+	output->previous_damage_idx += ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN - 1;
-					render_surface(icon, desktop, wlr_output, &now, icon_x, icon_y, 0);
+	output->previous_damage_idx %= ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN;
-				}
+	pixman_region32_copy(&output->previous_damage[output->previous_damage_idx],
+		&output->damage);
+	pixman_region32_clear(&output->damage);
+	output->last_frame = desktop->last_frame = now;
+
+damage_finish:
+	pixman_region32_fini(&damage);
+}
+
+static void output_handle_frame(struct wl_listener *listener, void *data) {
+	struct roots_output *output = wl_container_of(listener, output, frame);
+	render_output(output);
+}
+
+void output_damage_whole(struct roots_output *output) {
+	int width, height;
+	wlr_output_transformed_resolution(output->wlr_output, &width, &height);
+
+	pixman_region32_union_rect(&output->damage, &output->damage, 0, 0,
+		width, height);
+
+	wlr_output_schedule_frame(output->wlr_output);
+}
+
+static bool view_accept_damage(struct roots_output *output,
+		struct roots_view *view) {
+	if (output->fullscreen_view == NULL) {
+		return true;
+	}
+	if (output->fullscreen_view == view) {
+		return true;
+	}
+#ifdef WLR_HAS_XWAYLAND
+	if (output->fullscreen_view->type == ROOTS_XWAYLAND_VIEW &&
+			view->type == ROOTS_XWAYLAND_VIEW) {
+		// Special case: accept damage from children
+		struct wlr_xwayland_surface *xsurface = view->xwayland_surface;
+		while (xsurface != NULL) {
+			if (output->fullscreen_view->xwayland_surface == xsurface) {
+				return true;
 			}
+			xsurface = xsurface->parent;
 		}
 	}
+#endif
+	return false;
+}
+
+static void damage_whole_surface(struct wlr_surface *surface,
+		double lx, double ly, float rotation, void *data) {
+	struct roots_output *output = data;
+
+	if (!wlr_surface_has_buffer(surface)) {
+		return;
+	}
 
-	wlr_renderer_end(server->renderer);
+	int ow, oh;
-	wlr_output_swap_buffers(wlr_output);
+	wlr_output_transformed_resolution(output->wlr_output, &ow, &oh);
 
-	output->last_frame = desktop->last_frame = now;
+	struct wlr_box box;
+	bool intersects = surface_intersect_output(surface, output->desktop->layout,
+		output->wlr_output, lx, ly, rotation, &box);
+	if (!intersects) {
+		return;
+	}
+
+	wlr_box_rotated_bounds(&box, -rotation, &box);
+
+	pixman_region32_union_rect(&output->damage, &output->damage,
+		box.x, box.y, box.width, box.height);
+
+	wlr_output_schedule_frame(output->wlr_output);
+}
+
+static void damage_whole_decoration(struct roots_view *view,
+		struct roots_output *output) {
+	if (!view->decorated || view->wlr_surface == NULL) {
+		return;
+	}
+
+	struct wlr_box box;
+	get_decoration_box(view, output, &box);
+
+	wlr_box_rotated_bounds(&box, -view->rotation, &box);
+
+	pixman_region32_union_rect(&output->damage, &output->damage,
+		box.x, box.y, box.width, box.height);
+}
+
+void output_damage_whole_view(struct roots_output *output,
+		struct roots_view *view) {
+	if (!view_accept_damage(output, view)) {
+		return;
+	}
+
+	damage_whole_decoration(view, output);
+	view_for_each_surface(view, damage_whole_surface, output);
+}
+
+void output_damage_whole_drag_icon(struct roots_output *output,
+		struct roots_drag_icon *icon) {
+	surface_for_each_surface(icon->wlr_drag_icon->surface, icon->x, icon->y, 0,
+		damage_whole_surface, output);
+}
+
+static void damage_from_surface(struct wlr_surface *surface,
+		double lx, double ly, float rotation, void *data) {
+	struct roots_output *output = data;
+	struct wlr_output *wlr_output = output->wlr_output;
+
+	if (!wlr_surface_has_buffer(surface)) {
+		return;
+	}
+
+	int ow, oh;
+	wlr_output_transformed_resolution(wlr_output, &ow, &oh);
+
+	struct wlr_box box;
+	surface_intersect_output(surface, output->desktop->layout,
+		wlr_output, lx, ly, rotation, &box);
+
+	if (rotation == 0) {
+		pixman_region32_t damage;
+		pixman_region32_init(&damage);
+		pixman_region32_copy(&damage, &surface->current->surface_damage);
+		wlr_region_scale(&damage, &damage, wlr_output->scale);
+		if (ceil(wlr_output->scale) > surface->current->scale) {
+			// When scaling up a surface, it'll become blurry so we need to
+			// expand the damage region
+			wlr_region_expand(&damage, &damage,
+				ceil(wlr_output->scale) - surface->current->scale);
+		}
+		pixman_region32_translate(&damage, box.x, box.y);
+		pixman_region32_union(&output->damage, &output->damage, &damage);
+		pixman_region32_fini(&damage);
+	} else {
+		pixman_box32_t *extents =
+			pixman_region32_extents(&surface->current->surface_damage);
+		struct wlr_box damage_box = {
+			.x = box.x + extents->x1 * wlr_output->scale,
+			.y = box.y + extents->y1 * wlr_output->scale,
+			.width = (extents->x2 - extents->x1) * wlr_output->scale,
+			.height = (extents->y2 - extents->y1) * wlr_output->scale,
+		};
+		wlr_box_rotated_bounds(&damage_box, -rotation, &damage_box);
+		pixman_region32_union_rect(&output->damage, &output->damage,
+			damage_box.x, damage_box.y, damage_box.width, damage_box.height);
+	}
+
+	pixman_region32_intersect_rect(&output->damage, &output->damage, 0, 0,
+		ow, oh);
+
+	wlr_output_schedule_frame(wlr_output);
+}
+
+void output_damage_from_view(struct roots_output *output,
+		struct roots_view *view) {
+	if (!view_accept_damage(output, view)) {
+		return;
+	}
+
+	view_for_each_surface(view, damage_from_surface, output);
+}
+
+static void output_handle_mode(struct wl_listener *listener, void *data) {
+	struct roots_output *output = wl_container_of(listener, output, mode);
+	output_damage_whole(output);
+}
+
+static void output_handle_needs_swap(struct wl_listener *listener, void *data) {
+	struct roots_output *output =
+		wl_container_of(listener, output, needs_swap);
+	pixman_region32_union(&output->damage, &output->damage,
+		&output->wlr_output->damage);
+	wlr_output_schedule_frame(output->wlr_output);
 }
 
 static void set_mode(struct wlr_output *output,
@@ -372,9 +720,18 @@ void output_add_notify(struct wl_listener *listener, void *data) {
 	clock_gettime(CLOCK_MONOTONIC, &output->last_frame);
 	output->desktop = desktop;
 	output->wlr_output = wlr_output;
-	output->frame.notify = output_frame_notify;
-	wl_signal_add(&wlr_output->events.frame, &output->frame);
 	wl_list_insert(&desktop->outputs, &output->link);
+	pixman_region32_init(&output->damage);
+	for (size_t i = 0; i < ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN; ++i) {
+		pixman_region32_init(&output->previous_damage[i]);
+	}
+
+	output->frame.notify = output_handle_frame;
+	wl_signal_add(&wlr_output->events.frame, &output->frame);
+	output->mode.notify = output_handle_mode;
+	wl_signal_add(&wlr_output->events.mode, &output->mode);
+	output->needs_swap.notify = output_handle_needs_swap;
+	wl_signal_add(&wlr_output->events.needs_swap, &output->needs_swap);
 
 	struct roots_output_config *output_config =
 		roots_config_get_output(config, wlr_output);
@@ -399,6 +756,8 @@ void output_add_notify(struct wl_listener *listener, void *data) {
 		roots_seat_configure_cursor(seat);
 		roots_seat_configure_xcursor(seat);
 	}
+
+	output_damage_whole(output);
 }
 
 void output_remove_notify(struct wl_listener *listener, void *data) {
@@ -423,7 +782,13 @@ void output_remove_notify(struct wl_listener *listener, void *data) {
 	//example_config_configure_cursor(sample->config, sample->cursor,
 	//	sample->compositor);
 
+	pixman_region32_fini(&output->damage);
+	for (size_t i = 0; i < ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN; ++i) {
+		pixman_region32_fini(&output->previous_damage[i]);
+	}
 	wl_list_remove(&output->link);
 	wl_list_remove(&output->frame.link);
+	wl_list_remove(&output->mode.link);
+	wl_list_remove(&output->needs_swap.link);
 	free(output);
 }

rootston/seat.c

@@ -241,19 +241,97 @@ static void roots_seat_init_cursor(struct roots_seat *seat) {
 	seat->cursor->tool_tip.notify = handle_tool_tip;
 
 	wl_signal_add(&seat->seat->events.request_set_cursor,
-			&seat->cursor->request_set_cursor);
+		&seat->cursor->request_set_cursor);
 	seat->cursor->request_set_cursor.notify = handle_request_set_cursor;
 }
 
+static void roots_drag_icon_handle_surface_commit(struct wl_listener *listener,
+		void *data) {
+	struct roots_drag_icon *icon =
+		wl_container_of(listener, icon, surface_commit);
+	roots_drag_icon_damage_whole(icon);
+}
+
+static void roots_drag_icon_handle_map(struct wl_listener *listener,
+		void *data) {
+	struct roots_drag_icon *icon =
+		wl_container_of(listener, icon, map);
+	roots_drag_icon_damage_whole(icon);
+}
+
+static void roots_drag_icon_handle_destroy(struct wl_listener *listener,
+		void *data) {
+	struct roots_drag_icon *icon =
+		wl_container_of(listener, icon, destroy);
+	roots_drag_icon_damage_whole(icon);
+
+	wl_list_remove(&icon->link);
+	wl_list_remove(&icon->surface_commit.link);
+	wl_list_remove(&icon->map.link);
+	wl_list_remove(&icon->destroy.link);
+	free(icon);
+}
+
+static void roots_seat_handle_new_drag_icon(struct wl_listener *listener,
+		void *data) {
+	struct roots_seat *seat = wl_container_of(listener, seat, new_drag_icon);
+	struct wlr_drag_icon *wlr_drag_icon = data;
+
+	struct roots_drag_icon *icon = calloc(1, sizeof(struct roots_drag_icon));
+	if (icon == NULL) {
+		return;
+	}
+	icon->seat = seat;
+	icon->wlr_drag_icon = wlr_drag_icon;
+
+	icon->surface_commit.notify = roots_drag_icon_handle_surface_commit;
+	wl_signal_add(&wlr_drag_icon->surface->events.commit, &icon->surface_commit);
+	icon->map.notify = roots_drag_icon_handle_map;
+	wl_signal_add(&wlr_drag_icon->events.map, &icon->map);
+	icon->destroy.notify = roots_drag_icon_handle_destroy;
+	wl_signal_add(&wlr_drag_icon->events.destroy, &icon->destroy);
+
+	wl_list_insert(&seat->drag_icons, &icon->link);
+}
+
+void roots_drag_icon_update_position(struct roots_drag_icon *icon) {
+	roots_drag_icon_damage_whole(icon);
+
+	struct wlr_drag_icon *wlr_icon = icon->wlr_drag_icon;
+	struct roots_seat *seat = icon->seat;
+	struct wlr_cursor *cursor = seat->cursor->cursor;
+	if (wlr_icon->is_pointer) {
+		icon->x = cursor->x + wlr_icon->sx;
+		icon->y = cursor->y + wlr_icon->sy;
+	} else {
+		struct wlr_touch_point *point =
+			wlr_seat_touch_get_point(seat->seat, wlr_icon->touch_id);
+		if (point == NULL) {
+			return;
+		}
+		icon->x = seat->touch_x + wlr_icon->sx;
+		icon->y = seat->touch_y + wlr_icon->sy;
+	}
+
+	roots_drag_icon_damage_whole(icon);
+}
+
+void roots_drag_icon_damage_whole(struct roots_drag_icon *icon) {
+	struct roots_output *output;
+	wl_list_for_each(output, &icon->seat->input->server->desktop->outputs,
+			link) {
+		output_damage_whole_drag_icon(output, icon);
+	}
+}
+
 static void seat_view_destroy(struct roots_seat_view *seat_view);
 
-static void roots_seat_handle_seat_destroy(struct wl_listener *listener,
+static void roots_seat_handle_destroy(struct wl_listener *listener,
 		void *data) {
-	struct roots_seat *seat =
+	struct roots_seat *seat = wl_container_of(listener, seat, destroy);
-		wl_container_of(listener, seat, seat_destroy);
 
 	// TODO: probably more to be freed here
-	wl_list_remove(&seat->seat_destroy.link);
+	wl_list_remove(&seat->destroy.link);
 
 	struct roots_seat_view *view, *nview;
 	wl_list_for_each_safe(view, nview, &seat->views, link) {
@@ -262,7 +340,7 @@ static void roots_seat_handle_seat_destroy(struct wl_listener *listener,
 }
 
 void roots_seat_destroy(struct roots_seat *seat) {
-	roots_seat_handle_seat_destroy(&seat->seat_destroy, seat->seat);
+	roots_seat_handle_destroy(&seat->destroy, seat->seat);
 	wlr_seat_destroy(seat->seat);
 }
 
@@ -277,6 +355,7 @@ struct roots_seat *roots_seat_create(struct roots_input *input, char *name) {
 	wl_list_init(&seat->touch);
 	wl_list_init(&seat->tablet_tools);
 	wl_list_init(&seat->views);
+	wl_list_init(&seat->drag_icons);
 
 	seat->input = input;
 
@@ -295,8 +374,10 @@ struct roots_seat *roots_seat_create(struct roots_input *input, char *name) {
 
 	wl_list_insert(&input->seats, &seat->link);
 
-	seat->seat_destroy.notify = roots_seat_handle_seat_destroy;
+	seat->new_drag_icon.notify = roots_seat_handle_new_drag_icon;
-	wl_signal_add(&seat->seat->events.destroy, &seat->seat_destroy);
+	wl_signal_add(&seat->seat->events.new_drag_icon, &seat->new_drag_icon);
+	seat->destroy.notify = roots_seat_handle_destroy;
+	wl_signal_add(&seat->seat->events.destroy, &seat->destroy);
 
 	return seat;
 }
@@ -683,6 +764,8 @@ void roots_seat_set_focus(struct roots_seat *seat, struct roots_view *view) {
 	wl_list_remove(&seat_view->link);
 	wl_list_insert(&seat->views, &seat_view->link);
 
+	view_damage_whole(view);
+
 	struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->seat);
 	if (keyboard != NULL) {
 		wlr_seat_keyboard_notify_enter(seat->seat, view->wlr_surface,

rootston/wl_shell.c

@@ -10,6 +10,61 @@
 #include "rootston/server.h"
 #include "rootston/input.h"
 
+static void popup_destroy(struct roots_view_child *child) {
+	assert(child->destroy == popup_destroy);
+	struct roots_wl_shell_popup *popup = (struct roots_wl_shell_popup *)child;
+	if (popup == NULL) {
+		return;
+	}
+	wl_list_remove(&popup->destroy.link);
+	wl_list_remove(&popup->set_state.link);
+	wl_list_remove(&popup->new_popup.link);
+	view_child_finish(&popup->view_child);
+	free(popup);
+}
+
+static void popup_handle_destroy(struct wl_listener *listener, void *data) {
+	struct roots_wl_shell_popup *popup =
+		wl_container_of(listener, popup, destroy);
+	popup_destroy((struct roots_view_child *)popup);
+}
+
+static void popup_handle_set_state(struct wl_listener *listener, void *data) {
+	struct roots_wl_shell_popup *popup =
+		wl_container_of(listener, popup, set_state);
+	popup_destroy((struct roots_view_child *)popup);
+}
+
+static struct roots_wl_shell_popup *popup_create(struct roots_view *view,
+	struct wlr_wl_shell_surface *wlr_wl_shell_surface);
+
+static void popup_handle_new_popup(struct wl_listener *listener, void *data) {
+	struct roots_wl_shell_popup *popup =
+		wl_container_of(listener, popup, new_popup);
+	struct wlr_wl_shell_surface *wlr_wl_shell_surface = data;
+	popup_create(popup->view_child.view, wlr_wl_shell_surface);
+}
+
+static struct roots_wl_shell_popup *popup_create(struct roots_view *view,
+		struct wlr_wl_shell_surface *wlr_wl_shell_surface) {
+	struct roots_wl_shell_popup *popup =
+		calloc(1, sizeof(struct roots_wl_shell_popup));
+	if (popup == NULL) {
+		return NULL;
+	}
+	popup->wlr_wl_shell_surface = wlr_wl_shell_surface;
+	popup->view_child.destroy = popup_destroy;
+	view_child_init(&popup->view_child, view, wlr_wl_shell_surface->surface);
+	popup->destroy.notify = popup_handle_destroy;
+	wl_signal_add(&wlr_wl_shell_surface->events.destroy, &popup->destroy);
+	popup->set_state.notify = popup_handle_set_state;
+	wl_signal_add(&wlr_wl_shell_surface->events.set_state, &popup->set_state);
+	popup->new_popup.notify = popup_handle_new_popup;
+	wl_signal_add(&wlr_wl_shell_surface->events.new_popup, &popup->new_popup);
+	return popup;
+}
+
+
 static void resize(struct roots_view *view, uint32_t width, uint32_t height) {
 	assert(view->type == ROOTS_WL_SHELL_VIEW);
 	struct wlr_wl_shell_surface *surf = view->wl_shell_surface;
@@ -88,19 +143,32 @@ static void handle_surface_commit(struct wl_listener *listener, void *data) {
 	struct roots_view *view = roots_surface->view;
 	struct wlr_surface *wlr_surface = view->wlr_surface;
 
+	view_apply_damage(view);
+
 	int width = wlr_surface->current->width;
 	int height = wlr_surface->current->height;
+	view_update_size(view, width, height);
 
+	double x = view->x;
+	double y = view->y;
 	if (view->pending_move_resize.update_x) {
-		view->x = view->pending_move_resize.x +
+		x = view->pending_move_resize.x + view->pending_move_resize.width -
-			view->pending_move_resize.width - width;
+			width;
 		view->pending_move_resize.update_x = false;
 	}
 	if (view->pending_move_resize.update_y) {
-		view->y = view->pending_move_resize.y +
+		y = view->pending_move_resize.y + view->pending_move_resize.height -
-			view->pending_move_resize.height - height;
+			height;
 		view->pending_move_resize.update_y = false;
 	}
+	view_update_position(view, x, y);
+}
+
+static void handle_new_popup(struct wl_listener *listener, void *data) {
+	struct roots_wl_shell_surface *roots_surface =
+		wl_container_of(listener, roots_surface, new_popup);
+	struct wlr_wl_shell_surface *wlr_wl_shell_surface = data;
+	popup_create(roots_surface->view, wlr_wl_shell_surface);
 }
 
 static void handle_destroy(struct wl_listener *listener, void *data) {
@@ -114,16 +182,22 @@ static void handle_destroy(struct wl_listener *listener, void *data) {
 	wl_list_remove(&roots_surface->set_state.link);
 	wl_list_remove(&roots_surface->surface_commit.link);
 	wl_list_remove(&roots_surface->view->link);
-	view_destroy(roots_surface->view);
+	view_finish(roots_surface->view);
+	free(roots_surface->view);
 	free(roots_surface);
 }
 
 void handle_wl_shell_surface(struct wl_listener *listener, void *data) {
 	struct roots_desktop *desktop =
 		wl_container_of(listener, desktop, wl_shell_surface);
-
 	struct wlr_wl_shell_surface *surface = data;
-	wlr_log(L_DEBUG, "new shell surface: title=%s, class=%s",
+
+	if (surface->state == WLR_WL_SHELL_SURFACE_STATE_POPUP) {
+		wlr_log(L_DEBUG, "new wl shell popup");
+		return;
+	}
+
+	wlr_log(L_DEBUG, "new wl shell surface: title=%s, class=%s",
 		surface->title, surface->class);
 	wlr_wl_shell_surface_ping(surface);
 
@@ -134,6 +208,8 @@ void handle_wl_shell_surface(struct wl_listener *listener, void *data) {
 	}
 	roots_surface->destroy.notify = handle_destroy;
 	wl_signal_add(&surface->events.destroy, &roots_surface->destroy);
+	roots_surface->new_popup.notify = handle_new_popup;
+	wl_signal_add(&surface->events.new_popup, &roots_surface->new_popup);
 	roots_surface->request_move.notify = handle_request_move;
 	wl_signal_add(&surface->events.request_move, &roots_surface->request_move);
 	roots_surface->request_resize.notify = handle_request_resize;
@@ -157,6 +233,8 @@ void handle_wl_shell_surface(struct wl_listener *listener, void *data) {
 		return;
 	}
 	view->type = ROOTS_WL_SHELL_VIEW;
+	view->width = surface->surface->current->width;
+	view->height = surface->surface->current->height;
 
 	view->wl_shell_surface = surface;
 	view->roots_wl_shell_surface = roots_surface;

rootston/xdg_shell_v6.c

@@ -10,6 +10,52 @@
 #include "rootston/server.h"
 #include "rootston/input.h"
 
+static void popup_destroy(struct roots_view_child *child) {
+	assert(child->destroy == popup_destroy);
+	struct roots_xdg_popup_v6 *popup = (struct roots_xdg_popup_v6 *)child;
+	if (popup == NULL) {
+		return;
+	}
+	wl_list_remove(&popup->destroy.link);
+	wl_list_remove(&popup->new_popup.link);
+	view_child_finish(&popup->view_child);
+	free(popup);
+}
+
+static void popup_handle_destroy(struct wl_listener *listener, void *data) {
+	struct roots_xdg_popup_v6 *popup =
+		wl_container_of(listener, popup, destroy);
+	popup_destroy((struct roots_view_child *)popup);
+}
+
+static struct roots_xdg_popup_v6 *popup_create(struct roots_view *view,
+	struct wlr_xdg_popup_v6 *wlr_popup);
+
+static void popup_handle_new_popup(struct wl_listener *listener, void *data) {
+	struct roots_xdg_popup_v6 *popup =
+		wl_container_of(listener, popup, new_popup);
+	struct wlr_xdg_popup_v6 *wlr_popup = data;
+	popup_create(popup->view_child.view, wlr_popup);
+}
+
+static struct roots_xdg_popup_v6 *popup_create(struct roots_view *view,
+		struct wlr_xdg_popup_v6 *wlr_popup) {
+	struct roots_xdg_popup_v6 *popup =
+		calloc(1, sizeof(struct roots_xdg_popup_v6));
+	if (popup == NULL) {
+		return NULL;
+	}
+	popup->wlr_popup = wlr_popup;
+	popup->view_child.destroy = popup_destroy;
+	view_child_init(&popup->view_child, view, wlr_popup->base->surface);
+	popup->destroy.notify = popup_handle_destroy;
+	wl_signal_add(&wlr_popup->base->events.destroy, &popup->destroy);
+	popup->new_popup.notify = popup_handle_new_popup;
+	wl_signal_add(&wlr_popup->base->events.new_popup, &popup->new_popup);
+	return popup;
+}
+
+
 static void get_size(const struct roots_view *view, struct wlr_box *box) {
 	assert(view->type == ROOTS_XDG_SHELL_V6_VIEW);
 	struct wlr_xdg_surface_v6 *surface = view->xdg_surface_v6;
@@ -102,8 +148,7 @@ static void move_resize(struct roots_view *view, double x, double y,
 	if (serial > 0) {
 		roots_surface->pending_move_resize_configure_serial = serial;
 	} else if (roots_surface->pending_move_resize_configure_serial == 0) {
-		view->x = x;
+		view_update_position(view, x, y);
-		view->y = y;
 	}
 }
 
@@ -192,26 +237,32 @@ static void handle_request_fullscreen(struct wl_listener *listener,
 	view_set_fullscreen(view, e->fullscreen, e->output);
 }
 
-static void handle_commit(struct wl_listener *listener, void *data) {
+static void handle_surface_commit(struct wl_listener *listener, void *data) {
 	struct roots_xdg_surface_v6 *roots_surface =
-		wl_container_of(listener, roots_surface, commit);
+		wl_container_of(listener, roots_surface, surface_commit);
 	struct roots_view *view = roots_surface->view;
 	struct wlr_xdg_surface_v6 *surface = view->xdg_surface_v6;
 
+	view_apply_damage(view);
+
+	struct wlr_box size;
+	get_size(view, &size);
+	view_update_size(view, size.width, size.height);
+
 	uint32_t pending_serial =
 		roots_surface->pending_move_resize_configure_serial;
 	if (pending_serial > 0 && pending_serial >= surface->configure_serial) {
-		struct wlr_box size;
+		double x = view->x;
-		get_size(view, &size);
+		double y = view->y;
-
 		if (view->pending_move_resize.update_x) {
-			view->x = view->pending_move_resize.x +
+			x = view->pending_move_resize.x + view->pending_move_resize.width -
-				view->pending_move_resize.width - size.width;
+				size.width;
 		}
 		if (view->pending_move_resize.update_y) {
-			view->y = view->pending_move_resize.y +
+			y = view->pending_move_resize.y + view->pending_move_resize.height -
-				view->pending_move_resize.height - size.height;
+				size.height;
 		}
+		view_update_position(view, x, y);
 
 		if (pending_serial == surface->configure_serial) {
 			roots_surface->pending_move_resize_configure_serial = 0;
@@ -219,15 +270,26 @@ static void handle_commit(struct wl_listener *listener, void *data) {
 	}
 }
 
+static void handle_new_popup(struct wl_listener *listener, void *data) {
+	struct roots_xdg_surface_v6 *roots_xdg_surface =
+		wl_container_of(listener, roots_xdg_surface, new_popup);
+	struct wlr_xdg_popup_v6 *wlr_popup = data;
+	popup_create(roots_xdg_surface->view, wlr_popup);
+}
+
 static void handle_destroy(struct wl_listener *listener, void *data) {
 	struct roots_xdg_surface_v6 *roots_xdg_surface =
 		wl_container_of(listener, roots_xdg_surface, destroy);
-	wl_list_remove(&roots_xdg_surface->commit.link);
+	wl_list_remove(&roots_xdg_surface->surface_commit.link);
 	wl_list_remove(&roots_xdg_surface->destroy.link);
+	wl_list_remove(&roots_xdg_surface->new_popup.link);
 	wl_list_remove(&roots_xdg_surface->request_move.link);
 	wl_list_remove(&roots_xdg_surface->request_resize.link);
+	wl_list_remove(&roots_xdg_surface->request_maximize.link);
+	wl_list_remove(&roots_xdg_surface->request_fullscreen.link);
 	wl_list_remove(&roots_xdg_surface->view->link);
-	view_destroy(roots_xdg_surface->view);
+	view_finish(roots_xdg_surface->view);
+	free(roots_xdg_surface->view);
 	free(roots_xdg_surface);
 }
 
@@ -252,8 +314,9 @@ void handle_xdg_shell_v6_surface(struct wl_listener *listener, void *data) {
 	if (!roots_surface) {
 		return;
 	}
-	roots_surface->commit.notify = handle_commit;
+	roots_surface->surface_commit.notify = handle_surface_commit;
-	wl_signal_add(&surface->surface->events.commit, &roots_surface->commit);
+	wl_signal_add(&surface->surface->events.commit,
+		&roots_surface->surface_commit);
 	roots_surface->destroy.notify = handle_destroy;
 	wl_signal_add(&surface->events.destroy, &roots_surface->destroy);
 	roots_surface->request_move.notify = handle_request_move;
@@ -267,6 +330,8 @@ void handle_xdg_shell_v6_surface(struct wl_listener *listener, void *data) {
 	roots_surface->request_fullscreen.notify = handle_request_fullscreen;
 	wl_signal_add(&surface->events.request_fullscreen,
 		&roots_surface->request_fullscreen);
+	roots_surface->new_popup.notify = handle_new_popup;
+	wl_signal_add(&surface->events.new_popup, &roots_surface->new_popup);
 
 	struct roots_view *view = calloc(1, sizeof(struct roots_view));
 	if (!view) {
@@ -274,10 +339,10 @@ void handle_xdg_shell_v6_surface(struct wl_listener *listener, void *data) {
 		return;
 	}
 	view->type = ROOTS_XDG_SHELL_V6_VIEW;
+
 	view->xdg_surface_v6 = surface;
 	view->roots_xdg_surface_v6 = roots_surface;
 	view->wlr_surface = surface->surface;
-	view->get_size = get_size;
 	view->activate = activate;
 	view->resize = resize;
 	view->move_resize = move_resize;
@@ -285,6 +350,12 @@ void handle_xdg_shell_v6_surface(struct wl_listener *listener, void *data) {
 	view->set_fullscreen = set_fullscreen;
 	view->close = close;
 	roots_surface->view = view;
+
+	struct wlr_box box;
+	get_size(view, &box);
+	view->width = box.width;
+	view->height = box.height;
+
 	view_init(view, desktop);
 	wl_list_insert(&desktop->views, &view->link);
 

rootston/xwayland.c

@@ -18,8 +18,7 @@ static void activate(struct roots_view *view, bool active) {
 static void move(struct roots_view *view, double x, double y) {
 	assert(view->type == ROOTS_XWAYLAND_VIEW);
 	struct wlr_xwayland_surface *xwayland_surface = view->xwayland_surface;
-	view->x = x;
+	view_update_position(view, x, y);
-	view->y = y;
 	wlr_xwayland_surface_configure(xwayland_surface, x, y,
 		xwayland_surface->width, xwayland_surface->height);
 }
@@ -122,7 +121,8 @@ static void handle_destroy(struct wl_listener *listener, void *data) {
 	if (xwayland_surface->mapped) {
 		wl_list_remove(&roots_surface->view->link);
 	}
-	view_destroy(roots_surface->view);
+	view_finish(roots_surface->view);
+	free(roots_surface->view);
 	free(roots_surface);
 }
 
@@ -133,8 +133,7 @@ static void handle_request_configure(struct wl_listener *listener, void *data) {
 		roots_surface->view->xwayland_surface;
 	struct wlr_xwayland_surface_configure_event *event = data;
 
-	roots_surface->view->x = (double)event->x;
+	view_update_position(roots_surface->view, event->x, event->y);
-	roots_surface->view->y = (double)event->y;
 
 	wlr_xwayland_surface_configure(xwayland_surface, event->x, event->y,
 		event->width, event->height);
@@ -206,19 +205,25 @@ static void handle_surface_commit(struct wl_listener *listener, void *data) {
 	struct roots_view *view = roots_surface->view;
 	struct wlr_surface *wlr_surface = view->wlr_surface;
 
+	view_apply_damage(view);
+
 	int width = wlr_surface->current->width;
 	int height = wlr_surface->current->height;
+	view_update_size(view, width, height);
 
+	double x = view->x;
+	double y = view->y;
 	if (view->pending_move_resize.update_x) {
-		view->x = view->pending_move_resize.x +
+		x = view->pending_move_resize.x + view->pending_move_resize.width -
-			view->pending_move_resize.width - width;
+			width;
 		view->pending_move_resize.update_x = false;
 	}
 	if (view->pending_move_resize.update_y) {
-		view->y = view->pending_move_resize.y +
+		y = view->pending_move_resize.y + view->pending_move_resize.height -
-			view->pending_move_resize.height - height;
+			height;
 		view->pending_move_resize.update_y = false;
 	}
+	view_update_position(view, x, y);
 }
 
 static void handle_map_notify(struct wl_listener *listener, void *data) {
@@ -229,24 +234,48 @@ static void handle_map_notify(struct wl_listener *listener, void *data) {
 	struct roots_desktop *desktop = view->desktop;
 
 	view->wlr_surface = xsurface->surface;
-	view->x = (double)xsurface->x;
+	view->x = xsurface->x;
-	view->y = (double)xsurface->y;
+	view->y = xsurface->y;
+	view->width = xsurface->surface->current->width;
+	view->height = xsurface->surface->current->height;
+	wl_list_insert(&desktop->views, &view->link);
+
+	struct wlr_subsurface *subsurface;
+	wl_list_for_each(subsurface, &view->wlr_surface->subsurface_list,
+			parent_link) {
+		subsurface_create(view, subsurface);
+	}
+
+	view_damage_whole(view);
 
 	roots_surface->surface_commit.notify = handle_surface_commit;
 	wl_signal_add(&xsurface->surface->events.commit,
 		&roots_surface->surface_commit);
-
-	wl_list_insert(&desktop->views, &view->link);
 }
 
 static void handle_unmap_notify(struct wl_listener *listener, void *data) {
 	struct roots_xwayland_surface *roots_surface =
 		wl_container_of(listener, roots_surface, unmap_notify);
-	roots_surface->view->wlr_surface = NULL;
+	struct roots_view *view = roots_surface->view;
 
 	wl_list_remove(&roots_surface->surface_commit.link);
 
-	wl_list_remove(&roots_surface->view->link);
+	view_damage_whole(view);
+
+	struct roots_view_child *child, *tmp;
+	wl_list_for_each_safe(child, tmp, &view->children, link) {
+		child->destroy(child);
+	}
+
+	if (view->fullscreen_output != NULL) {
+		output_damage_whole(view->fullscreen_output);
+		view->fullscreen_output->fullscreen_view = NULL;
+		view->fullscreen_output = NULL;
+	}
+
+	view->wlr_surface = NULL;
+	view->width = view->height = 0;
+	wl_list_remove(&view->link);
 }
 
 void handle_xwayland_surface(struct wl_listener *listener, void *data) {
@@ -296,6 +325,8 @@ void handle_xwayland_surface(struct wl_listener *listener, void *data) {
 	view->type = ROOTS_XWAYLAND_VIEW;
 	view->x = (double)surface->x;
 	view->y = (double)surface->y;
+	view->width = surface->surface->current->width;
+	view->height = surface->surface->current->height;
 
 	view->xwayland_surface = surface;
 	view->roots_xwayland_surface = roots_surface;

types/wlr_box.c

@@ -67,47 +67,79 @@ bool wlr_box_contains_point(const struct wlr_box *box, double x, double y) {
 }
 
 void wlr_box_transform(const struct wlr_box *box,
-		enum wl_output_transform transform, struct wlr_box *dest) {
+		enum wl_output_transform transform, int width, int height,
+		struct wlr_box *dest) {
+	struct wlr_box src = *box;
+
 	if (transform % 2 == 0) {
-		dest->width = box->width;
+		dest->width = src.width;
-		dest->height = box->height;
+		dest->height = src.height;
 	} else {
-		dest->width = box->height;
+		dest->width = src.height;
-		dest->height = box->width;
+		dest->height = src.width;
 	}
 
 	switch (transform) {
 	case WL_OUTPUT_TRANSFORM_NORMAL:
-		dest->x = box->x;
+		dest->x = src.x;
-		dest->y = box->y;
+		dest->y = src.y;
 		break;
 	case WL_OUTPUT_TRANSFORM_90:
-		dest->x = box->y;
+		dest->x = src.y;
-		dest->y = box->width - box->x;
+		dest->y = width - src.x - src.width;
 		break;
 	case WL_OUTPUT_TRANSFORM_180:
-		dest->x = box->width - box->x;
+		dest->x = width - src.x - src.width;
-		dest->y = box->height - box->y;
+		dest->y = height - src.y - src.height;
 		break;
 	case WL_OUTPUT_TRANSFORM_270:
-		dest->x = box->height - box->y;
+		dest->x = height - src.y - src.height;
-		dest->y = box->x;
+		dest->y = src.x;
 		break;
 	case WL_OUTPUT_TRANSFORM_FLIPPED:
-		dest->x = box->width - box->x;
+		dest->x = width - src.x - src.width;
-		dest->y = box->y;
+		dest->y = src.y;
 		break;
 	case WL_OUTPUT_TRANSFORM_FLIPPED_90:
-		dest->x = box->height - box->y;
+		dest->x = height - src.y - src.height;
-		dest->y = box->width - box->x;
+		dest->y = width - src.x - src.width;
 		break;
 	case WL_OUTPUT_TRANSFORM_FLIPPED_180:
-		dest->x = box->x;
+		dest->x = src.x;
-		dest->y = box->height - box->y;
+		dest->y = height - src.y - src.height;
 		break;
 	case WL_OUTPUT_TRANSFORM_FLIPPED_270:
-		dest->x = box->y;
+		dest->x = src.y;
-		dest->y = box->x;
+		dest->y = src.x;
 		break;
 	}
 }
+
+void wlr_box_rotated_bounds(const struct wlr_box *box, float rotation,
+		struct wlr_box *dest) {
+	if (rotation == 0) {
+		*dest = *box;
+		return;
+	}
+
+	double ox = box->x + (double)box->width/2;
+	double oy = box->y + (double)box->height/2;
+
+	double c = fabs(cos(rotation));
+	double s = fabs(sin(rotation));
+
+	double x1 = ox + (box->x - ox) * c + (box->y - oy) * s;
+	double x2 = ox +
+		(box->x + box->width - ox) * c +
+		(box->y + box->height - oy) * s;
+
+	double y1 = oy + (box->x - ox) * s + (box->y - oy) * c;
+	double y2 = oy +
+		(box->x + box->width - ox) * s +
+		(box->y + box->height - oy) * c;
+
+	dest->x = floor(fmin(x1, x2));
+	dest->width = ceil(fmax(x1, x2) - fmin(x1, x2));
+	dest->y = floor(fmin(y1, y2));
+	dest->height = ceil(fmax(y1, y2) - fmin(y1, y2));
+}

types/wlr_compositor.c

@@ -35,7 +35,7 @@ static void wl_compositor_create_surface(struct wl_client *client,
 
 	wl_list_insert(&compositor->surfaces,
 		wl_resource_get_link(surface_resource));
-	wl_signal_emit(&compositor->events.create_surface, surface);
+	wl_signal_emit(&compositor->events.new_surface, surface);
 }
 
 static void wl_compositor_create_region(struct wl_client *client,
@@ -185,7 +185,7 @@ struct wlr_compositor *wlr_compositor_create(struct wl_display *display,
 
 	wl_list_init(&compositor->wl_resources);
 	wl_list_init(&compositor->surfaces);
-	wl_signal_init(&compositor->events.create_surface);
+	wl_signal_init(&compositor->events.new_surface);
 
 	compositor->display_destroy.notify = handle_display_destroy;
 	wl_display_add_destroy_listener(display, &compositor->display_destroy);

types/wlr_data_device.c

@@ -457,6 +457,7 @@ static void wlr_drag_end(struct wlr_drag *drag) {
 		if (drag->icon) {
 			drag->icon->mapped = false;
 			wl_list_remove(&drag->icon_destroy.link);
+			wl_signal_emit(&drag->icon->events.map, drag->icon);
 		}
 
 		free(drag);
@@ -676,8 +677,8 @@ static struct wlr_drag_icon *wlr_drag_icon_create(
 	icon->is_pointer = is_pointer;
 	icon->touch_id = touch_id;
 	icon->mapped = true;
-	wl_list_insert(&client->seat->drag_icons, &icon->link);
 
+	wl_signal_init(&icon->events.map);
 	wl_signal_init(&icon->events.destroy);
 
 	wl_signal_add(&icon->surface->events.destroy, &icon->surface_destroy);
@@ -689,6 +690,9 @@ static struct wlr_drag_icon *wlr_drag_icon_create(
 	wl_signal_add(&client->events.destroy, &icon->seat_client_destroy);
 	icon->seat_client_destroy.notify = handle_drag_icon_seat_client_destroy;
 
+	wl_list_insert(&client->seat->drag_icons, &icon->link);
+	wl_signal_emit(&client->seat->events.new_drag_icon, icon);
+
 	return icon;
 }
 

types/wlr_output.c

@@ -10,10 +10,9 @@
 #include <wlr/types/wlr_surface.h>
 #include <wlr/interfaces/wlr_output.h>
 #include <wlr/util/log.h>
-#include <GLES2/gl2.h>
 #include <wlr/render/matrix.h>
-#include <wlr/render/gles2.h>
 #include <wlr/render.h>
+#include <wlr/util/region.h>
 
 static void wl_output_send_to_resource(struct wl_resource *resource) {
 	assert(resource);
@@ -183,11 +182,6 @@ void wlr_output_update_mode(struct wlr_output *output,
 
 void wlr_output_update_custom_mode(struct wlr_output *output, int32_t width,
 		int32_t height, int32_t refresh) {
-	if (output->width == width && output->height == height &&
-			output->refresh == refresh) {
-		return;
-	}
-
 	output->width = width;
 	output->height = height;
 	wlr_output_update_matrix(output);
@@ -266,15 +260,19 @@ void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,
 	wl_list_init(&output->cursors);
 	wl_list_init(&output->wl_resources);
 	wl_signal_init(&output->events.frame);
+	wl_signal_init(&output->events.needs_swap);
 	wl_signal_init(&output->events.swap_buffers);
 	wl_signal_init(&output->events.enable);
 	wl_signal_init(&output->events.mode);
 	wl_signal_init(&output->events.scale);
 	wl_signal_init(&output->events.transform);
 	wl_signal_init(&output->events.destroy);
+	pixman_region32_init(&output->damage);
 
 	output->display_destroy.notify = handle_display_destroy;
 	wl_display_add_destroy_listener(display, &output->display_destroy);
+
+	output->frame_pending = true;
 }
 
 void wlr_output_destroy(struct wlr_output *output) {
@@ -286,6 +284,7 @@ void wlr_output_destroy(struct wlr_output *output) {
 	wlr_output_destroy_global(output);
 	wlr_output_set_fullscreen_surface(output, NULL);
 
+	wl_signal_emit(&output->backend->events.output_remove, output);
 	wl_signal_emit(&output->events.destroy, output);
 
 	struct wlr_output_mode *mode, *tmp_mode;
@@ -299,6 +298,8 @@ void wlr_output_destroy(struct wlr_output *output) {
 		wlr_output_cursor_destroy(cursor);
 	}
 
+	pixman_region32_fini(&output->damage);
+
 	if (output->impl && output->impl->destroy) {
 		output->impl->destroy(output);
 	} else {
@@ -306,55 +307,93 @@ void wlr_output_destroy(struct wlr_output *output) {
 	}
 }
 
-void wlr_output_effective_resolution(struct wlr_output *output,
+void wlr_output_transformed_resolution(struct wlr_output *output,
 		int *width, int *height) {
-	if (output->transform % 2 == 1) {
+	if (output->transform % 2 == 0) {
-		*width = output->height;
-		*height = output->width;
-	} else {
 		*width = output->width;
 		*height = output->height;
+	} else {
+		*width = output->height;
+		*height = output->width;
 	}
+}
+
+void wlr_output_effective_resolution(struct wlr_output *output,
+		int *width, int *height) {
+	wlr_output_transformed_resolution(output, width, height);
 	*width /= output->scale;
 	*height /= output->scale;
 }
 
-void wlr_output_make_current(struct wlr_output *output) {
+bool wlr_output_make_current(struct wlr_output *output, int *buffer_age) {
-	output->impl->make_current(output);
+	return output->impl->make_current(output, buffer_age);
 }
 
-static void output_fullscreen_surface_render(struct wlr_output *output,
+static void output_scissor(struct wlr_output *output, pixman_box32_t *rect) {
-		struct wlr_surface *surface, const struct timespec *when) {
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	assert(renderer);
+
+	struct wlr_box box = {
+		.x = rect->x1,
+		.y = rect->y1,
+		.width = rect->x2 - rect->x1,
+		.height = rect->y2 - rect->y1,
+	};
+
+	int ow, oh;
+	wlr_output_transformed_resolution(output, &ow, &oh);
+
+	// Scissor is in renderer coordinates, ie. upside down
+	enum wl_output_transform transform = wlr_output_transform_compose(
+		wlr_output_transform_invert(output->transform),
+		WL_OUTPUT_TRANSFORM_FLIPPED_180);
+	wlr_box_transform(&box, transform, ow, oh, &box);
+
+	wlr_renderer_scissor(renderer, &box);
+}
+
+static void output_fullscreen_surface_get_box(struct wlr_output *output,
+		struct wlr_surface *surface, struct wlr_box *box) {
 	int width, height;
 	wlr_output_effective_resolution(output, &width, &height);
 
 	int x = (width - surface->current->width) / 2;
 	int y = (height - surface->current->height) / 2;
 
-	int render_x = x * output->scale;
+	box->x = x * output->scale;
-	int render_y = y * output->scale;
+	box->y = y * output->scale;
-	int render_width = surface->current->width * output->scale;
+	box->width = surface->current->width * output->scale;
-	int render_height = surface->current->height * output->scale;
+	box->height = surface->current->height * output->scale;
+}
 
-	glViewport(0, 0, output->width, output->height);
+static void output_fullscreen_surface_render(struct wlr_output *output,
-	glClearColor(0, 0, 0, 0);
+		struct wlr_surface *surface, const struct timespec *when,
-	glClear(GL_COLOR_BUFFER_BIT);
+		pixman_region32_t *damage) {
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	assert(renderer);
 
 	if (!wlr_surface_has_buffer(surface)) {
+		wlr_renderer_clear(renderer, &(float[]){0, 0, 0, 0});
 		return;
 	}
 
-	float translate[16];
+	struct wlr_box box;
-	wlr_matrix_translate(&translate, render_x, render_y, 0);
+	output_fullscreen_surface_get_box(output, surface, &box);
-
-	float scale[16];
-	wlr_matrix_scale(&scale, render_width, render_height, 1);
 
 	float matrix[16];
-	wlr_matrix_mul(&translate, &scale, &matrix);
+	enum wl_output_transform transform =
-	wlr_matrix_mul(&output->transform_matrix, &matrix, &matrix);
+		wlr_output_transform_invert(surface->current->transform);
+	wlr_matrix_project_box(&matrix, &box, transform, 0,
+		&output->transform_matrix);
 
-	wlr_render_with_matrix(surface->renderer, surface->texture, &matrix);
+	int nrects;
+	pixman_box32_t *rects = pixman_region32_rectangles(damage, &nrects);
+	for (int i = 0; i < nrects; ++i) {
+		output_scissor(output, &rects[i]);
+		wlr_renderer_clear(renderer, &(float[]){0, 0, 0, 0});
+		wlr_render_with_matrix(surface->renderer, surface->texture, &matrix);
+	}
+	wlr_renderer_scissor(renderer, NULL);
 
 	wlr_surface_send_frame_done(surface, when);
 }
@@ -376,64 +415,133 @@ static void output_cursor_get_box(struct wlr_output_cursor *cursor,
 }
 
 static void output_cursor_render(struct wlr_output_cursor *cursor,
-		const struct timespec *when) {
+		const struct timespec *when, pixman_region32_t *damage) {
+	struct wlr_renderer *renderer =
+		wlr_backend_get_renderer(cursor->output->backend);
+	assert(renderer);
+
 	struct wlr_texture *texture = cursor->texture;
-	struct wlr_renderer *renderer = cursor->renderer;
 	if (cursor->surface != NULL) {
 		texture = cursor->surface->texture;
-		renderer = cursor->surface->renderer;
 	}
-
+	if (texture == NULL) {
-	if (texture == NULL || renderer == NULL) {
 		return;
 	}
 
-	glViewport(0, 0, cursor->output->width, cursor->output->height);
+	struct wlr_box box;
-	glEnable(GL_BLEND);
+	output_cursor_get_box(cursor, &box);
-	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
-
-	struct wlr_box cursor_box;
-	output_cursor_get_box(cursor, &cursor_box);
-
-	float translate[16];
-	wlr_matrix_translate(&translate, cursor_box.x, cursor_box.y, 0);
 
-	float scale[16];
+	pixman_region32_t surface_damage;
-	wlr_matrix_scale(&scale, cursor_box.width, cursor_box.height, 1);
+	pixman_region32_init(&surface_damage);
+	pixman_region32_union_rect(&surface_damage, &surface_damage, box.x, box.y,
+		box.width, box.height);
+	pixman_region32_intersect(&surface_damage, &surface_damage, damage);
+	if (!pixman_region32_not_empty(&surface_damage)) {
+		goto surface_damage_finish;
+	}
 
 	float matrix[16];
-	wlr_matrix_mul(&translate, &scale, &matrix);
+	wlr_matrix_project_box(&matrix, &box, WL_OUTPUT_TRANSFORM_NORMAL, 0,
-	wlr_matrix_mul(&cursor->output->transform_matrix, &matrix, &matrix);
+		&cursor->output->transform_matrix);
 
-	wlr_render_with_matrix(renderer, texture, &matrix);
+	int nrects;
+	pixman_box32_t *rects = pixman_region32_rectangles(&surface_damage, &nrects);
+	for (int i = 0; i < nrects; ++i) {
+		output_scissor(cursor->output, &rects[i]);
+		wlr_render_with_matrix(renderer, texture, &matrix);
+	}
+	wlr_renderer_scissor(renderer, NULL);
 
 	if (cursor->surface != NULL) {
 		wlr_surface_send_frame_done(cursor->surface, when);
 	}
+
+surface_damage_finish:
+	pixman_region32_fini(&surface_damage);
 }
 
-void wlr_output_swap_buffers(struct wlr_output *output) {
+bool wlr_output_swap_buffers(struct wlr_output *output, struct timespec *when,
-	wl_signal_emit(&output->events.swap_buffers, &output);
+		pixman_region32_t *damage) {
+	if (output->frame_pending) {
+		wlr_log(L_ERROR, "Tried to swap buffers when a frame is pending");
+		return false;
+	}
+	if (output->idle_frame != NULL) {
+		wl_event_source_remove(output->idle_frame);
+		output->idle_frame = NULL;
+	}
 
-	struct timespec now;
+	wl_signal_emit(&output->events.swap_buffers, damage);
-	clock_gettime(CLOCK_MONOTONIC, &now);
 
-	if (output->fullscreen_surface != NULL) {
+	int width, height;
-		output_fullscreen_surface_render(output, output->fullscreen_surface,
+	wlr_output_transformed_resolution(output, &width, &height);
-			&now);
+
+	pixman_region32_t render_damage;
+	pixman_region32_init(&render_damage);
+	pixman_region32_union_rect(&render_damage, &render_damage, 0, 0,
+		width, height);
+	if (damage != NULL) {
+		// Damage tracking supported
+		pixman_region32_intersect(&render_damage, &render_damage, damage);
+	}
+
+	if (when == NULL) {
+		struct timespec now;
+		clock_gettime(CLOCK_MONOTONIC, &now);
+		when = &now;
 	}
 
-	struct wlr_output_cursor *cursor;
+	if (pixman_region32_not_empty(&render_damage)) {
-	wl_list_for_each(cursor, &output->cursors, link) {
+		if (output->fullscreen_surface != NULL) {
-		if (!cursor->enabled || !cursor->visible ||
+			output_fullscreen_surface_render(output, output->fullscreen_surface,
-				output->hardware_cursor == cursor) {
+				when, &render_damage);
-			continue;
+		}
+
+		struct wlr_output_cursor *cursor;
+		wl_list_for_each(cursor, &output->cursors, link) {
+			if (!cursor->enabled || !cursor->visible ||
+					output->hardware_cursor == cursor) {
+				continue;
+			}
+			output_cursor_render(cursor, when, &render_damage);
 		}
-		output_cursor_render(cursor, &now);
 	}
 
-	output->impl->swap_buffers(output);
+	// TODO: provide `damage` (not `render_damage`) to backend
+	if (!output->impl->swap_buffers(output)) {
+		return false;
+	}
+
+	output->frame_pending = true;
 	output->needs_swap = false;
+	pixman_region32_clear(&output->damage);
+
+	pixman_region32_fini(&render_damage);
+	return true;
+}
+
+void wlr_output_send_frame(struct wlr_output *output) {
+	output->frame_pending = false;
+	wl_signal_emit(&output->events.frame, output);
+}
+
+static void schedule_frame_handle_idle_timer(void *data) {
+	struct wlr_output *output = data;
+	output->idle_frame = NULL;
+	if (!output->frame_pending) {
+		wlr_output_send_frame(output);
+	}
+}
+
+void wlr_output_schedule_frame(struct wlr_output *output) {
+	if (output->frame_pending || output->idle_frame != NULL) {
+		return;
+	}
+
+	// TODO: ask the backend to send a frame event when appropriate instead
+	struct wl_event_loop *ev = wl_display_get_event_loop(output->display);
+	output->idle_frame =
+		wl_event_loop_add_idle(ev, schedule_frame_handle_idle_timer, output);
 }
 
 void wlr_output_set_gamma(struct wlr_output *output,
@@ -450,12 +558,26 @@ uint32_t wlr_output_get_gamma_size(struct wlr_output *output) {
 	return output->impl->get_gamma_size(output);
 }
 
+void wlr_output_update_needs_swap(struct wlr_output *output) {
+	output->needs_swap = true;
+	wl_signal_emit(&output->events.needs_swap, output);
+}
+
+static void output_damage_whole(struct wlr_output *output) {
+	int width, height;
+	wlr_output_transformed_resolution(output, &width, &height);
+
+	pixman_region32_union_rect(&output->damage, &output->damage, 0, 0,
+		width, height);
+	wlr_output_update_needs_swap(output);
+}
+
 static void output_fullscreen_surface_reset(struct wlr_output *output) {
 	if (output->fullscreen_surface != NULL) {
 		wl_list_remove(&output->fullscreen_surface_commit.link);
 		wl_list_remove(&output->fullscreen_surface_destroy.link);
 		output->fullscreen_surface = NULL;
-		output->needs_swap = true;
+		output_damage_whole(output);
 	}
 }
 
@@ -463,7 +585,28 @@ static void output_fullscreen_surface_handle_commit(
 		struct wl_listener *listener, void *data) {
 	struct wlr_output *output = wl_container_of(listener, output,
 		fullscreen_surface_commit);
-	output->needs_swap = true;
+	struct wlr_surface *surface = output->fullscreen_surface;
+
+	if (output->fullscreen_width != surface->current->width ||
+			output->fullscreen_height != surface->current->height) {
+		output->fullscreen_width = surface->current->width;
+		output->fullscreen_height = surface->current->height;
+		output_damage_whole(output);
+		return;
+	}
+
+	struct wlr_box box;
+	output_fullscreen_surface_get_box(output, surface, &box);
+
+	pixman_region32_t damage;
+	pixman_region32_init(&damage);
+	pixman_region32_copy(&damage, &surface->current->surface_damage);
+	wlr_region_scale(&damage, &damage, output->scale);
+	pixman_region32_translate(&damage, box.x, box.y);
+	pixman_region32_union(&output->damage, &output->damage, &damage);
+	pixman_region32_fini(&damage);
+
+	wlr_output_update_needs_swap(output);
 }
 
 static void output_fullscreen_surface_handle_destroy(
@@ -484,7 +627,7 @@ void wlr_output_set_fullscreen_surface(struct wlr_output *output,
 	output_fullscreen_surface_reset(output);
 
 	output->fullscreen_surface = surface;
-	output->needs_swap = true;
+	output_damage_whole(output);
 
 	if (surface == NULL) {
 		return;
@@ -500,9 +643,17 @@ void wlr_output_set_fullscreen_surface(struct wlr_output *output,
 }
 
 
+static void output_cursor_damage_whole(struct wlr_output_cursor *cursor) {
+	struct wlr_box box;
+	output_cursor_get_box(cursor, &box);
+	pixman_region32_union_rect(&cursor->output->damage, &cursor->output->damage,
+		box.x, box.y, box.width, box.height);
+	wlr_output_update_needs_swap(cursor->output);
+}
+
 static void output_cursor_reset(struct wlr_output_cursor *cursor) {
 	if (cursor->output->hardware_cursor != cursor) {
-		cursor->output->needs_swap = true;
+		output_cursor_damage_whole(cursor);
 	}
 	if (cursor->surface != NULL) {
 		wl_list_remove(&cursor->surface_commit.link);
@@ -514,6 +665,10 @@ static void output_cursor_reset(struct wlr_output_cursor *cursor) {
 bool wlr_output_cursor_set_image(struct wlr_output_cursor *cursor,
 		const uint8_t *pixels, int32_t stride, uint32_t width, uint32_t height,
 		int32_t hotspot_x, int32_t hotspot_y) {
+	struct wlr_renderer *renderer =
+		wlr_backend_get_renderer(cursor->output->backend);
+	assert(renderer);
+
 	output_cursor_reset(cursor);
 
 	cursor->width = width;
@@ -536,22 +691,15 @@ bool wlr_output_cursor_set_image(struct wlr_output_cursor *cursor,
 	}
 
 	wlr_log(L_DEBUG, "Falling back to software cursor");
-	cursor->output->needs_swap = true;
+	output_cursor_damage_whole(cursor);
 
 	cursor->enabled = pixels != NULL;
 	if (!cursor->enabled) {
 		return true;
 	}
 
-	if (cursor->renderer == NULL) {
-		cursor->renderer = wlr_gles2_renderer_create(cursor->output->backend);
-		if (cursor->renderer == NULL) {
-			return false;
-		}
-	}
-
 	if (cursor->texture == NULL) {
-		cursor->texture = wlr_render_texture_create(cursor->renderer);
+		cursor->texture = wlr_render_texture_create(renderer);
 		if (cursor->texture == NULL) {
 			return false;
 		}
@@ -564,10 +712,8 @@ bool wlr_output_cursor_set_image(struct wlr_output_cursor *cursor,
 static void output_cursor_update_visible(struct wlr_output_cursor *cursor) {
 	struct wlr_box output_box;
 	output_box.x = output_box.y = 0;
-	wlr_output_effective_resolution(cursor->output, &output_box.width,
+	wlr_output_transformed_resolution(cursor->output, &output_box.width,
 		&output_box.height);
-	output_box.width *= cursor->output->scale;
-	output_box.height *= cursor->output->scale;
 
 	struct wlr_box cursor_box;
 	output_cursor_get_box(cursor, &cursor_box);
@@ -589,13 +735,17 @@ static void output_cursor_update_visible(struct wlr_output_cursor *cursor) {
 }
 
 static void output_cursor_commit(struct wlr_output_cursor *cursor) {
+	if (cursor->output->hardware_cursor != cursor) {
+		output_cursor_damage_whole(cursor);
+	}
+
 	// Some clients commit a cursor surface with a NULL buffer to hide it.
 	cursor->enabled = wlr_surface_has_buffer(cursor->surface);
 	cursor->width = cursor->surface->current->width * cursor->output->scale;
 	cursor->height = cursor->surface->current->height * cursor->output->scale;
 
 	if (cursor->output->hardware_cursor != cursor) {
-		cursor->output->needs_swap = true;
+		output_cursor_damage_whole(cursor);
 	} else {
 		// TODO: upload pixels
 
@@ -625,14 +775,23 @@ void wlr_output_cursor_set_surface(struct wlr_output_cursor *cursor,
 		return;
 	}
 
-	cursor->hotspot_x = hotspot_x * cursor->output->scale;
+	hotspot_x *= cursor->output->scale;
-	cursor->hotspot_y = hotspot_y * cursor->output->scale;
+	hotspot_y *= cursor->output->scale;
 
 	if (surface && surface == cursor->surface) {
+		// Only update the hotspot: surface hasn't changed
+
+		if (cursor->output->hardware_cursor != cursor) {
+			output_cursor_damage_whole(cursor);
+		}
+		cursor->hotspot_x = hotspot_x;
+		cursor->hotspot_y = hotspot_y;
+		if (cursor->output->hardware_cursor != cursor) {
+			output_cursor_damage_whole(cursor);
+		}
+
 		if (cursor->output->hardware_cursor == cursor &&
 				cursor->output->impl->set_cursor) {
-			// If the surface hasn't changed and it's an hardware cursor, only
-			// update the hotspot
 			cursor->output->impl->set_cursor(cursor->output, NULL, 0, 0, 0,
 				hotspot_x, hotspot_y, false);
 		}
@@ -651,6 +810,8 @@ void wlr_output_cursor_set_surface(struct wlr_output_cursor *cursor,
 	}
 
 	cursor->surface = surface;
+	cursor->hotspot_x = hotspot_x;
+	cursor->hotspot_y = hotspot_y;
 
 	if (surface != NULL) {
 		wl_signal_add(&surface->events.commit, &cursor->surface_commit);
@@ -670,6 +831,14 @@ void wlr_output_cursor_set_surface(struct wlr_output_cursor *cursor,
 
 bool wlr_output_cursor_move(struct wlr_output_cursor *cursor,
 		double x, double y) {
+	if (cursor->x == x && cursor->y == y) {
+		return true;
+	}
+
+	if (cursor->output->hardware_cursor != cursor) {
+		output_cursor_damage_whole(cursor);
+	}
+
 	x *= cursor->output->scale;
 	y *= cursor->output->scale;
 	cursor->x = x;
@@ -677,7 +846,7 @@ bool wlr_output_cursor_move(struct wlr_output_cursor *cursor,
 	output_cursor_update_visible(cursor);
 
 	if (cursor->output->hardware_cursor != cursor) {
-		cursor->output->needs_swap = true;
+		output_cursor_damage_whole(cursor);
 		return true;
 	}
 
@@ -720,9 +889,6 @@ void wlr_output_cursor_destroy(struct wlr_output_cursor *cursor) {
 	if (cursor->texture != NULL) {
 		wlr_texture_destroy(cursor->texture);
 	}
-	if (cursor->renderer != NULL) {
-		wlr_renderer_destroy(cursor->renderer);
-	}
 	wl_list_remove(&cursor->link);
 	free(cursor);
 }

types/wlr_screenshooter.c

@@ -41,8 +41,8 @@ static void output_handle_frame(struct wl_listener *listener, void *_data) {
 	int32_t width = wl_shm_buffer_get_width(shm_buffer);
 	int32_t height = wl_shm_buffer_get_height(shm_buffer);
 	int32_t stride = wl_shm_buffer_get_stride(shm_buffer);
-	void *data = wl_shm_buffer_get_data(shm_buffer);
 	wl_shm_buffer_begin_access(shm_buffer);
+	void *data = wl_shm_buffer_get_data(shm_buffer);
 	bool ok = wlr_renderer_read_pixels(renderer, format, stride, width, height,
 		0, 0, 0, 0, data);
 	wl_shm_buffer_end_access(shm_buffer);
@@ -127,6 +127,10 @@ static void screenshooter_shoot(struct wl_client *client,
 	state->screenshot = screenshot;
 	state->frame_listener.notify = output_handle_frame;
 	wl_signal_add(&output->events.swap_buffers, &state->frame_listener);
+
+	// Schedule a buffer swap
+	output->needs_swap = true;
+	wlr_output_schedule_frame(output);
 }
 
 static struct orbital_screenshooter_interface screenshooter_impl = {

types/wlr_seat.c

@@ -454,7 +454,10 @@ struct wlr_seat *wlr_seat_create(struct wl_display *display, const char *name) {
 	wl_list_init(&wlr_seat->clients);
 	wl_list_init(&wlr_seat->drag_icons);
 
+	wl_signal_init(&wlr_seat->events.new_drag_icon);
+
 	wl_signal_init(&wlr_seat->events.request_set_cursor);
+
 	wl_signal_init(&wlr_seat->events.selection);
 	wl_signal_init(&wlr_seat->events.primary_selection);
 

types/wlr_surface.c

@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <wayland-server.h>
 #include <wlr/util/log.h>
+#include <wlr/util/region.h>
 #include <wlr/render/interface.h>
 #include <wlr/types/wlr_surface.h>
 #include <wlr/render/egl.h>
@@ -133,11 +134,14 @@ static void surface_set_input_region(struct wl_client *client,
 	}
 }
 
-static void wlr_surface_update_size(struct wlr_surface *surface, struct wlr_surface_state *state) {
+static bool wlr_surface_update_size(struct wlr_surface *surface,
+		struct wlr_surface_state *state) {
 	if (!state->buffer) {
+		pixman_region32_union_rect(&state->surface_damage,
+			&state->surface_damage, 0, 0, state->width, state->height);
 		state->height = 0;
 		state->width = 0;
-		return;
+		return true;
 	}
 
 	int scale = state->scale;
@@ -146,16 +150,16 @@ static void wlr_surface_update_size(struct wlr_surface *surface, struct wlr_surf
 	wlr_texture_get_buffer_size(surface->texture, state->buffer,
 		&state->buffer_width, &state->buffer_height);
 
-	int _width = state->buffer_width / scale;
+	int width = state->buffer_width / scale;
-	int _height = state->buffer_height / scale;
+	int height = state->buffer_height / scale;
 
 	if (transform == WL_OUTPUT_TRANSFORM_90 ||
 		transform == WL_OUTPUT_TRANSFORM_270 ||
 		transform == WL_OUTPUT_TRANSFORM_FLIPPED_90 ||
 		transform == WL_OUTPUT_TRANSFORM_FLIPPED_270) {
-		int tmp = _width;
+		int tmp = width;
-		_width = _height;
+		width = height;
-		_height = tmp;
+		height = tmp;
 	}
 
 	struct wlr_frame_callback *cb, *tmp;
@@ -164,99 +168,34 @@ static void wlr_surface_update_size(struct wlr_surface *surface, struct wlr_surf
 	}
 	wl_list_init(&state->frame_callback_list);
 
-	state->width = _width;
+	bool update_damage = false;
-	state->height = _height;
+	if (width != state->width || height != state->height) {
-}
+		// Damage the whole surface on resize
-
+		// This isn't in the spec, but Weston does it and QT expects it
-static void wlr_surface_to_buffer_region(int scale,
+		pixman_region32_union_rect(&state->surface_damage,
-		enum wl_output_transform transform, pixman_region32_t *surface_region,
+			&state->surface_damage, 0, 0, state->width, state->height);
-		pixman_region32_t *buffer_region,
+		pixman_region32_union_rect(&state->surface_damage,
-		int width, int height) {
+			&state->surface_damage, 0, 0, width, height);
-	pixman_box32_t *src_rects, *dest_rects;
+		update_damage = true;
-	int nrects, i;
-
-	src_rects = pixman_region32_rectangles(surface_region, &nrects);
-	dest_rects = malloc(nrects * sizeof(*dest_rects));
-	if (!dest_rects) {
-		return;
-	}
-
-	for (i = 0; i < nrects; i++) {
-		switch (transform) {
-		default:
-		case WL_OUTPUT_TRANSFORM_NORMAL:
-			dest_rects[i].x1 = src_rects[i].x1;
-			dest_rects[i].y1 = src_rects[i].y1;
-			dest_rects[i].x2 = src_rects[i].x2;
-			dest_rects[i].y2 = src_rects[i].y2;
-			break;
-		case WL_OUTPUT_TRANSFORM_90:
-			dest_rects[i].x1 = height - src_rects[i].y2;
-			dest_rects[i].y1 = src_rects[i].x1;
-			dest_rects[i].x2 = height - src_rects[i].y1;
-			dest_rects[i].y2 = src_rects[i].x2;
-			break;
-		case WL_OUTPUT_TRANSFORM_180:
-			dest_rects[i].x1 = width - src_rects[i].x2;
-			dest_rects[i].y1 = height - src_rects[i].y2;
-			dest_rects[i].x2 = width - src_rects[i].x1;
-			dest_rects[i].y2 = height - src_rects[i].y1;
-			break;
-		case WL_OUTPUT_TRANSFORM_270:
-			dest_rects[i].x1 = src_rects[i].y1;
-			dest_rects[i].y1 = width - src_rects[i].x2;
-			dest_rects[i].x2 = src_rects[i].y2;
-			dest_rects[i].y2 = width - src_rects[i].x1;
-			break;
-		case WL_OUTPUT_TRANSFORM_FLIPPED:
-			dest_rects[i].x1 = width - src_rects[i].x2;
-			dest_rects[i].y1 = src_rects[i].y1;
-			dest_rects[i].x2 = width - src_rects[i].x1;
-			dest_rects[i].y2 = src_rects[i].y2;
-			break;
-		case WL_OUTPUT_TRANSFORM_FLIPPED_90:
-			dest_rects[i].x1 = height - src_rects[i].y2;
-			dest_rects[i].y1 = width - src_rects[i].x2;
-			dest_rects[i].x2 = height - src_rects[i].y1;
-			dest_rects[i].y2 = width - src_rects[i].x1;
-			break;
-		case WL_OUTPUT_TRANSFORM_FLIPPED_180:
-			dest_rects[i].x1 = src_rects[i].x1;
-			dest_rects[i].y1 = height - src_rects[i].y2;
-			dest_rects[i].x2 = src_rects[i].x2;
-			dest_rects[i].y2 = height - src_rects[i].y1;
-			break;
-		case WL_OUTPUT_TRANSFORM_FLIPPED_270:
-			dest_rects[i].x1 = src_rects[i].y1;
-			dest_rects[i].y1 = src_rects[i].x1;
-			dest_rects[i].x2 = src_rects[i].y2;
-			dest_rects[i].y2 = src_rects[i].x2;
-			break;
-		}
 	}
 
-	if (scale != 1) {
+	state->width = width;
-		for (i = 0; i < nrects; i++) {
+	state->height = height;
-			dest_rects[i].x1 *= scale;
-			dest_rects[i].x2 *= scale;
-			dest_rects[i].y1 *= scale;
-			dest_rects[i].y2 *= scale;
-		}
-	}
 
-	pixman_region32_fini(buffer_region);
+	return update_damage;
-	pixman_region32_init_rects(buffer_region, dest_rects, nrects);
-	free(dest_rects);
 }
 
 /**
  * Append pending state to current state and clear pending state.
  */
-static void wlr_surface_move_state(struct wlr_surface *surface, struct wlr_surface_state *next,
+static void wlr_surface_move_state(struct wlr_surface *surface,
-		struct wlr_surface_state *state) {
+		struct wlr_surface_state *next, struct wlr_surface_state *state) {
 	bool update_damage = false;
 	bool update_size = false;
 
+	int oldw = state->width;
+	int oldh = state->height;
+
 	if ((next->invalid & WLR_SURFACE_INVALID_SCALE)) {
 		state->scale = next->scale;
 		update_size = true;
@@ -274,40 +213,50 @@ static void wlr_surface_move_state(struct wlr_surface *surface, struct wlr_surfa
 		update_size = true;
 	}
 	if (update_size) {
-		wlr_surface_update_size(surface, state);
+		update_damage = wlr_surface_update_size(surface, state);
 	}
 	if ((next->invalid & WLR_SURFACE_INVALID_SURFACE_DAMAGE)) {
-		pixman_region32_union(&state->surface_damage,
+		pixman_region32_intersect_rect(&next->surface_damage,
-			&state->surface_damage,
+			&next->surface_damage, 0, 0, state->width, state->height);
+		pixman_region32_union(&state->surface_damage, &state->surface_damage,
 			&next->surface_damage);
-		pixman_region32_intersect_rect(&state->surface_damage,
-			&state->surface_damage, 0, 0, state->width,
-			state->height);
-
 		pixman_region32_clear(&next->surface_damage);
 		update_damage = true;
 	}
 	if ((next->invalid & WLR_SURFACE_INVALID_BUFFER_DAMAGE)) {
-		pixman_region32_union(&state->buffer_damage,
+		pixman_region32_intersect_rect(&next->buffer_damage,
-			&state->buffer_damage,
+			&next->buffer_damage, 0, 0, state->buffer_width,
+			state->buffer_height);
+		pixman_region32_union(&state->buffer_damage, &state->buffer_damage,
 			&next->buffer_damage);
-
 		pixman_region32_clear(&next->buffer_damage);
 		update_damage = true;
 	}
 	if (update_damage) {
-		pixman_region32_t buffer_damage;
+		pixman_region32_t buffer_damage, surface_damage;
 		pixman_region32_init(&buffer_damage);
-		wlr_surface_to_buffer_region(state->scale, state->transform,
+		pixman_region32_init(&surface_damage);
-			&state->surface_damage, &buffer_damage, state->width,
+
-			state->height);
+		// Surface to buffer damage
-		pixman_region32_union(&state->buffer_damage,
+		pixman_region32_copy(&buffer_damage, &state->surface_damage);
-			&state->buffer_damage, &buffer_damage);
+		wlr_region_transform(&buffer_damage, &buffer_damage,
-		pixman_region32_fini(&buffer_damage);
+			wlr_output_transform_invert(state->transform),
-
+			state->width, state->height);
-		pixman_region32_intersect_rect(&state->buffer_damage,
+		wlr_region_scale(&buffer_damage, &buffer_damage, state->scale);
-			&state->buffer_damage, 0, 0,
+
+		// Buffer to surface damage
+		pixman_region32_copy(&surface_damage, &state->buffer_damage);
+		wlr_region_transform(&surface_damage, &surface_damage, state->transform,
 			state->buffer_width, state->buffer_height);
+		wlr_region_scale(&surface_damage, &surface_damage, 1.0f/state->scale);
+
+		pixman_region32_union(&state->buffer_damage, &state->buffer_damage,
+			&buffer_damage);
+		pixman_region32_union(&state->surface_damage, &state->surface_damage,
+			&surface_damage);
+
+		pixman_region32_fini(&buffer_damage);
+		pixman_region32_fini(&surface_damage);
 	}
 	if ((next->invalid & WLR_SURFACE_INVALID_OPAQUE_REGION)) {
 		// TODO: process buffer
@@ -318,13 +267,25 @@ static void wlr_surface_move_state(struct wlr_surface *surface, struct wlr_surfa
 		pixman_region32_copy(&state->input, &next->input);
 	}
 	if ((next->invalid & WLR_SURFACE_INVALID_SUBSURFACE_POSITION)) {
+		// Subsurface has moved
+		int dx = state->subsurface_position.x - next->subsurface_position.x;
+		int dy = state->subsurface_position.y - next->subsurface_position.y;
+
 		state->subsurface_position.x = next->subsurface_position.x;
 		state->subsurface_position.y = next->subsurface_position.y;
 		next->subsurface_position.x = 0;
 		next->subsurface_position.y = 0;
+
+		if (dx != 0 || dy != 0) {
+			pixman_region32_union_rect(&state->surface_damage,
+				&state->surface_damage, dx, dy, oldw, oldh);
+			pixman_region32_union_rect(&state->surface_damage,
+				&state->surface_damage, 0, 0, state->width, state->height);
+		}
 	}
 	if ((next->invalid & WLR_SURFACE_INVALID_FRAME_CALLBACK_LIST)) {
-		wl_list_insert_list(&state->frame_callback_list, &next->frame_callback_list);
+		wl_list_insert_list(&state->frame_callback_list,
+			&next->frame_callback_list);
 		wl_list_init(&next->frame_callback_list);
 	}
 
@@ -351,7 +312,7 @@ static void wlr_surface_damage_subsurfaces(struct wlr_subsurface *subsurface) {
 	}
 }
 
-static void wlr_surface_flush_damage(struct wlr_surface *surface,
+static void wlr_surface_apply_damage(struct wlr_surface *surface,
 		bool reupload_buffer) {
 	if (!surface->current->buffer) {
 		return;
@@ -372,10 +333,12 @@ static void wlr_surface_flush_damage(struct wlr_surface *surface,
 	if (reupload_buffer) {
 		wlr_texture_upload_shm(surface->texture, format, buffer);
 	} else {
-		pixman_region32_t damage = surface->current->buffer_damage;
+		pixman_region32_t damage;
-		if (!pixman_region32_not_empty(&damage)) {
+		pixman_region32_init(&damage);
-			goto release;
+		pixman_region32_copy(&damage, &surface->current->buffer_damage);
-		}
+		pixman_region32_intersect_rect(&damage, &damage, 0, 0,
+			surface->current->buffer_width, surface->current->buffer_height);
+
 		int n;
 		pixman_box32_t *rects = pixman_region32_rectangles(&damage, &n);
 		for (int i = 0; i < n; ++i) {
@@ -388,12 +351,11 @@ static void wlr_surface_flush_damage(struct wlr_surface *surface,
 				break;
 			}
 		}
+
+		pixman_region32_fini(&damage);
 	}
 
 release:
-	pixman_region32_clear(&surface->current->surface_damage);
-	pixman_region32_clear(&surface->current->buffer_damage);
-
 	wlr_surface_state_release_buffer(surface->current);
 }
 
@@ -413,12 +375,12 @@ static void wlr_surface_commit_pending(struct wlr_surface *surface) {
 
 	bool reupload_buffer = oldw != surface->current->buffer_width ||
 		oldh != surface->current->buffer_height;
-	wlr_surface_flush_damage(surface, reupload_buffer);
+	wlr_surface_apply_damage(surface, reupload_buffer);
 
 	// commit subsurface order
 	struct wlr_subsurface *subsurface;
 	wl_list_for_each_reverse(subsurface, &surface->subsurface_pending_list,
-		parent_pending_link) {
+			parent_pending_link) {
 		wl_list_remove(&subsurface->parent_link);
 		wl_list_insert(&surface->subsurface_list, &subsurface->parent_link);
 
@@ -434,6 +396,9 @@ static void wlr_surface_commit_pending(struct wlr_surface *surface) {
 
 	// TODO: add the invalid bitfield to this callback
 	wl_signal_emit(&surface->events.commit, surface);
+
+	pixman_region32_clear(&surface->current->surface_damage);
+	pixman_region32_clear(&surface->current->buffer_damage);
 }
 
 static bool wlr_subsurface_is_synchronized(struct wlr_subsurface *subsurface) {
@@ -459,7 +424,6 @@ static void wlr_subsurface_parent_commit(struct wlr_subsurface *subsurface,
 		bool synchronized) {
 		struct wlr_surface *surface = subsurface->surface;
 	if (synchronized || subsurface->synchronized) {
-
 		if (subsurface->has_cache) {
 			wlr_surface_move_state(surface, subsurface->cached, surface->pending);
 			wlr_surface_commit_pending(surface);
@@ -595,6 +559,8 @@ static void wlr_surface_state_destroy(struct wlr_surface_state *state) {
 }
 
 void wlr_subsurface_destroy(struct wlr_subsurface *subsurface) {
+	wl_signal_emit(&subsurface->events.destroy, subsurface);
+
 	wlr_surface_state_destroy(subsurface->cached);
 
 	if (subsurface->parent) {
@@ -642,6 +608,7 @@ struct wlr_surface *wlr_surface_create(struct wl_resource *res,
 
 	wl_signal_init(&surface->events.commit);
 	wl_signal_init(&surface->events.destroy);
+	wl_signal_init(&surface->events.new_subsurface);
 	wl_list_init(&surface->subsurface_list);
 	wl_list_init(&surface->subsurface_pending_list);
 	wl_resource_set_implementation(res, &surface_interface,
@@ -732,10 +699,6 @@ static void subsurface_place_above(struct wl_client *client,
 		struct wl_resource *resource, struct wl_resource *sibling_resource) {
 	struct wlr_subsurface *subsurface = wl_resource_get_user_data(resource);
 
-	if (!subsurface) {
-		return;
-	}
-
 	struct wlr_surface *sibling_surface =
 		wl_resource_get_user_data(sibling_resource);
 	struct wlr_subsurface *sibling =
@@ -841,6 +804,7 @@ void wlr_surface_make_subsurface(struct wlr_surface *surface,
 	}
 	subsurface->synchronized = true;
 	subsurface->surface = surface;
+	wl_signal_init(&subsurface->events.destroy);
 
 	// link parent
 	subsurface->parent = parent;
@@ -866,6 +830,8 @@ void wlr_surface_make_subsurface(struct wlr_surface *surface,
 		subsurface_resource_destroy);
 
 	surface->subsurface = subsurface;
+
+	wl_signal_emit(&parent->events.new_subsurface, subsurface);
 }
 
 

types/wlr_wl_shell.c

@@ -221,6 +221,7 @@ static void shell_surface_popup_set_parent(struct wlr_wl_shell_surface *surface,
 	if (parent) {
 		wl_list_remove(&surface->popup_link);
 		wl_list_insert(&parent->popups, &surface->popup_link);
+		wl_signal_emit(&parent->events.new_popup, surface);
 	}
 }
 
@@ -519,6 +520,7 @@ static void shell_protocol_get_shell_surface(struct wl_client *client,
 
 	wl_signal_init(&wl_surface->events.destroy);
 	wl_signal_init(&wl_surface->events.ping_timeout);
+	wl_signal_init(&wl_surface->events.new_popup);
 	wl_signal_init(&wl_surface->events.request_move);
 	wl_signal_init(&wl_surface->events.request_resize);
 	wl_signal_init(&wl_surface->events.request_fullscreen);

types/wlr_xdg_shell_v6.c

@@ -206,7 +206,7 @@ static void xdg_surface_destroy(struct wlr_xdg_surface_v6 *surface) {
 			}
 		}
 
-		wl_list_remove(&surface->popup_link);
+		wl_list_remove(&surface->popup_state->link);
 		free(surface->popup_state);
 	}
 
@@ -505,12 +505,13 @@ static void xdg_surface_get_popup(struct wl_client *client,
 	surface->popup_state->parent = parent;
 	surface->popup_state->geometry =
 		xdg_positioner_get_geometry(positioner, surface, parent);
-	wl_list_insert(&surface->popup_state->parent->popups,
+	wl_list_insert(&parent->popups, &surface->popup_state->link);
-		&surface->popup_link);
 
 	wl_resource_set_implementation(surface->popup_state->resource,
 		&zxdg_popup_v6_implementation, surface,
 		xdg_popup_resource_destroy);
+
+	wl_signal_emit(&parent->events.new_popup, surface->popup_state);
 }
 
 
@@ -1187,6 +1188,7 @@ static void xdg_shell_get_xdg_surface(struct wl_client *wl_client,
 	wl_signal_init(&surface->events.request_show_window_menu);
 	wl_signal_init(&surface->events.destroy);
 	wl_signal_init(&surface->events.ping_timeout);
+	wl_signal_init(&surface->events.new_popup);
 
 	wl_signal_add(&surface->surface->events.destroy,
 		&surface->surface_destroy_listener);
@@ -1404,14 +1406,16 @@ struct wlr_xdg_surface_v6 *wlr_xdg_surface_v6_popup_at(
 	// XXX: I think this is so complicated because we're mixing geometry
 	// coordinates with surface coordinates. Input handling should only deal
 	// with surface coordinates.
-	struct wlr_xdg_surface_v6 *popup;
+	struct wlr_xdg_popup_v6 *popup_state;
-	wl_list_for_each(popup, &surface->popups, popup_link) {
+	wl_list_for_each(popup_state, &surface->popups, link) {
+		struct wlr_xdg_surface_v6 *popup = popup_state->base;
+
 		double _popup_sx =
-			surface->geometry->x + popup->popup_state->geometry.x;
+			surface->geometry->x + popup_state->geometry.x;
 		double _popup_sy =
-			surface->geometry->y + popup->popup_state->geometry.y;
+			surface->geometry->y + popup_state->geometry.y;
-		int popup_width =  popup->popup_state->geometry.width;
+		int popup_width =  popup_state->geometry.width;
-		int popup_height =  popup->popup_state->geometry.height;
+		int popup_height =  popup_state->geometry.height;
 
 		struct wlr_xdg_surface_v6 *_popup =
 			wlr_xdg_surface_v6_popup_at(popup,

util/meson.build

@@ -3,6 +3,8 @@ lib_wlr_util = static_library(
 	files(
 		'log.c',
 		'os-compatibility.c',
+		'region.c',
 	),
 	include_directories: wlr_inc,
+	dependencies: [wayland_server, pixman],
 )

util/region.c

@@ -0,0 +1,130 @@
+#include <stdlib.h>
+#include <math.h>
+#include <wlr/util/region.h>
+
+void wlr_region_scale(pixman_region32_t *dst, pixman_region32_t *src,
+		float scale) {
+	if (scale == 1) {
+		pixman_region32_copy(dst, src);
+		return;
+	}
+
+	int nrects;
+	pixman_box32_t *src_rects = pixman_region32_rectangles(src, &nrects);
+
+	pixman_box32_t *dst_rects = malloc(nrects * sizeof(pixman_box32_t));
+	if (dst_rects == NULL) {
+		return;
+	}
+
+	for (int i = 0; i < nrects; ++i) {
+		dst_rects[i].x1 = floor(src_rects[i].x1 * scale);
+		dst_rects[i].x2 = ceil(src_rects[i].x2 * scale);
+		dst_rects[i].y1 = floor(src_rects[i].y1 * scale);
+		dst_rects[i].y2 = ceil(src_rects[i].y2 * scale);
+	}
+
+	pixman_region32_fini(dst);
+	pixman_region32_init_rects(dst, dst_rects, nrects);
+	free(dst_rects);
+}
+
+void wlr_region_transform(pixman_region32_t *dst, pixman_region32_t *src,
+		enum wl_output_transform transform, int width, int height) {
+	if (transform == WL_OUTPUT_TRANSFORM_NORMAL) {
+		pixman_region32_copy(dst, src);
+		return;
+	}
+
+	int nrects;
+	pixman_box32_t *src_rects = pixman_region32_rectangles(src, &nrects);
+
+	pixman_box32_t *dst_rects = malloc(nrects * sizeof(pixman_box32_t));
+	if (dst_rects == NULL) {
+		return;
+	}
+
+	for (int i = 0; i < nrects; ++i) {
+		switch (transform) {
+		case WL_OUTPUT_TRANSFORM_NORMAL:
+			dst_rects[i].x1 = src_rects[i].x1;
+			dst_rects[i].y1 = src_rects[i].y1;
+			dst_rects[i].x2 = src_rects[i].x2;
+			dst_rects[i].y2 = src_rects[i].y2;
+			break;
+		case WL_OUTPUT_TRANSFORM_90:
+			dst_rects[i].x1 = src_rects[i].y1;
+			dst_rects[i].y1 = width - src_rects[i].x2;
+			dst_rects[i].x2 = src_rects[i].y2;
+			dst_rects[i].y2 = width - src_rects[i].x1;
+			break;
+		case WL_OUTPUT_TRANSFORM_180:
+			dst_rects[i].x1 = width - src_rects[i].x2;
+			dst_rects[i].y1 = height - src_rects[i].y2;
+			dst_rects[i].x2 = width - src_rects[i].x1;
+			dst_rects[i].y2 = height - src_rects[i].y1;
+			break;
+		case WL_OUTPUT_TRANSFORM_270:
+			dst_rects[i].x1 = height - src_rects[i].y2;
+			dst_rects[i].y1 = src_rects[i].x1;
+			dst_rects[i].x2 = height - src_rects[i].y1;
+			dst_rects[i].y2 = src_rects[i].x2;
+			break;
+		case WL_OUTPUT_TRANSFORM_FLIPPED:
+			dst_rects[i].x1 = width - src_rects[i].x2;
+			dst_rects[i].y1 = src_rects[i].y1;
+			dst_rects[i].x2 = width - src_rects[i].x1;
+			dst_rects[i].y2 = src_rects[i].y2;
+			break;
+		case WL_OUTPUT_TRANSFORM_FLIPPED_90:
+			dst_rects[i].x1 = height - src_rects[i].y2;
+			dst_rects[i].y1 = width - src_rects[i].x2;
+			dst_rects[i].x2 = height - src_rects[i].y1;
+			dst_rects[i].y2 = width - src_rects[i].x1;
+			break;
+		case WL_OUTPUT_TRANSFORM_FLIPPED_180:
+			dst_rects[i].x1 = src_rects[i].x1;
+			dst_rects[i].y1 = height - src_rects[i].y2;
+			dst_rects[i].x2 = src_rects[i].x2;
+			dst_rects[i].y2 = height - src_rects[i].y1;
+			break;
+		case WL_OUTPUT_TRANSFORM_FLIPPED_270:
+			dst_rects[i].x1 = src_rects[i].y1;
+			dst_rects[i].y1 = src_rects[i].x1;
+			dst_rects[i].x2 = src_rects[i].y2;
+			dst_rects[i].y2 = src_rects[i].x2;
+			break;
+		}
+	}
+
+	pixman_region32_fini(dst);
+	pixman_region32_init_rects(dst, dst_rects, nrects);
+	free(dst_rects);
+}
+
+void wlr_region_expand(pixman_region32_t *dst, pixman_region32_t *src,
+		int distance) {
+	if (distance == 0) {
+		pixman_region32_copy(dst, src);
+		return;
+	}
+
+	int nrects;
+	pixman_box32_t *src_rects = pixman_region32_rectangles(src, &nrects);
+
+	pixman_box32_t *dst_rects = malloc(nrects * sizeof(pixman_box32_t));
+	if (dst_rects == NULL) {
+		return;
+	}
+
+	for (int i = 0; i < nrects; ++i) {
+		dst_rects[i].x1 = src_rects[i].x1 - distance;
+		dst_rects[i].x2 = src_rects[i].x2 + distance;
+		dst_rects[i].y1 = src_rects[i].y1 - distance;
+		dst_rects[i].y2 = src_rects[i].y2 + distance;
+	}
+
+	pixman_region32_fini(dst);
+	pixman_region32_init_rects(dst, dst_rects, nrects);
+	free(dst_rects);
+}

xcursor/wlr_xcursor.c

@@ -24,7 +24,6 @@
  */
 
 #define _XOPEN_SOURCE 500
-#include <wlr/render.h>
 #include <wlr/xcursor.h>
 #include <wlr/util/log.h>
 #include <stdio.h>

xwayland/xwm.c

@@ -315,7 +315,7 @@ static void read_surface_parent(struct wlr_xwm *xwm,
 		wl_list_init(&xsurface->parent_link);
 	}
 
-	wlr_log(L_DEBUG, "XCB_ATOM_WM_TRANSIENT_FOR: %p", xid);
+	wlr_log(L_DEBUG, "XCB_ATOM_WM_TRANSIENT_FOR: %p", xsurface->parent);
 	wl_signal_emit(&xsurface->events.set_parent, xsurface);
 }
 
@@ -1407,7 +1407,7 @@ struct wlr_xwm *xwm_create(struct wlr_xwayland *wlr_xwayland) {
 	xwm_selection_init(xwm);
 
 	xwm->compositor_surface_create.notify = handle_compositor_surface_create;
-	wl_signal_add(&wlr_xwayland->compositor->events.create_surface,
+	wl_signal_add(&wlr_xwayland->compositor->events.new_surface,
 		&xwm->compositor_surface_create);
 
 	xwm_create_wm_window(xwm);