output: add wlr_output_schedule_frame

backend/drm/drm.c

@@ -881,7 +881,7 @@ 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/headless/output.c

@@ -85,7 +85,7 @@ 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/wayland/output.c

@@ -17,11 +17,11 @@ 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,
+		uint32_t time) {
 	struct wlr_wl_backend_output *output = data;
-	struct wlr_output *wlr_output = (struct wlr_output *)output;
-	assert(wlr_output);
-	wl_signal_emit(&wlr_output->events.frame, wlr_output);
+	assert(output);
+	wlr_output_send_frame(&output->wlr_output);
 	wl_callback_destroy(cb);
 	output->frame_callback = NULL;
 }

backend/x11/backend.c

@@ -44,7 +44,7 @@ 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:
@@ -174,7 +174,7 @@ 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;
 }

include/rootston/output.h

@@ -23,7 +23,6 @@ struct roots_output {
 
 	struct timespec last_frame;
 	pixman_region32_t damage; // in ouput-local coordinates
-	bool frame_pending;
 
 	// circular queue for previous damage
 	pixman_region32_t previous_damage[ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN];

include/wlr/interfaces/wlr_output.h

@@ -33,5 +33,6 @@ 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/types/wlr_output.h

@@ -63,6 +63,7 @@ struct wlr_output {
 	bool needs_swap;
 	// damage for cursors and fullscreen surface, in output-local coordinates
 	pixman_region32_t damage;
+	bool frame_pending;
 	float transform_matrix[16];
 
 	struct {
@@ -123,6 +124,11 @@ bool wlr_output_make_current(struct wlr_output *output, int *buffer_age);
  */
 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);

rootston/output.c

@@ -338,7 +338,6 @@ static void render_output(struct roots_output *output) {
 	struct roots_server *server = desktop->server;
 
 	if (!wlr_output->enabled) {
-		output->frame_pending = false;
 		return;
 	}
 
@@ -400,7 +399,6 @@ static void render_output(struct roots_output *output) {
 
 	if (!pixman_region32_not_empty(&damage) && !wlr_output->needs_swap) {
 		// Output doesn't need swap and isn't damaged, skip rendering completely
-		output->frame_pending = false;
 		goto damage_finish;
 	}
 
@@ -470,7 +468,6 @@ renderer_end:
 	wlr_renderer_scissor(output->desktop->server->renderer, NULL);
 	wlr_renderer_end(server->renderer);
 	wlr_output_swap_buffers(wlr_output, &now, &damage);
-	output->frame_pending = true;
 	// same as decrementing, but works on unsigned integers
 	output->previous_damage_idx += ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN - 1;
 	output->previous_damage_idx %= ROOTS_OUTPUT_PREVIOUS_DAMAGE_LEN;
@@ -488,21 +485,6 @@ static void output_handle_frame(struct wl_listener *listener, void *data) {
 	render_output(output);
 }
 
-static void handle_idle_render(void *data) {
-	struct roots_output *output = data;
-	render_output(output);
-}
-
-static void schedule_render(struct roots_output *output) {
-	if (!output->frame_pending) {
-		// TODO: ask the backend to send a frame event when appropriate instead
-		struct wl_event_loop *ev =
-			wl_display_get_event_loop(output->desktop->server->wl_display);
-		wl_event_loop_add_idle(ev, handle_idle_render, output);
-		output->frame_pending = true;
-	}
-}
-
 static void output_damage_whole(struct roots_output *output) {
 	int width, height;
 	output_get_transformed_size(output->wlr_output, &width, &height);
@@ -510,7 +492,7 @@ static void output_damage_whole(struct roots_output *output) {
 	pixman_region32_union_rect(&output->damage, &output->damage, 0, 0,
 		width, height);
 
-	schedule_render(output);
+	wlr_output_schedule_frame(output->wlr_output);
 }
 
 static bool view_accept_damage(struct roots_output *output,
@@ -553,7 +535,7 @@ static void damage_whole_surface(struct wlr_surface *surface,
 	pixman_region32_union_rect(&output->damage, &output->damage,
 		box.x, box.y, box.width, box.height);
 
-	schedule_render(output);
+	wlr_output_schedule_frame(output->wlr_output);
 }
 
 static void damage_whole_decoration(struct roots_view *view,
@@ -608,7 +590,7 @@ static void damage_from_surface(struct wlr_surface *surface,
 	pixman_region32_union(&output->damage, &output->damage, &damage);
 	pixman_region32_fini(&damage);
 
-	schedule_render(output);
+	wlr_output_schedule_frame(output->wlr_output);
 }
 
 void output_damage_from_view(struct roots_output *output,
@@ -630,7 +612,7 @@ static void output_handle_needs_swap(struct wl_listener *listener, void *data) {
 		wl_container_of(listener, output, needs_swap);
 	pixman_region32_union(&output->damage, &output->damage,
 		&output->wlr_output->damage);
-	schedule_render(output);
+	wlr_output_schedule_frame(output->wlr_output);
 }
 
 static void set_mode(struct wlr_output *output,

types/wlr_output.c

@@ -499,6 +499,7 @@ bool wlr_output_swap_buffers(struct wlr_output *output, struct timespec *when,
 		return false;
 	}
 
+	output->frame_pending = true;
 	output->needs_swap = false;
 	pixman_region32_clear(&output->damage);
 
@@ -509,6 +510,27 @@ bool wlr_output_swap_buffers(struct wlr_output *output, struct timespec *when,
 	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;
+	wlr_output_send_frame(output);
+}
+
+void wlr_output_schedule_frame(struct wlr_output *output) {
+	if (output->frame_pending) {
+		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);
+	wl_event_loop_add_idle(ev, schedule_frame_handle_idle_timer, output);
+	output->frame_pending = true;
+}
+
 void wlr_output_set_gamma(struct wlr_output *output,
 	uint32_t size, uint16_t *r, uint16_t *g, uint16_t *b) {
 	if (output->impl->set_gamma) {