backend/x11: fix input events

backend/x11/backend.c

@@ -1,4 +1,5 @@
 #define _POSIX_C_SOURCE 200112L
+#include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -32,6 +33,38 @@ struct wlr_x11_output *x11_output_from_window_id(struct wlr_x11_backend *x11,
 	return NULL;
 }
 
+void x11_output_layout_get_box(struct wlr_x11_backend *backend,
+		struct wlr_box *box) {
+	int min_x = INT_MAX, min_y = INT_MAX;
+	int max_x = INT_MIN, max_y = INT_MIN;
+
+	struct wlr_x11_output *output;
+	wl_list_for_each(output, &backend->outputs, link) {
+		struct wlr_output *wlr_output = &output->wlr_output;
+
+		int width, height;
+		wlr_output_effective_resolution(wlr_output, &width, &height);
+
+		if (wlr_output->lx < min_x) {
+			min_x = wlr_output->lx;
+		}
+		if (wlr_output->ly < min_y) {
+			min_y = wlr_output->ly;
+		}
+		if (wlr_output->lx + width > max_x) {
+			max_x = wlr_output->lx + width;
+		}
+		if (wlr_output->ly + height > max_y) {
+			max_y = wlr_output->ly + height;
+		}
+	}
+
+	box->x = min_x;
+	box->y = min_y;
+	box->width = max_x - min_x;
+	box->height = max_y - min_y;
+}
+
 static bool handle_x11_event(struct wlr_x11_backend *x11,
 		xcb_generic_event_t *event) {
 	if (x11_handle_input_event(x11, event)) {

backend/x11/input_device.c

@@ -87,15 +87,29 @@ bool x11_handle_input_event(struct wlr_x11_backend *x11,
 		if (output == NULL) {
 			return false;
 		}
+		struct wlr_output *wlr_output = &output->wlr_output;
 
-		struct wlr_event_pointer_motion_absolute abs = {
+		struct wlr_box box = { .x = ev->event_x, .y = ev->event_y };
+		wlr_box_transform(&box, wlr_output->transform, wlr_output->width,
+			wlr_output->height, &box);
+		box.x /= wlr_output->scale;
+		box.y /= wlr_output->scale;
+
+		struct wlr_box layout_box;
+		x11_output_layout_get_box(x11, &layout_box);
+
+		double ox = wlr_output->lx / (double)layout_box.width;
+		double oy = wlr_output->ly / (double)layout_box.height;
+
+		struct wlr_event_pointer_motion_absolute wlr_event = {
 			.device = &x11->pointer_dev,
 			.time_msec = ev->time,
-			.x = (double)ev->event_x / output->wlr_output.width,
-			.y = (double)ev->event_y / output->wlr_output.height,
+			.x = box.x / (double)layout_box.width + ox,
+			.y = box.y / (double)layout_box.height + oy,
 		};
 
-		wlr_signal_emit_safe(&x11->pointer.events.motion_absolute, &abs);
+		wlr_signal_emit_safe(&x11->pointer.events.motion_absolute, &wlr_event);
+
 		x11->time = ev->time;
 		return true;
 	}

include/backend/x11.h

@@ -69,6 +69,8 @@ struct wlr_x11_backend {
 
 struct wlr_x11_output *x11_output_from_window_id(struct wlr_x11_backend *x11,
 	xcb_window_t window);
+void x11_output_layout_get_box(struct wlr_x11_backend *backend,
+	struct wlr_box *box);
 
 const struct wlr_input_device_impl input_device_impl;