Fixes for multiple outputs

* Fixes output positions in screenshots
* Fixes Wayland backend pointer events when output layout doesn't start at (0, 0)

backend/wayland/wl_seat.c

@@ -74,8 +74,8 @@ static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
 	wlr_event.time_msec = time;
 	wlr_event.width_mm = layout_box.width;
 	wlr_event.height_mm = layout_box.height;
-	wlr_event.x_mm = transformed.x + wlr_output->lx + layout_box.x;
-	wlr_event.y_mm = transformed.y + wlr_output->ly + layout_box.y;
+	wlr_event.x_mm = transformed.x + wlr_output->lx - layout_box.x;
+	wlr_event.y_mm = transformed.y + wlr_output->ly - layout_box.y;
 	wl_signal_emit(&dev->pointer->events.motion_absolute, &wlr_event);
 }
 

examples/screenshot.c

@@ -220,16 +220,10 @@ static void write_image(const char *filename, int width, int height) {
 }
 
 static int set_buffer_size(int *width, int *height) {
-	struct screenshooter_output *output;
 	min_x = min_y = INT_MAX;
 	max_x = max_y = INT_MIN;
-	int position = 0;
-
-	wl_list_for_each_reverse(output, &output_list, link) {
-		output->offset_x = position;
-		position += output->width;
-	}
 
+	struct screenshooter_output *output;
 	wl_list_for_each(output, &output_list, link) {
 		min_x = MIN(min_x, output->offset_x);
 		min_y = MIN(min_y, output->offset_y);