wlr_scene: Add a way to choose when input interactions happen on a buffer

include/wlr/types/wlr_scene.h

@@ -28,6 +28,11 @@ struct wlr_output_layout;
 struct wlr_xdg_surface;
 struct wlr_layer_surface_v1;
 
+struct wlr_scene_buffer;
+
+typedef bool (*wlr_scene_buffer_point_accepts_input_func_t)(
+	struct wlr_scene_buffer *buffer, int sx, int sy);
+
 enum wlr_scene_node_type {
 	WLR_SCENE_NODE_ROOT,
 	WLR_SCENE_NODE_TREE,
@@ -118,6 +123,9 @@ struct wlr_scene_buffer {
 		struct wl_signal frame_done; // struct timespec
 	} events;
 
+	// May be NULL
+	wlr_scene_buffer_point_accepts_input_func_t point_accepts_input;
+
 	/**
 	 * The output that the largest area of this buffer is displayed on.
 	 * This may be NULL if the buffer is not currently displayed on any

types/scene/wlr_scene.c

@@ -771,12 +771,22 @@ struct wlr_scene_node *wlr_scene_node_at(struct wlr_scene_node *node,
 		struct wlr_scene_surface *scene_surface = wlr_scene_surface_from_node(node);
 		intersects = wlr_surface_point_accepts_input(scene_surface->surface, lx, ly);
 		break;
-	case WLR_SCENE_NODE_RECT:
-	case WLR_SCENE_NODE_BUFFER:;
+	case WLR_SCENE_NODE_RECT:;
 		int width, height;
 		scene_node_get_size(node, &width, &height);
 		intersects = lx >= 0 && lx < width && ly >= 0 && ly < height;
 		break;
+	case WLR_SCENE_NODE_BUFFER:;
+		struct wlr_scene_buffer *scene_buffer = scene_buffer_from_node(node);
+
+		if (scene_buffer->point_accepts_input) {
+			intersects = scene_buffer->point_accepts_input(scene_buffer, lx, ly);
+		} else {
+			int width, height;
+			scene_node_get_size(node, &width, &height);
+			intersects = lx >= 0 && lx < width && ly >= 0 && ly < height;
+		}
+		break;
 	}
 
 	if (intersects) {