Provide visual feedback as to whether drop is supported

Change the cursor in response to target events.

clients/dnd.c

@@ -45,7 +45,8 @@ struct dnd {
 	uint32_t key;
 	struct item *items[16];
 
-	struct wl_buffer *buffer;
+	struct wl_buffer *translucent_buffer;
+	struct wl_buffer *opaque_buffer;
 	int hotspot_x, hotspot_y;
 	uint32_t tag;
 	const char *drag_type;
@@ -198,8 +199,14 @@ static struct item *
 dnd_get_item(struct dnd *dnd, int32_t x, int32_t y)
 {
 	struct item *item;
+	struct rectangle rectangle;
 	int i;
 
+	window_get_child_rectangle(dnd->window, &rectangle);
+
+	x -= rectangle.x;
+	y -= rectangle.y;
+
 	for (i = 0; i < ARRAY_LENGTH(dnd->items); i++) {
 		item = dnd->items[i];
 		if (item &&
@@ -231,10 +238,16 @@ drag_pointer_focus(void *data,
 
 	fprintf(stderr, "drag pointer focus %p\n", surface);
 
-	if (surface) {
+	if (!surface) {
+		dnd->drag_type = NULL;
+		return;
+	}
+
+	if (!dnd_get_item(dnd, surface_x, surface_y)) {
 		wl_drag_accept(drag, "text/plain");
 		dnd->drag_type = "text/plain";
 	} else {
+		wl_drag_accept(drag, NULL);
 		dnd->drag_type = NULL;
 	}
 }
@@ -258,8 +271,13 @@ drag_motion(void *data,
 	 * Problem is, we don't know when we've seen that last offer
 	 * event, and we might need to look at all of them before we
 	 * can decide which one to go with. */
+	if (!dnd_get_item(dnd, surface_x, surface_y)) {
 		wl_drag_accept(drag, "text/plain");
 		dnd->drag_type = "text/plain";
+	} else {
+		wl_drag_accept(drag, NULL);
+		dnd->drag_type = NULL;
+	}
 }
 
 static void
@@ -270,9 +288,14 @@ drag_target(void *data,
 	struct input *input;
 	struct wl_input_device *device;
 
+	fprintf(stderr, "target %s\n", mime_type);
 	input = wl_drag_get_user_data(drag);
 	device = input_get_input_device(input);
-	wl_input_device_attach(device, dnd->buffer,
+	if (mime_type)
+		wl_input_device_attach(device, dnd->opaque_buffer,
+				       dnd->hotspot_x, dnd->hotspot_y);
+	else
+		wl_input_device_attach(device, dnd->translucent_buffer,
 				       dnd->hotspot_x, dnd->hotspot_y);
 }
 
@@ -305,6 +328,10 @@ drag_drop(void *data, struct wl_drag *drag)
 
 	if (!dnd->drag_type) {
 		fprintf(stderr, "got 'drop', but no target\n");
+		/* FIXME: Should send response so compositor and
+		 * source knows it's over. Can't send -1 to indicate
+		 * 'no target' though becauses of the way fd passing
+		 * currently works.  */
 		return;
 	}
 
@@ -339,28 +366,16 @@ static const struct wl_drag_listener drag_listener = {
 	drag_finish
 };
 
-static void
-dnd_button_handler(struct window *window,
-		   struct input *input, uint32_t time,
-		   int button, int state, void *data)
+static cairo_surface_t *
+create_drag_cursor(struct dnd *dnd, struct item *item, int32_t x, int32_t y,
+		   double opacity)
 {
-	struct dnd *dnd = data;
-	int32_t x, y, hotspot_x, hotspot_y, pointer_width, pointer_height;
-	struct rectangle rectangle;
-	struct item *item;
 	cairo_surface_t *surface, *pointer;
+	int32_t pointer_width, pointer_height, hotspot_x, hotspot_y;
+	struct rectangle rectangle;
+	cairo_pattern_t *pattern;
 	cairo_t *cr;
 
-	input_get_position(input, &x, &y);
-	window_get_child_rectangle(dnd->window, &rectangle);
-
-	x -= rectangle.x;
-	y -= rectangle.y;
-	item = dnd_get_item(dnd, x, y);
-
-	if (item && state == 1) {
-		fprintf(stderr, "start drag, item %p\n", item);
-
 	pointer = display_get_pointer_surface(dnd->display,
 					      POINTER_DRAGGING,
 					      &pointer_width,
@@ -381,20 +396,53 @@ dnd_button_handler(struct window *window,
 
 	cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
 	cairo_set_source_surface(cr, item->surface, 0, 0);
-		cairo_paint(cr);
+	pattern = cairo_pattern_create_rgba(0, 0, 0, opacity);
+	cairo_mask(cr, pattern);
+	cairo_pattern_destroy(pattern);
 
 	cairo_set_source_surface(cr, pointer,
 				 x - item->x - hotspot_x,
 				 y - item->y - hotspot_y);
 	cairo_surface_destroy(pointer);
 	cairo_paint(cr);
+	/* FIXME: more cairo-gl brokeness */
+	display_flush_cairo_device(dnd->display);
 	cairo_destroy(cr);
 
-		dnd->buffer = display_get_buffer_for_surface(dnd->display,
-							     surface);
 	dnd->hotspot_x = pointer_width + x - item->x;
 	dnd->hotspot_y = pointer_height + y - item->y;
 
+	return surface;
+}
+
+static void
+dnd_button_handler(struct window *window,
+		   struct input *input, uint32_t time,
+		   int button, int state, void *data)
+{
+	struct dnd *dnd = data;
+	int32_t x, y;
+	struct item *item;
+	cairo_surface_t *surface;
+	struct rectangle rectangle;
+
+	window_get_child_rectangle(dnd->window, &rectangle);
+	input_get_position(input, &x, &y);
+	item = dnd_get_item(dnd, x, y);
+	x -= rectangle.x;
+	y -= rectangle.y;
+
+	if (item && state == 1) {
+		fprintf(stderr, "start drag, item %p\n", item);
+
+		surface = create_drag_cursor(dnd, item, x, y, 1);
+		dnd->opaque_buffer =
+			display_get_buffer_for_surface(dnd->display, surface);
+
+		surface = create_drag_cursor(dnd, item, x, y, 0.2);
+		dnd->translucent_buffer =
+			display_get_buffer_for_surface(dnd->display, surface);
+
 		window_start_drag(window, input, time);
 
 		/* FIXME: We leak the surface because we can't free it
@@ -410,10 +458,8 @@ dnd_motion_handler(struct window *window,
 {
 	struct dnd *dnd = data;
 	struct item *item;
-	struct rectangle rectangle;
 
-	window_get_child_rectangle(dnd->window, &rectangle);
-	item = dnd_get_item(dnd, sx - rectangle.x, sy - rectangle.y);
+	item = dnd_get_item(dnd, sx, sy);
 
 	if (item)
 		return POINTER_HAND1;

clients/window.c

@@ -407,6 +407,12 @@ window_draw_decorations(struct window *window)
 	cairo_device_flush (window->display->device);
 }
 
+void
+display_flush_cairo_device(struct display *display)
+{
+	cairo_device_flush (display->device);
+}
+
 static void
 window_draw_fullscreen(struct window *window)
 {

clients/window.h

@@ -64,6 +64,9 @@ display_add_drag_listener(struct display *display,
 			  const struct wl_drag_listener *drag_listener,
 			  void *data);
 
+void
+display_flush_cairo_device(struct display *display);
+
 void
 display_run(struct display *d);