More work on dnd

TODO

@@ -50,6 +50,19 @@ Core wayland protocol
       finish event too.  Either way, the state of the drag blocks on
       the client.  What if we drag to a client that doesn't doo dnd?
 
+   How do we animate the drag icon back to the drag origin in case of
+   a failed drag?
+
+   How to handle surfaces from clients that don't know about dnd or
+   don't care?  Maybe the dnd object should have a
+   dnd.register_surface() method so clients can opt-in the surfaces
+   that will participate in dnd.  Or just assume client is not
+   participating until we receive an accept request.
+
+   May need to look at all offer events before we can decide which one
+   to go with.  Problem is, we don't know when we've seen that last
+   offer event.
+
  - copy-n-paste, store data in server (only one mime-type available)
    or do X style (content mime-type negotiation, but data goes away
    when client quits).

clients/dnd.c

@@ -206,6 +206,82 @@ dnd_get_item(struct dnd *dnd, int32_t x, int32_t y)
 	return NULL;
 }
 
+static void
+drag_handle_device(void *data,
+		   struct wl_drag *drag, struct wl_input_device *device)
+{
+}
+
+static void
+drag_pointer_focus(void *data,
+		   struct wl_drag *drag,
+		   uint32_t time, struct wl_surface *surface,
+		   int32_t x, int32_t y, int32_t surface_x, int32_t surface_y)
+{
+	fprintf(stderr, "drag pointer focus %p\n", surface);
+
+	wl_drag_accept(drag, "text/plain");
+}
+
+static void
+drag_offer(void *data,
+	   struct wl_drag *drag, const char *type)
+{
+	fprintf(stderr, "drag offer %s\n", type);
+}
+
+static void
+drag_motion(void *data,
+	    struct wl_drag *drag,
+	    uint32_t time,
+	    int32_t x, int32_t y, int32_t surface_x, int32_t surface_y)
+{
+	fprintf(stderr, "drag motion %d,%d\n", surface_x, surface_y);
+
+	/* FIXME: Need to correlate this with the offer event.
+	 * 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. */
+	wl_drag_accept(drag, "text/plain");
+}
+
+static void
+drag_target(void *data,
+	    struct wl_drag *drag, const char *mime_type)
+{
+	fprintf(stderr, "target %s\n", mime_type);
+}
+
+static void
+drag_finish(void *data, struct wl_drag *drag)
+{
+	fprintf(stderr, "drag finish\n");
+	struct wl_array a;
+	char text[] = "[drop data]";
+
+	a.data = text;
+	a.size = sizeof text;
+
+	wl_drag_send(drag, &a);
+}
+
+static void
+drag_data(void *data,
+	  struct wl_drag *drag, struct wl_array *contents)
+{
+	fprintf(stderr, "drag drop, data %s\n", contents->data);
+}
+
+static const struct wl_drag_listener drag_listener = {
+	drag_handle_device,
+	drag_pointer_focus,
+	drag_offer,
+	drag_motion,
+	drag_target,
+	drag_finish,
+	drag_data
+};
+
 static void
 dnd_button_handler(struct window *window,
 		   struct input *input, uint32_t time,
@@ -352,6 +428,8 @@ main(int argc, char *argv[])
 
 	d = display_create(&argc, &argv, option_entries);
 
+	display_add_drag_listener(d, &drag_listener, d);
+
 	dnd = dnd_create (d);
 
 	display_run(d);

clients/window.c

@@ -57,7 +57,6 @@ struct display {
 	struct wl_shell *shell;
 	struct wl_drm *drm;
 	struct wl_output *output;
-	struct wl_drag *drag;
 	struct rectangle screen_allocation;
 	int authenticated;
 	EGLDisplay dpy;
@@ -718,6 +717,17 @@ input_get_position(struct input *input, int32_t *x, int32_t *y)
 	*y = input->sy;
 }
 
+void
+display_add_drag_listener(struct display *display,
+			  const struct wl_drag_listener *drag_listener,
+			  void *data)
+{
+	struct input *input;
+
+	wl_list_for_each(input, &display->input_list, link)
+		wl_drag_add_listener(input->drag, drag_listener, data);
+}
+
 void
 window_start_drag(struct window *window, struct input *input, uint32_t time,
 		  struct wl_buffer *buffer, int32_t x, int32_t y)
@@ -1072,7 +1082,7 @@ drag_handle_device(void *data,
 
 	input = wl_input_device_get_user_data(device);
 	input->drag = drag;
-
+	wl_drag_set_user_data(drag, input);
 }
 
 static void
@@ -1081,14 +1091,12 @@ drag_pointer_focus(void *data,
 		   uint32_t time, struct wl_surface *surface,
 		   int32_t x, int32_t y, int32_t surface_x, int32_t surface_y)
 {
-	fprintf(stderr, "drag pointer focus %p\n", surface);
 }
 
 static void
 drag_offer(void *data,
 	   struct wl_drag *drag, const char *type)
 {
-	fprintf(stderr, "drag offer %s\n", type);
 }
 
 static void
@@ -1097,7 +1105,6 @@ drag_motion(void *data,
 	    uint32_t time,
 	    int32_t x, int32_t y, int32_t surface_x, int32_t surface_y)
 {
-	fprintf(stderr, "drag motion %d,%d\n", surface_x, surface_y);
 }
 
 static void
@@ -1109,7 +1116,6 @@ drag_target(void *data,
 static void
 drag_finish(void *data, struct wl_drag *drag)
 {
-	fprintf(stderr, "drag finish\n");
 }
 
 static void
@@ -1133,6 +1139,7 @@ display_handle_global(struct wl_display *display, uint32_t id,
 		      const char *interface, uint32_t version, void *data)
 {
 	struct display *d = data;
+	struct wl_drag *drag;
 
 	if (strcmp(interface, "compositor") == 0) {
 		d->compositor = wl_compositor_create(display, id);
@@ -1150,8 +1157,8 @@ display_handle_global(struct wl_display *display, uint32_t id,
 		d->drm = wl_drm_create(display, id);
 		wl_drm_add_listener(d->drm, &drm_listener, d);
 	} else if (strcmp(interface, "drag") == 0) {
-		d->drag = wl_drag_create(display, id);
+		drag = wl_drag_create(display, id);
-		wl_drag_add_listener(d->drag, &drag_listener, d);
+		wl_drag_add_listener(drag, &drag_listener, NULL);
 	}
 }
 

clients/window.h

@@ -59,6 +59,11 @@ display_get_pointer_surface(struct display *display, int pointer,
 			    int *width, int *height,
 			    int *hotspot_x, int *hotspot_y);
 
+void
+display_add_drag_listener(struct display *display,
+			  const struct wl_drag_listener *drag_listener,
+			  void *data);
+
 void
 display_run(struct display *d);
 

compositor.c

@@ -1000,6 +1000,8 @@ wl_drag_set_pointer_focus(struct wl_drag *drag,
 			  struct wlsc_surface *surface, uint32_t time,
 			  int32_t x, int32_t y, int32_t sx, int32_t sy)
 {
+	char **p, **end;
+
 	if (drag->pointer_focus == &surface->base)
 		return;
 
@@ -1009,13 +1011,21 @@ wl_drag_set_pointer_focus(struct wl_drag *drag,
 				      &drag->base,
 				      WL_DRAG_POINTER_FOCUS,
 				      time, NULL, 0, 0, 0, 0);
-	if (surface)
+	if (surface) {
 		wl_surface_post_event(&surface->base,
 				      &drag->base,
 				      WL_DRAG_POINTER_FOCUS,
 				      time, &surface->base,
 				      x, y, sx, sy);
 
+		end = drag->types.data + drag->types.size;
+		for (p = drag->types.data; p < end; p++)
+			wl_surface_post_event(&surface->base,
+					      &drag->base,
+					      WL_DRAG_OFFER, *p);
+	}
+
+
 	drag->pointer_focus = &surface->base;
 }
 
@@ -1133,6 +1143,26 @@ drag_accept(struct wl_client *client,
 {
 	char **p, **end;
 
+	/* If the client responds to drag motion events after the
+	 * pointer has left the surface, we just discard the accept
+	 * requests.  The drag source just won't get the corresponding
+	 * 'target' events and the next surface/root will start
+	 * sending events. */
+	if (drag->pointer_focus == NULL)
+		return;
+
+	/* The accept request may arrive after the pointer has left
+	 * the surface that received the drag motion events that
+	 * triggered the request.  But if the pointer re-enters the
+	 * surface (or another surface from the same client) and we
+	 * receive the 'accept' requests from the first visit to the
+	 * surface later, this check will pass.  Then we end up
+	 * sending the 'target' event for the old 'accept' requests
+	 * events *after* potentially sending 'target' from the root
+	 * surface, out of order.  So we need to track the time of
+	 * pointer_focus and this request needs a time stamp so we can
+	 * compare and reject 'accept' requests that are older than
+	 * the pointer_focus in timestamp. */
 	if (drag->pointer_focus->client != client)
 		return;