surface-role-cursor: Send frame callbacks for backend handled cursors

For backend handled cursors, if nothing else changes on the clutter
stage, we end up not sending out frame callbacks since clutter doesn't
draw a new frame.

To fix this, we'll keep cursor surfaces' frame callbacks separate from
other surfaces' and trigger them from the new
MetaCursorRenderer::cursor-painted signal which handles both software
and hardware cursors.

https://bugzilla.gnome.org/show_bug.cgi?id=749913

src/wayland/meta-wayland-surface-role-cursor.c

@@ -27,6 +27,7 @@
 #include "meta-wayland-buffer.h"
 #include "meta-xwayland.h"
 #include "screen-private.h"
+#include "meta-wayland-private.h"
 
 typedef struct _MetaWaylandSurfaceRoleCursorPrivate MetaWaylandSurfaceRoleCursorPrivate;
 
@@ -37,6 +38,8 @@ struct _MetaWaylandSurfaceRoleCursorPrivate
   MetaCursorSprite *cursor_sprite;
   MetaCursorRenderer *cursor_renderer;
   MetaWaylandBuffer *buffer;
+  struct wl_list frame_callbacks;
+  gulong cursor_painted_handler_id;
 };
 
 G_DEFINE_TYPE_WITH_PRIVATE (MetaWaylandSurfaceRoleCursor,
@@ -124,7 +127,9 @@ cursor_surface_role_assigned (MetaWaylandSurfaceRole *surface_role)
       meta_wayland_surface_ref_buffer_use_count (surface);
     }
 
-  meta_wayland_surface_queue_pending_frame_callbacks (surface);
+  wl_list_insert_list (&priv->frame_callbacks,
+                       &surface->pending_frame_callback_list);
+  wl_list_init (&surface->pending_frame_callback_list);
 }
 
 static void
@@ -164,7 +169,9 @@ cursor_surface_role_commit (MetaWaylandSurfaceRole  *surface_role,
         meta_wayland_surface_ref_buffer_use_count (surface);
     }
 
-  meta_wayland_surface_queue_pending_state_frame_callbacks (surface, pending);
+  wl_list_insert_list (&priv->frame_callbacks,
+                       &pending->frame_callback_list);
+  wl_list_init (&pending->frame_callback_list);
 
   if (pending->newly_attached)
     update_cursor_sprite_texture (META_WAYLAND_SURFACE_ROLE_CURSOR (surface_role));
@@ -196,6 +203,10 @@ cursor_surface_role_dispose (GObject *object)
     meta_wayland_surface_role_cursor_get_instance_private (cursor_role);
   MetaWaylandSurface *surface =
     meta_wayland_surface_role_get_surface (META_WAYLAND_SURFACE_ROLE (object));
+  MetaWaylandFrameCallback *cb, *next;
+
+  wl_list_for_each_safe (cb, next, &priv->frame_callbacks, link)
+    wl_resource_destroy (cb->resource);
 
   g_signal_handlers_disconnect_by_func (priv->cursor_sprite,
                                         cursor_sprite_prepare_at, cursor_role);
@@ -224,6 +235,7 @@ meta_wayland_surface_role_cursor_init (MetaWaylandSurfaceRoleCursor *role)
                            G_CALLBACK (cursor_sprite_prepare_at),
                            role,
                            0);
+  wl_list_init (&priv->frame_callbacks);
 }
 
 static void
@@ -281,6 +293,28 @@ meta_wayland_surface_role_cursor_get_hotspot (MetaWaylandSurfaceRoleCursor *curs
     *hotspot_y = priv->hot_y;
 }
 
+static void
+on_cursor_painted (MetaCursorRenderer           *renderer,
+                   MetaCursorSprite             *displayed_sprite,
+                   MetaWaylandSurfaceRoleCursor *cursor_role)
+{
+  MetaWaylandSurfaceRoleCursorPrivate *priv =
+    meta_wayland_surface_role_cursor_get_instance_private (cursor_role);
+  guint32 time = (guint32) (g_get_monotonic_time () / 1000);
+
+  if (displayed_sprite != priv->cursor_sprite)
+    return;
+
+  while (!wl_list_empty (&priv->frame_callbacks))
+    {
+      MetaWaylandFrameCallback *callback =
+        wl_container_of (priv->frame_callbacks.next, callback, link);
+
+      wl_callback_send_done (callback->resource, time);
+      wl_resource_destroy (callback->resource);
+    }
+}
+
 void
 meta_wayland_surface_role_cursor_set_renderer (MetaWaylandSurfaceRoleCursor *cursor_role,
                                                MetaCursorRenderer           *renderer)
@@ -291,10 +325,20 @@ meta_wayland_surface_role_cursor_set_renderer (MetaWaylandSurfaceRoleCursor *cur
   if (priv->cursor_renderer == renderer)
     return;
 
-  if (renderer)
-    g_object_ref (renderer);
   if (priv->cursor_renderer)
-    g_object_unref (priv->cursor_renderer);
+    {
+      g_signal_handler_disconnect (priv->cursor_renderer,
+                                   priv->cursor_painted_handler_id);
+      priv->cursor_painted_handler_id = 0;
+      g_object_unref (priv->cursor_renderer);
+    }
+  if (renderer)
+    {
+      priv->cursor_painted_handler_id =
+        g_signal_connect_object (renderer, "cursor-painted",
+                                 G_CALLBACK (on_cursor_painted), cursor_role, 0);
+      g_object_ref (renderer);
+    }
 
   priv->cursor_renderer = renderer;
   update_cursor_sprite_texture (cursor_role);