[gtk+] gdkwindow-wayland: Obey Wayland buffer semantics

[Jasper St. Pierre <jstpierre src gnome org>]

commit 8061df15441910037be4ef633744f1bfb52efff5
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Mon Feb 3 18:45:32 2014 -0500

    gdkwindow-wayland: Obey Wayland buffer semantics
    
    We can't destroy buffers if they're in-use by the compositor. Well,
    technically we can, but that is considered undefined by Wayland and
    mutter won't cope with it very well -- it simply kills the client.
    
    To solve this, we need to delay the destroy operation until the
    compositor tells us that it's released the buffer. To do this, hold
    an extra ref on the cairo surface as long as the surface is in-use
    by the compositor.

 gdk/wayland/gdkwindow-wayland.c |   21 +++++++++++++--------
 1 files changed, 13 insertions(+), 8 deletions(-)
---
diff --git a/gdk/wayland/gdkwindow-wayland.c b/gdk/wayland/gdkwindow-wayland.c
index 025b03b..41a6998 100644
--- a/gdk/wayland/gdkwindow-wayland.c
+++ b/gdk/wayland/gdkwindow-wayland.c
@@ -417,7 +417,11 @@ on_frame_clock_after_paint (GdkFrameClock *clock,
 
   data = cairo_surface_get_user_data (impl->cairo_surface,
                                       &gdk_wayland_cairo_key);
-  data->busy = TRUE;
+  if (!data->busy)
+    {
+      data->busy = TRUE;
+      cairo_surface_reference (impl->cairo_surface);
+    }
 }
 
 static void
@@ -610,7 +614,6 @@ gdk_wayland_cairo_surface_destroy (void *p)
   g_free (data);
 }
 
-
 struct wl_shm_pool *
 _create_shm_pool (struct wl_shm  *shm,
                   int             width,
@@ -667,9 +670,11 @@ static void
 buffer_release_callback (void             *_data,
                          struct wl_buffer *wl_buffer)
 {
-  GdkWaylandCairoSurfaceData *data = _data;
+  cairo_surface_t *surface = _data;
+  GdkWaylandCairoSurfaceData *data = cairo_surface_get_user_data (surface, &gdk_wayland_cairo_key);
 
   data->busy = FALSE;
+  cairo_surface_destroy (surface);
 }
 
 static const struct wl_buffer_listener buffer_listener = {
@@ -702,17 +707,17 @@ gdk_wayland_create_cairo_surface (GdkWaylandDisplay *display,
                                  &data->buf_length,
                                  &data->buf);
 
-  data->buffer = wl_shm_pool_create_buffer (data->pool, 0,
-                                            width*scale, height*scale,
-                                            stride*scale, WL_SHM_FORMAT_ARGB8888);
-  wl_buffer_add_listener (data->buffer, &buffer_listener, data);
-
   surface = cairo_image_surface_create_for_data (data->buf,
                                                  CAIRO_FORMAT_ARGB32,
                                                  width*scale,
                                                  height*scale,
                                                  stride*scale);
 
+  data->buffer = wl_shm_pool_create_buffer (data->pool, 0,
+                                            width*scale, height*scale,
+                                            stride*scale, WL_SHM_FORMAT_ARGB8888);
+  wl_buffer_add_listener (data->buffer, &buffer_listener, surface);
+
   cairo_surface_set_user_data (surface, &gdk_wayland_cairo_key,
                                data, gdk_wayland_cairo_surface_destroy);