[GTK+3] re-add ability to show alt-tab thumbnails when compositor is on

adapted from:
https://git.gnome.org/browse/metacity/commit/?id=e6828a3ee2cab1ec1acbdd5a444dc1cb98215a75
https://git.gnome.org/browse/metacity/commit/?id=758902aef22629943738241cea1f597b6db4b18e
https://git.gnome.org/browse/metacity/commit/?id=c6ba6dc7f458720d9f8666881f45a830580468cb
https://git.gnome.org/browse/metacity/commit/?id=68bdf1ab9de815e07f5cd75b2e1fa24ba92ae319
https://git.gnome.org/browse/metacity/commit/?id=78bbf4423f72797a05bfaddd4121d70db30de9a3

3 files changed, 71 insertions, 0 deletions

diff --git a/src/compositor/compositor-private.h b/src/compositor/compositor-private.h
index 61e7ffb0..1eef9633 100644
--- a/src/compositor/compositor-private.h
+++ b/src/compositor/compositor-private.h
@@ -44,8 +44,13 @@ struct _MetaCompositor
   void (*process_event) (MetaCompositor *compositor,
                          XEvent         *event,
                          MetaWindow     *window);
+#if GTK_CHECK_VERSION (3, 0, 0)
+  cairo_surface_t *(* get_window_surface) (MetaCompositor *compositor,
+                                           MetaWindow     *window);
+#else
   Pixmap (*get_window_pixmap) (MetaCompositor *compositor,
                                MetaWindow     *window);
+#endif
   void (*set_active_window) (MetaCompositor *compositor,
                              MetaScreen     *screen,
                              MetaWindow     *window);
diff --git a/src/compositor/compositor-xrender.c b/src/compositor/compositor-xrender.c
index 5080f80d..1da598c5 100644
--- a/src/compositor/compositor-xrender.c
+++ b/src/compositor/compositor-xrender.c
@@ -34,6 +34,11 @@
 #include <unistd.h>
 
 #include <gdk/gdk.h>
+#include <gtk/gtk.h>
+
+#if GTK_CHECK_VERSION (3, 0, 0)
+#include <cairo/cairo-xlib.h>
+#endif
 
 #include "display.h"
 #include "screen.h"
@@ -2797,6 +2802,46 @@ xrender_process_event (MetaCompositor *compositor,
 #endif
 }
 
+#if GTK_CHECK_VERSION (3, 0, 0)
+static cairo_surface_t *
+xrender_get_window_surface (MetaCompositor *compositor,
+                            MetaWindow     *window)
+{
+#ifdef HAVE_COMPOSITE_EXTENSIONS
+  MetaFrame *frame;
+  Window xwindow;
+  MetaScreen *screen;
+  MetaCompWindow *cw;
+  MetaCompositorXRender *xrc;
+  Display *display;
+  Pixmap pixmap;
+
+  frame = meta_window_get_frame (window);
+
+  if (frame)
+    xwindow = meta_frame_get_xwindow (frame);
+  else
+    xwindow = meta_window_get_xwindow (window);
+
+  screen = meta_window_get_screen (window);
+  cw = find_window_for_screen (screen, xwindow);
+
+  if (cw == NULL)
+    return NULL;
+
+  xrc = (MetaCompositorXRender *) compositor;
+  display = meta_display_get_xdisplay (xrc->display);
+
+  if (meta_window_is_shaded (window))
+    pixmap = cw->shaded_back_pixmap;
+  else
+    pixmap = cw->back_pixmap;
+
+  return cairo_xlib_surface_create (display, pixmap, cw->attrs.visual,
+                                    cw->attrs.width, cw->attrs.height);
+#endif
+}
+#else
 static Pixmap
 xrender_get_window_pixmap (MetaCompositor *compositor,
                            MetaWindow     *window)
@@ -2817,6 +2862,7 @@ xrender_get_window_pixmap (MetaCompositor *compositor,
     return cw->back_pixmap;
 #endif
 }
+#endif  /* GTK_CHECK_VERSION */
 
 static void
 xrender_set_active_window (MetaCompositor *compositor,
@@ -3000,7 +3046,11 @@ static MetaCompositor comp_info = {
   xrender_remove_window,
   xrender_set_updates,
   xrender_process_event,
+#if GTK_CHECK_VERSION (3, 0, 0)
+  xrender_get_window_surface,
+#else
   xrender_get_window_pixmap,
+#endif
   xrender_set_active_window,
   xrender_free_window,
   xrender_maximize_window,
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index f7a28261..4d3f370b 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -107,6 +107,21 @@ meta_compositor_process_event (MetaCompositor *compositor,
 #endif
 }
 
+#if GTK_CHECK_VERSION (3, 0, 0)
+cairo_surface_t *
+meta_compositor_get_window_surface (MetaCompositor *compositor,
+                                    MetaWindow     *window)
+{
+#ifdef HAVE_COMPOSITE_EXTENSIONS
+  if (compositor && compositor->get_window_surface)
+    return compositor->get_window_surface (compositor, window);
+  else
+    return NULL;
+#else
+  return NULL;
+#endif
+}
+#else
 Pixmap
 meta_compositor_get_window_pixmap (MetaCompositor *compositor,
                                    MetaWindow     *window)
@@ -120,6 +135,7 @@ meta_compositor_get_window_pixmap (MetaCompositor *compositor,
   return None;
 #endif
 }
+#endif  /* GTK_CHECK_VERSION */
 
 void
 meta_compositor_set_active_window (MetaCompositor *compositor,