[gtk+] Cache default gdk visuals in the GDK_VISUALS property on the root window

[Alexander Larsson <alexl src gnome org>]

commit 8c7623de84d13437e951d37ded04dbefdea5c88c
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Oct 29 13:33:08 2014 +0100

    Cache default gdk visuals in the GDK_VISUALS property on the root window
    
    This means we don't have to try to initialize opengl in every gtk
    instance that is stated. It will only happen for the first one.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=738670

 gdk/x11/gdkdisplay-x11.c   |    3 +-
 gdk/x11/gdkglcontext-x11.c |   88 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 3 deletions(-)
---
diff --git a/gdk/x11/gdkdisplay-x11.c b/gdk/x11/gdkdisplay-x11.c
index be3ec71..358ae84 100644
--- a/gdk/x11/gdkdisplay-x11.c
+++ b/gdk/x11/gdkdisplay-x11.c
@@ -165,7 +165,8 @@ static const char *const precache_atoms[] = {
   "_NET_WM_USER_TIME_WINDOW",
   "_NET_VIRTUAL_ROOTS",
   "GDK_SELECTION",
-  "_NET_WM_STATE_FOCUSED"
+  "_NET_WM_STATE_FOCUSED",
+  "GDK_VISUALS"
 };
 
 static char *gdk_sm_client_id;
diff --git a/gdk/x11/gdkglcontext-x11.c b/gdk/x11/gdkglcontext-x11.c
index 72079af..aa46868 100644
--- a/gdk/x11/gdkglcontext-x11.c
+++ b/gdk/x11/gdkglcontext-x11.c
@@ -30,6 +30,8 @@
 #include "gdkx11window.h"
 #include "gdkx11visual.h"
 #include "gdkvisualprivate.h"
+#include "gdkx11property.h"
+#include <X11/Xatom.h>
 
 #include "gdkinternals.h"
 
@@ -817,6 +819,66 @@ pick_better_visual_for_gl (GdkX11Screen *x11_screen,
   return compatible;
 }
 
+static gboolean
+get_cached_gl_visuals (GdkDisplay *display, int *system, int *rgba)
+{
+  gboolean found;
+  Atom type_return;
+  gint format_return;
+  gulong nitems_return;
+  gulong bytes_after_return;
+  guchar *data = NULL;
+  Display *dpy;
+
+  dpy = gdk_x11_display_get_xdisplay (display);
+
+  found = FALSE;
+
+  gdk_x11_display_error_trap_push (display);
+  if (XGetWindowProperty (dpy, DefaultRootWindow (dpy),
+                          gdk_x11_get_xatom_by_name_for_display (display, "GDK_VISUALS"),
+                          0, 2, False, XA_INTEGER, &type_return,
+                          &format_return, &nitems_return,
+                          &bytes_after_return, &data) == Success)
+    {
+      if (type_return == XA_INTEGER &&
+          format_return == 32 &&
+          nitems_return == 2 &&
+          data != NULL)
+        {
+          long *visuals = (long *) data;
+
+          *system = (int)visuals[0];
+          *rgba = (int)visuals[1];
+          found = TRUE;
+        }
+    }
+  gdk_x11_display_error_trap_pop_ignored (display);
+
+  if (data)
+    XFree (data);
+
+  return found;
+}
+
+static void
+save_cached_gl_visuals (GdkDisplay *display, int system, int rgba)
+{
+  long visualdata[2];
+  Display *dpy;
+
+  dpy = gdk_x11_display_get_xdisplay (display);
+
+  visualdata[0] = system;
+  visualdata[1] = rgba;
+
+  gdk_x11_display_error_trap_push (display);
+  XChangeProperty(dpy, DefaultRootWindow (dpy), gdk_x11_get_xatom_by_name_for_display (display, 
"GDK_VISUALS"),
+                  XA_INTEGER, 32, PropModeReplace, (unsigned char *)visualdata, 2);
+  gdk_x11_display_error_trap_pop_ignored (display);
+}
+
+
 void
 _gdk_x11_screen_update_visuals_for_gl (GdkScreen *screen)
 {
@@ -826,16 +888,34 @@ _gdk_x11_screen_update_visuals_for_gl (GdkScreen *screen)
   Display *dpy;
   struct glvisualinfo *gl_info;
   int i;
+  int system_visual_id, rgba_visual_id;
 
   x11_screen = GDK_X11_SCREEN (screen);
   display = x11_screen->display;
   display_x11 = GDK_X11_DISPLAY (display);
+  dpy = gdk_x11_display_get_xdisplay (display);
+
+  /* We save the default visuals as a property on the root window to avoid
+     having to initialize GL each time, as it may not be used later. */
+  if (get_cached_gl_visuals (display, &system_visual_id, &rgba_visual_id))
+    {
+      for (i = 0; i < x11_screen->nvisuals; i++)
+        {
+          GdkVisual *visual = x11_screen->visuals[i];
+          int visual_id = gdk_x11_visual_get_xvisual (visual)->visualid;
+
+          if (visual_id == system_visual_id)
+            x11_screen->system_visual = visual;
+          if (visual_id == rgba_visual_id)
+            x11_screen->rgba_visual = visual;
+        }
+
+      return;
+    }
 
   if (!gdk_x11_screen_init_gl (screen))
     return;
 
-  dpy = gdk_x11_display_get_xdisplay (display);
-
   gl_info = g_new0 (struct glvisualinfo, x11_screen->nvisuals);
 
   for (i = 0; i < x11_screen->nvisuals; i++)
@@ -872,6 +952,10 @@ _gdk_x11_screen_update_visuals_for_gl (GdkScreen *screen)
   x11_screen->system_visual = pick_better_visual_for_gl (x11_screen, gl_info, x11_screen->system_visual);
   if (x11_screen->rgba_visual)
     x11_screen->rgba_visual = pick_better_visual_for_gl (x11_screen, gl_info, x11_screen->rgba_visual);
+
+  save_cached_gl_visuals (display,
+                          gdk_x11_visual_get_xvisual (x11_screen->system_visual)->visualid,
+                          x11_screen->rgba_visual ? gdk_x11_visual_get_xvisual 
(x11_screen->rgba_visual)->visualid : 0);
 }