[gtk/wip/otte/gleanup: 3/22] glx: Remove Visual cache

[Benjamin Otte <otte src gnome org>]

commit e4d02fa56d210a877f1adea41c5fc985ae477d53
Author: Benjamin Otte <otte redhat com>
Date:   Sat Jun 12 11:13:22 2021 +0200

    glx: Remove Visual cache
    
    1. We're using EGL most of the time anyway, so if we wanted to cache
       things, we'd need to port it there.
    2. Our GL handling is massively configurable, so determining when to use
       the cache and when not is a challenge.
    3. It makes startup nondeterministic and depend on whether a GTK4 app
       has previously been started on this display and nobody thinks about
       that when debugging.
    4. The only benefit of the caching is delaying GL initialization - which
       made sense in GTK3 where almost no app used GL but doesn't make sense
       in GTK4 where almost every app uses GL.
    
    So unless I find a big benefit to reintroducing it, this cache will be
    gone for good.

 gdk/x11/gdkglcontext-glx.c | 82 +---------------------------------------------
 1 file changed, 1 insertion(+), 81 deletions(-)
---
diff --git a/gdk/x11/gdkglcontext-glx.c b/gdk/x11/gdkglcontext-glx.c
index 3bdfe431ea..4ebc30bd89 100644
--- a/gdk/x11/gdkglcontext-glx.c
+++ b/gdk/x11/gdkglcontext-glx.c
@@ -947,64 +947,6 @@ pick_better_visual_for_gl (GdkX11Screen *x11_screen,
   return compatible;
 }
 
-#define STRINGIFY_WITHOUT_BRACKETS(x) G_STRINGIFY x
-#define CACHED_VISUAL_ATOM_NAME "GDK" STRINGIFY_WITHOUT_BRACKETS(GDK_MAJOR_VERSION) "_GLX_VISUAL"
-
-static VisualID
-get_cached_gl_visual (GdkDisplay *display)
-{
-  Atom type_return;
-  int format_return;
-  gulong nitems_return;
-  gulong bytes_after_return;
-  guchar *data = NULL;
-  Display *dpy;
-  VisualID result;
-
-  dpy = gdk_x11_display_get_xdisplay (display);
-  result = 0;
-
-  gdk_x11_display_error_trap_push (display);
-  if (XGetWindowProperty (dpy, DefaultRootWindow (dpy),
-                          gdk_x11_get_xatom_by_name_for_display (display, CACHED_VISUAL_ATOM_NAME),
-                          0, 1, False, XA_VISUALID, &type_return,
-                          &format_return, &nitems_return,
-                          &bytes_after_return, &data) == Success)
-    {
-      if (type_return == XA_VISUALID &&
-          format_return == 32 &&
-          nitems_return == 1 &&
-          data != NULL)
-        {
-          result = *(unsigned long *) data;
-        }
-    }
-  gdk_x11_display_error_trap_pop_ignored (display);
-
-  if (data)
-    XFree (data);
-
-  return result;
-}
-
-static void
-save_cached_gl_visual (GdkDisplay *display, VisualID visual)
-{
-  unsigned long visualdata[1];
-  Display *dpy;
-
-  dpy = gdk_x11_display_get_xdisplay (display);
-
-  visualdata[0] = visual;
-
-  gdk_x11_display_error_trap_push (display);
-  XChangeProperty (dpy, DefaultRootWindow (dpy),
-                   gdk_x11_get_xatom_by_name_for_display (display, CACHED_VISUAL_ATOM_NAME),
-                   XA_VISUALID, 32, PropModeReplace,
-                   (unsigned char *) visualdata, 2);
-  gdk_x11_display_error_trap_pop_ignored (display);
-}
-
 static void
 gdk_x11_screen_update_visuals_for_glx (GdkX11Screen *x11_screen)
 {
@@ -1013,30 +955,11 @@ gdk_x11_screen_update_visuals_for_glx (GdkX11Screen *x11_screen)
   Display *dpy;
   struct glvisualinfo *gl_info;
   int i;
-  int rgba_visual_id;
 
   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. */
-  rgba_visual_id = get_cached_gl_visual (display);
-  if (rgba_visual_id)
-    {
-      for (i = 0; i < x11_screen->nvisuals; i++)
-        {
-          GdkX11Visual *visual = x11_screen->visuals[i];
-          int visual_id = gdk_x11_visual_get_xvisual (visual)->visualid;
-
-          if (visual_id == rgba_visual_id)
-            {
-              x11_screen->rgba_visual = visual;
-              return;
-            }
-        }
-    }
-
   gl_info = g_new0 (struct glvisualinfo, x11_screen->nvisuals);
 
   for (i = 0; i < x11_screen->nvisuals; i++)
@@ -1071,10 +994,7 @@ gdk_x11_screen_update_visuals_for_glx (GdkX11Screen *x11_screen)
     }
 
   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_visual (display, gdk_x11_visual_get_xvisual (x11_screen->rgba_visual)->visualid);
-    }
+    x11_screen->rgba_visual = pick_better_visual_for_gl (x11_screen, gl_info, x11_screen->rgba_visual);
 
   g_free (gl_info);
 }