From 80f79e0cc7509b79b38193a006b0d98d03432044 Mon Sep 17 00:00:00 2001
From: Ray Strode <rstrode@redhat.com>
Date: Mon, 5 Aug 2019 14:39:21 -0400
Subject: [PATCH] iconcache: Avoid xrender picture formats when creating cairo
 surface

If an application provides its window icon via wmhints, then mutter
loads the pixmap specified by the application into a cairo xlib surface. When
creating the surface it specifies the visual, indirectly, via an XRender
picture format.

This is suboptimal, since XRender picture formats don't have a way to specify
16bpp depth, which an application may be using.

In particular, applications are likely to use 16bpp depth pixmaps for their
icons, if the video card offers a 16bpp framebuffer/root window.

This commit drops the XRender middleman, and just tells cairo a visual to use
directly.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/715
---
 src/x11/iconcache.c | 31 ++++++-------------------------
 1 file changed, 6 insertions(+), 25 deletions(-)

diff --git a/src/x11/iconcache.c b/src/x11/iconcache.c
index 15d72da65..521c77b8d 100644
--- a/src/x11/iconcache.c
+++ b/src/x11/iconcache.c
@@ -261,97 +261,78 @@ get_pixmap_geometry (MetaX11Display *x11_display,
                      Pixmap          pixmap,
                      int            *w,
                      int            *h,
                      int            *d)
 {
   Window root_ignored;
   int x_ignored, y_ignored;
   guint width, height;
   guint border_width_ignored;
   guint depth;
 
   if (w)
     *w = 1;
   if (h)
     *h = 1;
   if (d)
     *d = 1;
 
   XGetGeometry (x11_display->xdisplay,
                 pixmap, &root_ignored, &x_ignored, &y_ignored,
                 &width, &height, &border_width_ignored, &depth);
 
   if (w)
     *w = width;
   if (h)
     *h = height;
   if (d)
     *d = depth;
 }
 
-static int
-standard_pict_format_for_depth (int depth)
-{
-  switch (depth)
-    {
-    case 1:
-      return PictStandardA1;
-    case 24:
-      return PictStandardRGB24;
-    case 32:
-      return PictStandardARGB32;
-    default:
-      g_assert_not_reached ();
-    }
-  return 0;
-}
-
-static XRenderPictFormat *
-pict_format_for_depth (Display *xdisplay, int depth)
-{
-  return XRenderFindStandardFormat (xdisplay, standard_pict_format_for_depth (depth));
-}
-
 static cairo_surface_t *
 surface_from_pixmap (Display *xdisplay, Pixmap xpixmap,
                      int width, int height)
 {
   Window root_return;
+  XVisualInfo visual_info;
   int x_ret, y_ret;
   unsigned int w_ret, h_ret, bw_ret, depth_ret;
 
   if (!XGetGeometry (xdisplay, xpixmap, &root_return,
                      &x_ret, &y_ret, &w_ret, &h_ret, &bw_ret, &depth_ret))
     return NULL;
 
-  return cairo_xlib_surface_create_with_xrender_format (xdisplay, xpixmap, DefaultScreenOfDisplay (xdisplay),
-                                                        pict_format_for_depth (xdisplay, depth_ret), w_ret, h_ret);
+  if (!XMatchVisualInfo (xdisplay, DefaultScreen (xdisplay),
+                         depth_ret, TrueColor, &visual_info))
+    return NULL;
+
+  return cairo_xlib_surface_create (xdisplay, xpixmap, visual_info.visual, w_ret, h_ret);
 }
 
 static gboolean
 try_pixmap_and_mask (MetaX11Display   *x11_display,
                      Pixmap            src_pixmap,
                      Pixmap            src_mask,
                      cairo_surface_t **iconp)
 {
   Display *xdisplay = x11_display->xdisplay;
   cairo_surface_t *icon, *mask = NULL;
   int w, h, d;
 
   if (src_pixmap == None)
     return FALSE;
 
   meta_x11_error_trap_push (x11_display);
 
   get_pixmap_geometry (x11_display, src_pixmap, &w, &h, &d);
   icon = surface_from_pixmap (xdisplay, src_pixmap, w, h);
 
   if (icon && src_mask != None)
     {
       get_pixmap_geometry (x11_display, src_mask, &w, &h, &d);
 
       if (d == 1)
         mask = surface_from_pixmap (xdisplay, src_mask, w, h);
     }
 
   meta_x11_error_trap_pop (x11_display);
 
-- 
2.21.0