From 39897b3b712e902a8eabdf7b947b5d82ca5e8754 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michel=20D=C3=A4nzer?= <mdaenzer@redhat.com>
Date: Thu, 30 Oct 2025 16:45:23 +0100
Subject: [PATCH] composite: Skip copying parent pixmap contents when possible

If the parent window has a different depth (which means pWin can't have
valid contents yet) and pWin has effective background other than None.

Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2092>
---
 composite/compalloc.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/composite/compalloc.c b/composite/compalloc.c
index 63b3059e9..51ceeab7e 100644
--- a/composite/compalloc.c
+++ b/composite/compalloc.c
@@ -528,6 +528,15 @@ compUnredirectOneSubwindow(WindowPtr pParent, WindowPtr pWin)
     return Success;
 }
 
+static unsigned
+compGetBackgroundState(WindowPtr pWin)
+{
+    while (pWin->backgroundState == ParentRelative)
+        pWin = pWin->parent;
+
+    return pWin->backgroundState;
+}
+
 static PixmapPtr
 compNewPixmap(WindowPtr pWin, int x, int y, int w, int h)
 {
@@ -562,7 +571,7 @@ compNewPixmap(WindowPtr pWin, int x, int y, int w, int h)
             FreeScratchGC(pGC);
         }
     }
-    else {
+    else if (compGetBackgroundState(pWin) == None) {
         PictFormatPtr pSrcFormat = PictureWindowFormat(pParent);
         PictFormatPtr pDstFormat = PictureWindowFormat(pWin);
         XID inferiors = IncludeInferiors;