From 2573bec755a85ef773c3916bb6d75ae9e523ef43 Mon Sep 17 00:00:00 2001
From: Jacopo De Simoi <wilderkde@gmail.com>
Date: Mon, 9 May 2011 11:13:05 -0400
Subject: [PATCH] XRender backend: do not process invalid shadow data

---
 scene_xrender.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scene_xrender.cpp b/scene_xrender.cpp
index 5c7663b795..a1ed9e0b3d 100644
--- a/scene_xrender.cpp
+++ b/scene_xrender.cpp
@@ -732,7 +732,7 @@ void SceneXrender::Window::performPaint(int mask, QRegion region, WindowPaintDat
     }
 
     //shadow
-    if (m_shadow && !(mask & PAINT_DECORATION_ONLY)) {
+    if (m_shadow && !(m_shadow->shadowRegion().isEmpty()) && !(mask & PAINT_DECORATION_ONLY)) {
         QRect stlr, str, strr, srr, sbrr, sbr, sblr, slr;
         SceneXRenderShadow* m_xrenderShadow = static_cast<SceneXRenderShadow*>(m_shadow);
         m_xrenderShadow->layoutShadowRects(str, strr, srr, sbrr, sbr, sblr, slr, stlr);
@@ -1092,6 +1092,10 @@ void SceneXRenderShadow::buildQuads()
 {
     Shadow::buildQuads();
 
+    if (shadowQuads().count() == 0) {
+        return;
+    }
+
     QRect stlr, str, strr, srr, sbrr, sbr, sblr, slr;
     layoutShadowRects(str, strr, srr, sbrr, sbr, sblr, slr, stlr);