From 8940385270d2752e03117fa6c24adafff7586422 Mon Sep 17 00:00:00 2001
From: Aaron Plattner <aaronp@nvidia.com>
Date: Tue, 24 Nov 2009 11:08:42 -0500
Subject: [PATCH] Patch over performance regression in KDE

---
 fb/fbpict.c |   27 ++++++++++++++++++++++++++-
 1 files changed, 26 insertions(+), 1 deletions(-)

diff --git a/fb/fbpict.c b/fb/fbpict.c
index 5c96427..5799e37 100644
--- a/fb/fbpict.c
+++ b/fb/fbpict.c
@@ -317,6 +317,27 @@ destroy_drawable (pixman_image_t *image, void *data)
     pScreen->DestroyPixmap ((PixmapPtr)pDrawable);
 }
 
+/*
+ * Returns TRUE when the specified window is fully contained within its bounding
+ * pixmap.
+ */
+static Bool
+window_is_fully_contained(WindowPtr pWin)
+{
+    PixmapPtr pBoundingPix = (*pWin->drawable.pScreen->GetWindowPixmap)(pWin);
+    int x = pWin->drawable.x, y = pWin->drawable.y;
+
+#ifdef COMPOSITE
+    /* Translate from screen coordinates to pixmap coordinates */
+    x -= pBoundingPix->screen_x;
+    y -= pBoundingPix->screen_y;
+#endif
+
+    return x >= 0 && y >= 0 &&
+	   x + pWin->drawable.width <= pBoundingPix->drawable.width &&
+	   y + pWin->drawable.height <= pBoundingPix->drawable.height;
+}
+
 static pixman_image_t *
 create_bits_picture (PicturePtr pict,
 		     Bool	has_clip,
@@ -328,7 +349,11 @@ create_bits_picture (PicturePtr pict,
     pixman_image_t *image;
     DrawablePtr drawable;
 
-    if (is_src && pict->pDrawable->type == DRAWABLE_WINDOW)
+    /* Copy the source window if part of it lies outside its bounding pixmap to
+     * avoid reading outside that pixmap's bounds, since Pixman doesn't clip the
+     * source image per pixel */
+    if (is_src && pict->pDrawable->type == DRAWABLE_WINDOW &&
+	    !window_is_fully_contained((WindowPtr)pict->pDrawable))
 	drawable = copy_drawable (pict->pDrawable);
     else
 	drawable = pict->pDrawable;
-- 
1.6.5.2