From 5a0d03626e5676efd122bb758431f612765cb8d1 Mon Sep 17 00:00:00 2001
From: Anthony Jones <ajones@mozilla.com>
Date: Sun, 2 Sep 2012 19:07:05 -0400
Subject: [PATCH] Bug 781731 - Fix Azure Cairo GTK perf by removing xlib to
 buffered image conversion. r=mattwoodrow

---
 gfx/thebes/gfxPlatform.cpp | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/gfx/thebes/gfxPlatform.cpp b/gfx/thebes/gfxPlatform.cpp
index 582dd3ca4887..e8d1d79a1974 100644
--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -535,8 +535,23 @@ gfxPlatform::GetSourceSurfaceForSurface(DrawTarget *aTarget, gfxASurface *aSurfa
       dt->Flush();
     }
     srcBuffer = aTarget->CreateSourceSurfaceFromNativeSurface(surf);
-  }
+  } else
 #endif
+  if (aSurface->CairoSurface() && aTarget->GetType() == BACKEND_CAIRO) {
+    // If this is an xlib cairo surface we don't want to fetch it into memory
+    // because this is a major slow down.
+    NativeSurface surf;
+    surf.mFormat = format;
+    surf.mType = NATIVE_SURFACE_CAIRO_SURFACE;
+    surf.mSurface = aSurface->CairoSurface();
+    srcBuffer = aTarget->CreateSourceSurfaceFromNativeSurface(surf);
+
+    if (srcBuffer) {
+      // It's cheap enough to make a new one so we won't keep it around and
+      // keeping it creates a cycle.
+      return srcBuffer;
+    }
+  }
 
   if (!srcBuffer) {
     nsRefPtr<gfxImageSurface> imgSurface = aSurface->GetAsImageSurface();