From 71f949fbcc3523a2d6f906ff9eb61aa87abcc88e Mon Sep 17 00:00:00 2001
From: Nicholas Cameron <ncameron@mozilla.com>
Date: Mon, 9 Dec 2013 09:47:57 +1300
Subject: [PATCH] Bug 946532. Fix crash on startup with basic compositor and
 d2d. r=

---
 widget/windows/nsWindow.cpp | 42 ++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index ce319a62764..11f8bd38a81 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -3514,19 +3514,36 @@ mozilla::TemporaryRef<mozilla::gfx::DrawTarget>
 nsWindow::StartRemoteDrawing()
 {
   MOZ_ASSERT(!mCompositeDC);
+  NS_ASSERTION(IsRenderMode(gfxWindowsPlatform::RENDER_DIRECT2D)) ||
+               IsRenderMode(gfxWindowsPlatform::RENDER_GDI)),
+               "Unexpected render mode for remote drawing");
 
   HDC dc = (HDC)GetNativeData(NS_NATIVE_GRAPHIC);
-  if (!dc) {
-    return nullptr;
-  }
+  nsRefPtr<gfxASurface> surf;
 
-  uint32_t flags = (mTransparencyMode == eTransparencyOpaque) ? 0 :
-      gfxWindowsSurface::FLAG_IS_TRANSPARENT;
-  nsRefPtr<gfxASurface> surf = new gfxWindowsSurface(dc, flags);
+  if (mTransparencyMode == eTransparencyTransparent) {
+    if (!mTransparentSurface) {
+      SetupTranslucentWindowMemoryBitmap(mTransparencyMode);
+    }
+    if (mTransparentSurface) {
+      surf = mTransparentSurface;
+    }
+  } 
+  
+  if (!surf) {
+    if (!dc) {
+      return nullptr;
+    }
+    uint32_t flags = (mTransparencyMode == eTransparencyOpaque) ? 0 :
+        gfxWindowsSurface::FLAG_IS_TRANSPARENT;
+    surf = new gfxWindowsSurface(dc, flags);
+  }
 
   mozilla::gfx::IntSize size(surf->GetSize().width, surf->GetSize().height);
   if (size.width <= 0 || size.height <= 0) {
-    FreeNativeData(dc, NS_NATIVE_GRAPHIC);
+    if (dc) {
+      FreeNativeData(dc, NS_NATIVE_GRAPHIC);
+    }
     return nullptr;
   }
 
@@ -3539,9 +3556,14 @@ nsWindow::StartRemoteDrawing()
 void
 nsWindow::EndRemoteDrawing()
 {
-  MOZ_ASSERT(mCompositeDC);
-  UpdateTranslucentWindow();
-  FreeNativeData(mCompositeDC, NS_NATIVE_GRAPHIC);
+  if (mTransparencyMode == eTransparencyTransparent) {
+    MOZ_ASSERT(IsRenderMode(gfxWindowsPlatform::RENDER_DIRECT2D))
+               || mTransparentSurface);
+    UpdateTranslucentWindow();
+  }
+  if (mCompositeDC) {
+    FreeNativeData(mCompositeDC, NS_NATIVE_GRAPHIC);
+  }
   mCompositeDC = nullptr;
 }