b=561168; convert canvas to use layers for rendering - followup; r=roc

gfx/layers/opengl/CanvasLayerOGL.cpp

@@ -73,6 +73,7 @@ CanvasLayerOGL::Initialize(const Data& aData)
     mSurface = aData.mSurface;
     NS_ASSERTION(aData.mGLContext == nsnull,
                  "CanvasLayerOGL can't have both surface and GLContext");
+    mNeedsYFlip = PR_TRUE;
   } else if (aData.mGLContext) {
     // this must be a pbuffer context
     void *pbuffer = aData.mGLContext->GetNativeData(GLContext::NativePBuffer);
@@ -83,6 +84,7 @@ CanvasLayerOGL::Initialize(const Data& aData)
 
     mGLContext = aData.mGLContext;
     mGLBufferIsPremultiplied = aData.mGLBufferIsPremultiplied;
+    mNeedsYFlip = PR_FALSE;
   } else {
     NS_WARNING("CanvasLayerOGL::Initialize called without surface or GL context!");
     return;
@@ -213,6 +215,10 @@ CanvasLayerOGL::RenderLayer(int aPreviousDestination)
   // XXX We're going to need a different program depending on if
   // mGLBufferIsPremultiplied is TRUE or not.  The RGBLayerProgram
   // assumes that it's true.
+
+  // XXX this function needs to handle both mNeedsYFlip -- right now,
+  // as written, PBuffer canvas layers will be drawn upside-down.
+
   RGBLayerProgram *program = glManager->GetRGBLayerProgram();
 
   program->Activate();