Bug 793365: Make sure (again) that the entire buffer is valid when we might be asynchronously composited. r=roc

gfx/layers/basic/BasicLayerManager.cpp

@@ -3,6 +3,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "mozilla/dom/TabChild.h"
 #include "mozilla/layers/PLayerChild.h"
 #include "mozilla/layers/PLayersChild.h"
 #include "mozilla/layers/PLayersParent.h"
@@ -25,6 +26,7 @@
 #include "mozilla/Preferences.h"
 #include "nsIWidget.h"
 
+using namespace mozilla::dom;
 using namespace mozilla::gfx;
 
 namespace mozilla {
@@ -215,6 +217,7 @@ BasicLayerManager::BasicLayerManager(nsIWidget* aWidget) :
   , mDoubleBuffering(BUFFER_NONE), mUsingDefaultTarget(false)
   , mCachedSurfaceInUse(false)
   , mTransactionIncomplete(false)
+  , mCompositorMightResample(false)
 {
   MOZ_COUNT_CTOR(BasicLayerManager);
   NS_ASSERTION(aWidget, "Must provide a widget");
@@ -1090,6 +1093,17 @@ BasicShadowLayerManager::BeginTransactionWithTarget(gfxContext* aTarget)
   if (HasShadowManager()) {
     ShadowLayerForwarder::BeginTransaction(mTargetBounds, mTargetRotation);
 
+    // If we're drawing on behalf of a context with async pan/zoom
+    // enabled, then the entire buffer of thebes layers might be
+    // composited (including resampling) asynchronously before we get
+    // a chance to repaint, so we have to ensure that it's all valid
+    // and not rotated.
+    if (mWidget) {
+      if (TabChild* window = mWidget->GetOwningTabChild()) {
+        mCompositorMightResample = window->IsAsyncPanZoomEnabled();
+      }
+    }
+
     // If we have a non-default target, we need to let our shadow manager draw
     // to it. This will happen at the end of the transaction.
     if (aTarget && (aTarget != mDefaultTarget) &&

gfx/layers/basic/BasicLayers.h

@@ -153,6 +153,7 @@ public:
 
   virtual bool IsCompositingCheap() { return false; }
   virtual int32_t GetMaxTextureSize() const { return PR_INT32_MAX; }
+  bool CompositorMightResample() { return mCompositorMightResample; }
 
 protected:
   enum TransactionPhase {
@@ -200,10 +201,11 @@ protected:
   // Cached surface for double buffering
   gfxCachedTempSurface mCachedSurface;
 
-  BufferMode   mDoubleBuffering;
+  BufferMode mDoubleBuffering;
   bool mUsingDefaultTarget;
   bool mCachedSurfaceInUse;
-  bool         mTransactionIncomplete;
+  bool mTransactionIncomplete;
+  bool mCompositorMightResample;
 };
  
 

gfx/layers/basic/BasicThebesLayer.cpp

@@ -4,11 +4,10 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "BasicThebesLayer.h"
-
+#include "gfxUtils.h"
 #include "nsIWidget.h"
 #include "RenderTrace.h"
 #include "sampler.h"
-#include "gfxUtils.h"
 
 #include "prprf.h"
 
@@ -156,12 +155,17 @@ BasicThebesLayer::PaintThebes(gfxContext* aContext,
 
   {
     uint32_t flags = 0;
-#ifndef MOZ_GFX_OPTIMIZE_MOBILE
+#ifndef MOZ_WIDGET_ANDROID
-    gfxMatrix transform;
+    if (BasicManager()->CompositorMightResample()) {
-    if (!GetEffectiveTransform().CanDraw2D(&transform) ||
-        transform.HasNonIntegerTranslation()) {
       flags |= ThebesLayerBuffer::PAINT_WILL_RESAMPLE;
     }
+    if (!(flags & ThebesLayerBuffer::PAINT_WILL_RESAMPLE)) {
+      gfxMatrix transform;
+      if (!GetEffectiveTransform().CanDraw2D(&transform) ||
+          transform.HasNonIntegerTranslation()) {
+        flags |= ThebesLayerBuffer::PAINT_WILL_RESAMPLE;
+      }
+    }
 #endif
     if (mDrawAtomically) {
       flags |= ThebesLayerBuffer::PAINT_NO_ROTATION;

widget/nsIWidget.h

@@ -1623,6 +1623,12 @@ class nsIWidget : public nsISupports {
      */
     virtual const SizeConstraints& GetSizeConstraints() const = 0;
 
+    /**
+     * If this is owned by a TabChild, return that.  Otherwise return
+     * null.
+     */
+    virtual TabChild* GetOwningTabChild() { return nullptr; }
+
 protected:
 
     // keep the list of children.  We also keep track of our siblings.

widget/xpwidgets/PuppetWidget.h

@@ -172,6 +172,8 @@ public:
   // later on.
   virtual float GetDPI();
 
+  virtual TabChild* GetOwningTabChild() MOZ_OVERRIDE { return mTabChild; }
+
 private:
   nsresult Paint();