Bug 1151145 - Add assertions to detect unbalanced calls to CGContextSaveGState / CGContextRestoreGState. r=jrmuizel

--HG--
extra : rebase_source : d5f12fa26ec4524ec798704f3851c47215a79f31

gfx/2d/DrawTargetCG.cpp

@@ -1961,6 +1961,10 @@ DrawTargetCG::PushClipRect(const Rect &aRect)
     return;
   }
 
+#ifdef DEBUG
+  mSavedClipBounds.push_back(CGContextGetClipBoundingBox(mCg));
+#endif
+
   CGContextSaveGState(mCg);
 
   /* We go through a bit of trouble to temporarilly set the transform
@@ -1979,6 +1983,10 @@ DrawTargetCG::PushClip(const Path *aPath)
     return;
   }
 
+#ifdef DEBUG
+  mSavedClipBounds.push_back(CGContextGetClipBoundingBox(mCg));
+#endif
+
   CGContextSaveGState(mCg);
 
   CGContextBeginPath(mCg);
@@ -2013,6 +2021,13 @@ void
 DrawTargetCG::PopClip()
 {
   CGContextRestoreGState(mCg);
+
+#ifdef DEBUG
+  MOZ_ASSERT(!mSavedClipBounds.empty(), "Unbalanced PopClip");
+  MOZ_ASSERT(CGRectEqualToRect(mSavedClipBounds.back(), CGContextGetClipBoundingBox(mCg)),
+             "PopClip didn't restore original clip");
+  mSavedClipBounds.pop_back();
+#endif
 }
 
 void

gfx/2d/DrawTargetCG.h

@@ -207,6 +207,10 @@ private:
 
   RefPtr<SourceSurfaceCGContext> mSnapshot;
   bool mMayContainInvalidPremultipliedData;
+
+#ifdef DEBUG
+  std::vector<CGRect> mSavedClipBounds;
+#endif
 };
 
 }