Bug 1323912 - Part 5. Apply opacity in mask layer painting path. r=mstange

MozReview-Commit-ID: HX2Tcum2smO

--HG--
extra : rebase_source : 8a28c67b898efbea304d71709c0fd13e25632032

layout/painting/nsDisplayList.cpp

@@ -7351,11 +7351,9 @@ bool nsDisplayMask::ShouldPaintOnMaskLayer(LayerManager* aManager)
   nsSVGUtils::MaskUsage maskUsage;
   nsSVGUtils::DetermineMaskUsage(mFrame, mHandleOpacity, maskUsage);
 
-  // XXX Bug 1323912. nsSVGIntegrationUtils::PaintMask can not handle opacity
-  // correctly. Turn it off before bug fixed.
   // XXX Temporary disable paint clip-path onto mask before figure out
   // performance regression(bug 1325550).
-  if (maskUsage.opacity != 1.0 || maskUsage.shouldApplyClipPath) {
+  if (maskUsage.shouldApplyClipPath) {
     return false;
   }
 

layout/svg/nsSVGIntegrationUtils.cpp

@@ -725,6 +725,25 @@ nsSVGIntegrationUtils::IsMaskResourceReady(nsIFrame* aFrame)
   return true;
 }
 
+class AutoPopGroup
+{
+public:
+  AutoPopGroup() : mContext(nullptr) { }
+
+  ~AutoPopGroup() {
+    if (mContext) {
+      mContext->PopGroupAndBlend();
+    }
+  }
+
+  void SetContext(gfxContext* aContext) {
+    mContext = aContext;
+  }
+
+private:
+  gfxContext* mContext;
+};
+
 DrawResult
 nsSVGIntegrationUtils::PaintMask(const PaintFramesParams& aParams)
 {
@@ -737,10 +756,6 @@ nsSVGIntegrationUtils::PaintMask(const PaintFramesParams& aParams)
     return DrawResult::SUCCESS;
   }
 
-  // XXX Bug 1323912.
-  MOZ_ASSERT(maskUsage.opacity == 1.0,
-             "nsSVGIntegrationUtils::PaintMask can not handle opacity now.");
-
   gfxContext& ctx = aParams.ctx;
   nsIFrame* firstFrame =
     nsLayoutUtils::FirstContinuationOrIBSplitSibling(frame);
@@ -762,6 +777,15 @@ nsSVGIntegrationUtils::PaintMask(const PaintFramesParams& aParams)
                                                      SurfaceFormat::A8);
   }
 
+  nsTArray<nsSVGMaskFrame *> maskFrames = effectProperties.GetMaskFrames();
+  AutoPopGroup autoPop;
+  bool shouldPushOpacity = (maskUsage.opacity != 1.0) &&
+                           (maskFrames.Length() != 1);
+  if (shouldPushOpacity) {
+    ctx.PushGroupForBlendBack(gfxContentType::COLOR_ALPHA, maskUsage.opacity);
+    autoPop.SetContext(&ctx);
+  }
+
   gfxContextMatrixAutoSaveRestore matSR;
   nsPoint offsetToBoundingBox;
   nsPoint offsetToUserSpace;
@@ -793,9 +817,8 @@ nsSVGIntegrationUtils::PaintMask(const PaintFramesParams& aParams)
 
     SetupContextMatrix(frame, aParams, offsetToBoundingBox,
                        offsetToUserSpace);
-    nsTArray<nsSVGMaskFrame *> maskFrames = effectProperties.GetMaskFrames();
-
-    result = PaintMaskSurface(aParams, maskTarget, 1.0,
+    result = PaintMaskSurface(aParams, maskTarget,
+                              shouldPushOpacity ?  1.0 : maskUsage.opacity,
                               firstFrame->StyleContext(), maskFrames,
                               ctx.CurrentMatrix(), offsetToUserSpace);
     if (result != DrawResult::SUCCESS) {