Bug 1234485 - Part 3. Implement nsSVGIntegrationUtils::PaintMask. r=mstange

Unlike nsSVGIntegrationUtils::PaintMaskAndClipPath, which paints masked content
onto aParam.ctx, nsSVGIntegrationUtils::PaintMask paints only mask, no content,
onto aParams.ctx.

MozReview-Commit-ID: BaRbtHpoHzj

--HG--
extra : rebase_source : 4a258b7332ba7a7edbffdc13c7f4b065fbe5eaa4

layout/svg/nsSVGIntegrationUtils.cpp

@@ -749,6 +749,60 @@ nsSVGIntegrationUtils::IsMaskResourceReady(nsIFrame* aFrame)
   return true;
 }
 
+DrawResult
+nsSVGIntegrationUtils::PaintMask(const PaintFramesParams& aParams)
+{
+  MaskUsage maskUsage;
+  DetermineMaskUsage(aParams.frame, aParams.handleOpacity, maskUsage);
+  MOZ_ASSERT(maskUsage.shouldGenerateMaskLayer);
+
+  nsIFrame* frame = aParams.frame;
+  DrawResult result = DrawResult::SUCCESS;
+  if (!ValidateSVGFrame(frame)) {
+    return result;
+  }
+
+  if (maskUsage.opacity == 0.0f) {
+    return DrawResult::SUCCESS;
+  }
+
+  gfxContext& ctx = aParams.ctx;
+
+  Matrix maskTransform;
+  RefPtr<SourceSurface> maskSurface;
+
+  gfxContextMatrixAutoSaveRestore matSR(&ctx);
+
+  nsIFrame* firstFrame =
+    nsLayoutUtils::FirstContinuationOrIBSplitSibling(frame);
+  nsSVGEffects::EffectProperties effectProperties =
+    nsSVGEffects::GetEffectProperties(firstFrame);
+  nsTArray<nsSVGMaskFrame *> maskFrames = effectProperties.GetMaskFrames();
+  bool opacityApplied = false;
+
+  nsPoint offsetToBoundingBox;
+  nsPoint offsetToUserSpace;
+  SetupContextMatrix(frame, aParams, offsetToBoundingBox,
+                     offsetToUserSpace, false);
+  result = GenerateMaskSurface(aParams, maskUsage.opacity,
+                               firstFrame->StyleContext(),
+                               maskFrames, offsetToUserSpace,
+                               maskTransform, maskSurface, opacityApplied);
+  if (!maskSurface) {
+    // Entire surface is clipped out.
+    return result;
+  }
+
+  ctx.Multiply(ThebesMatrix(maskTransform));
+
+  DrawTarget* target = ctx.GetDrawTarget();
+  MOZ_ASSERT(target->GetFormat() == SurfaceFormat::A8);
+  Rect drawingRect(Point(0, 0), Size(target->GetSize()));
+  target->DrawSurface(maskSurface, drawingRect, drawingRect);
+
+  return result;
+}
+
 DrawResult
 nsSVGIntegrationUtils::PaintMaskAndClipPath(const PaintFramesParams& aParams)
 {

layout/svg/nsSVGIntegrationUtils.h

@@ -160,6 +160,13 @@ public:
   static DrawResult
   PaintMaskAndClipPath(const PaintFramesParams& aParams);
 
+  /**
+   * Paint mask of non-SVG frame onto a given context, aParams.ctx.
+   * aParams.ctx must contain an A8 surface.
+   */
+  static DrawResult
+  PaintMask(const PaintFramesParams& aParams);
+
   struct MaskUsage {
     bool shouldGenerateMaskLayer;
     bool shouldGenerateClipMaskLayer;