Bug 1520652 - Clip SVG filters to the PrimitiveSubregion when using WebRender. r=mstange

This patch changes a few things:
* Restores clipping to the computed clip, but just for SVG filters.
* Computes the clip just from the primitive subregion, not the bounds of the filtered content.
* Unconditionally clips all SVG filters using the primitive subregion
* Allows clips to be combined, if they will be sharing a coordinate space
* Fixes coordinate space of the clip region.

Differential Revision: https://phabricator.services.mozilla.com/D16941

--HG--
extra : moz-landing-system : lando

layout/painting/nsDisplayList.cpp

@@ -9350,29 +9350,34 @@ bool nsDisplayFilters::CreateWebRenderCommands(
     const StackingContextHelper& aSc,
     mozilla::layers::RenderRootStateManager* aManager,
     nsDisplayListBuilder* aDisplayListBuilder) {
-  bool snap;
   float auPerDevPixel = mFrame->PresContext()->AppUnitsPerDevPixel();
-  nsRect displayBounds = GetBounds(aDisplayListBuilder, &snap);
-  auto postFilterBounds = LayoutDeviceIntRect::Round(
-      LayoutDeviceRect::FromAppUnits(displayBounds, auPerDevPixel));
-  auto preFilterBounds = LayoutDeviceIntRect::Round(
-      LayoutDeviceRect::FromAppUnits(mBounds, auPerDevPixel));
 
   nsTArray<mozilla::wr::FilterOp> wrFilters;
+  Maybe<nsRect> filterClip;
   if (!CreateWebRenderCSSFilters(wrFilters) &&
-      !nsSVGIntegrationUtils::BuildWebRenderFilters(
-          mFrame, preFilterBounds, wrFilters, postFilterBounds)) {
+      !nsSVGIntegrationUtils::BuildWebRenderFilters(mFrame, wrFilters,
+                                                    filterClip)) {
     return false;
   }
 
+  wr::WrStackingContextClip clip;
+  if (filterClip) {
+    auto devPxRect = LayoutDeviceRect::FromAppUnits(
+        filterClip.value() + ToReferenceFrame(), auPerDevPixel);
+    wr::WrClipId clipId =
+        aBuilder.DefineClip(Nothing(), wr::ToRoundedLayoutRect(devPxRect));
+    clip = wr::WrStackingContextClip::ClipId(clipId);
+  } else {
+    clip = wr::WrStackingContextClip::ClipChain(aBuilder.CurrentClipChainId());
+  }
+
   float opacity = mFrame->StyleEffects()->mOpacity;
   StackingContextHelper sc(
       aSc, GetActiveScrolledRoot(), mFrame, this, aBuilder, wrFilters,
       LayoutDeviceRect(), nullptr, nullptr,
       opacity != 1.0f && mHandleOpacity ? &opacity : nullptr, nullptr,
       wr::ReferenceFrameKind::Transform, gfx::CompositionOp::OP_OVER, true,
-      false, Nothing(),
-      wr::WrStackingContextClip::ClipChain(aBuilder.CurrentClipChainId()));
+      false, Nothing(), clip);
 
   nsDisplayEffectsBase::CreateWebRenderCommands(aBuilder, aResources, sc,
                                                 aManager, aDisplayListBuilder);

layout/reftests/svg/filters/css-filter-chains/reftest.list

@@ -2,6 +2,6 @@
 # e.g. filter: blur(3px) grayscale(0.5) invert(0.2);
 
 # Some platforms render this complex filter chain a little differently, and that's ok.
-fuzzy(0-5,0-13638) fuzzy-if(/^Windows\x20NT\x2010\.0/.test(http.oscpu)&&layersGPUAccelerated,0-35,0-13638) fuzzy-if(webrender,4-6,12000-18853) == long-chain.html long-chain-ref.html # Win10: Bug 1258241
+fuzzy(0-5,0-13638) fuzzy-if(/^Windows\x20NT\x2010\.0/.test(http.oscpu)&&layersGPUAccelerated,0-35,0-13638) fuzzy-if(webrender,4-6,12000-18946) == long-chain.html long-chain-ref.html # Win10: Bug 1258241
 == moz-element.html moz-element-ref.html
-== same-filter.html same-filter-ref.html
+fuzzy-if(webrender,13-15,7682-7966) == same-filter.html same-filter-ref.html

layout/reftests/svg/filters/css-filters/reftest.list

@@ -6,7 +6,7 @@
 == blur-calc.html blur-calc-ref.html
 == blur-calc-negative.html blur-calc-negative-ref.html
 fuzzy-if(cocoaWidget&&webrender,0-1,0-2) skip-if(d2d) == blur-cap-large-radius-on-software.html blur-cap-large-radius-on-software-ref.html
-fails-if(webrender) == blur-clip-rect.html ../feGaussianBlur-4-ref.svg
+fuzzy-if(webrender,3-4,5760-6424) == blur-clip-rect.html ../feGaussianBlur-4-ref.svg
 == blur-em-radius.html blur-em-radius-ref.html
 == blur-invalid-radius.html blur-invalid-radius-ref.html
 == blur-rem-radius.html blur-rem-radius-ref.html

layout/reftests/svg/filters/css-svg-filter-chains/reftest.list

@@ -3,6 +3,6 @@
 # e.g. filter: url(#f1) blur(3px) url(#2) grayscale(0.5);
 
 == clip-input-css-filter.html clip-input-css-filter-ref.html
-== css-filter-first.html css-filter-first-ref.html
+fuzzy-if(webrender,0-1,0-288) == css-filter-first.html css-filter-first-ref.html
 == css-filter-last.html css-filter-last-ref.html
 == css-filter-middle.html css-filter-middle-ref.html

layout/svg/nsFilterInstance.cpp

@@ -93,10 +93,9 @@ void nsFilterInstance::PaintFilteredFrame(
   }
 }
 
-bool nsFilterInstance::BuildWebRenderFilters(
-    nsIFrame* aFilteredFrame, const LayoutDeviceIntRect& aPreFilterBounds,
-    nsTArray<wr::FilterOp>& aWrFilters,
-    LayoutDeviceIntRect& aPostFilterBounds) {
+bool nsFilterInstance::BuildWebRenderFilters(nsIFrame* aFilteredFrame,
+                                             nsTArray<wr::FilterOp>& aWrFilters,
+                                             Maybe<nsRect>& aPostFilterClip) {
   aWrFilters.Clear();
 
   auto& filterChain = aFilteredFrame->StyleEffects()->mFilters;
@@ -121,7 +120,7 @@ bool nsFilterInstance::BuildWebRenderFilters(
     return false;
   }
 
-  Maybe<LayoutDeviceIntRect> finalClip;
+  Maybe<IntRect> finalClip;
   bool srgb = true;
   // We currently apply the clip on the stacking context after applying filters,
   // but primitive subregions imply clipping after each filter and not just the
@@ -132,17 +131,7 @@ bool nsFilterInstance::BuildWebRenderFilters(
   // We can lift this restriction once we have added support for primitive
   // subregions to WebRender's filters.
 
-  // During the loop this tracks whether any of the previous filters in the
-  // chain affected by the primitive subregion.
-  bool chainIsAffectedByPrimSubregion = false;
-  // During the loop this tracks whether the current filter is affected by the
-  // primitive subregion.
-  bool filterIsAffectedByPrimSubregion = false;
-
   for (const auto& primitive : instance.mFilterDescription.mPrimitives) {
-    chainIsAffectedByPrimSubregion |= filterIsAffectedByPrimSubregion;
-    filterIsAffectedByPrimSubregion = false;
-
     bool primIsSrgb = primitive.OutputColorSpace() == gfx::ColorSpace::SRGB;
     if (srgb && !primIsSrgb) {
       aWrFilters.AppendElement(wr::FilterOp::SrgbToLinear());
@@ -153,26 +142,6 @@ bool nsFilterInstance::BuildWebRenderFilters(
     }
 
     const PrimitiveAttributes& attr = primitive.Attributes();
-    auto subregion = LayoutDeviceIntRect::FromUnknownRect(
-        primitive.PrimitiveSubregion() +
-        aPreFilterBounds.TopLeft().ToUnknownPoint());
-
-    if (!subregion.Contains(aPreFilterBounds)) {
-      if (!aPostFilterBounds.Contains(subregion)) {
-        filterIsAffectedByPrimSubregion = true;
-      }
-
-      subregion = subregion.Intersect(aPostFilterBounds);
-
-      if (finalClip.isNothing()) {
-        finalClip = Some(subregion);
-      } else if (!subregion.IsEqualEdges(finalClip.value())) {
-        // We don't currently support rendering a chain of filters with
-        // different primitive subregions in WebRender so bail out in that
-        // situation.
-        return false;
-      }
-    }
 
     bool filterIsNoop = false;
 
@@ -213,7 +182,7 @@ bool nsFilterInstance::BuildWebRenderFilters(
 
       aWrFilters.AppendElement(wr::FilterOp::ColorMatrix(matrix));
     } else if (attr.is<GaussianBlurAttributes>()) {
-      if (chainIsAffectedByPrimSubregion) {
+      if (finalClip) {
         // There's a clip that needs to apply before the blur filter, but
         // WebRender only lets us apply the clip at the end of the filter
         // chain. Clipping after a blur is not equivalent to clipping before
@@ -235,7 +204,7 @@ bool nsFilterInstance::BuildWebRenderFilters(
         filterIsNoop = true;
       }
     } else if (attr.is<DropShadowAttributes>()) {
-      if (chainIsAffectedByPrimSubregion) {
+      if (finalClip) {
         // We have to bail out for the same reason we would with a blur filter.
         return false;
       }
@@ -271,18 +240,24 @@ bool nsFilterInstance::BuildWebRenderFilters(
       Unused << aWrFilters.PopLastElement();
       srgb = !srgb;
     }
+
+    if (!filterIsNoop) {
+      if (finalClip.isNothing()) {
+        finalClip = Some(primitive.PrimitiveSubregion());
+      } else {
+        finalClip =
+            Some(primitive.PrimitiveSubregion().Intersect(finalClip.value()));
+      }
+    }
   }
 
   if (!srgb) {
     aWrFilters.AppendElement(wr::FilterOp::LinearToSrgb());
   }
 
-  // Only adjust the post filter clip if we are able to render this without
-  // fallback.
-  if (finalClip.isSome()) {
-    aPostFilterBounds = finalClip.value();
+  if (finalClip) {
+    aPostFilterClip = Some(instance.FilterSpaceToFrameSpace(finalClip.value()));
   }
-
   return true;
 }
 

layout/svg/nsFilterInstance.h

@@ -122,11 +122,9 @@ class nsFilterInstance {
    * Try to build WebRender filters for a frame if the filters applied to it are
    * supported.
    */
-  static bool BuildWebRenderFilters(
-      nsIFrame* aFilteredFrame,
-      const mozilla::LayoutDeviceIntRect& aPreFilterBounds,
-      nsTArray<mozilla::wr::FilterOp>& aWrFilters,
-      mozilla::LayoutDeviceIntRect& aPostFilterBounds);
+  static bool BuildWebRenderFilters(nsIFrame* aFilteredFrame,
+                                    nsTArray<mozilla::wr::FilterOp>& aWrFilters,
+                                    mozilla::Maybe<nsRect>& aPostFilterClip);
 
  private:
   /**

layout/svg/nsSVGIntegrationUtils.cpp

@@ -1086,12 +1086,10 @@ void nsSVGIntegrationUtils::PaintFilter(const PaintFramesParams& aParams) {
 }
 
 bool nsSVGIntegrationUtils::BuildWebRenderFilters(
-    nsIFrame* aFilteredFrame,
-    const mozilla::LayoutDeviceIntRect& aPreFilterBounds,
-    nsTArray<mozilla::wr::FilterOp>& aWrFilters,
-    mozilla::LayoutDeviceIntRect& aPostFilterBounds) {
-  return nsFilterInstance::BuildWebRenderFilters(
-      aFilteredFrame, aPreFilterBounds, aWrFilters, aPostFilterBounds);
+    nsIFrame* aFilteredFrame, nsTArray<mozilla::wr::FilterOp>& aWrFilters,
+    Maybe<nsRect>& aPostFilterClip) {
+  return nsFilterInstance::BuildWebRenderFilters(aFilteredFrame, aWrFilters,
+                                                 aPostFilterClip);
 }
 
 class PaintFrameCallback : public gfxDrawingCallback {

layout/svg/nsSVGIntegrationUtils.h

@@ -195,11 +195,9 @@ class nsSVGIntegrationUtils final {
    * Try to build WebRender filters for a frame if the filters applied to it are
    * supported.
    */
-  static bool BuildWebRenderFilters(
-      nsIFrame* aFilteredFrame,
-      const mozilla::LayoutDeviceIntRect& aPreFilterBounds,
-      nsTArray<mozilla::wr::FilterOp>& aWrFilters,
-      mozilla::LayoutDeviceIntRect& aPostFilterBounds);
+  static bool BuildWebRenderFilters(nsIFrame* aFilteredFrame,
+                                    nsTArray<mozilla::wr::FilterOp>& aWrFilters,
+                                    mozilla::Maybe<nsRect>& aPostFilterClip);
 
   /**
    * @param aRenderingContext the target rendering context in which the paint