Bug 1852323 - Part 1: Update the mapping of geometry box for clip-pat…

…h. r=emilio

It seems mask-origin/mask-clip/clip-path use different mapping for
geometry-box. We should specialize each one. In this patch, we focus on
clip-path.

Differential Revision: https://phabricator.services.mozilla.com/D188146

layout/base/nsLayoutUtils.cpp

@@ -9708,6 +9708,17 @@ StyleGeometryBox nsLayoutUtils::CoordBoxToGeometryBox(StyleCoordBox aCoordBox) {
   return StyleGeometryBox::BorderBox;
 }
 
+/* static */
+nsRect nsLayoutUtils::ComputeGeometryBox(nsIFrame* aFrame,
+                                         StyleGeometryBox aGeometryBox) {
+  // We use ComputeSVGReferenceRect for all SVG elements, except <svg>
+  // element, which does have an associated CSS layout box. In this case we
+  // should still use ComputeHTMLReferenceRect for region computing.
+  return aFrame->HasAnyStateBits(NS_FRAME_SVG_LAYOUT)
+             ? ComputeSVGReferenceRect(aFrame, aGeometryBox)
+             : ComputeHTMLReferenceRect(aFrame, aGeometryBox);
+}
+
 static StyleGeometryBox ShapeBoxToGeometryBox(const StyleShapeBox& aBox) {
   switch (aBox) {
     case StyleShapeBox::BorderBox:
@@ -9742,25 +9753,56 @@ static StyleGeometryBox ClipPathBoxToGeometryBox(
   return StyleGeometryBox::NoBox;
 }
 
+// The mapping is from
+// https://drafts.fxtf.org/css-masking-1/#typedef-geometry-box
 /* static */
-nsRect nsLayoutUtils::ComputeGeometryBox(nsIFrame* aFrame,
-                                         StyleGeometryBox aGeometryBox) {
-  // We use ComputeSVGReferenceRect for all SVG elements, except <svg>
-  // element, which does have an associated CSS layout box. In this case we
-  // should still use ComputeHTMLReferenceRect for region computing.
-  return aFrame->HasAnyStateBits(NS_FRAME_SVG_LAYOUT)
-             ? ComputeSVGReferenceRect(aFrame, aGeometryBox)
-             : ComputeHTMLReferenceRect(aFrame, aGeometryBox);
-}
-
-nsRect nsLayoutUtils::ComputeGeometryBox(nsIFrame* aFrame,
-                                         const StyleShapeBox& aBox) {
-  return ComputeGeometryBox(aFrame, ShapeBoxToGeometryBox(aBox));
-}
+nsRect nsLayoutUtils::ComputeClipPathGeometryBox(
+    nsIFrame* aFrame, const StyleShapeGeometryBox& aBox) {
+  StyleGeometryBox box = ClipPathBoxToGeometryBox(aBox);
+
+  if (aFrame->HasAnyStateBits(NS_FRAME_SVG_LAYOUT)) {
+    // For SVG elements without associated CSS layout box, the used value for
+    // content-box and padding-box is fill-box and for border-box and margin-box
+    // is stroke-box.
+    switch (box) {
+      case StyleGeometryBox::ContentBox:
+      case StyleGeometryBox::PaddingBox:
+      case StyleGeometryBox::FillBox:
+        return ComputeSVGReferenceRect(aFrame, StyleGeometryBox::FillBox);
+      case StyleGeometryBox::NoBox:
+      case StyleGeometryBox::BorderBox:
+      case StyleGeometryBox::MarginBox:
+      case StyleGeometryBox::StrokeBox:
+        return ComputeSVGReferenceRect(aFrame, StyleGeometryBox::StrokeBox);
+      case StyleGeometryBox::ViewBox:
+        return ComputeSVGReferenceRect(aFrame, StyleGeometryBox::ViewBox);
+      default:
+        MOZ_ASSERT_UNREACHABLE("Unknown clip-path geometry box");
+        // Use default, border-box (as stroke-box in SVG layout).
+        return ComputeSVGReferenceRect(aFrame, StyleGeometryBox::StrokeBox);
+    }
+  }
 
-nsRect nsLayoutUtils::ComputeGeometryBox(nsIFrame* aFrame,
-                                         const StyleShapeGeometryBox& aBox) {
-  return ComputeGeometryBox(aFrame, ClipPathBoxToGeometryBox(aBox));
+  // For elements with associated CSS layout box, the used value for fill-box is
+  // content-box and for stroke-box and view-box is border-box.
+  switch (box) {
+    case StyleGeometryBox::FillBox:
+    case StyleGeometryBox::ContentBox:
+      return ComputeHTMLReferenceRect(aFrame, StyleGeometryBox::ContentBox);
+    case StyleGeometryBox::NoBox:
+    case StyleGeometryBox::StrokeBox:
+    case StyleGeometryBox::ViewBox:
+    case StyleGeometryBox::BorderBox:
+      return ComputeHTMLReferenceRect(aFrame, StyleGeometryBox::BorderBox);
+    case StyleGeometryBox::PaddingBox:
+      return ComputeHTMLReferenceRect(aFrame, StyleGeometryBox::PaddingBox);
+    case StyleGeometryBox::MarginBox:
+      return ComputeHTMLReferenceRect(aFrame, StyleGeometryBox::MarginBox);
+    default:
+      MOZ_ASSERT_UNREACHABLE("Unknown clip-path geometry box");
+      // Use default, border-box.
+      return ComputeHTMLReferenceRect(aFrame, StyleGeometryBox::BorderBox);
+  }
 }
 
 /* static */

layout/base/nsLayoutUtils.h

@@ -2964,10 +2964,8 @@ class nsLayoutUtils {
 
   static nsRect ComputeGeometryBox(nsIFrame*, StyleGeometryBox);
 
-  static nsRect ComputeGeometryBox(nsIFrame*,
-                                   const mozilla::StyleShapeGeometryBox&);
-
-  static nsRect ComputeGeometryBox(nsIFrame*, const mozilla::StyleShapeBox&);
+  static nsRect ComputeClipPathGeometryBox(
+      nsIFrame*, const mozilla::StyleShapeGeometryBox&);
 
   static nsPoint ComputeOffsetToUserSpace(nsDisplayListBuilder* aBuilder,
                                           nsIFrame* aFrame);

layout/painting/nsDisplayList.cpp

@@ -8022,7 +8022,7 @@ static Maybe<wr::WrClipChainId> CreateSimpleClipRegion(
 
   auto appUnitsPerDevPixel = frame->PresContext()->AppUnitsPerDevPixel();
   const nsRect refBox =
-      nsLayoutUtils::ComputeGeometryBox(frame, clipPath.AsShape()._1);
+      nsLayoutUtils::ComputeClipPathGeometryBox(frame, clipPath.AsShape()._1);
 
   wr::WrClipId clipId{};
 
@@ -8103,7 +8103,7 @@ static void FillPolygonDataForDisplayItem(
   const auto& clipPath = style->mClipPath;
   const auto& shape = *clipPath.AsShape()._0;
   const nsRect refBox =
-      nsLayoutUtils::ComputeGeometryBox(frame, clipPath.AsShape()._1);
+      nsLayoutUtils::ComputeClipPathGeometryBox(frame, clipPath.AsShape()._1);
 
   // We only fill polygon data for polygons that are below a complexity
   // limit.

layout/reftests/svg/svg-integration/clip-path/clip-path-polygon-010.html

@@ -31,6 +31,7 @@
 </style>
 <body>
   <p>The test passes if you see a green vertical stripe next to a lime green vertical stripe, both stripes should be of equal size and there should be no red.</p>
-  <div style="clip-path: polygon(0% 25%, 50% 50px, 100px 75%, 0 150px) fill-box"></div>
+  <div style="clip-path: polygon(-75px -50%, 50% -25px, 25px 150%, -75px 75px)
+    fill-box"></div>
 </body>
-</html>
+</html>

layout/svg/CSSClipPathInstance.cpp

@@ -93,13 +93,9 @@ already_AddRefed<Path> CSSClipPathInstance::CreateClipPath(
   nscoord appUnitsPerDevPixel =
       mTargetFrame->PresContext()->AppUnitsPerDevPixel();
 
-  nsRect r;
-  if (mClipPathStyle.IsBox()) {
-    r = nsLayoutUtils::ComputeGeometryBox(mTargetFrame, mClipPathStyle.AsBox());
-  } else {
-    r = nsLayoutUtils::ComputeGeometryBox(mTargetFrame,
-                                          mClipPathStyle.AsShape()._1);
-  }
+  nsRect r = nsLayoutUtils::ComputeClipPathGeometryBox(
+      mTargetFrame, mClipPathStyle.IsBox() ? mClipPathStyle.AsBox()
+                                           : mClipPathStyle.AsShape()._1);
 
   gfxRect rr(r.x, r.y, r.width, r.height);
   rr.Scale(1.0 / AppUnitsPerCSSPixel());