Anti-aliased box borders (overdraw)

Source/core/paint/BoxPainter.cpp

Index: Source/core/paint/BoxPainter.cpp
diff --git a/Source/core/paint/BoxPainter.cpp b/Source/core/paint/BoxPainter.cpp
index 4b8298c32d0e443b430e42306c7257abb1da8df0..e26cb9fca66c4fc66901de31a5e7f72ed73ff630 100644
--- a/Source/core/paint/BoxPainter.cpp
+++ b/Source/core/paint/BoxPainter.cpp
@@ -19,6 +19,7 @@
 #include "core/style/BorderEdge.h"
 #include "core/style/ShadowList.h"
 #include "core/paint/BackgroundImageGeometry.h"
+#include "core/paint/BoxBorderPainter.h"
 #include "core/paint/BoxDecorationData.h"
 #include "core/paint/DeprecatedPaintLayer.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
@@ -1147,14 +1148,6 @@ static FloatRect calculateSideRect(const FloatRoundedRect& outerBorder, const Bo
     return sideRect;
 }
 
-enum BorderEdgeFlag {
-    TopBorderEdge = 1 << BSTop,
-    RightBorderEdge = 1 << BSRight,
-    BottomBorderEdge = 1 << BSBottom,
-    LeftBorderEdge = 1 << BSLeft,
-    AllBorderEdges = TopBorderEdge | BottomBorderEdge | LeftBorderEdge | RightBorderEdge
-};
-
 static inline BorderEdgeFlag edgeFlagForSide(BoxSide side)
 {
     return static_cast<BorderEdgeFlag>(1 << side);
@@ -1443,75 +1436,6 @@ bool allCornersClippedOut(const FloatRoundedRect& border, const IntRect& intClip
     return true;
 }
 
-// TODO(fmalita): Border painting is complex enough to warrant a standalone class. Move all related
-//                logic out into BoxBorderPainter or such.
-// TODO(fmalita): Move static BoxPainter border methods to anonymous ns and update to use a
-//                BoxBorderInfo argument.
-struct BoxBorderInfo {
-    STACK_ALLOCATED();
-public:
-    BoxBorderInfo(const ComputedStyle& style, BackgroundBleedAvoidance bleedAvoidance,
-        bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
-        : style(style)
-        , bleedAvoidance(bleedAvoidance)
-        , includeLogicalLeftEdge(includeLogicalLeftEdge)
-        , includeLogicalRightEdge(includeLogicalRightEdge)
-        , visibleEdgeCount(0)
-        , firstVisibleEdge(0)
-        , visibleEdgeSet(0)
-        , isUniformStyle(true)
-        , isUniformWidth(true)
-        , isUniformColor(true)
-        , hasAlpha(false)
-    {
-
-        style.getBorderEdgeInfo(edges, includeLogicalLeftEdge, includeLogicalRightEdge);
-
-        for (unsigned i = 0; i < WTF_ARRAY_LENGTH(edges); ++i) {
-            const BorderEdge& edge = edges[i];
-
-            if (!edge.shouldRender()) {
-                if (edge.presentButInvisible()) {
-                    isUniformWidth = false;
-                    isUniformColor = false;
-                }
-
-                continue;
-            }
-
-            visibleEdgeCount++;
-            visibleEdgeSet |= edgeFlagForSide(static_cast<BoxSide>(i));
-
-            hasAlpha = hasAlpha || edge.color.hasAlpha();
-
-            if (visibleEdgeCount == 1) {
-                firstVisibleEdge = i;
-                continue;
-            }
-
-            isUniformStyle = isUniformStyle && (edge.borderStyle() == edges[firstVisibleEdge].borderStyle());
-            isUniformWidth = isUniformWidth && (edge.width == edges[firstVisibleEdge].width);
-            isUniformColor = isUniformColor && (edge.color == edges[firstVisibleEdge].color);
-        }
-    }
-
-    const ComputedStyle& style;
-    const BackgroundBleedAvoidance bleedAvoidance;
-    const bool includeLogicalLeftEdge;
-    const bool includeLogicalRightEdge;
-
-    BorderEdge edges[4];
-
-    unsigned visibleEdgeCount;
-    unsigned firstVisibleEdge;
-    BorderEdgeFlags visibleEdgeSet;
-
-    bool isUniformStyle;
-    bool isUniformWidth;
-    bool isUniformColor;
-    bool hasAlpha;
-};
-
 LayoutRectOutsets doubleStripeInsets(const BorderEdge edges[], BorderEdge::DoubleBorderStripe stripe)
 {
     // Insets are representes as negative outsets.
@@ -1699,14 +1623,19 @@ void BoxPainter::paintBorder(LayoutBoxModelObject& obj, const PaintInfo& info, c
             graphicsContext->clipOutRoundedRect(innerBorder);
     }
 
+    if (RuntimeEnabledFeatures::antiAliasBordersEnabled() || RuntimeEnabledFeatures::slimmingPaintEnabled()) {
+        BoxBorderPainter(borderInfo, outerBorder, innerBorder).paint(graphicsContext);
+        return;
+    }
+
     // If only one edge visible antialiasing doesn't create seams
     bool antialias = shouldAntialiasLines(graphicsContext) || borderInfo.visibleEdgeCount == 1;
     if (borderInfo.hasAlpha) {
         paintTranslucentBorderSides(graphicsContext, style, outerBorder, innerBorder, borderInfo.edges,
-        borderInfo.visibleEdgeSet, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
+            borderInfo.visibleEdgeSet, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
     } else {
         paintBorderSides(graphicsContext, style, outerBorder, innerBorder, borderInfo.edges,
-        borderInfo.visibleEdgeSet, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
+            borderInfo.visibleEdgeSet, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
     }
 }
 
@@ -2125,8 +2054,6 @@ void BoxPainter::clipBorderSidePolygon(GraphicsContext* graphicsContext, const F
     const LayoutRect outerRect(outerBorder.rect());
     const LayoutRect innerRect(innerBorder.rect());
 
-    FloatPoint centerPoint(innerRect.location().x().toFloat() + innerRect.width().toFloat() / 2, innerRect.location().y().toFloat() + innerRect.height().toFloat() / 2);
-
     // For each side, create a quad that encompasses all parts of that side that may draw,
     // including areas inside the innerBorder.
     //