Move a bunch more painting code out of RenderBoxModelObject and into BoxPainter.

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 1621ed78fa7a5474efbda32f676893a8b1e3e6ab..06211c7dc3ed81dea29991697e69c9ea07802a8a 100644
--- a/Source/core/paint/BoxPainter.cpp
+++ b/Source/core/paint/BoxPainter.cpp
@@ -15,10 +15,12 @@
 #include "core/rendering/RenderBox.h"
 #include "core/rendering/RenderBoxModelObject.h"
 #include "core/rendering/RenderLayer.h"
+#include "core/rendering/RenderObject.h"
 #include "core/rendering/RenderTable.h"
 #include "core/rendering/RenderTheme.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/compositing/CompositedLayerMapping.h"
+#include "core/rendering/style/BorderEdge.h"
 #include "core/rendering/style/ShadowList.h"
 #include "platform/LengthFunctions.h"
 #include "platform/geometry/LayoutPoint.h"
@@ -54,7 +56,7 @@ void BoxPainter::paintBoxDecorationBackgroundWithRect(PaintInfo& paintInfo, cons
     // FIXME: Should eventually give the theme control over whether the box shadow should paint, since controls could have
     // custom shadows of their own.
     if (!m_renderBox.boxShadowShouldBeAppliedToBackground(boxDecorationData.bleedAvoidance()))
-        m_renderBox.paintBoxShadow(paintInfo, paintRect, style, Normal);
+        paintBoxShadow(paintInfo, paintRect, style, Normal);
 
     GraphicsContextStateSaver stateSaver(*paintInfo.context, false);
     if (boxDecorationData.bleedAvoidance() == BackgroundBleedClipBackground) {
@@ -69,20 +71,20 @@ void BoxPainter::paintBoxDecorationBackgroundWithRect(PaintInfo& paintInfo, cons
     bool themePainted = boxDecorationData.hasAppearance && !RenderTheme::theme().paint(&m_renderBox, paintInfo, snappedPaintRect);
     if (!themePainted) {
         if (boxDecorationData.bleedAvoidance() == BackgroundBleedBackgroundOverBorder)
-            m_renderBox.paintBorder(paintInfo, paintRect, style, boxDecorationData.bleedAvoidance());
+            paintBorder(m_renderBox, paintInfo, paintRect, style, boxDecorationData.bleedAvoidance());
 
         paintBackground(paintInfo, paintRect, boxDecorationData.backgroundColor, boxDecorationData.bleedAvoidance());
 
         if (boxDecorationData.hasAppearance)
             RenderTheme::theme().paintDecorations(&m_renderBox, paintInfo, snappedPaintRect);
     }
-    m_renderBox.paintBoxShadow(paintInfo, paintRect, style, Inset);
+    paintBoxShadow(paintInfo, paintRect, style, Inset);
 
     // The theme will tell us whether or not we should also paint the CSS border.
     if (boxDecorationData.hasBorder && boxDecorationData.bleedAvoidance() != BackgroundBleedBackgroundOverBorder
         && (!boxDecorationData.hasAppearance || (!themePainted && RenderTheme::theme().paintBorderOnly(&m_renderBox, paintInfo, snappedPaintRect)))
         && !(m_renderBox.isTable() && toRenderTable(&m_renderBox)->collapseBorders()))
-        m_renderBox.paintBorder(paintInfo, paintRect, style, boxDecorationData.bleedAvoidance());
+        paintBorder(m_renderBox, paintInfo, paintRect, style, boxDecorationData.bleedAvoidance());
 }
 
 static bool skipBodyBackground(const RenderBox* bodyElementRenderer)
@@ -525,7 +527,7 @@ void BoxPainter::paintMaskImages(const PaintInfo& paintInfo, const LayoutRect& p
 
     if (allMaskImagesLoaded) {
         paintFillLayers(paintInfo, Color::transparent, m_renderBox.style()->maskLayers(), paintRect, BackgroundBleedNone, compositeOp);
-        m_renderBox.paintNinePieceImage(paintInfo.context, paintRect, m_renderBox.style(), m_renderBox.style()->maskBoxImage(), compositeOp);
+        paintNinePieceImage(m_renderBox, paintInfo.context, paintRect, m_renderBox.style(), m_renderBox.style()->maskBoxImage(), compositeOp);
     }
 
     if (pushTransparencyLayer)
@@ -864,4 +866,1291 @@ IntSize BoxPainter::calculateFillTileSize(const RenderBoxModelObject& obj, const
     return IntSize();
 }
 
+static LayoutUnit computeBorderImageSide(const BorderImageLength& borderSlice, LayoutUnit borderSide, LayoutUnit imageSide, LayoutUnit boxExtent)
+{
+    if (borderSlice.isNumber())
+        return borderSlice.number() * borderSide;
+    if (borderSlice.length().isAuto())
+        return imageSide;
+    return valueForLength(borderSlice.length(), boxExtent);
+}
+
+bool BoxPainter::paintNinePieceImage(RenderBoxModelObject& obj, GraphicsContext* graphicsContext, const LayoutRect& rect, const RenderStyle* style, const NinePieceImage& ninePieceImage, CompositeOperator op)
+{
+    StyleImage* styleImage = ninePieceImage.image();
+    if (!styleImage)
+        return false;
+
+    if (!styleImage->isLoaded())
+        return true; // Never paint a nine-piece image incrementally, but don't paint the fallback borders either.
+
+    if (!styleImage->canRender(obj, style->effectiveZoom()))
+        return false;
+
+    // FIXME: border-image is broken with full page zooming when tiling has to happen, since the tiling function
+    // doesn't have any understanding of the zoom that is in effect on the tile.
+    LayoutRect rectWithOutsets = rect;
+    rectWithOutsets.expand(style->imageOutsets(ninePieceImage));
+    IntRect borderImageRect = pixelSnappedIntRect(rectWithOutsets);
+
+    IntSize imageSize = obj.calculateImageIntrinsicDimensions(styleImage, borderImageRect.size(), RenderBoxModelObject::DoNotScaleByEffectiveZoom);
+
+    // If both values are ‘auto’ then the intrinsic width and/or height of the image should be used, if any.
+    styleImage->setContainerSizeForRenderer(&obj, imageSize, style->effectiveZoom());
+
+    int imageWidth = imageSize.width();
+    int imageHeight = imageSize.height();
+
+    float imageScaleFactor = styleImage->imageScaleFactor();
+    int topSlice = std::min<int>(imageHeight, valueForLength(ninePieceImage.imageSlices().top(), imageHeight)) * imageScaleFactor;
+    int rightSlice = std::min<int>(imageWidth, valueForLength(ninePieceImage.imageSlices().right(), imageWidth)) * imageScaleFactor;
+    int bottomSlice = std::min<int>(imageHeight, valueForLength(ninePieceImage.imageSlices().bottom(), imageHeight)) * imageScaleFactor;
+    int leftSlice = std::min<int>(imageWidth, valueForLength(ninePieceImage.imageSlices().left(), imageWidth)) * imageScaleFactor;
+
+    ENinePieceImageRule hRule = ninePieceImage.horizontalRule();
+    ENinePieceImageRule vRule = ninePieceImage.verticalRule();
+
+    int topWidth = computeBorderImageSide(ninePieceImage.borderSlices().top(), style->borderTopWidth(), topSlice, borderImageRect.height());
+    int rightWidth = computeBorderImageSide(ninePieceImage.borderSlices().right(), style->borderRightWidth(), rightSlice, borderImageRect.width());
+    int bottomWidth = computeBorderImageSide(ninePieceImage.borderSlices().bottom(), style->borderBottomWidth(), bottomSlice, borderImageRect.height());
+    int leftWidth = computeBorderImageSide(ninePieceImage.borderSlices().left(), style->borderLeftWidth(), leftSlice, borderImageRect.width());
+
+    // Reduce the widths if they're too large.
+    // The spec says: Given Lwidth as the width of the border image area, Lheight as its height, and Wside as the border image width
+    // offset for the side, let f = min(Lwidth/(Wleft+Wright), Lheight/(Wtop+Wbottom)). If f < 1, then all W are reduced by
+    // multiplying them by f.
+    int borderSideWidth = std::max(1, leftWidth + rightWidth);
+    int borderSideHeight = std::max(1, topWidth + bottomWidth);
+    float borderSideScaleFactor = std::min((float)borderImageRect.width() / borderSideWidth, (float)borderImageRect.height() / borderSideHeight);
+    if (borderSideScaleFactor < 1) {
+        topWidth *= borderSideScaleFactor;
+        rightWidth *= borderSideScaleFactor;
+        bottomWidth *= borderSideScaleFactor;
+        leftWidth *= borderSideScaleFactor;
+    }
+
+    bool drawLeft = leftSlice > 0 && leftWidth > 0;
+    bool drawTop = topSlice > 0 && topWidth > 0;
+    bool drawRight = rightSlice > 0 && rightWidth > 0;
+    bool drawBottom = bottomSlice > 0 && bottomWidth > 0;
+    bool drawMiddle = ninePieceImage.fill() && (imageWidth - leftSlice - rightSlice) > 0 && (borderImageRect.width() - leftWidth - rightWidth) > 0
+        && (imageHeight - topSlice - bottomSlice) > 0 && (borderImageRect.height() - topWidth - bottomWidth) > 0;
+
+    RefPtr<Image> image = styleImage->image(&obj, imageSize);
+
+    float destinationWidth = borderImageRect.width() - leftWidth - rightWidth;
+    float destinationHeight = borderImageRect.height() - topWidth - bottomWidth;
+
+    float sourceWidth = imageWidth - leftSlice - rightSlice;
+    float sourceHeight = imageHeight - topSlice - bottomSlice;
+
+    float leftSideScale = drawLeft ? (float)leftWidth / leftSlice : 1;
+    float rightSideScale = drawRight ? (float)rightWidth / rightSlice : 1;
+    float topSideScale = drawTop ? (float)topWidth / topSlice : 1;
+    float bottomSideScale = drawBottom ? (float)bottomWidth / bottomSlice : 1;
+
+    if (drawLeft) {
+        // Paint the top and bottom left corners.
+
+        // The top left corner rect is (tx, ty, leftWidth, topWidth)
+        // The rect to use from within the image is obtained from our slice, and is (0, 0, leftSlice, topSlice)
+        if (drawTop) {
+            graphicsContext->drawImage(image.get(), IntRect(borderImageRect.location(), IntSize(leftWidth, topWidth)),
+                LayoutRect(0, 0, leftSlice, topSlice), op);
+        }
+
+        // The bottom left corner rect is (tx, ty + h - bottomWidth, leftWidth, bottomWidth)
+        // The rect to use from within the image is (0, imageHeight - bottomSlice, leftSlice, botomSlice)
+        if (drawBottom) {
+            graphicsContext->drawImage(image.get(), IntRect(borderImageRect.x(), borderImageRect.maxY() - bottomWidth, leftWidth, bottomWidth),
+                LayoutRect(0, imageHeight - bottomSlice, leftSlice, bottomSlice), op);
+        }
+
+        // Paint the left edge.
+        // Have to scale and tile into the border rect.
+        if (sourceHeight > 0) {
+            graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.x(), borderImageRect.y() + topWidth, leftWidth, destinationHeight),
+                IntRect(0, topSlice, leftSlice, sourceHeight), FloatSize(leftSideScale, leftSideScale), Image::StretchTile, (Image::TileRule)vRule, op);
+        }
+    }
+
+    if (drawRight) {
+        // Paint the top and bottom right corners
+        // The top right corner rect is (tx + w - rightWidth, ty, rightWidth, topWidth)
+        // The rect to use from within the image is obtained from our slice, and is (imageWidth - rightSlice, 0, rightSlice, topSlice)
+        if (drawTop) {
+            graphicsContext->drawImage(image.get(), IntRect(borderImageRect.maxX() - rightWidth, borderImageRect.y(), rightWidth, topWidth),
+                LayoutRect(imageWidth - rightSlice, 0, rightSlice, topSlice), op);
+        }
+
+        // The bottom right corner rect is (tx + w - rightWidth, ty + h - bottomWidth, rightWidth, bottomWidth)
+        // The rect to use from within the image is (imageWidth - rightSlice, imageHeight - bottomSlice, rightSlice, bottomSlice)
+        if (drawBottom) {
+            graphicsContext->drawImage(image.get(), IntRect(borderImageRect.maxX() - rightWidth, borderImageRect.maxY() - bottomWidth, rightWidth, bottomWidth),
+                LayoutRect(imageWidth - rightSlice, imageHeight - bottomSlice, rightSlice, bottomSlice), op);
+        }
+
+        // Paint the right edge.
+        if (sourceHeight > 0) {
+            graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.maxX() - rightWidth, borderImageRect.y() + topWidth, rightWidth,
+                destinationHeight),
+                IntRect(imageWidth - rightSlice, topSlice, rightSlice, sourceHeight),
+                FloatSize(rightSideScale, rightSideScale),
+                Image::StretchTile, (Image::TileRule)vRule, op);
+        }
+    }
+
+    // Paint the top edge.
+    if (drawTop && sourceWidth > 0) {
+        graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.x() + leftWidth, borderImageRect.y(), destinationWidth, topWidth),
+            IntRect(leftSlice, 0, sourceWidth, topSlice),
+            FloatSize(topSideScale, topSideScale), (Image::TileRule)hRule, Image::StretchTile, op);
+    }
+
+    // Paint the bottom edge.
+    if (drawBottom && sourceWidth > 0) {
+        graphicsContext->drawTiledImage(image.get(), IntRect(borderImageRect.x() + leftWidth, borderImageRect.maxY() - bottomWidth,
+            destinationWidth, bottomWidth),
+            IntRect(leftSlice, imageHeight - bottomSlice, sourceWidth, bottomSlice),
+            FloatSize(bottomSideScale, bottomSideScale),
+            (Image::TileRule)hRule, Image::StretchTile, op);
+    }
+
+    // Paint the middle.
+    if (drawMiddle) {
+        FloatSize middleScaleFactor(1, 1);
+        if (drawTop)
+            middleScaleFactor.setWidth(topSideScale);
+        else if (drawBottom)
+            middleScaleFactor.setWidth(bottomSideScale);
+        if (drawLeft)
+            middleScaleFactor.setHeight(leftSideScale);
+        else if (drawRight)
+            middleScaleFactor.setHeight(rightSideScale);
+
+        // For "stretch" rules, just override the scale factor and replace. We only had to do this for the
+        // center tile, since sides don't even use the scale factor unless they have a rule other than "stretch".
+        // The middle however can have "stretch" specified in one axis but not the other, so we have to
+        // correct the scale here.
+        if (hRule == StretchImageRule)
+            middleScaleFactor.setWidth(destinationWidth / sourceWidth);
+
+        if (vRule == StretchImageRule)
+            middleScaleFactor.setHeight(destinationHeight / sourceHeight);
+
+        graphicsContext->drawTiledImage(image.get(),
+            IntRect(borderImageRect.x() + leftWidth, borderImageRect.y() + topWidth, destinationWidth, destinationHeight),
+            IntRect(leftSlice, topSlice, sourceWidth, sourceHeight),
+            middleScaleFactor, (Image::TileRule)hRule, (Image::TileRule)vRule, op);
+    }
+
+    return true;
+}
+
+static IntRect calculateSideRect(const RoundedRect& outerBorder, const BorderEdge edges[], int side)
+{
+    IntRect sideRect = outerBorder.rect();
+    int width = edges[side].width;
+
+    if (side == BSTop)
+        sideRect.setHeight(width);
+    else if (side == BSBottom)
+        sideRect.shiftYEdgeTo(sideRect.maxY() - width);
+    else if (side == BSLeft)
+        sideRect.setWidth(width);
+    else
+        sideRect.shiftXEdgeTo(sideRect.maxX() - width);
+
+    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);
+}
+
+static inline bool includesEdge(BorderEdgeFlags flags, BoxSide side)
+{
+    return flags & edgeFlagForSide(side);
+}
+
+inline bool styleRequiresClipPolygon(EBorderStyle style)
+{
+    return style == DOTTED || style == DASHED; // These are drawn with a stroke, so we have to clip to get corner miters.
+}
+
+static bool borderStyleFillsBorderArea(EBorderStyle style)
+{
+    return !(style == DOTTED || style == DASHED || style == DOUBLE);
+}
+
+static bool borderStyleHasInnerDetail(EBorderStyle style)
+{
+    return style == GROOVE || style == RIDGE || style == DOUBLE;
+}
+
+static bool borderStyleIsDottedOrDashed(EBorderStyle style)
+{
+    return style == DOTTED || style == DASHED;
+}
+
+// OUTSET darkens the bottom and right (and maybe lightens the top and left)
+// INSET darkens the top and left (and maybe lightens the bottom and right)
+static inline bool borderStyleHasUnmatchedColorsAtCorner(EBorderStyle style, BoxSide side, BoxSide adjacentSide)
+{
+    // These styles match at the top/left and bottom/right.
+    if (style == INSET || style == GROOVE || style == RIDGE || style == OUTSET) {
+        const BorderEdgeFlags topRightFlags = edgeFlagForSide(BSTop) | edgeFlagForSide(BSRight);
+        const BorderEdgeFlags bottomLeftFlags = edgeFlagForSide(BSBottom) | edgeFlagForSide(BSLeft);
+
+        BorderEdgeFlags flags = edgeFlagForSide(side) | edgeFlagForSide(adjacentSide);
+        return flags == topRightFlags || flags == bottomLeftFlags;
+    }
+    return false;
+}
+
+static inline bool colorsMatchAtCorner(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[])
+{
+    if (edges[side].shouldRender() != edges[adjacentSide].shouldRender())
+        return false;
+
+    if (!edges[side].sharesColorWith(edges[adjacentSide]))
+        return false;
+
+    return !borderStyleHasUnmatchedColorsAtCorner(edges[side].borderStyle(), side, adjacentSide);
+}
+
+static inline bool colorNeedsAntiAliasAtCorner(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[])
+{
+    if (!edges[side].color.hasAlpha())
+        return false;
+
+    if (edges[side].shouldRender() != edges[adjacentSide].shouldRender())
+        return false;
+
+    if (!edges[side].sharesColorWith(edges[adjacentSide]))
+        return true;
+
+    return borderStyleHasUnmatchedColorsAtCorner(edges[side].borderStyle(), side, adjacentSide);
+}
+
+bool BoxPainter::shouldAntialiasLines(GraphicsContext* context)
+{
+    // FIXME: We may want to not antialias when scaled by an integral value,
+    // and we may want to antialias when translated by a non-integral value.
+    // FIXME: See crbug.com/382491. getCTM does not include scale factors applied at raster time, such
+    // as device zoom.
+    return !context->getCTM().isIdentityOrTranslationOrFlipped();
+}
+
+static bool borderWillArcInnerEdge(const LayoutSize& firstRadius, const FloatSize& secondRadius)
+{
+    return !firstRadius.isZero() || !secondRadius.isZero();
+}
+
+// This assumes that we draw in order: top, bottom, left, right.
+static inline bool willBeOverdrawn(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[])
+{
+    switch (side) {
+    case BSTop:
+    case BSBottom:
+        if (edges[adjacentSide].presentButInvisible())
+            return false;
+
+        if (!edges[side].sharesColorWith(edges[adjacentSide]) && edges[adjacentSide].color.hasAlpha())
+            return false;
+
+        if (!borderStyleFillsBorderArea(edges[adjacentSide].borderStyle()))
+            return false;
+
+        return true;
+
+    case BSLeft:
+    case BSRight:
+        // These draw last, so are never overdrawn.
+        return false;
+    }
+    return false;
+}
+
+static inline bool borderStylesRequireMitre(BoxSide side, BoxSide adjacentSide, EBorderStyle style, EBorderStyle adjacentStyle)
+{
+    if (style == DOUBLE || adjacentStyle == DOUBLE || adjacentStyle == GROOVE || adjacentStyle == RIDGE)
+        return true;
+
+    if (borderStyleIsDottedOrDashed(style) != borderStyleIsDottedOrDashed(adjacentStyle))
+        return true;
+
+    if (style != adjacentStyle)
+        return true;
+
+    return borderStyleHasUnmatchedColorsAtCorner(style, side, adjacentSide);
+}
+
+static bool joinRequiresMitre(BoxSide side, BoxSide adjacentSide, const BorderEdge edges[], bool allowOverdraw)
+{
+    if ((edges[side].isTransparent && edges[adjacentSide].isTransparent) || !edges[adjacentSide].isPresent)
+        return false;
+
+    if (allowOverdraw && willBeOverdrawn(side, adjacentSide, edges))
+        return false;
+
+    if (!edges[side].sharesColorWith(edges[adjacentSide]))
+        return true;
+
+    if (borderStylesRequireMitre(side, adjacentSide, edges[side].borderStyle(), edges[adjacentSide].borderStyle()))
+        return true;
+
+    return false;
+}
+
+static IntRect calculateSideRectIncludingInner(const RoundedRect& outerBorder, const BorderEdge edges[], BoxSide side)
+{
+    IntRect sideRect = outerBorder.rect();
+    int width;
+
+    switch (side) {
+    case BSTop:
+        width = sideRect.height() - edges[BSBottom].width;
+        sideRect.setHeight(width);
+        break;
+    case BSBottom:
+        width = sideRect.height() - edges[BSTop].width;
+        sideRect.shiftYEdgeTo(sideRect.maxY() - width);
+        break;
+    case BSLeft:
+        width = sideRect.width() - edges[BSRight].width;
+        sideRect.setWidth(width);
+        break;
+    case BSRight:
+        width = sideRect.width() - edges[BSLeft].width;
+        sideRect.shiftXEdgeTo(sideRect.maxX() - width);
+        break;
+    }
+
+    return sideRect;
+}
+
+static RoundedRect calculateAdjustedInnerBorder(const RoundedRect&innerBorder, BoxSide side)
+{
+    // Expand the inner border as necessary to make it a rounded rect (i.e. radii contained within each edge).
+    // This function relies on the fact we only get radii not contained within each edge if one of the radii
+    // for an edge is zero, so we can shift the arc towards the zero radius corner.
+    RoundedRect::Radii newRadii = innerBorder.radii();
+    IntRect newRect = innerBorder.rect();
+
+    float overshoot;
+    float maxRadii;
+
+    switch (side) {
+    case BSTop:
+        overshoot = newRadii.topLeft().width() + newRadii.topRight().width() - newRect.width();
+        if (overshoot > 0) {
+            ASSERT(!(newRadii.topLeft().width() && newRadii.topRight().width()));
+            newRect.setWidth(newRect.width() + overshoot);
+            if (!newRadii.topLeft().width())
+                newRect.move(-overshoot, 0);
+        }
+        newRadii.setBottomLeft(IntSize(0, 0));
+        newRadii.setBottomRight(IntSize(0, 0));
+        maxRadii = std::max(newRadii.topLeft().height(), newRadii.topRight().height());
+        if (maxRadii > newRect.height())
+            newRect.setHeight(maxRadii);
+        break;
+
+    case BSBottom:
+        overshoot = newRadii.bottomLeft().width() + newRadii.bottomRight().width() - newRect.width();
+        if (overshoot > 0) {
+            ASSERT(!(newRadii.bottomLeft().width() && newRadii.bottomRight().width()));
+            newRect.setWidth(newRect.width() + overshoot);
+            if (!newRadii.bottomLeft().width())
+                newRect.move(-overshoot, 0);
+        }
+        newRadii.setTopLeft(IntSize(0, 0));
+        newRadii.setTopRight(IntSize(0, 0));
+        maxRadii = std::max(newRadii.bottomLeft().height(), newRadii.bottomRight().height());
+        if (maxRadii > newRect.height()) {
+            newRect.move(0, newRect.height() - maxRadii);
+            newRect.setHeight(maxRadii);
+        }
+        break;
+
+    case BSLeft:
+        overshoot = newRadii.topLeft().height() + newRadii.bottomLeft().height() - newRect.height();
+        if (overshoot > 0) {
+            ASSERT(!(newRadii.topLeft().height() && newRadii.bottomLeft().height()));
+            newRect.setHeight(newRect.height() + overshoot);
+            if (!newRadii.topLeft().height())
+                newRect.move(0, -overshoot);
+        }
+        newRadii.setTopRight(IntSize(0, 0));
+        newRadii.setBottomRight(IntSize(0, 0));
+        maxRadii = std::max(newRadii.topLeft().width(), newRadii.bottomLeft().width());
+        if (maxRadii > newRect.width())
+            newRect.setWidth(maxRadii);
+        break;
+
+    case BSRight:
+        overshoot = newRadii.topRight().height() + newRadii.bottomRight().height() - newRect.height();
+        if (overshoot > 0) {
+            ASSERT(!(newRadii.topRight().height() && newRadii.bottomRight().height()));
+            newRect.setHeight(newRect.height() + overshoot);
+            if (!newRadii.topRight().height())
+                newRect.move(0, -overshoot);
+        }
+        newRadii.setTopLeft(IntSize(0, 0));
+        newRadii.setBottomLeft(IntSize(0, 0));
+        maxRadii = std::max(newRadii.topRight().width(), newRadii.bottomRight().width());
+        if (maxRadii > newRect.width()) {
+            newRect.move(newRect.width() - maxRadii, 0);
+            newRect.setWidth(maxRadii);
+        }
+        break;
+    }
+
+    return RoundedRect(newRect, newRadii);
+}
+
+void BoxPainter::clipBorderSideForComplexInnerPath(GraphicsContext* graphicsContext, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
+    BoxSide side, const BorderEdge edges[])
+{
+    graphicsContext->clip(calculateSideRectIncludingInner(outerBorder, edges, side));
+    RoundedRect adjustedInnerRect = calculateAdjustedInnerBorder(innerBorder, side);
+    if (!adjustedInnerRect.isEmpty())
+        graphicsContext->clipOutRoundedRect(adjustedInnerRect);
+}
+
+static bool allCornersClippedOut(const RoundedRect& border, const LayoutRect& clipRect)
+{
+    LayoutRect boundingRect = border.rect();
+    if (clipRect.contains(boundingRect))
+        return false;
+
+    RoundedRect::Radii radii = border.radii();
+
+    LayoutRect topLeftRect(boundingRect.location(), radii.topLeft());
+    if (clipRect.intersects(topLeftRect))
+        return false;
+
+    LayoutRect topRightRect(boundingRect.location(), radii.topRight());
+    topRightRect.setX(boundingRect.maxX() - topRightRect.width());
+    if (clipRect.intersects(topRightRect))
+        return false;
+
+    LayoutRect bottomLeftRect(boundingRect.location(), radii.bottomLeft());
+    bottomLeftRect.setY(boundingRect.maxY() - bottomLeftRect.height());
+    if (clipRect.intersects(bottomLeftRect))
+        return false;
+
+    LayoutRect bottomRightRect(boundingRect.location(), radii.bottomRight());
+    bottomRightRect.setX(boundingRect.maxX() - bottomRightRect.width());
+    bottomRightRect.setY(boundingRect.maxY() - bottomRightRect.height());
+    if (clipRect.intersects(bottomRightRect))
+        return false;
+
+    return true;
+}
+
+void BoxPainter::paintBorder(RenderBoxModelObject& obj, const PaintInfo& info, const LayoutRect& rect, const RenderStyle* style, BackgroundBleedAvoidance bleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
+{
+    GraphicsContext* graphicsContext = info.context;
+    // border-image is not affected by border-radius.
+    if (paintNinePieceImage(obj, graphicsContext, rect, style, style->borderImage()))
+        return;
+
+    BorderEdge edges[4];
+    style->getBorderEdgeInfo(edges, includeLogicalLeftEdge, includeLogicalRightEdge);
+    RoundedRect outerBorder = style->getRoundedBorderFor(rect, includeLogicalLeftEdge, includeLogicalRightEdge);
+    RoundedRect innerBorder = style->getRoundedInnerBorderFor(borderInnerRectAdjustedForBleedAvoidance(graphicsContext, rect, bleedAvoidance), includeLogicalLeftEdge, includeLogicalRightEdge);
+
+    if (outerBorder.rect().isEmpty())
+        return;
+
+    bool haveAlphaColor = false;
+    bool haveAllSolidEdges = true;
+    bool haveAllDoubleEdges = true;
+    int numEdgesVisible = 4;
+    bool allEdgesShareColor = true;
+    bool allEdgesShareWidth = true;
+    int firstVisibleEdge = -1;
+    BorderEdgeFlags edgesToDraw = 0;
+
+    for (int i = BSTop; i <= BSLeft; ++i) {
+        const BorderEdge& currEdge = edges[i];
+
+        if (edges[i].shouldRender())
+            edgesToDraw |= edgeFlagForSide(static_cast<BoxSide>(i));
+
+        if (currEdge.presentButInvisible()) {
+            --numEdgesVisible;
+            allEdgesShareColor = false;
+            allEdgesShareWidth = false;
+            continue;
+        }
+
+        if (!currEdge.shouldRender()) {
+            --numEdgesVisible;
+            continue;
+        }
+
+        if (firstVisibleEdge == -1) {
+            firstVisibleEdge = i;
+        } else {
+            if (currEdge.color != edges[firstVisibleEdge].color)
+                allEdgesShareColor = false;
+            if (currEdge.width != edges[firstVisibleEdge].width)
+                allEdgesShareWidth = false;
+        }
+
+        if (currEdge.color.hasAlpha())
+            haveAlphaColor = true;
+
+        if (currEdge.borderStyle() != SOLID)
+            haveAllSolidEdges = false;
+
+        if (currEdge.borderStyle() != DOUBLE)
+            haveAllDoubleEdges = false;
+    }
+
+    // If no corner intersects the clip region, we can pretend outerBorder is
+    // rectangular to improve performance.
+    if (haveAllSolidEdges && outerBorder.isRounded() && allCornersClippedOut(outerBorder, info.rect))
+        outerBorder.setRadii(RoundedRect::Radii());
+
+    // isRenderable() check avoids issue described in https://bugs.webkit.org/show_bug.cgi?id=38787
+    if ((haveAllSolidEdges || haveAllDoubleEdges) && allEdgesShareColor && innerBorder.isRenderable()) {
+        // Fast path for drawing all solid edges and all unrounded double edges
+
+        if (numEdgesVisible == 4 && (outerBorder.isRounded() || haveAlphaColor)
+            && (haveAllSolidEdges || (!outerBorder.isRounded() && !innerBorder.isRounded()))) {
+            Path path;
+
+            if (outerBorder.isRounded() && allEdgesShareWidth) {
+
+                // Very fast path for single stroked round rect with circular corners
+
+                graphicsContext->fillBetweenRoundedRects(outerBorder, innerBorder, edges[firstVisibleEdge].color);
+                return;
+            }
+            if (outerBorder.isRounded() && bleedAvoidance != BackgroundBleedClipBackground)
+                path.addRoundedRect(outerBorder);
+            else
+                path.addRect(outerBorder.rect());
+
+            if (haveAllDoubleEdges) {
+                IntRect innerThirdRect = outerBorder.rect();
+                IntRect outerThirdRect = outerBorder.rect();
+                for (int side = BSTop; side <= BSLeft; ++side) {
+                    int outerWidth;
+                    int innerWidth;
+                    edges[side].getDoubleBorderStripeWidths(outerWidth, innerWidth);
+
+                    if (side == BSTop) {
+                        innerThirdRect.shiftYEdgeTo(innerThirdRect.y() + innerWidth);
+                        outerThirdRect.shiftYEdgeTo(outerThirdRect.y() + outerWidth);
+                    } else if (side == BSBottom) {
+                        innerThirdRect.setHeight(innerThirdRect.height() - innerWidth);
+                        outerThirdRect.setHeight(outerThirdRect.height() - outerWidth);
+                    } else if (side == BSLeft) {
+                        innerThirdRect.shiftXEdgeTo(innerThirdRect.x() + innerWidth);
+                        outerThirdRect.shiftXEdgeTo(outerThirdRect.x() + outerWidth);
+                    } else {
+                        innerThirdRect.setWidth(innerThirdRect.width() - innerWidth);
+                        outerThirdRect.setWidth(outerThirdRect.width() - outerWidth);
+                    }
+                }
+
+                RoundedRect outerThird = outerBorder;
+                RoundedRect innerThird = innerBorder;
+                innerThird.setRect(innerThirdRect);
+                outerThird.setRect(outerThirdRect);
+
+                if (outerThird.isRounded() && bleedAvoidance != BackgroundBleedClipBackground)
+                    path.addRoundedRect(outerThird);
+                else
+                    path.addRect(outerThird.rect());
+
+                if (innerThird.isRounded() && bleedAvoidance != BackgroundBleedClipBackground)
+                    path.addRoundedRect(innerThird);
+                else
+                    path.addRect(innerThird.rect());
+            }
+
+            if (innerBorder.isRounded())
+                path.addRoundedRect(innerBorder);
+            else
+                path.addRect(innerBorder.rect());
+
+            graphicsContext->setFillRule(RULE_EVENODD);
+            graphicsContext->setFillColor(edges[firstVisibleEdge].color);
+            graphicsContext->fillPath(path);
+            return;
+        }
+        // Avoid creating transparent layers
+        if (haveAllSolidEdges && numEdgesVisible != 4 && !outerBorder.isRounded() && haveAlphaColor) {
+            Path path;
+
+            for (int i = BSTop; i <= BSLeft; ++i) {
+                const BorderEdge& currEdge = edges[i];
+                if (currEdge.shouldRender()) {
+                    IntRect sideRect = calculateSideRect(outerBorder, edges, i);
+                    path.addRect(sideRect);
+                }
+            }
+
+            graphicsContext->setFillRule(RULE_NONZERO);
+            graphicsContext->setFillColor(edges[firstVisibleEdge].color);
+            graphicsContext->fillPath(path);
+            return;
+        }
+    }
+
+    bool clipToOuterBorder = outerBorder.isRounded();
+    GraphicsContextStateSaver stateSaver(*graphicsContext, clipToOuterBorder);
+    if (clipToOuterBorder) {
+        // Clip to the inner and outer radii rects.
+        if (bleedAvoidance != BackgroundBleedClipBackground)
+            graphicsContext->clipRoundedRect(outerBorder);
+        // isRenderable() check avoids issue described in https://bugs.webkit.org/show_bug.cgi?id=38787
+        // The inside will be clipped out later (in clipBorderSideForComplexInnerPath)
+        if (innerBorder.isRenderable() && !innerBorder.isEmpty())
+            graphicsContext->clipOutRoundedRect(innerBorder);
+    }
+
+    // If only one edge visible antialiasing doesn't create seams
+    bool antialias = shouldAntialiasLines(graphicsContext) || numEdgesVisible == 1;
+    RoundedRect unadjustedInnerBorder = (bleedAvoidance == BackgroundBleedBackgroundOverBorder) ? style->getRoundedInnerBorderFor(rect, includeLogicalLeftEdge, includeLogicalRightEdge) : innerBorder;
+    IntPoint innerBorderAdjustment(innerBorder.rect().x() - unadjustedInnerBorder.rect().x(), innerBorder.rect().y() - unadjustedInnerBorder.rect().y());
+    if (haveAlphaColor)
+        paintTranslucentBorderSides(obj, graphicsContext, style, outerBorder, unadjustedInnerBorder, innerBorderAdjustment, edges, edgesToDraw, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
+    else
+        paintBorderSides(obj, graphicsContext, style, outerBorder, unadjustedInnerBorder, innerBorderAdjustment, edges, edgesToDraw, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias);
+}
+
+static inline bool includesAdjacentEdges(BorderEdgeFlags flags)
+{
+    return (flags & (TopBorderEdge | RightBorderEdge)) == (TopBorderEdge | RightBorderEdge)
+        || (flags & (RightBorderEdge | BottomBorderEdge)) == (RightBorderEdge | BottomBorderEdge)
+        || (flags & (BottomBorderEdge | LeftBorderEdge)) == (BottomBorderEdge | LeftBorderEdge)
+        || (flags & (LeftBorderEdge | TopBorderEdge)) == (LeftBorderEdge | TopBorderEdge);
+}
+
+void BoxPainter::paintTranslucentBorderSides(RenderObject& obj, GraphicsContext* graphicsContext, const RenderStyle* style, const RoundedRect& outerBorder, const RoundedRect& innerBorder, const IntPoint& innerBorderAdjustment,
+    const BorderEdge edges[], BorderEdgeFlags edgesToDraw, BackgroundBleedAvoidance bleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias)
+{
+    // willBeOverdrawn assumes that we draw in order: top, bottom, left, right.
+    // This is different from BoxSide enum order.
+    static const BoxSide paintOrder[] = { BSTop, BSBottom, BSLeft, BSRight };
+
+    while (edgesToDraw) {
+        // Find undrawn edges sharing a color.
+        Color commonColor;
+
+        BorderEdgeFlags commonColorEdgeSet = 0;
+        for (size_t i = 0; i < sizeof(paintOrder) / sizeof(paintOrder[0]); ++i) {
+            BoxSide currSide = paintOrder[i];
+            if (!includesEdge(edgesToDraw, currSide))
+                continue;
+
+            bool includeEdge;
+            if (!commonColorEdgeSet) {
+                commonColor = edges[currSide].color;
+                includeEdge = true;
+            } else {
+                includeEdge = edges[currSide].color == commonColor;
+            }
+
+            if (includeEdge)
+                commonColorEdgeSet |= edgeFlagForSide(currSide);
+        }
+
+        bool useTransparencyLayer = includesAdjacentEdges(commonColorEdgeSet) && commonColor.hasAlpha();
+        if (useTransparencyLayer) {
+            graphicsContext->beginTransparencyLayer(static_cast<float>(commonColor.alpha()) / 255);
+            commonColor = Color(commonColor.red(), commonColor.green(), commonColor.blue());
+        }
+
+        paintBorderSides(obj, graphicsContext, style, outerBorder, innerBorder, innerBorderAdjustment, edges, commonColorEdgeSet, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, &commonColor);
+
+        if (useTransparencyLayer)
+            graphicsContext->endLayer();
+
+        edgesToDraw &= ~commonColorEdgeSet;
+    }
+}
+
+LayoutRect BoxPainter::borderInnerRectAdjustedForBleedAvoidance(GraphicsContext* context, const LayoutRect& rect, BackgroundBleedAvoidance bleedAvoidance)
+{
+    // We shrink the rectangle by one pixel on each side to make it fully overlap the anti-aliased background border
+    return (bleedAvoidance == BackgroundBleedBackgroundOverBorder) ? shrinkRectByOnePixel(context, rect) : rect;
+}
+
+void BoxPainter::paintOneBorderSide(RenderObject& obj, GraphicsContext* graphicsContext, const RenderStyle* style, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
+    const IntRect& sideRect, BoxSide side, BoxSide adjacentSide1, BoxSide adjacentSide2, const BorderEdge edges[], const Path* path,
+    BackgroundBleedAvoidance bleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias, const Color* overrideColor)
+{
+    const BorderEdge& edgeToRender = edges[side];
+    ASSERT(edgeToRender.width);
+    const BorderEdge& adjacentEdge1 = edges[adjacentSide1];
+    const BorderEdge& adjacentEdge2 = edges[adjacentSide2];
+
+    bool mitreAdjacentSide1 = joinRequiresMitre(side, adjacentSide1, edges, !antialias);
+    bool mitreAdjacentSide2 = joinRequiresMitre(side, adjacentSide2, edges, !antialias);
+
+    bool adjacentSide1StylesMatch = colorsMatchAtCorner(side, adjacentSide1, edges);
+    bool adjacentSide2StylesMatch = colorsMatchAtCorner(side, adjacentSide2, edges);
+
+    const Color& colorToPaint = overrideColor ? *overrideColor : edgeToRender.color;
+
+    if (path) {
+        GraphicsContextStateSaver stateSaver(*graphicsContext);
+        if (innerBorder.isRenderable())
+            clipBorderSidePolygon(graphicsContext, outerBorder, innerBorder, side, adjacentSide1StylesMatch, adjacentSide2StylesMatch);
+        else
+            clipBorderSideForComplexInnerPath(graphicsContext, outerBorder, innerBorder, side, edges);
+        float thickness = std::max(std::max(edgeToRender.width, adjacentEdge1.width), adjacentEdge2.width);
+        drawBoxSideFromPath(graphicsContext, outerBorder.rect(), *path, edges, edgeToRender.width, thickness, side, style,
+            colorToPaint, edgeToRender.borderStyle(), bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
+    } else {
+        bool clipForStyle = styleRequiresClipPolygon(edgeToRender.borderStyle()) && (mitreAdjacentSide1 || mitreAdjacentSide2);
+        bool clipAdjacentSide1 = colorNeedsAntiAliasAtCorner(side, adjacentSide1, edges) && mitreAdjacentSide1;
+        bool clipAdjacentSide2 = colorNeedsAntiAliasAtCorner(side, adjacentSide2, edges) && mitreAdjacentSide2;
+        bool shouldClip = clipForStyle || clipAdjacentSide1 || clipAdjacentSide2;
+
+        GraphicsContextStateSaver clipStateSaver(*graphicsContext, shouldClip);
+        if (shouldClip) {
+            bool aliasAdjacentSide1 = clipAdjacentSide1 || (clipForStyle && mitreAdjacentSide1);
+            bool aliasAdjacentSide2 = clipAdjacentSide2 || (clipForStyle && mitreAdjacentSide2);
+            clipBorderSidePolygon(graphicsContext, outerBorder, innerBorder, side, !aliasAdjacentSide1, !aliasAdjacentSide2);
+            // Since we clipped, no need to draw with a mitre.
+            mitreAdjacentSide1 = false;
+            mitreAdjacentSide2 = false;
+        }
+
+        obj.drawLineForBoxSide(graphicsContext, sideRect.x(), sideRect.y(), sideRect.maxX(), sideRect.maxY(), side, colorToPaint, edgeToRender.borderStyle(),
+            mitreAdjacentSide1 ? adjacentEdge1.width : 0, mitreAdjacentSide2 ? adjacentEdge2.width : 0, antialias);
+    }
+}
+
+void BoxPainter::paintBorderSides(RenderObject& obj, GraphicsContext* graphicsContext, const RenderStyle* style, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
+    const IntPoint& innerBorderAdjustment, const BorderEdge edges[], BorderEdgeFlags edgeSet, BackgroundBleedAvoidance bleedAvoidance,
+    bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias, const Color* overrideColor)
+{
+    bool renderRadii = outerBorder.isRounded();
+
+    Path roundedPath;
+    if (renderRadii)
+        roundedPath.addRoundedRect(outerBorder);
+
+    // The inner border adjustment for bleed avoidance mode BackgroundBleedBackgroundOverBorder
+    // is only applied to sideRect, which is okay since BackgroundBleedBackgroundOverBorder
+    // is only to be used for solid borders and the shape of the border painted by drawBoxSideFromPath
+    // only depends on sideRect when painting solid borders.
+
+    if (edges[BSTop].shouldRender() && includesEdge(edgeSet, BSTop)) {
+        IntRect sideRect = outerBorder.rect();
+        sideRect.setHeight(edges[BSTop].width + innerBorderAdjustment.y());
+
+        bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSTop].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().topLeft(), innerBorder.radii().topRight()));
+        paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSTop, BSLeft, BSRight, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
+    }
+
+    if (edges[BSBottom].shouldRender() && includesEdge(edgeSet, BSBottom)) {
+        IntRect sideRect = outerBorder.rect();
+        sideRect.shiftYEdgeTo(sideRect.maxY() - edges[BSBottom].width - innerBorderAdjustment.y());
+
+        bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSBottom].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().bottomLeft(), innerBorder.radii().bottomRight()));
+        paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSBottom, BSLeft, BSRight, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
+    }
+
+    if (edges[BSLeft].shouldRender() && includesEdge(edgeSet, BSLeft)) {
+        IntRect sideRect = outerBorder.rect();
+        sideRect.setWidth(edges[BSLeft].width + innerBorderAdjustment.x());
+
+        bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSLeft].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().bottomLeft(), innerBorder.radii().topLeft()));
+        paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSLeft, BSTop, BSBottom, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
+    }
+
+    if (edges[BSRight].shouldRender() && includesEdge(edgeSet, BSRight)) {
+        IntRect sideRect = outerBorder.rect();
+        sideRect.shiftXEdgeTo(sideRect.maxX() - edges[BSRight].width - innerBorderAdjustment.x());
+
+        bool usePath = renderRadii && (borderStyleHasInnerDetail(edges[BSRight].borderStyle()) || borderWillArcInnerEdge(innerBorder.radii().bottomRight(), innerBorder.radii().topRight()));
+        paintOneBorderSide(obj, graphicsContext, style, outerBorder, innerBorder, sideRect, BSRight, BSTop, BSBottom, edges, usePath ? &roundedPath : 0, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge, antialias, overrideColor);
+    }
+}
+
+void BoxPainter::drawBoxSideFromPath(GraphicsContext* graphicsContext, const LayoutRect& borderRect, const Path& borderPath, const BorderEdge edges[],
+    float thickness, float drawThickness, BoxSide side, const RenderStyle* style, Color color, EBorderStyle borderStyle, BackgroundBleedAvoidance bleedAvoidance,
+    bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
+{
+    if (thickness <= 0)
+        return;
+
+    if (borderStyle == DOUBLE && thickness < 3)
+        borderStyle = SOLID;
+
+    switch (borderStyle) {
+    case BNONE:
+    case BHIDDEN:
+        return;
+    case DOTTED:
+    case DASHED: {
+        graphicsContext->setStrokeColor(color);
+
+        // The stroke is doubled here because the provided path is the
+        // outside edge of the border so half the stroke is clipped off.
+        // The extra multiplier is so that the clipping mask can antialias
+        // the edges to prevent jaggies.
+        graphicsContext->setStrokeThickness(drawThickness * 2 * 1.1f);
+        graphicsContext->setStrokeStyle(borderStyle == DASHED ? DashedStroke : DottedStroke);
+
+        // If the number of dashes that fit in the path is odd and non-integral then we
+        // will have an awkwardly-sized dash at the end of the path. To try to avoid that
+        // here, we simply make the whitespace dashes ever so slightly bigger.
+        // FIXME: This could be even better if we tried to manipulate the dash offset
+        // and possibly the gapLength to get the corners dash-symmetrical.
+        float dashLength = thickness * ((borderStyle == DASHED) ? 3.0f : 1.0f);
+        float gapLength = dashLength;
+        float numberOfDashes = borderPath.length() / dashLength;
+        // Don't try to show dashes if we have less than 2 dashes + 2 gaps.
+        // FIXME: should do this test per side.
+        if (numberOfDashes >= 4) {
+            bool evenNumberOfFullDashes = !((int)numberOfDashes % 2);
+            bool integralNumberOfDashes = !(numberOfDashes - (int)numberOfDashes);
+            if (!evenNumberOfFullDashes && !integralNumberOfDashes) {
+                float numberOfGaps = numberOfDashes / 2;
+                gapLength += (dashLength  / numberOfGaps);
+            }
+
+            DashArray lineDash;
+            lineDash.append(dashLength);
+            lineDash.append(gapLength);
+            graphicsContext->setLineDash(lineDash, dashLength);
+        }
+
+        // FIXME: stroking the border path causes issues with tight corners:
+        // https://bugs.webkit.org/show_bug.cgi?id=58711
+        // Also, to get the best appearance we should stroke a path between the two borders.
+        graphicsContext->strokePath(borderPath);
+        return;
+    }
+    case DOUBLE: {
+        // Get the inner border rects for both the outer border line and the inner border line
+        int outerBorderTopWidth;
+        int innerBorderTopWidth;
+        edges[BSTop].getDoubleBorderStripeWidths(outerBorderTopWidth, innerBorderTopWidth);
+
+        int outerBorderRightWidth;
+        int innerBorderRightWidth;
+        edges[BSRight].getDoubleBorderStripeWidths(outerBorderRightWidth, innerBorderRightWidth);
+
+        int outerBorderBottomWidth;
+        int innerBorderBottomWidth;
+        edges[BSBottom].getDoubleBorderStripeWidths(outerBorderBottomWidth, innerBorderBottomWidth);
+
+        int outerBorderLeftWidth;
+        int innerBorderLeftWidth;
+        edges[BSLeft].getDoubleBorderStripeWidths(outerBorderLeftWidth, innerBorderLeftWidth);
+
+        // Draw inner border line
+        {
+            GraphicsContextStateSaver stateSaver(*graphicsContext);
+            RoundedRect innerClip = style->getRoundedInnerBorderFor(borderRect,
+                innerBorderTopWidth, innerBorderBottomWidth, innerBorderLeftWidth, innerBorderRightWidth,
+                includeLogicalLeftEdge, includeLogicalRightEdge);
+
+            graphicsContext->clipRoundedRect(innerClip);
+            drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, SOLID, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
+        }
+
+        // Draw outer border line
+        {
+            GraphicsContextStateSaver stateSaver(*graphicsContext);
+            LayoutRect outerRect = borderRect;
+            if (bleedAvoidance == BackgroundBleedClipBackground) {
+                outerRect.inflate(1);
+                ++outerBorderTopWidth;
+                ++outerBorderBottomWidth;
+                ++outerBorderLeftWidth;
+                ++outerBorderRightWidth;
+            }
+
+            RoundedRect outerClip = style->getRoundedInnerBorderFor(outerRect,
+                outerBorderTopWidth, outerBorderBottomWidth, outerBorderLeftWidth, outerBorderRightWidth,
+                includeLogicalLeftEdge, includeLogicalRightEdge);
+            graphicsContext->clipOutRoundedRect(outerClip);
+            drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, SOLID, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
+        }
+        return;
+    }
+    case RIDGE:
+    case GROOVE:
+    {
+        EBorderStyle s1;
+        EBorderStyle s2;
+        if (borderStyle == GROOVE) {
+            s1 = INSET;
+            s2 = OUTSET;
+        } else {
+            s1 = OUTSET;
+            s2 = INSET;
+        }
+
+        // Paint full border
+        drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, s1, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
+
+        // Paint inner only
+        GraphicsContextStateSaver stateSaver(*graphicsContext);
+        LayoutUnit topWidth = edges[BSTop].usedWidth() / 2;
+        LayoutUnit bottomWidth = edges[BSBottom].usedWidth() / 2;
+        LayoutUnit leftWidth = edges[BSLeft].usedWidth() / 2;
+        LayoutUnit rightWidth = edges[BSRight].usedWidth() / 2;
+
+        RoundedRect clipRect = style->getRoundedInnerBorderFor(borderRect,
+            topWidth, bottomWidth, leftWidth, rightWidth,
+            includeLogicalLeftEdge, includeLogicalRightEdge);
+
+        graphicsContext->clipRoundedRect(clipRect);
+        drawBoxSideFromPath(graphicsContext, borderRect, borderPath, edges, thickness, drawThickness, side, style, color, s2, bleedAvoidance, includeLogicalLeftEdge, includeLogicalRightEdge);
+        return;
+    }
+    case INSET:
+        if (side == BSTop || side == BSLeft)
+            color = color.dark();
+        break;
+    case OUTSET:
+        if (side == BSBottom || side == BSRight)
+            color = color.dark();
+        break;
+    default:
+        break;
+    }
+
+    graphicsContext->setStrokeStyle(NoStroke);
+    graphicsContext->setFillColor(color);
+    graphicsContext->drawRect(pixelSnappedIntRect(borderRect));
+}
+
+void BoxPainter::paintBoxShadow(const PaintInfo& info, const LayoutRect& paintRect, const RenderStyle* s, ShadowStyle shadowStyle, bool includeLogicalLeftEdge, bool includeLogicalRightEdge)
+{
+    // FIXME: Deal with border-image. Would be great to use border-image as a mask.
+    GraphicsContext* context = info.context;
+    if (!s->boxShadow())
+        return;
+
+    RoundedRect border = (shadowStyle == Inset) ? s->getRoundedInnerBorderFor(paintRect, includeLogicalLeftEdge, includeLogicalRightEdge)
+        : s->getRoundedBorderFor(paintRect, includeLogicalLeftEdge, includeLogicalRightEdge);
+
+    bool hasBorderRadius = s->hasBorderRadius();
+    bool isHorizontal = s->isHorizontalWritingMode();
+    bool hasOpaqueBackground = s->visitedDependentColor(CSSPropertyBackgroundColor).alpha() == 255;
+
+    GraphicsContextStateSaver stateSaver(*context, false);
+
+    const ShadowList* shadowList = s->boxShadow();
+    for (size_t i = shadowList->shadows().size(); i--; ) {
+        const ShadowData& shadow = shadowList->shadows()[i];
+        if (shadow.style() != shadowStyle)
+            continue;
+
+        FloatSize shadowOffset(shadow.x(), shadow.y());
+        float shadowBlur = shadow.blur();
+        float shadowSpread = shadow.spread();
+
+        if (shadowOffset.isZero() && !shadowBlur && !shadowSpread)
+            continue;
+
+        const Color& shadowColor = shadow.color();
+
+        if (shadow.style() == Normal) {
+            FloatRect fillRect = border.rect();
+            fillRect.inflate(shadowSpread);
+            if (fillRect.isEmpty())
+                continue;
+
+            FloatRect shadowRect(border.rect());
+            shadowRect.inflate(shadowBlur + shadowSpread);
+            shadowRect.move(shadowOffset);
+
+            // Save the state and clip, if not already done.
+            // The clip does not depend on any shadow-specific properties.
+            if (!stateSaver.saved()) {
+                stateSaver.save();
+                if (hasBorderRadius) {
+                    RoundedRect rectToClipOut = border;
+
+                    // If the box is opaque, it is unnecessary to clip it out. However, doing so saves time
+                    // when painting the shadow. On the other hand, it introduces subpixel gaps along the
+                    // corners. Those are avoided by insetting the clipping path by one pixel.
+                    if (hasOpaqueBackground)
+                        rectToClipOut.inflateWithRadii(-1);
+
+                    if (!rectToClipOut.isEmpty()) {
+                        context->clipOutRoundedRect(rectToClipOut);
+                    }
+                } else {
+                    // This IntRect is correct even with fractional shadows, because it is used for the rectangle
+                    // of the box itself, which is always pixel-aligned.
+                    IntRect rectToClipOut = border.rect();
+
+                    // If the box is opaque, it is unnecessary to clip it out. However, doing so saves time
+                    // when painting the shadow. On the other hand, it introduces subpixel gaps along the
+                    // edges if they are not pixel-aligned. Those are avoided by insetting the clipping path
+                    // by one pixel.
+                    if (hasOpaqueBackground) {
+                        // FIXME: The function to decide on the policy based on the transform should be a named function.
+                        // FIXME: It's not clear if this check is right. What about integral scale factors?
+                        // FIXME: See crbug.com/382491. The use of getCTM may also be wrong because it does not include
+                        // device zoom applied at raster time.
+                        AffineTransform transform = context->getCTM();
+                        if (transform.a() != 1 || (transform.d() != 1 && transform.d() != -1) || transform.b() || transform.c())
+                            rectToClipOut.inflate(-1);
+                    }
+
+                    if (!rectToClipOut.isEmpty()) {
+                        context->clipOut(rectToClipOut);
+                    }
+                }
+            }
+
+            // Draw only the shadow.
+            OwnPtr<DrawLooperBuilder> drawLooperBuilder = DrawLooperBuilder::create();
+            drawLooperBuilder->addShadow(shadowOffset, shadowBlur, shadowColor,
+                DrawLooperBuilder::ShadowRespectsTransforms, DrawLooperBuilder::ShadowIgnoresAlpha);
+            context->setDrawLooper(drawLooperBuilder.release());
+
+            if (hasBorderRadius) {
+                RoundedRect influenceRect(pixelSnappedIntRect(LayoutRect(shadowRect)), border.radii());
+                influenceRect.expandRadii(2 * shadowBlur + shadowSpread);
+                if (allCornersClippedOut(influenceRect, info.rect)) {
+                    context->fillRect(fillRect, Color::black);
+                } else {
+                    // TODO: support non-integer shadows - crbug.com/334829
+                    RoundedRect roundedFillRect = border;
+                    roundedFillRect.inflate(shadowSpread);
+
+                    roundedFillRect.expandRadii(shadowSpread);
+                    if (!roundedFillRect.isRenderable())
+                        roundedFillRect.adjustRadii();
+                    context->fillRoundedRect(roundedFillRect, Color::black);
+                }
+            } else {
+                context->fillRect(fillRect, Color::black);
+            }
+        } else {
+            // The inset shadow case.
+            GraphicsContext::Edges clippedEdges = GraphicsContext::NoEdge;
+            if (!includeLogicalLeftEdge) {
+                if (isHorizontal)
+                    clippedEdges |= GraphicsContext::LeftEdge;
+                else
+                    clippedEdges |= GraphicsContext::TopEdge;
+            }
+            if (!includeLogicalRightEdge) {
+                if (isHorizontal)
+                    clippedEdges |= GraphicsContext::RightEdge;
+                else
+                    clippedEdges |= GraphicsContext::BottomEdge;
+            }
+            // TODO: support non-integer shadows - crbug.com/334828
+            context->drawInnerShadow(border, shadowColor, flooredIntSize(shadowOffset), shadowBlur, shadowSpread, clippedEdges);
+        }
+    }
+}
+
+void BoxPainter::clipBorderSidePolygon(GraphicsContext* graphicsContext, const RoundedRect& outerBorder, const RoundedRect& innerBorder, BoxSide side, bool firstEdgeMatches, bool secondEdgeMatches)
+{
+    FloatPoint quad[4];
+
+    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.
+    //
+    //         0----------------3
+    //       0  \              /  0
+    //       |\  1----------- 2  /|
+    //       | 1                1 |
+    //       | |                | |
+    //       | |                | |
+    //       | 2                2 |
+    //       |/  1------------2  \|
+    //       3  /              \  3
+    //         0----------------3
+    //
+    switch (side) {
+    case BSTop:
+        quad[0] = outerRect.minXMinYCorner();
+        quad[1] = innerRect.minXMinYCorner();
+        quad[2] = innerRect.maxXMinYCorner();
+        quad[3] = outerRect.maxXMinYCorner();
+
+        if (!innerBorder.radii().topLeft().isZero()) {
+            findIntersection(quad[0], quad[1],
+                FloatPoint(
+                    quad[1].x() + innerBorder.radii().topLeft().width(),
+                    quad[1].y()),
+                FloatPoint(
+                    quad[1].x(),
+                    quad[1].y() + innerBorder.radii().topLeft().height()),
+                quad[1]);
+        }
+
+        if (!innerBorder.radii().topRight().isZero()) {
+            findIntersection(quad[3], quad[2],
+                FloatPoint(
+                    quad[2].x() - innerBorder.radii().topRight().width(),
+                    quad[2].y()),
+                FloatPoint(
+                    quad[2].x(),
+                    quad[2].y() + innerBorder.radii().topRight().height()),
+                quad[2]);
+        }
+        break;
+
+    case BSLeft:
+        quad[0] = outerRect.minXMinYCorner();
+        quad[1] = innerRect.minXMinYCorner();
+        quad[2] = innerRect.minXMaxYCorner();
+        quad[3] = outerRect.minXMaxYCorner();
+
+        if (!innerBorder.radii().topLeft().isZero()) {
+            findIntersection(quad[0], quad[1],
+                FloatPoint(
+                    quad[1].x() + innerBorder.radii().topLeft().width(),
+                    quad[1].y()),
+                FloatPoint(
+                    quad[1].x(),
+                    quad[1].y() + innerBorder.radii().topLeft().height()),
+                quad[1]);
+        }
+
+        if (!innerBorder.radii().bottomLeft().isZero()) {
+            findIntersection(quad[3], quad[2],
+                FloatPoint(
+                    quad[2].x() + innerBorder.radii().bottomLeft().width(),
+                    quad[2].y()),
+                FloatPoint(
+                    quad[2].x(),
+                    quad[2].y() - innerBorder.radii().bottomLeft().height()),
+                quad[2]);
+        }
+        break;
+
+    case BSBottom:
+        quad[0] = outerRect.minXMaxYCorner();
+        quad[1] = innerRect.minXMaxYCorner();
+        quad[2] = innerRect.maxXMaxYCorner();
+        quad[3] = outerRect.maxXMaxYCorner();
+
+        if (!innerBorder.radii().bottomLeft().isZero()) {
+            findIntersection(quad[0], quad[1],
+                FloatPoint(
+                    quad[1].x() + innerBorder.radii().bottomLeft().width(),
+                    quad[1].y()),
+                FloatPoint(
+                    quad[1].x(),
+                    quad[1].y() - innerBorder.radii().bottomLeft().height()),
+                quad[1]);
+        }
+
+        if (!innerBorder.radii().bottomRight().isZero()) {
+            findIntersection(quad[3], quad[2],
+                FloatPoint(
+                    quad[2].x() - innerBorder.radii().bottomRight().width(),
+                    quad[2].y()),
+                FloatPoint(
+                    quad[2].x(),
+                    quad[2].y() - innerBorder.radii().bottomRight().height()),
+                quad[2]);
+        }
+        break;
+
+    case BSRight:
+        quad[0] = outerRect.maxXMinYCorner();
+        quad[1] = innerRect.maxXMinYCorner();
+        quad[2] = innerRect.maxXMaxYCorner();
+        quad[3] = outerRect.maxXMaxYCorner();
+
+        if (!innerBorder.radii().topRight().isZero()) {
+            findIntersection(quad[0], quad[1],
+                FloatPoint(
+                    quad[1].x() - innerBorder.radii().topRight().width(),
+                    quad[1].y()),
+                FloatPoint(
+                    quad[1].x(),
+                    quad[1].y() + innerBorder.radii().topRight().height()),
+                quad[1]);
+        }
+
+        if (!innerBorder.radii().bottomRight().isZero()) {
+            findIntersection(quad[3], quad[2],
+                FloatPoint(
+                    quad[2].x() - innerBorder.radii().bottomRight().width(),
+                    quad[2].y()),
+                FloatPoint(
+                    quad[2].x(),
+                    quad[2].y() - innerBorder.radii().bottomRight().height()),
+                quad[2]);
+        }
+        break;
+    }
+
+    // If the border matches both of its adjacent sides, don't anti-alias the clip, and
+    // if neither side matches, anti-alias the clip.
+    if (firstEdgeMatches == secondEdgeMatches) {
+        graphicsContext->clipConvexPolygon(4, quad, !firstEdgeMatches);
+        return;
+    }
+
+    // If antialiasing settings for the first edge and second edge is different,
+    // they have to be addressed separately. We do this by breaking the quad into
+    // two parallelograms, made by moving quad[1] and quad[2].
+    float ax = quad[1].x() - quad[0].x();
+    float ay = quad[1].y() - quad[0].y();
+    float bx = quad[2].x() - quad[1].x();
+    float by = quad[2].y() - quad[1].y();
+    float cx = quad[3].x() - quad[2].x();
+    float cy = quad[3].y() - quad[2].y();
+
+    const static float kEpsilon = 1e-2f;
+    float r1, r2;
+    if (fabsf(bx) < kEpsilon && fabsf(by) < kEpsilon) {
+        // The quad was actually a triangle.
+        r1 = r2 = 1.0f;
+    } else {
+        // Extend parallelogram a bit to hide calculation error
+        const static float kExtendFill = 1e-2f;
+
+        r1 = (-ax * by + ay * bx) / (cx * by - cy * bx) + kExtendFill;
+        r2 = (-cx * by + cy * bx) / (ax * by - ay * bx) + kExtendFill;
+    }
+
+    FloatPoint firstQuad[4];
+    firstQuad[0] = quad[0];
+    firstQuad[1] = quad[1];
+    firstQuad[2] = FloatPoint(quad[3].x() + r2 * ax, quad[3].y() + r2 * ay);
+    firstQuad[3] = quad[3];
+    graphicsContext->clipConvexPolygon(4, firstQuad, !firstEdgeMatches);
+
+    FloatPoint secondQuad[4];
+    secondQuad[0] = quad[0];
+    secondQuad[1] = FloatPoint(quad[0].x() - r1 * cx, quad[0].y() - r1 * cy);
+    secondQuad[2] = quad[2];
+    secondQuad[3] = quad[3];
+    graphicsContext->clipConvexPolygon(4, secondQuad, !secondEdgeMatches);
+}
+
 } // namespace blink