Move NinePieceImage painting to a separate class

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 4ccd991b64153a65a34747e058f3c7ecd4fe0694..3af70d161b292b959b1e04832f0436eeb09e8f41 100644
--- a/Source/core/paint/BoxPainter.cpp
+++ b/Source/core/paint/BoxPainter.cpp
@@ -23,6 +23,7 @@
 #include "core/paint/BoxDecorationData.h"
 #include "core/paint/DeprecatedPaintLayer.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
+#include "core/paint/NinePieceImagePainter.h"
 #include "core/paint/PaintInfo.h"
 #include "core/paint/RoundedInnerRectClipper.h"
 #include "core/paint/ThemePainter.h"
@@ -945,190 +946,10 @@ IntSize BoxPainter::calculateFillTileSize(const LayoutBoxModelObject& 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(LayoutBoxModelObject& obj, GraphicsContext* graphicsContext, const LayoutRect& rect, const ComputedStyle& style, const NinePieceImage& ninePieceImage, SkXfermode::Mode 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(), LayoutBoxModelObject::DoNotScaleByEffectiveZoom);
-
-    // If both values are 'auto' then the intrinsic width and/or height of the image should be used, if any.
-    styleImage->setContainerSizeForLayoutObject(&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;
-
-    InterpolationQuality interpolationQuality = chooseInterpolationQuality(obj, graphicsContext, image.get(), 0, rectWithOutsets.size());
-    InterpolationQuality previousInterpolationQuality = graphicsContext->imageInterpolationQuality();
-    graphicsContext->setImageInterpolationQuality(interpolationQuality);
-
-    TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "PaintImage", "data", InspectorPaintImageEvent::data(obj, *styleImage));
-    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);
-    }
-    graphicsContext->setImageInterpolationQuality(previousInterpolationQuality);
-    return true;
+    NinePieceImagePainter ninePieceImagePainter(obj);
+    return ninePieceImagePainter.paint(graphicsContext, rect, style, ninePieceImage, op);
 }
 
 bool BoxPainter::shouldAntialiasLines(GraphicsContext* context)