Change filter quality when scaling-down in drawImage

third_party/WebKit/Source/core/svg/graphics/SVGImage.cpp

 /*
  * Copyright (C) 2006 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 215 matching lines @@
         }
 
         ASSERT(solutionHeight <= defaultObjectSize.height());
         return FloatSize(defaultObjectSize.width(), solutionHeight);
     }
 
     return defaultObjectSize;
 }
 
 void SVGImage::drawForContainer(SkCanvas* canvas, const SkPaint& paint, const FloatSize containerSize, float zoom, const FloatRect& dstRect,
-    const FloatRect& srcRect, const KURL& url)
+    const FloatRect& srcRect, bool imageSmoothingEnabled, const KURL& url)
 {
     if (!m_page)
         return;
 
     // Temporarily disable the image observer to prevent changeInRect() calls due re-laying out the image.
     ImageObserverDisabler imageObserverDisabler(this);
 
     IntSize roundedContainerSize = roundedIntSize(containerSize);
 
     if (SVGSVGElement* rootElement = svgRootElement(m_page.get())) {
         if (LayoutSVGRoot* layoutObject = toLayoutSVGRoot(rootElement->layoutObject()))
             layoutObject->setContainerSize(roundedContainerSize);
     }
 
     FloatRect scaledSrc = srcRect;
     scaledSrc.scale(1 / zoom);
 
     // Compensate for the container size rounding by adjusting the source rect.
     FloatSize adjustedSrcSize = scaledSrc.size();
     adjustedSrcSize.scale(roundedContainerSize.width() / containerSize.width(), roundedContainerSize.height() / containerSize.height());
     scaledSrc.setSize(adjustedSrcSize);
 
-    drawInternal(canvas, paint, dstRect, scaledSrc, DoNotRespectImageOrientation, ClampImageToSourceRect, url);
+    SkPaint adjustedPaint = paint;
+    if (!imageSmoothingEnabled && Image::isDrawScalingDown(scaledSrc, dstRect))
+        adjustedPaint.setFilterQuality(kLow_SkFilterQuality);

[fs, 2016/07/18 15:56:55]

This should not have any effect. Ditto below, and likely for other cases like
GradientGeneratedImage.

+
+    drawInternal(canvas, adjustedPaint, dstRect, scaledSrc, DoNotRespectImageOrientation, ClampImageToSourceRect, url);
 }
 
 PassRefPtr<SkImage> SVGImage::imageForCurrentFrame()
 {
     return imageForCurrentFrameForContainer(KURL(), FloatSize(size()));
 }
 
 void SVGImage::drawPatternForContainer(GraphicsContext& context, const FloatSize containerSize,
     float zoom, const FloatRect& srcRect, const FloatSize& tileScale, const FloatPoint& phase,
     SkXfermode::Mode compositeOp, const FloatRect& dstRect,
     const FloatSize& repeatSpacing, const KURL& url)
 {
     // Tile adjusted for scaling/stretch.
     FloatRect tile(srcRect);
     tile.scale(tileScale.width(), tileScale.height());
 
     // Expand the tile to account for repeat spacing.
     FloatRect spacedTile(tile);
     spacedTile.expand(FloatSize(repeatSpacing));
 
     SkPictureBuilder patternPicture(spacedTile, nullptr, &context);
     {
         DrawingRecorder patternPictureRecorder(patternPicture.context(), patternPicture, DisplayItem::Type::SVGImage, spacedTile);
         // When generating an expanded tile, make sure we don't draw into the spacing area.
         if (tile != spacedTile)
             patternPicture.context().clip(tile);
         SkPaint paint;
-        drawForContainer(patternPicture.context().canvas(), paint, containerSize, zoom, tile, srcRect, url);
+        drawForContainer(patternPicture.context().canvas(), paint, containerSize, zoom, tile, srcRect, true, url);
     }
     RefPtr<SkPicture> tilePicture = patternPicture.endRecording();
 
     SkMatrix patternTransform;
     patternTransform.setTranslate(phase.x() + spacedTile.x(), phase.y() + spacedTile.y());
 
     SkPaint paint;
     paint.setShader(SkShader::MakePictureShader(toSkSp(tilePicture.release()),
         SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode, &patternTransform, nullptr));
     paint.setXfermodeMode(compositeOp);
     paint.setColorFilter(sk_ref_sp(context.colorFilter()));
     context.drawRect(dstRect, paint);
 }
 
 PassRefPtr<SkImage> SVGImage::imageForCurrentFrameForContainer(const KURL& url, const FloatSize& containerSize)
 {
     if (!m_page)
         return nullptr;
 
     SkPictureRecorder recorder;
     SkCanvas* canvas = recorder.beginRecording(width(), height());
-    drawForContainer(canvas, SkPaint(), containerSize, 1, rect(), rect(), url);
+    drawForContainer(canvas, SkPaint(), containerSize, 1, rect(), rect(), true, url);
 
     return fromSkSp(SkImage::MakeFromPicture(recorder.finishRecordingAsPicture(),
         SkISize::Make(width(), height()), nullptr, nullptr));
 }
 
 static bool drawNeedsLayer(const SkPaint& paint)
 {
     if (SkColorGetA(paint.getColor()) < 255)
         return true;
 
     SkXfermode::Mode xfermode;
     if (SkXfermode::AsMode(paint.getXfermode(), &xfermode)) {
         if (xfermode != SkXfermode::kSrcOver_Mode)
             return true;
     }
 
     return false;
 }
 
 void SVGImage::draw(SkCanvas* canvas, const SkPaint& paint, const FloatRect& dstRect, const FloatRect& srcRect,
-    RespectImageOrientationEnum shouldRespectImageOrientation, ImageClampingMode clampMode)
+    bool imageSmoothingEnabled, RespectImageOrientationEnum shouldRespectImageOrientation, ImageClampingMode clampMode)
 {
     if (!m_page)
         return;
 
-    drawInternal(canvas, paint, dstRect, srcRect, shouldRespectImageOrientation, clampMode, KURL());
+    SkPaint adjustedPaint = paint;
+    if (!imageSmoothingEnabled && Image::isDrawScalingDown(srcRect, dstRect))
+        adjustedPaint.setFilterQuality(kLow_SkFilterQuality);
+
+    drawInternal(canvas, adjustedPaint, dstRect, srcRect, shouldRespectImageOrientation, clampMode, KURL());
 }
 
 void SVGImage::drawInternal(SkCanvas* canvas, const SkPaint& paint, const FloatRect& dstRect, const FloatRect& srcRect,
     RespectImageOrientationEnum, ImageClampingMode, const KURL& url)
 {
     DCHECK(m_page);
     FrameView* view = toLocalFrame(m_page->mainFrame())->view();
     view->resize(containerSize());
 
     // Always call processUrlFragment, even if the url is empty, because
@@ skipping 215 matching lines @@
 
     return m_page;
 }
 
 String SVGImage::filenameExtension() const
 {
     return "svg";
 }
 
 } // namespace blink