Fix display list canvas not rendering correctly on high dpi displays

Source/platform/graphics/GraphicsContext.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. 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.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 42 matching lines @@
 #include "third_party/skia/include/effects/SkCornerPathEffect.h"
 #include "third_party/skia/include/effects/SkDropShadowImageFilter.h"
 #include "third_party/skia/include/effects/SkLumaColorFilter.h"
 #include "third_party/skia/include/effects/SkMatrixImageFilter.h"
 #include "third_party/skia/include/effects/SkPictureImageFilter.h"
 #include "third_party/skia/include/gpu/GrRenderTarget.h"
 #include "third_party/skia/include/gpu/GrTexture.h"
 #include "wtf/Assertions.h"
 #include "wtf/MathExtras.h"
 
-namespace {
-
-// Tolerance value use for comparing scale factor to 1..
-// Numerical error should not reach 6th decimal except for highly degenerate cases,
-// and effect of 6th decimal on scale is negligible over max span of a skia canvas
-// which is 32k pixels.
-const float cPictureScaleEpsilon = 0.000001;
-
-}
-
 namespace blink {
 
 class GraphicsContext::RecordingState {
     WTF_MAKE_FAST_ALLOCATED;
     WTF_MAKE_NONCOPYABLE(RecordingState);
 public:
     static PassOwnPtr<RecordingState> Create(SkCanvas* canvas, const SkMatrix& matrix, unsigned trackingMode)
     {
         return adoptPtr(new RecordingState(canvas, matrix, static_cast<RegionTrackingMode>(trackingMode)));
     }
@@ skipping 488 matching lines @@
 
     if (regionTrackingEnabled()) {
         // Since we don't track regions within display lists, conservatively
         // mark the bounds as non-opaque.
         SkPaint paint;
         paint.setXfermodeMode(SkXfermode::kClear_Mode);
         m_trackedRegion.didDrawBounded(this, picture->cullRect(), paint);
     }
 }
 
-static inline bool pictureScaleIsApproximatelyOne(float x)
-{
-    return fabsf(x - 1.0f) < cPictureScaleEpsilon;
-}
-
-void GraphicsContext::drawPicture(SkPicture* picture, const FloatRect& dest, const FloatRect& src, CompositeOperator op, WebBlendMode blendMode)
+void GraphicsContext::compositePicture(SkPicture* picture, const FloatRect& dest, const FloatRect& src, CompositeOperator op, WebBlendMode blendMode)
 {
     ASSERT(m_canvas);
     if (contextDisabled() || !picture)
         return;
 
-    SkMatrix ctm = m_canvas->getTotalMatrix();
-    SkRect deviceDest;
-    ctm.mapRect(&deviceDest, dest);
-    float scaleX = deviceDest.width() / src.width();
-    float scaleY = deviceDest.height() / src.height();
-
     SkPaint picturePaint;
     picturePaint.setXfermodeMode(WebCoreCompositeToSkiaComposite(op, blendMode));
+    m_canvas->save();
     SkRect sourceBounds = WebCoreFloatRectToSKRect(src);
-    if (pictureScaleIsApproximatelyOne(scaleX * m_deviceScaleFactor) && pictureScaleIsApproximatelyOne(scaleY * m_deviceScaleFactor)) {
-        // Fast path for canvases that are rasterized at screen resolution
-        SkRect skBounds = WebCoreFloatRectToSKRect(dest);
-        m_canvas->saveLayer(&skBounds, &picturePaint);
-        SkMatrix pictureTransform;
-        pictureTransform.setRectToRect(sourceBounds, skBounds, SkMatrix::kFill_ScaleToFit);
-        m_canvas->concat(pictureTransform);
-        m_canvas->drawPicture(picture);
-        m_canvas->restore();
-    } else {
-        RefPtr<SkPictureImageFilter> pictureFilter = adoptRef(SkPictureImageFilter::Create(picture, sourceBounds));
-        SkMatrix layerScale;
-        layerScale.setScale(scaleX, scaleY);
-        RefPtr<SkMatrixImageFilter> matrixFilter = adoptRef(SkMatrixImageFilter::Create(layerScale, SkPaint::kLow_FilterLevel, pictureFilter.get()));
-        picturePaint.setImageFilter(matrixFilter.get());
-        SkRect layerBounds = SkRect::MakeWH(std::max(deviceDest.width(), sourceBounds.width()), std::max(deviceDest.height(), sourceBounds.height()));
-        m_canvas->save();
-        m_canvas->resetMatrix();
-        m_canvas->translate(deviceDest.x(), deviceDest.y());
-        m_canvas->saveLayer(&layerBounds, &picturePaint);
-        m_canvas->restore();
-        m_canvas->restore();
-    }
+    SkRect skBounds = WebCoreFloatRectToSKRect(dest);
+    SkMatrix pictureTransform;
+    pictureTransform.setRectToRect(sourceBounds, skBounds, SkMatrix::kFill_ScaleToFit);
+    m_canvas->concat(pictureTransform);
+    RefPtr<SkPictureImageFilter> pictureFilter = adoptRef(SkPictureImageFilter::CreateForLocalSpace(picture, sourceBounds, static_cast<SkPaint::FilterLevel>(imageInterpolationQuality())));
+    picturePaint.setImageFilter(pictureFilter.get());
+    m_canvas->saveLayer(&sourceBounds, &picturePaint);
+    m_canvas->restore();
+    m_canvas->restore();
 }
 
 void GraphicsContext::fillPolygon(size_t numPoints, const FloatPoint* points, const Color& color,
     bool shouldAntialias)
 {
     if (contextDisabled())
         return;
 
     ASSERT(numPoints > 2);
 
@@ skipping 1354 matching lines @@
 GraphicsContext::AutoCanvasRestorer::~AutoCanvasRestorer()
 {
     while (m_restoreCount) {
         m_canvas->restore();
         m_restoreCount--;
     }
 
 }
 
 } // namespace blink