[poc] curve-filter

third_party/WebKit/Source/platform/graphics/ImagePattern.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/ImagePattern.h"
 
+#include "platform/graphics/BitmapImage.h"
+#include "platform/graphics/GraphicsScreen.h"
 #include "platform/graphics/Image.h"
 #include "platform/graphics/skia/SkiaUtils.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkImage.h"
 #include "third_party/skia/include/core/SkShader.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
 namespace blink {
 
 PassRefPtr<ImagePattern> ImagePattern::create(PassRefPtr<Image> image, RepeatMode repeatMode)
 {
     return adoptRef(new ImagePattern(image, repeatMode));
 }
 
 ImagePattern::ImagePattern(PassRefPtr<Image> image, RepeatMode repeatMode)
     : Pattern(repeatMode)
     , m_tileImage(image->imageForCurrentFrame())
 {
+    if (!m_tileImage)
+        return;
+
+    // Patterns of tagged images (those that have a color profile) are drawn to sRGB
+    // on supported platforms. The only allowed caller is the <canvas> element. Grab
+    // the image assuming <canvas>: createShader() checks for it again on draw.
+
+    if (image->isBitmapImage()) {
+        WillPaintForDevice device(ScreenDevice::sRGBCanvas);
+        m_tileImage = toBitmapImage(image.get())->pictureForCurrentFrame();
+    }
+
     if (m_tileImage) {
         // TODO(fmalita): mechanism to extract the actual SkImageInfo from an SkImage?
         const SkImageInfo info =
             SkImageInfo::MakeN32Premul(m_tileImage->width(), m_tileImage->height());
         adjustExternalMemoryAllocated(info.getSafeSize(info.minRowBytes()));
     }
 }
 
 PassRefPtr<SkShader> ImagePattern::createShader()
 {
+    RELEASE_ASSERT(currentScreenId() == ScreenDevice::sRGBCanvas);
+
     if (!m_tileImage)
         return adoptRef(SkShader::CreateColorShader(SK_ColorTRANSPARENT));
 
     SkMatrix localMatrix = affineTransformToSkMatrix(m_patternSpaceTransformation);
 
     if (isRepeatXY()) {
         // Fast path: for repeatXY we just return a shader from the original image.
         return adoptRef(m_tileImage->newShader(SkShader::kRepeat_TileMode,
             SkShader::kRepeat_TileMode, &localMatrix));
     }
 
     // Skia does not have a "draw the tile only once" option. Clamp_TileMode
     // repeats the last line of the image after drawing one tile. To avoid
     // filling the space with arbitrary pixels, this workaround forces the
     // image to have a line of transparent pixels on the "repeated" edge(s),
     // thus causing extra space to be transparent filled.
     SkShader::TileMode tileModeX = isRepeatX()
         ? SkShader::kRepeat_TileMode : SkShader::kClamp_TileMode;
     SkShader::TileMode tileModeY = isRepeatY()
         ? SkShader::kRepeat_TileMode : SkShader::kClamp_TileMode;
     int expandW = isRepeatX() ? 0 : 1;
     int expandH = isRepeatY() ? 0 : 1;
 
     // Create a transparent image 1 pixel wider and/or taller than the
     // original, then copy the orignal into it.
     // FIXME: Is there a better way to pad (not scale) an image in skia?
+    // since the drawing is noticably pixelated compared to drawing the
+    // same tiled image with Image:drawTiled (which is used to draw CSS
+    // background-image repeat tiles).
     RefPtr<SkSurface> surface = adoptRef(SkSurface::NewRasterN32Premul(
         m_tileImage->width() + expandW, m_tileImage->height() + expandH));
     if (!surface)
         return adoptRef(SkShader::CreateColorShader(SK_ColorTRANSPARENT));
+    surface->getCanvas()->clear(SK_ColorTRANSPARENT);
 
-    surface->getCanvas()->clear(SK_ColorTRANSPARENT);
     SkPaint paint;
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
     surface->getCanvas()->drawImage(m_tileImage.get(), 0, 0, &paint);
-    RefPtr<SkImage> expandedImage = adoptRef(surface->newImageSnapshot());
 
-    return adoptRef(expandedImage->newShader(tileModeX, tileModeY, &localMatrix));
+    RefPtr<SkImage> image = adoptRef(surface->newImageSnapshot());
+    return adoptRef(image->newShader(tileModeX, tileModeY, &localMatrix));
 }
 
 bool ImagePattern::isTextureBacked() const
 {
     return m_tileImage && m_tileImage->isTextureBacked();
 }
 
 } // namespace