Add support for converting Colors to linear RGB; Fix relevant filters

Source/platform/graphics/ImageBuffer.cpp

 /*
  * Copyright (c) 2008, Google Inc. All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
@@ skipping 202 matching lines @@
     const FloatPoint& phase, CompositeOperator op, const FloatRect& destRect, blink::WebBlendMode blendMode, const IntSize& repeatSpacing)
 {
     if (!isValid())
         return;
 
     const SkBitmap& bitmap = m_surface->bitmap();
     RefPtr<Image> image = BitmapImage::create(NativeImageSkia::create(drawNeedsCopy(m_context.get(), context) ? deepSkBitmapCopy(bitmap) : bitmap));
     image->drawPattern(context, srcRect, scale, phase, op, destRect, blendMode, repeatSpacing);
 }
 
-static const Vector<uint8_t>& getLinearRgbLUT()
-{
-    DEFINE_STATIC_LOCAL(Vector<uint8_t>, linearRgbLUT, ());
-    if (linearRgbLUT.isEmpty()) {
-        linearRgbLUT.reserveCapacity(256);
-        for (unsigned i = 0; i < 256; i++) {
-            float color = i  / 255.0f;
-            color = (color <= 0.04045f ? color / 12.92f : pow((color + 0.055f) / 1.055f, 2.4f));
-            color = std::max(0.0f, color);
-            color = std::min(1.0f, color);
-            linearRgbLUT.append(static_cast<uint8_t>(round(color * 255)));
-        }
-    }
-    return linearRgbLUT;
-}
-
-static const Vector<uint8_t>& getDeviceRgbLUT()
-{
-    DEFINE_STATIC_LOCAL(Vector<uint8_t>, deviceRgbLUT, ());
-    if (deviceRgbLUT.isEmpty()) {
-        deviceRgbLUT.reserveCapacity(256);
-        for (unsigned i = 0; i < 256; i++) {
-            float color = i / 255.0f;
-            color = (powf(color, 1.0f / 2.4f) * 1.055f) - 0.055f;
-            color = std::max(0.0f, color);
-            color = std::min(1.0f, color);
-            deviceRgbLUT.append(static_cast<uint8_t>(round(color * 255)));
-        }
-    }
-    return deviceRgbLUT;
-}
-
 void ImageBuffer::transformColorSpace(ColorSpace srcColorSpace, ColorSpace dstColorSpace)
 {
-    if (srcColorSpace == dstColorSpace)
-        return;
-
-    // only sRGB <-> linearRGB are supported at the moment
-    if ((srcColorSpace != ColorSpaceLinearRGB && srcColorSpace != ColorSpaceDeviceRGB)
-        || (dstColorSpace != ColorSpaceLinearRGB && dstColorSpace != ColorSpaceDeviceRGB))
+    const uint8_t* lookUpTable = ColorSpaceUtilities::getConversionLUT(dstColorSpace, srcColorSpace);
+    if (!lookUpTable)
         return;
 
     // FIXME: Disable color space conversions on accelerated canvases (for now).
     if (context()->isAccelerated() || !isValid())
         return;
 
     const SkBitmap& bitmap = m_surface->bitmap();
     if (bitmap.isNull())
         return;
 
-    const Vector<uint8_t>& lookUpTable = dstColorSpace == ColorSpaceLinearRGB ?
-        getLinearRgbLUT() : getDeviceRgbLUT();
-
     ASSERT(bitmap.config() == SkBitmap::kARGB_8888_Config);
     IntSize size = m_surface->size();
     SkAutoLockPixels bitmapLock(bitmap);
     for (int y = 0; y < size.height(); ++y) {
         uint32_t* srcRow = bitmap.getAddr32(0, y);
         for (int x = 0; x < size.width(); ++x) {
             SkColor color = SkPMColorToColor(srcRow[x]);
             srcRow[x] = SkPreMultiplyARGB(
                 SkColorGetA(color),
                 lookUpTable[SkColorGetR(color)],
                 lookUpTable[SkColorGetG(color)],
                 lookUpTable[SkColorGetB(color)]);
         }
     }
 }
 
 PassRefPtr<SkColorFilter> ImageBuffer::createColorSpaceFilter(ColorSpace srcColorSpace,
     ColorSpace dstColorSpace)
 {
-    if ((srcColorSpace == dstColorSpace)
-        || (srcColorSpace != ColorSpaceLinearRGB && srcColorSpace != ColorSpaceDeviceRGB)
-        || (dstColorSpace != ColorSpaceLinearRGB && dstColorSpace != ColorSpaceDeviceRGB))
-        return 0;
-
-    const uint8_t* lut = 0;
-    if (dstColorSpace == ColorSpaceLinearRGB)
-        lut = &getLinearRgbLUT()[0];
-    else if (dstColorSpace == ColorSpaceDeviceRGB)
-        lut = &getDeviceRgbLUT()[0];
-    else
+    const uint8_t* lut = ColorSpaceUtilities::getConversionLUT(dstColorSpace, srcColorSpace);
+    if (!lut)
         return 0;
 
     return adoptRef(SkTableColorFilter::CreateARGB(0, lut, lut, lut));
 }
 
 template <Multiply multiplied>
 PassRefPtr<Uint8ClampedArray> getImageData(const IntRect& rect, GraphicsContext* context, const IntSize& size)
 {
     float area = 4.0f * rect.width() * rect.height();
     if (area > static_cast<float>(std::numeric_limits<int>::max()))
@@ skipping 130 matching lines @@
     if (!encodeImage(imageData, mimeType, quality, &encodedImage))
         return "data:,";
 
     Vector<char> base64Data;
     base64Encode(encodedImage, base64Data);
 
     return "data:" + mimeType + ";base64," + base64Data;
 }
 
 } // namespace WebCore