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      1 /*
      2  * Copyright (C) 2009 Dirk Schulze <krit (at) webkit.org>
      3  * Copyright (C) 2013 Google Inc. All rights reserved.
      4  *
      5  * This library is free software; you can redistribute it and/or
      6  * modify it under the terms of the GNU Library General Public
      7  * License as published by the Free Software Foundation; either
      8  * version 2 of the License, or (at your option) any later version.
      9  *
     10  * This library is distributed in the hope that it will be useful,
     11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13  * Library General Public License for more details.
     14  *
     15  * You should have received a copy of the GNU Library General Public License
     16  * along with this library; see the file COPYING.LIB.  If not, write to
     17  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     18  * Boston, MA 02110-1301, USA.
     19  */
     20 
     21 #include "config.h"
     22 #include "platform/graphics/filters/SourceAlpha.h"
     23 
     24 #include "platform/graphics/Color.h"
     25 #include "platform/graphics/GraphicsContext.h"
     26 #include "platform/graphics/filters/Filter.h"
     27 #include "platform/graphics/filters/SkiaImageFilterBuilder.h"
     28 #include "platform/graphics/filters/SourceGraphic.h"
     29 #include "platform/text/TextStream.h"
     30 #include "third_party/skia/include/effects/SkColorFilterImageFilter.h"
     31 #include "third_party/skia/include/effects/SkColorMatrixFilter.h"
     32 #include "wtf/StdLibExtras.h"
     33 #include "wtf/text/WTFString.h"
     34 
     35 namespace blink {
     36 
     37 PassRefPtr<SourceAlpha> SourceAlpha::create(Filter* filter)
     38 {
     39     return adoptRef(new SourceAlpha(filter));
     40 }
     41 
     42 const AtomicString& SourceAlpha::effectName()
     43 {
     44     DEFINE_STATIC_LOCAL(const AtomicString, s_effectName, ("SourceAlpha", AtomicString::ConstructFromLiteral));
     45     return s_effectName;
     46 }
     47 
     48 FloatRect SourceAlpha::determineAbsolutePaintRect(const FloatRect& requestedRect)
     49 {
     50     FloatRect srcRect = filter()->sourceImageRect();
     51     srcRect.intersect(requestedRect);
     52     addAbsolutePaintRect(srcRect);
     53     return srcRect;
     54 }
     55 
     56 void SourceAlpha::applySoftware()
     57 {
     58     ImageBuffer* resultImage = createImageBufferResult();
     59     Filter* filter = this->filter();
     60     if (!resultImage || !filter->sourceImage())
     61         return;
     62 
     63     setIsAlphaImage(true);
     64 
     65     FloatRect imageRect(FloatPoint(), absolutePaintRect().size());
     66     GraphicsContext* filterContext = resultImage->context();
     67     filterContext->fillRect(imageRect, Color::black);
     68 
     69     IntRect srcRect = filter->sourceImageRect();
     70     if (ImageBuffer* sourceImageBuffer = filter->sourceImage()) {
     71         filterContext->drawImageBuffer(sourceImageBuffer,
     72             FloatRect(IntPoint(srcRect.location() - absolutePaintRect().location()), sourceImageBuffer->size()),
     73             0, CompositeDestinationIn);
     74     }
     75 }
     76 
     77 PassRefPtr<SkImageFilter> SourceAlpha::createImageFilter(SkiaImageFilterBuilder* builder)
     78 {
     79     RefPtr<SkImageFilter> sourceGraphic(builder->build(builder->sourceGraphic(), operatingColorSpace()));
     80     SkScalar matrix[20] = {
     81         0, 0, 0, 0, 0,
     82         0, 0, 0, 0, 0,
     83         0, 0, 0, 0, 0,
     84         0, 0, 0, SK_Scalar1, 0
     85     };
     86     RefPtr<SkColorFilter> colorFilter(adoptRef(SkColorMatrixFilter::Create(matrix)));
     87     return adoptRef(SkColorFilterImageFilter::Create(colorFilter.get(), sourceGraphic.get()));
     88 }
     89 
     90 TextStream& SourceAlpha::externalRepresentation(TextStream& ts, int indent) const
     91 {
     92     writeIndent(ts, indent);
     93     ts << "[SourceAlpha]\n";
     94     return ts;
     95 }
     96 
     97 } // namespace blink
     98