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      1 /*
      2  * Copyright (C) 2013 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #include "config.h"
     32 #include "platform/graphics/DrawLooperBuilder.h"
     33 
     34 #include "platform/geometry/FloatSize.h"
     35 #include "platform/graphics/Color.h"
     36 #include "third_party/skia/include/core/SkColor.h"
     37 #include "third_party/skia/include/core/SkColorFilter.h"
     38 #include "third_party/skia/include/core/SkDrawLooper.h"
     39 #include "third_party/skia/include/core/SkPaint.h"
     40 #include "third_party/skia/include/core/SkXfermode.h"
     41 #include "third_party/skia/include/effects/SkBlurMaskFilter.h"
     42 #include "wtf/RefPtr.h"
     43 
     44 namespace blink {
     45 
     46 DrawLooperBuilder::DrawLooperBuilder() { }
     47 
     48 DrawLooperBuilder::~DrawLooperBuilder() { }
     49 
     50 PassOwnPtr<DrawLooperBuilder> DrawLooperBuilder::create()
     51 {
     52     return adoptPtr(new DrawLooperBuilder);
     53 }
     54 
     55 PassRefPtr<SkDrawLooper> DrawLooperBuilder::detachDrawLooper()
     56 {
     57     return adoptRef(m_skDrawLooperBuilder.detachLooper());
     58 }
     59 
     60 void DrawLooperBuilder::addUnmodifiedContent()
     61 {
     62     SkLayerDrawLooper::LayerInfo info;
     63     m_skDrawLooperBuilder.addLayerOnTop(info);
     64 }
     65 
     66 // This replicates the old skia behavior when it used to take radius for blur. Now it takes sigma.
     67 static SkScalar RadiusToSigma(SkScalar radius)
     68 {
     69     SkASSERT(radius > 0);
     70     return 0.57735f * radius + 0.5f;
     71 }
     72 
     73 void DrawLooperBuilder::addShadow(const FloatSize& offset, float blur, const Color& color,
     74     ShadowTransformMode shadowTransformMode, ShadowAlphaMode shadowAlphaMode)
     75 {
     76     // Detect when there's no effective shadow.
     77     if (!color.alpha())
     78         return;
     79 
     80     SkColor skColor = color.rgb();
     81 
     82     SkLayerDrawLooper::LayerInfo info;
     83 
     84     switch (shadowAlphaMode) {
     85     case ShadowRespectsAlpha:
     86         info.fColorMode = SkXfermode::kDst_Mode;
     87         break;
     88     case ShadowIgnoresAlpha:
     89         info.fColorMode = SkXfermode::kSrc_Mode;
     90         break;
     91     default:
     92         ASSERT_NOT_REACHED();
     93     }
     94 
     95     if (blur)
     96         info.fPaintBits |= SkLayerDrawLooper::kMaskFilter_Bit; // our blur
     97     info.fPaintBits |= SkLayerDrawLooper::kColorFilter_Bit;
     98     info.fOffset.set(offset.width(), offset.height());
     99     info.fPostTranslate = (shadowTransformMode == ShadowIgnoresTransforms);
    100 
    101     SkPaint* paint = m_skDrawLooperBuilder.addLayerOnTop(info);
    102 
    103     if (blur) {
    104         const SkScalar sigma = RadiusToSigma(blur / 2);
    105         uint32_t mfFlags = SkBlurMaskFilter::kHighQuality_BlurFlag;
    106         if (shadowTransformMode == ShadowIgnoresTransforms)
    107             mfFlags |= SkBlurMaskFilter::kIgnoreTransform_BlurFlag;
    108         RefPtr<SkMaskFilter> mf = adoptRef(SkBlurMaskFilter::Create(kNormal_SkBlurStyle, sigma, mfFlags));
    109         paint->setMaskFilter(mf.get());
    110     }
    111 
    112     RefPtr<SkColorFilter> cf = adoptRef(SkColorFilter::CreateModeFilter(skColor, SkXfermode::kSrcIn_Mode));
    113     paint->setColorFilter(cf.get());
    114 }
    115 
    116 } // namespace blink
    117