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
44namespace blink {
45
46DrawLooperBuilder::DrawLooperBuilder() { }
47
48DrawLooperBuilder::~DrawLooperBuilder() { }
49
50PassOwnPtr<DrawLooperBuilder> DrawLooperBuilder::create()
51{
52    return adoptPtr(new DrawLooperBuilder);
53}
54
55PassRefPtr<SkDrawLooper> DrawLooperBuilder::detachDrawLooper()
56{
57    return adoptRef(m_skDrawLooperBuilder.detachLooper());
58}
59
60void 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.
67static SkScalar RadiusToSigma(SkScalar radius)
68{
69    SkASSERT(radius > 0);
70    return 0.57735f * radius + 0.5f;
71}
72
73void 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