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1 /*
2  * Copyright 2018 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #include "SkCanvas.h"
9 #include "SkMaskFilterBase.h"
10 #include "SkReadBuffer.h"
11 #include "SkShaderMaskFilter.h"
12 #include "SkShaderBase.h"
13 #include "SkString.h"
14 
15 class SkShaderMF : public SkMaskFilterBase {
16 public:
SkShaderMF(sk_sp<SkShader> shader)17     SkShaderMF(sk_sp<SkShader> shader) : fShader(std::move(shader)) {}
18 
getFormat() const19     SkMask::Format getFormat() const override { return SkMask::kA8_Format; }
20 
21     bool filterMask(SkMask* dst, const SkMask& src, const SkMatrix&,
22                     SkIPoint* margin) const override;
23 
computeFastBounds(const SkRect & src,SkRect * dst) const24     void computeFastBounds(const SkRect& src, SkRect* dst) const override {
25         *dst = src;
26     }
27 
asABlur(BlurRec *) const28     bool asABlur(BlurRec*) const override { return false; }
29 
30 protected:
31 #if SK_SUPPORT_GPU
32     std::unique_ptr<GrFragmentProcessor> onAsFragmentProcessor(const GrFPArgs&) const override;
33     bool onHasFragmentProcessor() const override;
34 #endif
35 
36 private:
37     SK_FLATTENABLE_HOOKS(SkShaderMF)
38 
39     sk_sp<SkShader> fShader;
40 
41     SkShaderMF(SkReadBuffer&);
42     void flatten(SkWriteBuffer&) const override;
43 
44     friend class SkShaderMaskFilter;
45 
46     typedef SkMaskFilter INHERITED;
47 };
48 
CreateProc(SkReadBuffer & buffer)49 sk_sp<SkFlattenable> SkShaderMF::CreateProc(SkReadBuffer& buffer) {
50     return SkShaderMaskFilter::Make(buffer.readShader());
51 }
52 
flatten(SkWriteBuffer & buffer) const53 void SkShaderMF::flatten(SkWriteBuffer& buffer) const {
54     buffer.writeFlattenable(fShader.get());
55 }
56 
rect_memcpy(void * dst,size_t dstRB,const void * src,size_t srcRB,size_t copyBytes,int rows)57 static void rect_memcpy(void* dst, size_t dstRB, const void* src, size_t srcRB,
58                         size_t copyBytes, int rows) {
59     for (int i = 0; i < rows; ++i) {
60         memcpy(dst, src, copyBytes);
61         dst = (char*)dst + dstRB;
62         src = (const char*)src + srcRB;
63     }
64 }
65 
filterMask(SkMask * dst,const SkMask & src,const SkMatrix & ctm,SkIPoint * margin) const66 bool SkShaderMF::filterMask(SkMask* dst, const SkMask& src, const SkMatrix& ctm,
67                             SkIPoint* margin) const {
68     if (src.fFormat != SkMask::kA8_Format) {
69         return false;
70     }
71 
72     if (margin) {
73         margin->set(0, 0);
74     }
75     dst->fBounds   = src.fBounds;
76     dst->fRowBytes = src.fBounds.width();   // need alignment?
77     dst->fFormat   = SkMask::kA8_Format;
78 
79     if (src.fImage == nullptr) {
80         dst->fImage = nullptr;
81         return true;
82     }
83     size_t size = dst->computeImageSize();
84     if (0 == size) {
85         return false;   // too big to allocate, abort
86     }
87 
88     // Allocate and initialize dst image with a copy of the src image
89     dst->fImage = SkMask::AllocImage(size);
90     rect_memcpy(dst->fImage, dst->fRowBytes, src.fImage, src.fRowBytes,
91                 src.fBounds.width() * sizeof(uint8_t), src.fBounds.height());
92 
93     // Now we have a dst-mask, just need to setup a canvas and draw into it
94     SkBitmap bitmap;
95     if (!bitmap.installMaskPixels(*dst)) {
96         return false;
97     }
98 
99     SkPaint paint;
100     paint.setShader(fShader);
101     paint.setFilterQuality(SkFilterQuality::kLow_SkFilterQuality);
102     // this blendmode is the trick: we only draw the shader where the mask is
103     paint.setBlendMode(SkBlendMode::kSrcIn);
104 
105     SkCanvas canvas(bitmap);
106     canvas.translate(-SkIntToScalar(dst->fBounds.fLeft), -SkIntToScalar(dst->fBounds.fTop));
107     canvas.concat(ctm);
108     canvas.drawPaint(paint);
109     return true;
110 }
111 
112 ///////////////////////////////////////////////////////////////////////////////////////////////////
113 #if SK_SUPPORT_GPU
114 #include "GrFragmentProcessor.h"
115 
onAsFragmentProcessor(const GrFPArgs & args) const116 std::unique_ptr<GrFragmentProcessor> SkShaderMF::onAsFragmentProcessor(const GrFPArgs& args) const {
117     return GrFragmentProcessor::MulInputByChildAlpha(as_SB(fShader)->asFragmentProcessor(args));
118 }
119 
onHasFragmentProcessor() const120 bool SkShaderMF::onHasFragmentProcessor() const {
121     return true;
122 }
123 
124 #endif
125 ///////////////////////////////////////////////////////////////////////////////////////////////////
126 
Make(sk_sp<SkShader> shader)127 sk_sp<SkMaskFilter> SkShaderMaskFilter::Make(sk_sp<SkShader> shader) {
128     return shader ? sk_sp<SkMaskFilter>(new SkShaderMF(std::move(shader))) : nullptr;
129 }
130 
RegisterFlattenables()131 void SkShaderMaskFilter::RegisterFlattenables() { SK_REGISTER_FLATTENABLE(SkShaderMF); }
132