1 /*
2 * Copyright 2020 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 "modules/svg/include/SkSVGFilterContext.h"
9
10 #include "include/core/SkBlendMode.h"
11 #include "include/core/SkColor.h"
12 #include "include/core/SkColorFilter.h"
13 #include "include/core/SkColorSpace.h"
14 #include "include/core/SkPaint.h"
15 #include "include/core/SkShader.h"
16 #include "include/effects/SkColorMatrix.h"
17 #include "include/effects/SkImageFilters.h"
18 #include "include/private/base/SkAssert.h"
19 #include "include/private/base/SkDebug.h"
20 #include "modules/svg/include/SkSVGRenderContext.h"
21 #include "modules/svg/include/SkSVGTypes.h"
22 #include "src/base/SkTLazy.h"
23
24 #include <utility>
25
26 namespace {
27
ConvertFilterColorspace(sk_sp<SkImageFilter> && input,SkSVGColorspace src,SkSVGColorspace dst)28 sk_sp<SkImageFilter> ConvertFilterColorspace(sk_sp<SkImageFilter>&& input,
29 SkSVGColorspace src,
30 SkSVGColorspace dst) {
31 if (src == dst) {
32 return std::move(input);
33 } else if (src == SkSVGColorspace::kSRGB && dst == SkSVGColorspace::kLinearRGB) {
34 return SkImageFilters::ColorFilter(SkColorFilters::SRGBToLinearGamma(), input);
35 } else {
36 SkASSERT(src == SkSVGColorspace::kLinearRGB && dst == SkSVGColorspace::kSRGB);
37 return SkImageFilters::ColorFilter(SkColorFilters::LinearToSRGBGamma(), input);
38 }
39 }
40
paint_as_shader(const SkPaint & paint)41 sk_sp<SkShader> paint_as_shader(const SkPaint& paint) {
42 sk_sp<SkShader> shader = paint.refShader();
43 auto color = paint.getColor4f();
44 if (shader && color.fA < 1.f) {
45 // Multiply by paint alpha
46 shader = shader->makeWithColorFilter(
47 SkColorFilters::Blend(color, /*colorSpace=*/nullptr, SkBlendMode::kDstIn));
48 } else if (!shader) {
49 shader = SkShaders::Color(color, /*colorSpace=*/nullptr);
50 }
51 if (paint.getColorFilter()) {
52 shader = shader->makeWithColorFilter(paint.refColorFilter());
53 }
54 return shader;
55 }
56
57 } // namespace
58
findResultById(const SkSVGStringType & id) const59 const SkSVGFilterContext::Result* SkSVGFilterContext::findResultById(
60 const SkSVGStringType& id) const {
61 return fResults.find(id);
62 }
63
filterPrimitiveSubregion(const SkSVGFeInputType & input) const64 const SkRect& SkSVGFilterContext::filterPrimitiveSubregion(const SkSVGFeInputType& input) const {
65 const Result* res = nullptr;
66 if (input.type() == SkSVGFeInputType::Type::kFilterPrimitiveReference) {
67 res = fResults.find(input.id());
68 } else if (input.type() == SkSVGFeInputType::Type::kUnspecified) {
69 res = &fPreviousResult;
70 }
71 return res ? res->fFilterSubregion : fFilterEffectsRegion;
72 }
73
registerResult(const SkSVGStringType & id,const sk_sp<SkImageFilter> & result,const SkRect & subregion,SkSVGColorspace resultColorspace)74 void SkSVGFilterContext::registerResult(const SkSVGStringType& id,
75 const sk_sp<SkImageFilter>& result,
76 const SkRect& subregion,
77 SkSVGColorspace resultColorspace) {
78 SkASSERT(!id.isEmpty());
79 fResults[id] = {result, subregion, resultColorspace};
80 }
81
setPreviousResult(const sk_sp<SkImageFilter> & result,const SkRect & subregion,SkSVGColorspace resultColorspace)82 void SkSVGFilterContext::setPreviousResult(const sk_sp<SkImageFilter>& result,
83 const SkRect& subregion,
84 SkSVGColorspace resultColorspace) {
85 fPreviousResult = {result, subregion, resultColorspace};
86 }
87
previousResultIsSourceGraphic() const88 bool SkSVGFilterContext::previousResultIsSourceGraphic() const {
89 return fPreviousResult.fImageFilter == nullptr;
90 }
91
92 // https://www.w3.org/TR/SVG11/filters.html#FilterPrimitiveInAttribute
getInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const93 std::tuple<sk_sp<SkImageFilter>, SkSVGColorspace> SkSVGFilterContext::getInput(
94 const SkSVGRenderContext& ctx, const SkSVGFeInputType& inputType) const {
95 SkSVGColorspace inputCS = SkSVGColorspace::kSRGB;
96 sk_sp<SkImageFilter> result;
97 switch (inputType.type()) {
98 case SkSVGFeInputType::Type::kSourceAlpha: {
99 SkColorMatrix m;
100 m.setScale(0, 0, 0, 1.0f);
101 result = SkImageFilters::ColorFilter(SkColorFilters::Matrix(m), nullptr);
102 break;
103 }
104 case SkSVGFeInputType::Type::kSourceGraphic:
105 // Do nothing.
106 break;
107 case SkSVGFeInputType::Type::kFillPaint: {
108 const auto& fillPaint = ctx.fillPaint();
109 if (fillPaint.isValid()) {
110 auto dither = fillPaint->isDither() ? SkImageFilters::Dither::kYes
111 : SkImageFilters::Dither::kNo;
112 result = SkImageFilters::Shader(paint_as_shader(*fillPaint), dither);
113 }
114 break;
115 }
116 case SkSVGFeInputType::Type::kStrokePaint: {
117 // The paint filter doesn't apply fill/stroke styling, but use the paint settings
118 // defined for strokes.
119 const auto& strokePaint = ctx.strokePaint();
120 if (strokePaint.isValid()) {
121 auto dither = strokePaint->isDither() ? SkImageFilters::Dither::kYes
122 : SkImageFilters::Dither::kNo;
123 result = SkImageFilters::Shader(paint_as_shader(*strokePaint), dither);
124 }
125 break;
126 }
127 case SkSVGFeInputType::Type::kFilterPrimitiveReference: {
128 const Result* res = findResultById(inputType.id());
129 if (res) {
130 result = res->fImageFilter;
131 inputCS = res->fColorspace;
132 }
133 break;
134 }
135 case SkSVGFeInputType::Type::kUnspecified: {
136 result = fPreviousResult.fImageFilter;
137 inputCS = fPreviousResult.fColorspace;
138 break;
139 }
140 default:
141 SkDEBUGF("unhandled filter input type %d\n", (int)inputType.type());
142 break;
143 }
144
145 return {result, inputCS};
146 }
147
resolveInputColorspace(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const148 SkSVGColorspace SkSVGFilterContext::resolveInputColorspace(
149 const SkSVGRenderContext& ctx, const SkSVGFeInputType& inputType) const {
150 return std::get<1>(this->getInput(ctx, inputType));
151 }
152
resolveInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const153 sk_sp<SkImageFilter> SkSVGFilterContext::resolveInput(const SkSVGRenderContext& ctx,
154 const SkSVGFeInputType& inputType) const {
155 return std::get<0>(this->getInput(ctx, inputType));
156 }
157
resolveInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType,SkSVGColorspace colorspace) const158 sk_sp<SkImageFilter> SkSVGFilterContext::resolveInput(const SkSVGRenderContext& ctx,
159 const SkSVGFeInputType& inputType,
160 SkSVGColorspace colorspace) const {
161 auto [result, inputCS] = this->getInput(ctx, inputType);
162 return ConvertFilterColorspace(std::move(result), inputCS, colorspace);
163 }
164