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 "include/core/SkColorFilter.h"
9 #include "include/core/SkColorSpace.h"
10 #include "include/effects/SkColorMatrix.h"
11 #include "include/effects/SkImageFilters.h"
12 #include "modules/svg/include/SkSVGFilterContext.h"
13 #include "modules/svg/include/SkSVGNode.h"
14 #include "modules/svg/include/SkSVGRenderContext.h"
15 #include "modules/svg/include/SkSVGTypes.h"
16
17 namespace {
18
ConvertFilterColorspace(sk_sp<SkImageFilter> && input,SkSVGColorspace src,SkSVGColorspace dst)19 sk_sp<SkImageFilter> ConvertFilterColorspace(sk_sp<SkImageFilter>&& input,
20 SkSVGColorspace src,
21 SkSVGColorspace dst) {
22 if (src == dst) {
23 return std::move(input);
24 } else if (src == SkSVGColorspace::kSRGB && dst == SkSVGColorspace::kLinearRGB) {
25 return SkImageFilters::ColorFilter(SkColorFilters::SRGBToLinearGamma(), input);
26 } else {
27 SkASSERT(src == SkSVGColorspace::kLinearRGB && dst == SkSVGColorspace::kSRGB);
28 return SkImageFilters::ColorFilter(SkColorFilters::LinearToSRGBGamma(), input);
29 }
30 }
31
paint_as_shader(const SkPaint & paint)32 sk_sp<SkShader> paint_as_shader(const SkPaint& paint) {
33 sk_sp<SkShader> shader = paint.refShader();
34 auto color = paint.getColor4f();
35 if (shader && color.fA < 1.f) {
36 // Multiply by paint alpha
37 shader = shader->makeWithColorFilter(
38 SkColorFilters::Blend(color, /*colorSpace=*/nullptr, SkBlendMode::kDstIn));
39 } else if (!shader) {
40 shader = SkShaders::Color(color, /*colorSpace=*/nullptr);
41 }
42 if (paint.getColorFilter()) {
43 shader = shader->makeWithColorFilter(paint.refColorFilter());
44 }
45 return shader;
46 }
47
48 } // namespace
49
findResultById(const SkSVGStringType & id) const50 const SkSVGFilterContext::Result* SkSVGFilterContext::findResultById(
51 const SkSVGStringType& id) const {
52 return fResults.find(id);
53 }
54
filterPrimitiveSubregion(const SkSVGFeInputType & input) const55 const SkRect& SkSVGFilterContext::filterPrimitiveSubregion(const SkSVGFeInputType& input) const {
56 const Result* res = nullptr;
57 if (input.type() == SkSVGFeInputType::Type::kFilterPrimitiveReference) {
58 res = fResults.find(input.id());
59 } else if (input.type() == SkSVGFeInputType::Type::kUnspecified) {
60 res = &fPreviousResult;
61 }
62 return res ? res->fFilterSubregion : fFilterEffectsRegion;
63 }
64
registerResult(const SkSVGStringType & id,const sk_sp<SkImageFilter> & result,const SkRect & subregion,SkSVGColorspace resultColorspace)65 void SkSVGFilterContext::registerResult(const SkSVGStringType& id,
66 const sk_sp<SkImageFilter>& result,
67 const SkRect& subregion,
68 SkSVGColorspace resultColorspace) {
69 SkASSERT(!id.isEmpty());
70 fResults[id] = {result, subregion, resultColorspace};
71 }
72
setPreviousResult(const sk_sp<SkImageFilter> & result,const SkRect & subregion,SkSVGColorspace resultColorspace)73 void SkSVGFilterContext::setPreviousResult(const sk_sp<SkImageFilter>& result,
74 const SkRect& subregion,
75 SkSVGColorspace resultColorspace) {
76 fPreviousResult = {result, subregion, resultColorspace};
77 }
78
previousResultIsSourceGraphic() const79 bool SkSVGFilterContext::previousResultIsSourceGraphic() const {
80 return fPreviousResult.fImageFilter == nullptr;
81 }
82
83 // https://www.w3.org/TR/SVG11/filters.html#FilterPrimitiveInAttribute
getInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const84 std::tuple<sk_sp<SkImageFilter>, SkSVGColorspace> SkSVGFilterContext::getInput(
85 const SkSVGRenderContext& ctx, const SkSVGFeInputType& inputType) const {
86 SkSVGColorspace inputCS = SkSVGColorspace::kSRGB;
87 sk_sp<SkImageFilter> result;
88 switch (inputType.type()) {
89 case SkSVGFeInputType::Type::kSourceAlpha: {
90 SkColorMatrix m;
91 m.setScale(0, 0, 0, 1.0f);
92 result = SkImageFilters::ColorFilter(SkColorFilters::Matrix(m), nullptr);
93 break;
94 }
95 case SkSVGFeInputType::Type::kSourceGraphic:
96 // Do nothing.
97 break;
98 case SkSVGFeInputType::Type::kFillPaint: {
99 const auto& fillPaint = ctx.fillPaint();
100 if (fillPaint.isValid()) {
101 auto dither = fillPaint->isDither() ? SkImageFilters::Dither::kYes
102 : SkImageFilters::Dither::kNo;
103 result = SkImageFilters::Shader(paint_as_shader(*fillPaint), dither);
104 }
105 break;
106 }
107 case SkSVGFeInputType::Type::kStrokePaint: {
108 // The paint filter doesn't apply fill/stroke styling, but use the paint settings
109 // defined for strokes.
110 const auto& strokePaint = ctx.strokePaint();
111 if (strokePaint.isValid()) {
112 auto dither = strokePaint->isDither() ? SkImageFilters::Dither::kYes
113 : SkImageFilters::Dither::kNo;
114 result = SkImageFilters::Shader(paint_as_shader(*strokePaint), dither);
115 }
116 break;
117 }
118 case SkSVGFeInputType::Type::kFilterPrimitiveReference: {
119 const Result* res = findResultById(inputType.id());
120 if (res) {
121 result = res->fImageFilter;
122 inputCS = res->fColorspace;
123 }
124 break;
125 }
126 case SkSVGFeInputType::Type::kUnspecified: {
127 result = fPreviousResult.fImageFilter;
128 inputCS = fPreviousResult.fColorspace;
129 break;
130 }
131 default:
132 SkDebugf("unhandled filter input type %d\n", (int)inputType.type());
133 break;
134 }
135
136 return {result, inputCS};
137 }
138
resolveInputColorspace(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const139 SkSVGColorspace SkSVGFilterContext::resolveInputColorspace(
140 const SkSVGRenderContext& ctx, const SkSVGFeInputType& inputType) const {
141 return std::get<1>(this->getInput(ctx, inputType));
142 }
143
resolveInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const144 sk_sp<SkImageFilter> SkSVGFilterContext::resolveInput(const SkSVGRenderContext& ctx,
145 const SkSVGFeInputType& inputType) const {
146 return std::get<0>(this->getInput(ctx, inputType));
147 }
148
resolveInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType,SkSVGColorspace colorspace) const149 sk_sp<SkImageFilter> SkSVGFilterContext::resolveInput(const SkSVGRenderContext& ctx,
150 const SkSVGFeInputType& inputType,
151 SkSVGColorspace colorspace) const {
152 auto [result, inputCS] = this->getInput(ctx, inputType);
153 return ConvertFilterColorspace(std::move(result), inputCS, colorspace);
154 }
155