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 #include "modules/svg/include/SkSVGFilterContext.h"
8
9 #include "include/core/SkBlendMode.h"
10 #include "include/core/SkColorFilter.h"
11 #include "include/core/SkColorSpace.h"
12 #include "include/effects/SkColorMatrix.h"
13 #include "include/effects/SkImageFilters.h"
14 #include "modules/svg/include/SkSVGNode.h"
15 #include "modules/svg/include/SkSVGRenderContext.h"
16 #include "modules/svg/include/SkSVGTypes.h"
17
18 namespace {
19
ConvertFilterColorspace(sk_sp<SkImageFilter> && input,SkSVGColorspace src,SkSVGColorspace dst)20 sk_sp<SkImageFilter> ConvertFilterColorspace(sk_sp<SkImageFilter>&& input,
21 SkSVGColorspace src,
22 SkSVGColorspace dst) {
23 if (src == dst) {
24 return std::move(input);
25 } else if (src == SkSVGColorspace::kSRGB && dst == SkSVGColorspace::kLinearRGB) {
26 return SkImageFilters::ColorFilter(SkColorFilters::SRGBToLinearGamma(), input);
27 } else {
28 SkASSERT(src == SkSVGColorspace::kLinearRGB && dst == SkSVGColorspace::kSRGB);
29 return SkImageFilters::ColorFilter(SkColorFilters::LinearToSRGBGamma(), input);
30 }
31 }
32
paint_as_shader(const SkPaint & paint)33 sk_sp<SkShader> paint_as_shader(const SkPaint& paint) {
34 sk_sp<SkShader> shader = paint.refShader();
35 auto color = paint.getColor4f();
36 if (shader && color.fA < 1.f) {
37 // Multiply by paint alpha
38 shader = shader->makeWithColorFilter(
39 SkColorFilters::Blend(color, /*colorSpace=*/nullptr, SkBlendMode::kDstIn));
40 } else if (!shader) {
41 shader = SkShaders::Color(color, /*colorSpace=*/nullptr);
42 }
43 if (paint.getColorFilter()) {
44 shader = shader->makeWithColorFilter(paint.refColorFilter());
45 }
46 return shader;
47 }
48
49 } // namespace
50
findResultById(const SkSVGStringType & id) const51 const SkSVGFilterContext::Result* SkSVGFilterContext::findResultById(
52 const SkSVGStringType& id) const {
53 return fResults.find(id);
54 }
55
filterPrimitiveSubregion(const SkSVGFeInputType & input) const56 const SkRect& SkSVGFilterContext::filterPrimitiveSubregion(const SkSVGFeInputType& input) const {
57 const Result* res = nullptr;
58 if (input.type() == SkSVGFeInputType::Type::kFilterPrimitiveReference) {
59 res = fResults.find(input.id());
60 } else if (input.type() == SkSVGFeInputType::Type::kUnspecified) {
61 res = &fPreviousResult;
62 }
63 return res ? res->fFilterSubregion : fFilterEffectsRegion;
64 }
65
registerResult(const SkSVGStringType & id,const sk_sp<SkImageFilter> & result,const SkRect & subregion,SkSVGColorspace resultColorspace)66 void SkSVGFilterContext::registerResult(const SkSVGStringType& id,
67 const sk_sp<SkImageFilter>& result,
68 const SkRect& subregion,
69 SkSVGColorspace resultColorspace) {
70 SkASSERT(!id.isEmpty());
71 fResults[id] = {result, subregion, resultColorspace};
72 }
73
setPreviousResult(const sk_sp<SkImageFilter> & result,const SkRect & subregion,SkSVGColorspace resultColorspace)74 void SkSVGFilterContext::setPreviousResult(const sk_sp<SkImageFilter>& result,
75 const SkRect& subregion,
76 SkSVGColorspace resultColorspace) {
77 fPreviousResult = {result, subregion, resultColorspace};
78 }
79
previousResultIsSourceGraphic() const80 bool SkSVGFilterContext::previousResultIsSourceGraphic() const {
81 return fPreviousResult.fImageFilter == nullptr;
82 }
83
84 // https://www.w3.org/TR/SVG11/filters.html#FilterPrimitiveInAttribute
getInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const85 std::tuple<sk_sp<SkImageFilter>, SkSVGColorspace> SkSVGFilterContext::getInput(
86 const SkSVGRenderContext& ctx, const SkSVGFeInputType& inputType) const {
87 SkSVGColorspace inputCS = SkSVGColorspace::kSRGB;
88 sk_sp<SkImageFilter> result;
89 switch (inputType.type()) {
90 case SkSVGFeInputType::Type::kSourceAlpha: {
91 SkColorMatrix m;
92 m.setScale(0, 0, 0, 1.0f);
93 result = SkImageFilters::ColorFilter(SkColorFilters::Matrix(m), nullptr);
94 break;
95 }
96 case SkSVGFeInputType::Type::kSourceGraphic:
97 // Do nothing.
98 break;
99 case SkSVGFeInputType::Type::kFillPaint: {
100 const auto& fillPaint = ctx.fillPaint();
101 if (fillPaint.isValid()) {
102 auto dither = fillPaint->isDither() ? SkImageFilters::Dither::kYes
103 : SkImageFilters::Dither::kNo;
104 result = SkImageFilters::Shader(paint_as_shader(*fillPaint), dither);
105 }
106 break;
107 }
108 case SkSVGFeInputType::Type::kStrokePaint: {
109 // The paint filter doesn't apply fill/stroke styling, but use the paint settings
110 // defined for strokes.
111 const auto& strokePaint = ctx.strokePaint();
112 if (strokePaint.isValid()) {
113 auto dither = strokePaint->isDither() ? SkImageFilters::Dither::kYes
114 : SkImageFilters::Dither::kNo;
115 result = SkImageFilters::Shader(paint_as_shader(*strokePaint), dither);
116 }
117 break;
118 }
119 case SkSVGFeInputType::Type::kFilterPrimitiveReference: {
120 const Result* res = findResultById(inputType.id());
121 if (res) {
122 result = res->fImageFilter;
123 inputCS = res->fColorspace;
124 }
125 break;
126 }
127 case SkSVGFeInputType::Type::kUnspecified: {
128 result = fPreviousResult.fImageFilter;
129 inputCS = fPreviousResult.fColorspace;
130 break;
131 }
132 default:
133 SkDebugf("unhandled filter input type %d\n", (int)inputType.type());
134 break;
135 }
136
137 return {result, inputCS};
138 }
139
resolveInputColorspace(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const140 SkSVGColorspace SkSVGFilterContext::resolveInputColorspace(
141 const SkSVGRenderContext& ctx, const SkSVGFeInputType& inputType) const {
142 return std::get<1>(this->getInput(ctx, inputType));
143 }
144
resolveInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType) const145 sk_sp<SkImageFilter> SkSVGFilterContext::resolveInput(const SkSVGRenderContext& ctx,
146 const SkSVGFeInputType& inputType) const {
147 return std::get<0>(this->getInput(ctx, inputType));
148 }
149
resolveInput(const SkSVGRenderContext & ctx,const SkSVGFeInputType & inputType,SkSVGColorspace colorspace) const150 sk_sp<SkImageFilter> SkSVGFilterContext::resolveInput(const SkSVGRenderContext& ctx,
151 const SkSVGFeInputType& inputType,
152 SkSVGColorspace colorspace) const {
153 auto [result, inputCS] = this->getInput(ctx, inputType);
154 return ConvertFilterColorspace(std::move(result), inputCS, colorspace);
155 }
156