1 /*
2 * Copyright 2016 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 "SkGradientShader.h"
9 #include "SkSVGLinearGradient.h"
10 #include "SkSVGRenderContext.h"
11 #include "SkSVGStop.h"
12 #include "SkSVGValue.h"
13
SkSVGLinearGradient()14 SkSVGLinearGradient::SkSVGLinearGradient() : INHERITED(SkSVGTag::kLinearGradient) {}
15
setHref(const SkSVGStringType & href)16 void SkSVGLinearGradient::setHref(const SkSVGStringType& href) {
17 fHref = std::move(href);
18 }
19
setGradientTransform(const SkSVGTransformType & t)20 void SkSVGLinearGradient::setGradientTransform(const SkSVGTransformType& t) {
21 fGradientTransform = t;
22 }
23
setSpreadMethod(const SkSVGSpreadMethod & spread)24 void SkSVGLinearGradient::setSpreadMethod(const SkSVGSpreadMethod& spread) {
25 fSpreadMethod = spread;
26 }
27
setX1(const SkSVGLength & x1)28 void SkSVGLinearGradient::setX1(const SkSVGLength& x1) {
29 fX1 = x1;
30 }
31
setY1(const SkSVGLength & y1)32 void SkSVGLinearGradient::setY1(const SkSVGLength& y1) {
33 fY1 = y1;
34 }
35
setX2(const SkSVGLength & x2)36 void SkSVGLinearGradient::setX2(const SkSVGLength& x2) {
37 fX2 = x2;
38 }
39
setY2(const SkSVGLength & y2)40 void SkSVGLinearGradient::setY2(const SkSVGLength& y2) {
41 fY2 = y2;
42 }
43
onSetAttribute(SkSVGAttribute attr,const SkSVGValue & v)44 void SkSVGLinearGradient::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
45 switch (attr) {
46 case SkSVGAttribute::kGradientTransform:
47 if (const auto* t = v.as<SkSVGTransformValue>()) {
48 this->setGradientTransform(*t);
49 }
50 break;
51 case SkSVGAttribute::kHref:
52 if (const auto* href = v.as<SkSVGStringValue>()) {
53 this->setHref(*href);
54 }
55 break;
56 case SkSVGAttribute::kSpreadMethod:
57 if (const auto* spread = v.as<SkSVGSpreadMethodValue>()) {
58 this->setSpreadMethod(*spread);
59 }
60 break;
61 case SkSVGAttribute::kX1:
62 if (const auto* x1 = v.as<SkSVGLengthValue>()) {
63 this->setX1(*x1);
64 }
65 break;
66 case SkSVGAttribute::kY1:
67 if (const auto* y1 = v.as<SkSVGLengthValue>()) {
68 this->setY1(*y1);
69 }
70 break;
71 case SkSVGAttribute::kX2:
72 if (const auto* x2 = v.as<SkSVGLengthValue>()) {
73 this->setX2(*x2);
74 }
75 break;
76 case SkSVGAttribute::kY2:
77 if (const auto* y2 = v.as<SkSVGLengthValue>()) {
78 this->setY2(*y2);
79 }
80 break;
81 default:
82 this->INHERITED::onSetAttribute(attr, v);
83 }
84 }
85
86 // https://www.w3.org/TR/SVG/pservers.html#LinearGradientElementHrefAttribute
collectColorStops(const SkSVGRenderContext & ctx,SkSTArray<2,SkScalar,true> * pos,SkSTArray<2,SkColor,true> * colors) const87 void SkSVGLinearGradient::collectColorStops(const SkSVGRenderContext& ctx,
88 SkSTArray<2, SkScalar, true>* pos,
89 SkSTArray<2, SkColor, true>* colors) const {
90 // Used to resolve percentage offsets.
91 const SkSVGLengthContext ltx(SkSize::Make(1, 1));
92
93 for (const auto& child : fChildren) {
94 if (child->tag() != SkSVGTag::kStop) {
95 continue;
96 }
97
98 const auto& stop = static_cast<const SkSVGStop&>(*child);
99 colors->push_back(SkColorSetA(stop.stopColor(),
100 SkScalarRoundToInt(stop.stopOpacity() * 255)));
101 pos->push_back(SkTPin(ltx.resolve(stop.offset(), SkSVGLengthContext::LengthType::kOther),
102 0.f, 1.f));
103 }
104
105 SkASSERT(colors->count() == pos->count());
106
107 if (pos->empty() && !fHref.value().isEmpty()) {
108 const auto* ref = ctx.findNodeById(fHref);
109 if (ref && ref->tag() == SkSVGTag::kLinearGradient) {
110 static_cast<const SkSVGLinearGradient*>(ref)->collectColorStops(ctx, pos, colors);
111 }
112 }
113 }
114
onAsPaint(const SkSVGRenderContext & ctx,SkPaint * paint) const115 bool SkSVGLinearGradient::onAsPaint(const SkSVGRenderContext& ctx, SkPaint* paint) const {
116 const auto& lctx = ctx.lengthContext();
117 const auto x1 = lctx.resolve(fX1, SkSVGLengthContext::LengthType::kHorizontal);
118 const auto y1 = lctx.resolve(fY1, SkSVGLengthContext::LengthType::kVertical);
119 const auto x2 = lctx.resolve(fX2, SkSVGLengthContext::LengthType::kHorizontal);
120 const auto y2 = lctx.resolve(fY2, SkSVGLengthContext::LengthType::kVertical);
121
122 const SkPoint pts[2] = { {x1, y1}, {x2, y2}};
123 SkSTArray<2, SkColor , true> colors;
124 SkSTArray<2, SkScalar, true> pos;
125
126 this->collectColorStops(ctx, &pos, &colors);
127 // TODO:
128 // * stop (lazy?) sorting
129 // * href loop detection
130 // * href attribute inheritance (not just color stops)
131 // * objectBoundingBox units support
132
133 static_assert(static_cast<SkShader::TileMode>(SkSVGSpreadMethod::Type::kPad) ==
134 SkShader::kClamp_TileMode, "SkSVGSpreadMethod::Type is out of sync");
135 static_assert(static_cast<SkShader::TileMode>(SkSVGSpreadMethod::Type::kRepeat) ==
136 SkShader::kRepeat_TileMode, "SkSVGSpreadMethod::Type is out of sync");
137 static_assert(static_cast<SkShader::TileMode>(SkSVGSpreadMethod::Type::kReflect) ==
138 SkShader::kMirror_TileMode, "SkSVGSpreadMethod::Type is out of sync");
139 const auto tileMode = static_cast<SkShader::TileMode>(fSpreadMethod.type());
140
141 paint->setShader(SkGradientShader::MakeLinear(pts, colors.begin(), pos.begin(), colors.count(),
142 tileMode, 0, &fGradientTransform.value()));
143 return true;
144 }
145