1 /*
2 * Copyright 2017 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 "SkSVGPattern.h"
9
10 #include "SkPictureRecorder.h"
11 #include "SkShader.h"
12 #include "SkSVGRenderContext.h"
13 #include "SkSVGValue.h"
14
SkSVGPattern()15 SkSVGPattern::SkSVGPattern() : INHERITED(SkSVGTag::kPattern) {}
16
setX(const SkSVGLength & x)17 void SkSVGPattern::setX(const SkSVGLength& x) {
18 fAttributes.fX.set(x);
19 }
20
setY(const SkSVGLength & y)21 void SkSVGPattern::setY(const SkSVGLength& y) {
22 fAttributes.fY.set(y);
23 }
24
setWidth(const SkSVGLength & w)25 void SkSVGPattern::setWidth(const SkSVGLength& w) {
26 fAttributes.fWidth.set(w);
27 }
28
setHeight(const SkSVGLength & h)29 void SkSVGPattern::setHeight(const SkSVGLength& h) {
30 fAttributes.fHeight.set(h);
31 }
32
setHref(const SkSVGStringType & href)33 void SkSVGPattern::setHref(const SkSVGStringType& href) {
34 fHref = std::move(href);
35 }
36
setPatternTransform(const SkSVGTransformType & patternTransform)37 void SkSVGPattern::setPatternTransform(const SkSVGTransformType& patternTransform) {
38 fAttributes.fPatternTransform.set(patternTransform);
39 }
40
onSetAttribute(SkSVGAttribute attr,const SkSVGValue & v)41 void SkSVGPattern::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
42 switch (attr) {
43 case SkSVGAttribute::kX:
44 if (const auto* x = v.as<SkSVGLengthValue>()) {
45 this->setX(*x);
46 }
47 break;
48 case SkSVGAttribute::kY:
49 if (const auto* y = v.as<SkSVGLengthValue>()) {
50 this->setY(*y);
51 }
52 break;
53 case SkSVGAttribute::kWidth:
54 if (const auto* w = v.as<SkSVGLengthValue>()) {
55 this->setWidth(*w);
56 }
57 break;
58 case SkSVGAttribute::kHeight:
59 if (const auto* h = v.as<SkSVGLengthValue>()) {
60 this->setHeight(*h);
61 }
62 break;
63 case SkSVGAttribute::kHref:
64 if (const auto* href = v.as<SkSVGStringValue>()) {
65 this->setHref(*href);
66 }
67 break;
68 case SkSVGAttribute::kPatternTransform:
69 if (const auto* t = v.as<SkSVGTransformValue>()) {
70 this->setPatternTransform(*t);
71 }
72 break;
73 default:
74 this->INHERITED::onSetAttribute(attr, v);
75 }
76 }
77
hrefTarget(const SkSVGRenderContext & ctx) const78 const SkSVGPattern* SkSVGPattern::hrefTarget(const SkSVGRenderContext& ctx) const {
79 if (fHref.value().isEmpty()) {
80 return nullptr;
81 }
82
83 const auto* href = ctx.findNodeById(fHref);
84 if (!href || href->tag() != SkSVGTag::kPattern) {
85 return nullptr;
86 }
87
88 return static_cast<const SkSVGPattern*>(href);
89 }
90
91 template <typename T>
inherit_if_needed(const SkTLazy<T> & src,SkTLazy<T> & dst)92 bool inherit_if_needed(const SkTLazy<T>& src, SkTLazy<T>& dst) {
93 if (!dst.isValid()) {
94 dst = src;
95 return true;
96 }
97
98 return false;
99 }
100
101 /* https://www.w3.org/TR/SVG/pservers.html#PatternElementHrefAttribute
102 *
103 * Any attributes which are defined on the referenced element which are not defined on this element
104 * are inherited by this element. If this element has no children, and the referenced element does
105 * (possibly due to its own ‘xlink:href’ attribute), then this element inherits the children from
106 * the referenced element. Inheritance can be indirect to an arbitrary level; thus, if the
107 * referenced element inherits attributes or children due to its own ‘xlink:href’ attribute, then
108 * the current element can inherit those attributes or children.
109 */
resolveHref(const SkSVGRenderContext & ctx,PatternAttributes * attrs) const110 const SkSVGPattern* SkSVGPattern::resolveHref(const SkSVGRenderContext& ctx,
111 PatternAttributes* attrs) const {
112 const SkSVGPattern *currentNode = this,
113 *contentNode = this;
114 do {
115 // Bitwise OR to avoid short-circuiting.
116 const bool didInherit =
117 inherit_if_needed(currentNode->fAttributes.fX , attrs->fX) |
118 inherit_if_needed(currentNode->fAttributes.fY , attrs->fY) |
119 inherit_if_needed(currentNode->fAttributes.fWidth , attrs->fWidth) |
120 inherit_if_needed(currentNode->fAttributes.fHeight , attrs->fHeight) |
121 inherit_if_needed(currentNode->fAttributes.fPatternTransform, attrs->fPatternTransform);
122
123 if (!contentNode->hasChildren()) {
124 contentNode = currentNode;
125 }
126
127 if (contentNode->hasChildren() && !didInherit) {
128 // All attributes have been resolved, and a valid content node has been found.
129 // We can terminate the href chain early.
130 break;
131 }
132
133 // TODO: reference loop mitigation.
134 currentNode = currentNode->hrefTarget(ctx);
135 } while (currentNode);
136
137 return contentNode;
138 }
139
onAsPaint(const SkSVGRenderContext & ctx,SkPaint * paint) const140 bool SkSVGPattern::onAsPaint(const SkSVGRenderContext& ctx, SkPaint* paint) const {
141 PatternAttributes attrs;
142 const auto* contentNode = this->resolveHref(ctx, &attrs);
143
144 const auto tile = ctx.lengthContext().resolveRect(
145 attrs.fX.isValid() ? *attrs.fX.get() : SkSVGLength(0),
146 attrs.fY.isValid() ? *attrs.fY.get() : SkSVGLength(0),
147 attrs.fWidth.isValid() ? *attrs.fWidth.get() : SkSVGLength(0),
148 attrs.fHeight.isValid() ? *attrs.fHeight.get() : SkSVGLength(0));
149
150 if (tile.isEmpty()) {
151 return false;
152 }
153
154 const SkMatrix* patternTransform = attrs.fPatternTransform.isValid()
155 ? &attrs.fPatternTransform.get()->value()
156 : nullptr;
157
158 SkPictureRecorder recorder;
159 SkSVGRenderContext recordingContext(ctx, recorder.beginRecording(tile));
160
161 // Cannot call into INHERITED:: because SkSVGHiddenContainer skips rendering.
162 contentNode->SkSVGContainer::onRender(recordingContext);
163
164 paint->setShader(SkShader::MakePictureShader(recorder.finishRecordingAsPicture(),
165 SkShader::kRepeat_TileMode,
166 SkShader::kRepeat_TileMode,
167 patternTransform,
168 &tile));
169 return true;
170 }
171