1 /*
2 * Copyright 2021 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/SkSVGMask.h"
9
10 #include "include/core/SkCanvas.h"
11 #include "include/core/SkColorFilter.h"
12 #include "include/core/SkM44.h"
13 #include "include/core/SkPaint.h"
14 #include "include/effects/SkLumaColorFilter.h"
15 #include "include/private/base/SkTArray.h"
16 #include "modules/svg/include/SkSVGAttribute.h"
17 #include "modules/svg/include/SkSVGAttributeParser.h"
18 #include "modules/svg/include/SkSVGRenderContext.h"
19
20 #include <utility>
21
parseAndSetAttribute(const char * n,const char * v)22 bool SkSVGMask::parseAndSetAttribute(const char* n, const char* v) {
23 return INHERITED::parseAndSetAttribute(n, v) ||
24 this->setX(SkSVGAttributeParser::parse<SkSVGLength>("x", n, v)) ||
25 this->setY(SkSVGAttributeParser::parse<SkSVGLength>("y", n, v)) ||
26 this->setWidth(SkSVGAttributeParser::parse<SkSVGLength>("width", n, v)) ||
27 this->setHeight(SkSVGAttributeParser::parse<SkSVGLength>("height", n, v)) ||
28 this->setMaskUnits(
29 SkSVGAttributeParser::parse<SkSVGObjectBoundingBoxUnits>("maskUnits", n, v)) ||
30 this->setMaskContentUnits(
31 SkSVGAttributeParser::parse<SkSVGObjectBoundingBoxUnits>("maskContentUnits", n, v));
32 }
33
bounds(const SkSVGRenderContext & ctx) const34 SkRect SkSVGMask::bounds(const SkSVGRenderContext& ctx) const {
35 return ctx.resolveOBBRect(fX, fY, fWidth, fHeight, fMaskUnits);
36 }
37
renderMask(const SkSVGRenderContext & ctx) const38 void SkSVGMask::renderMask(const SkSVGRenderContext& ctx) const {
39 // https://www.w3.org/TR/SVG11/masking.html#Masking
40
41 // Propagate any inherited properties that may impact mask effect behavior (e.g.
42 // color-interpolation). We call this explicitly here because the SkSVGMask
43 // nodes do not participate in the normal onRender path, which is when property
44 // propagation currently occurs.
45 // The local context also restores the filter layer created below on scope exit.
46 SkSVGRenderContext lctx(ctx);
47 this->onPrepareToRender(&lctx);
48
49 const auto ci = *lctx.presentationContext().fInherited.fColorInterpolation;
50 auto ci_filter = (ci == SkSVGColorspace::kLinearRGB)
51 ? SkColorFilters::SRGBToLinearGamma()
52 : nullptr;
53
54 SkPaint mask_filter;
55 mask_filter.setColorFilter(
56 SkColorFilters::Compose(SkLumaColorFilter::Make(), std::move(ci_filter)));
57
58 // Mask color filter layer.
59 // Note: We could avoid this extra layer if we invert the stacking order
60 // (mask/content -> content/mask, kSrcIn -> kDstIn) and apply the filter
61 // via the top (mask) layer paint. That requires deferring mask rendering
62 // until after node content, which introduces extra state/complexity.
63 // Something to consider if masking performance ever becomes an issue.
64 lctx.canvas()->saveLayer(nullptr, &mask_filter);
65
66 const auto obbt = ctx.transformForCurrentOBB(fMaskContentUnits);
67 lctx.canvas()->translate(obbt.offset.x, obbt.offset.y);
68 lctx.canvas()->scale(obbt.scale.x, obbt.scale.y);
69
70 for (const auto& child : fChildren) {
71 child->render(lctx);
72 }
73 }
74