1 /*
2 * Copyright 2018 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/sksg/include/SkSGMaskEffect.h"
9
10 #include "include/core/SkBlendMode.h"
11 #include "include/core/SkCanvas.h"
12 #include "include/core/SkColorFilter.h"
13 #include "include/core/SkPaint.h"
14 #include "include/effects/SkLumaColorFilter.h"
15 #include "include/private/base/SkAssert.h"
16 #include "include/private/base/SkTo.h"
17 #include "modules/sksg/include/SkSGNode.h"
18
19 class SkMatrix;
20 struct SkPoint;
21
22 namespace sksg {
23
is_inverted(sksg::MaskEffect::Mode mode)24 static bool is_inverted(sksg::MaskEffect::Mode mode) {
25 return static_cast<uint32_t>(mode) & 1;
26 }
27
is_luma(sksg::MaskEffect::Mode mode)28 static bool is_luma(sksg::MaskEffect::Mode mode) {
29 return static_cast<uint32_t>(mode) & 2;
30 }
31
MaskEffect(sk_sp<RenderNode> child,sk_sp<RenderNode> mask,Mode mode)32 MaskEffect::MaskEffect(sk_sp<RenderNode> child, sk_sp<RenderNode> mask, Mode mode)
33 : INHERITED(std::move(child))
34 , fMaskNode(std::move(mask))
35 , fMaskMode(mode) {
36 this->observeInval(fMaskNode);
37 }
38
~MaskEffect()39 MaskEffect::~MaskEffect() {
40 this->unobserveInval(fMaskNode);
41 }
42
onRender(SkCanvas * canvas,const RenderContext * ctx) const43 void MaskEffect::onRender(SkCanvas* canvas, const RenderContext* ctx) const {
44 SkAutoCanvasRestore acr(canvas, false);
45
46 // The mask mode covers two independent bits.
47 //
48 // - mask source controls how the mask coverage is generated:
49 // * alpha => coverage = mask_alpha
50 // * luma => coverage = luma(mask_rgb)
51 //
52 // - mask type controls how the mask coverage is interpreted:
53 // * normal => coverage' = coverage
54 // * inverted => coverage' = 1 - coverage
55
56 {
57 // Outer layer: mask coverage stored in the alpha channel.
58 SkPaint mask_layer_paint;
59 if (ctx) {
60 // Apply all optional context overrides upfront.
61 ctx->modulatePaint(canvas->getTotalMatrix(), &mask_layer_paint);
62 }
63
64 RenderContext mask_render_context;
65 if (is_luma(fMaskMode)) {
66 mask_render_context.fColorFilter = SkLumaColorFilter::Make();
67 }
68
69 // TODO: could be an A8 layer?
70 canvas->saveLayer(this->bounds(), &mask_layer_paint);
71 fMaskNode->render(canvas, &mask_render_context);
72
73 {
74 // Inner layer: masked content.
75 SkPaint content_layer_paint;
76 content_layer_paint.setBlendMode(is_inverted(fMaskMode) ? SkBlendMode::kSrcOut
77 : SkBlendMode::kSrcIn);
78 canvas->saveLayer(this->bounds(), &content_layer_paint);
79
80 this->INHERITED::onRender(canvas, nullptr);
81 }
82 }
83 }
84
onNodeAt(const SkPoint & p) const85 const RenderNode* MaskEffect::onNodeAt(const SkPoint& p) const {
86 const auto mask_hit = (SkToBool(fMaskNode->nodeAt(p)) == !is_inverted(fMaskMode));
87
88 if (!mask_hit) {
89 return nullptr;
90 }
91
92 return this->INHERITED::onNodeAt(p);
93 }
94
onRevalidate(InvalidationController * ic,const SkMatrix & ctm)95 SkRect MaskEffect::onRevalidate(InvalidationController* ic, const SkMatrix& ctm) {
96 SkASSERT(this->hasInval());
97
98 const auto maskBounds = fMaskNode->revalidate(ic, ctm);
99 auto childBounds = this->INHERITED::onRevalidate(ic, ctm);
100
101 return (is_inverted(fMaskMode) || childBounds.intersect(maskBounds))
102 ? childBounds
103 : SkRect::MakeEmpty();
104 }
105
106 } // namespace sksg
107