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
8 #include "modules/skottie/src/effects/Effects.h"
9
10 #include "include/effects/SkRuntimeEffect.h"
11 #include "include/private/base/SkTPin.h"
12 #include "modules/skottie/src/Adapter.h"
13 #include "modules/skottie/src/SkottieJson.h"
14 #include "modules/skottie/src/SkottieValue.h"
15 #include "modules/sksg/include/SkSGColorFilter.h"
16
17 namespace skottie::internal {
18
19 #ifdef SK_ENABLE_SKSL
20
21 namespace {
22
23 // The B&W effect allows controlling individual luminance contribution of
24 // primary and secondary colors.
25 //
26 // The implementation relies on computing primary/secondary relative weights
27 // for the input color on the hue hexagon, and modulating based on weight
28 // coefficients.
29 //
30 // Note:
31 // - at least one of (dr,dg,db) is 0
32 // - at least two of (wr,wg,wb) and two of (wy,wc,wm) are 0
33 // => we are effectively selecting the color hue sextant without explicit branching
34 //
35 // (inspired by https://github.com/RoyiAvital/StackExchangeCodes/blob/master/SignalProcessing/Q688/ApplyBlackWhiteFilter.m)
36
make_effect()37 static sk_sp<SkRuntimeEffect> make_effect() {
38 static constexpr char BLACK_AND_WHITE_EFFECT[] =
39 "uniform half kR, kY, kG, kC, kB, kM;"
40
41 "half4 main(half4 c) {"
42 "half m = min(min(c.r, c.g), c.b),"
43
44 "dr = c.r - m,"
45 "dg = c.g - m,"
46 "db = c.b - m,"
47
48 // secondaries weights
49 "wy = min(dr,dg),"
50 "wc = min(dg,db),"
51 "wm = min(db,dr),"
52
53 // primaries weights
54 "wr = dr - wy - wm,"
55 "wg = dg - wy - wc,"
56 "wb = db - wc - wm,"
57
58 // final luminance
59 "l = m + kR*wr + kY*wy + kG*wg + kC*wc + kB*wb + kM*wm;"
60
61 "return half4(l, l, l, c.a);"
62 "}"
63 ;
64
65 static const SkRuntimeEffect* effect =
66 SkRuntimeEffect::MakeForColorFilter(SkString(BLACK_AND_WHITE_EFFECT)).effect.release();
67 SkASSERT(effect);
68
69 return sk_ref_sp(effect);
70 }
71
72 class BlackAndWhiteAdapter final : public DiscardableAdapterBase<BlackAndWhiteAdapter,
73 sksg::ExternalColorFilter> {
74 public:
BlackAndWhiteAdapter(const skjson::ArrayValue & jprops,const AnimationBuilder & abuilder,sk_sp<sksg::RenderNode> layer)75 BlackAndWhiteAdapter(const skjson::ArrayValue& jprops,
76 const AnimationBuilder& abuilder,
77 sk_sp<sksg::RenderNode> layer)
78 : INHERITED(sksg::ExternalColorFilter::Make(std::move(layer)))
79 , fEffect(make_effect())
80 {
81 SkASSERT(fEffect);
82
83 enum : size_t {
84 kReds_Index = 0,
85 kYellows_Index = 1,
86 kGreens_Index = 2,
87 kCyans_Index = 3,
88 kBlues_Index = 4,
89 kMagentas_Index = 5,
90 // TODO
91 // kTint_Index = 6,
92 // kTintColorIndex = 7,
93 };
94
95 EffectBinder(jprops, abuilder, this)
96 .bind( kReds_Index, fCoeffs[0])
97 .bind( kYellows_Index, fCoeffs[1])
98 .bind( kGreens_Index, fCoeffs[2])
99 .bind( kCyans_Index, fCoeffs[3])
100 .bind( kBlues_Index, fCoeffs[4])
101 .bind(kMagentas_Index, fCoeffs[5]);
102 }
103
104 private:
onSync()105 void onSync() override {
106 struct {
107 float normalized_coeffs[6];
108 } coeffs = {
109 (fCoeffs[0] ) / 100,
110 (fCoeffs[1] ) / 100,
111 (fCoeffs[2] ) / 100,
112 (fCoeffs[3] ) / 100,
113 (fCoeffs[4] ) / 100,
114 (fCoeffs[5] ) / 100,
115 };
116
117 this->node()->setColorFilter(
118 fEffect->makeColorFilter(SkData::MakeWithCopy(&coeffs, sizeof(coeffs))));
119 }
120
121 const sk_sp<SkRuntimeEffect> fEffect;
122
123 ScalarValue fCoeffs[6];
124
125 using INHERITED = DiscardableAdapterBase<BlackAndWhiteAdapter, sksg::ExternalColorFilter>;
126 };
127
128 } // namespace
129
130 #endif // SK_ENABLE_SKSL
131
attachBlackAndWhiteEffect(const skjson::ArrayValue & jprops,sk_sp<sksg::RenderNode> layer) const132 sk_sp<sksg::RenderNode> EffectBuilder::attachBlackAndWhiteEffect(
133 const skjson::ArrayValue& jprops, sk_sp<sksg::RenderNode> layer) const {
134 #ifdef SK_ENABLE_SKSL
135 return fBuilder->attachDiscardableAdapter<BlackAndWhiteAdapter>(jprops,
136 *fBuilder,
137 std::move(layer));
138 #else
139 // TODO(skia:12197)
140 return layer;
141 #endif
142 }
143
144 } // namespace skottie::internal
145