1/*
2 * Copyright 2019 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/private/SkColorData.h"
11#include "modules/skottie/src/SkottieJson.h"
12#include "modules/skottie/src/SkottieValue.h"
13#include "modules/sksg/include/SkSGColorFilter.h"
14
15namespace skottie {
16namespace internal {
17
18namespace {
19
20/*
21 * AE's Shift Channels effect overrides individual channels based on a selectable function:
22 *
23 * C' = {fR(C), fG(C), fB(C), fA(C)}
24 *
25 * where fR, fG, fB, fA can be one of
26 *
27 * C.r, C.g, C.b, C.a, Luminance(C), Hue(C), Saturation(C), Lightness(C), 1 or 0.
28 */
29class ShiftChannelsEffectAdapter final : public AnimatablePropertyContainer {
30public:
31 static sk_sp<ShiftChannelsEffectAdapter> Make(const skjson::ArrayValue& jprops,
32 sk_sp<sksg::RenderNode> layer,
33 const AnimationBuilder* abuilder) {
34 return sk_sp<ShiftChannelsEffectAdapter>(
35 new ShiftChannelsEffectAdapter(jprops, std::move(layer), abuilder));
36 }
37
38 const sk_sp<sksg::ExternalColorFilter>& node() const { return fColorFilter; }
39
40private:
41 ShiftChannelsEffectAdapter(const skjson::ArrayValue& jprops,
42 sk_sp<sksg::RenderNode> layer,
43 const AnimationBuilder* abuilder)
44 : fColorFilter(sksg::ExternalColorFilter::Make(std::move(layer))) {
45 enum : size_t {
46 kTakeAlphaFrom_Index = 0,
47 kTakeRedFrom_Index = 1,
48 kTakeGreenFrom_Index = 2,
49 kTakeBlueFrom_Index = 3,
50 };
51
52 EffectBinder(jprops, *abuilder, this)
53 .bind( kTakeRedFrom_Index, fR)
54 .bind(kTakeGreenFrom_Index, fG)
55 .bind( kTakeBlueFrom_Index, fB)
56 .bind(kTakeAlphaFrom_Index, fA);
57 }
58
59 enum class Source : uint8_t {
60 kAlpha = 1,
61 kRed = 2,
62 kGreen = 3,
63 kBlue = 4,
64 kLuminance = 5,
65 kHue = 6,
66 kLightness = 7,
67 kSaturation = 8,
68 kFullOn = 9,
69 kFullOff = 10,
70
71 kMax = kFullOff
72 };
73
74 void onSync() override {
75 // TODO: support for HSL sources will require a custom color filter.
76
77 static constexpr float gSourceCoeffs[][5] = {
78 { 0, 0, 0, 1, 0}, // kAlpha
79 { 1, 0, 0, 0, 0}, // kRed
80 { 0, 1, 0, 0, 0}, // kGreen
81 { 0, 0, 1, 0, 0}, // kBlue
82 {SK_LUM_COEFF_R, SK_LUM_COEFF_G, SK_LUM_COEFF_B, 0, 0}, // kLuminance
83 { 0, 0, 0, 0, 0}, // TODO: kHue
84 { 0, 0, 0, 0, 0}, // TODO: kLightness
85 { 0, 0, 0, 0, 0}, // TODO: kSaturation
86 { 0, 0, 0, 0, 1}, // kFullOn
87 { 0, 0, 0, 0, 0}, // kFullOff
88 };
89 static_assert(SK_ARRAY_COUNT(gSourceCoeffs) == static_cast<size_t>(Source::kMax), "");
90
91 auto coeffs = [](float src) {
92 // Channel sources are encoded as Source enum values.
93 // We map these onto our coeffs table.
94 src = SkTPin(src, 1.0f, static_cast<float>(Source::kMax));
95 return gSourceCoeffs[static_cast<size_t>(src) - 1];
96 };
97
98 const float* rc = coeffs(fR);
99 const float* gc = coeffs(fG);
100 const float* bc = coeffs(fB);
101 const float* ac = coeffs(fA);
102
103 const float cm[] = {
104 rc[0], rc[1], rc[2], rc[3], rc[4],
105 gc[0], gc[1], gc[2], gc[3], gc[4],
106 bc[0], bc[1], bc[2], bc[3], bc[4],
107 ac[0], ac[1], ac[2], ac[3], ac[4],
108 };
109
110 fColorFilter->setColorFilter(SkColorFilters::Matrix(cm));
111 }
112
113 const sk_sp<sksg::ExternalColorFilter> fColorFilter;
114
115 ScalarValue fR = static_cast<float>(Source::kRed),
116 fG = static_cast<float>(Source::kGreen),
117 fB = static_cast<float>(Source::kBlue),
118 fA = static_cast<float>(Source::kAlpha);
119};
120
121} // namespace
122
123
124sk_sp<sksg::RenderNode> EffectBuilder::attachShiftChannelsEffect(
125 const skjson::ArrayValue& jprops, sk_sp<sksg::RenderNode> layer) const {
126 return fBuilder->attachDiscardableAdapter<ShiftChannelsEffectAdapter>(jprops,
127 std::move(layer),
128 fBuilder);
129}
130
131} // namespace internal
132} // namespace skottie
133