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 "include/private/SkTPin.h"
12#include "modules/skottie/src/SkottieJson.h"
13#include "modules/skottie/src/SkottieValue.h"
14#include "modules/sksg/include/SkSGColorFilter.h"
15
16namespace skottie {
17namespace internal {
18
19namespace {
20
21/*
22 * AE's Shift Channels effect overrides individual channels based on a selectable function:
23 *
24 *     C' = {fR(C), fG(C), fB(C), fA(C)}
25 *
26 * where fR, fG, fB, fA can be one of
27 *
28 *     C.r, C.g, C.b, C.a, Luminance(C), Hue(C), Saturation(C), Lightness(C), 1 or 0.
29 */
30class ShiftChannelsEffectAdapter final : public AnimatablePropertyContainer {
31public:
32    static sk_sp<ShiftChannelsEffectAdapter> Make(const skjson::ArrayValue& jprops,
33                                                  sk_sp<sksg::RenderNode> layer,
34                                                  const AnimationBuilder* abuilder) {
35        return sk_sp<ShiftChannelsEffectAdapter>(
36                    new ShiftChannelsEffectAdapter(jprops, std::move(layer), abuilder));
37    }
38
39    const sk_sp<sksg::ExternalColorFilter>& node() const { return fColorFilter; }
40
41private:
42    ShiftChannelsEffectAdapter(const skjson::ArrayValue& jprops,
43                               sk_sp<sksg::RenderNode> layer,
44                               const AnimationBuilder* abuilder)
45        : fColorFilter(sksg::ExternalColorFilter::Make(std::move(layer))) {
46        enum : size_t {
47            kTakeAlphaFrom_Index = 0,
48              kTakeRedFrom_Index = 1,
49            kTakeGreenFrom_Index = 2,
50             kTakeBlueFrom_Index = 3,
51        };
52
53        EffectBinder(jprops, *abuilder, this)
54                .bind(  kTakeRedFrom_Index, fR)
55                .bind(kTakeGreenFrom_Index, fG)
56                .bind( kTakeBlueFrom_Index, fB)
57                .bind(kTakeAlphaFrom_Index, fA);
58    }
59
60    enum class Source : uint8_t {
61        kAlpha      = 1,
62        kRed        = 2,
63        kGreen      = 3,
64        kBlue       = 4,
65        kLuminance  = 5,
66        kHue        = 6,
67        kLightness  = 7,
68        kSaturation = 8,
69        kFullOn     = 9,
70        kFullOff    = 10,
71
72        kMax        = kFullOff
73    };
74
75    void onSync() override {
76        // TODO: support for HSL sources will require a custom color filter.
77
78        static constexpr float gSourceCoeffs[][5] = {
79            {             0,              0,              0, 1, 0}, // kAlpha
80            {             1,              0,              0, 0, 0}, // kRed
81            {             0,              1,              0, 0, 0}, // kGreen
82            {             0,              0,              1, 0, 0}, // kBlue
83            {SK_LUM_COEFF_R, SK_LUM_COEFF_G, SK_LUM_COEFF_B, 0, 0}, // kLuminance
84            {             0,              0,              0, 0, 0}, // TODO: kHue
85            {             0,              0,              0, 0, 0}, // TODO: kLightness
86            {             0,              0,              0, 0, 0}, // TODO: kSaturation
87            {             0,              0,              0, 0, 1}, // kFullOn
88            {             0,              0,              0, 0, 0}, // kFullOff
89        };
90        static_assert(SK_ARRAY_COUNT(gSourceCoeffs) == static_cast<size_t>(Source::kMax), "");
91
92        auto coeffs = [](float src) {
93            // Channel sources are encoded as Source enum values.
94            // We map these onto our coeffs table.
95            src = SkTPin(src, 1.0f, static_cast<float>(Source::kMax));
96            return gSourceCoeffs[static_cast<size_t>(src) - 1];
97        };
98
99        const float* rc = coeffs(fR);
100        const float* gc = coeffs(fG);
101        const float* bc = coeffs(fB);
102        const float* ac = coeffs(fA);
103
104        const float cm[] = {
105            rc[0], rc[1], rc[2], rc[3], rc[4],
106            gc[0], gc[1], gc[2], gc[3], gc[4],
107            bc[0], bc[1], bc[2], bc[3], bc[4],
108            ac[0], ac[1], ac[2], ac[3], ac[4],
109        };
110
111        fColorFilter->setColorFilter(SkColorFilters::Matrix(cm));
112    }
113
114    const sk_sp<sksg::ExternalColorFilter> fColorFilter;
115
116    ScalarValue fR = static_cast<float>(Source::kRed),
117                fG = static_cast<float>(Source::kGreen),
118                fB = static_cast<float>(Source::kBlue),
119                fA = static_cast<float>(Source::kAlpha);
120};
121
122} // namespace
123
124
125sk_sp<sksg::RenderNode> EffectBuilder::attachShiftChannelsEffect(
126        const skjson::ArrayValue& jprops, sk_sp<sksg::RenderNode> layer) const {
127    return fBuilder->attachDiscardableAdapter<ShiftChannelsEffectAdapter>(jprops,
128                                                                          std::move(layer),
129                                                                          fBuilder);
130}
131
132} // namespace internal
133} // namespace skottie
134