1/*
2 * Copyright 2016 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 "include/core/SkUnPreMultiply.h"
9#include "include/effects/SkOverdrawColorFilter.h"
10#include "src/core/SkArenaAlloc.h"
11#include "src/core/SkEffectPriv.h"
12#include "src/core/SkRasterPipeline.h"
13#include "src/core/SkReadBuffer.h"
14#include "src/core/SkVM.h"
15
16#if SK_SUPPORT_GPU
17#include "include/effects/SkRuntimeEffect.h"
18#include "src/gpu/effects/GrSkSLFP.h"
19
20GR_FP_SRC_STRING SKSL_OVERDRAW_SRC = R"(
21uniform half4 color0;
22uniform half4 color1;
23uniform half4 color2;
24uniform half4 color3;
25uniform half4 color4;
26uniform half4 color5;
27
28void main(inout half4 color) {
29 half alpha = 255.0 * color.a;
30 if (alpha < 0.5) {
31 color = color0;
32 } else if (alpha < 1.5) {
33 color = color1;
34 } else if (alpha < 2.5) {
35 color = color2;
36 } else if (alpha < 3.5) {
37 color = color3;
38 } else if (alpha < 4.5) {
39 color = color4;
40 } else {
41 color = color5;
42 }
43}
44)";
45#endif
46
47static void convert_to_pm4f(SkPMColor4f dst[], const SkColor src[]) {
48 for (int i = 0; i < SkOverdrawColorFilter::kNumColors; ++i) {
49 dst[i] = SkColor4f::FromColor(src[i]).premul();
50 }
51}
52
53bool SkOverdrawColorFilter::onAppendStages(const SkStageRec& rec, bool shader_is_opaque) const {
54 struct Ctx : public SkRasterPipeline_CallbackCtx {
55 SkPMColor4f colors[kNumColors];
56 };
57 // TODO: do we care about transforming to dstCS?
58 auto ctx = rec.fAlloc->make<Ctx>();
59 convert_to_pm4f(ctx->colors, fColors);
60
61 ctx->fn = [](SkRasterPipeline_CallbackCtx* arg, int active_pixels) {
62 auto ctx = (Ctx*)arg;
63 auto pixels = (SkPMColor4f*)ctx->rgba;
64 for (int i = 0; i < active_pixels; i++) {
65 uint8_t alpha = (int)(pixels[i].fA * 255);
66 if (alpha >= kNumColors) {
67 alpha = kNumColors - 1;
68 }
69 pixels[i] = ctx->colors[alpha];
70 }
71 };
72 rec.fPipeline->append(SkRasterPipeline::callback, ctx);
73 return true;
74}
75
76skvm::Color SkOverdrawColorFilter::onProgram(skvm::Builder* p, skvm::Color c,
77 SkColorSpace* /*dstCS*/, skvm::Uniforms* uniforms,
78 SkArenaAlloc* alloc) const {
79 skvm::I32 index = min(to_unorm(8,c.a), kNumColors - 1);
80 c = unpack_8888(gather32(uniforms->pushPtr(fColors), index));
81 std::swap(c.r, c.b); // The SkColors in fColors are BGRA, but we want RGBA
82 return c;
83}
84
85void SkOverdrawColorFilter::flatten(SkWriteBuffer& buffer) const {
86 buffer.writeByteArray(fColors, kNumColors * sizeof(SkPMColor));
87}
88
89sk_sp<SkFlattenable> SkOverdrawColorFilter::CreateProc(SkReadBuffer& buffer) {
90 SkPMColor colors[kNumColors];
91 size_t size = buffer.getArrayCount();
92 if (!buffer.validate(size == sizeof(colors))) {
93 return nullptr;
94 }
95 if (!buffer.readByteArray(colors, sizeof(colors))) {
96 return nullptr;
97 }
98
99 return sk_sp<SkColorFilter>(new SkOverdrawColorFilter(colors));
100}
101
102void SkOverdrawColorFilter::RegisterFlattenables() {
103 SK_REGISTER_FLATTENABLE(SkOverdrawColorFilter);
104}
105#if SK_SUPPORT_GPU
106
107#include "include/private/GrRecordingContext.h"
108
109std::unique_ptr<GrFragmentProcessor> SkOverdrawColorFilter::asFragmentProcessor(
110 GrRecordingContext* context, const GrColorInfo&) const {
111 static auto effect = std::get<0>(SkRuntimeEffect::Make(SkString(SKSL_OVERDRAW_SRC)));
112 SkASSERT(effect->inputSize() == (kNumColors * sizeof(SkPMColor4f)));
113
114 auto inputs = SkData::MakeUninitialized(kNumColors * sizeof(SkPMColor4f));
115 convert_to_pm4f(reinterpret_cast<SkPMColor4f*>(inputs->writable_data()), fColors);
116
117 return GrSkSLFP::Make(context, effect, "Overdraw", std::move(inputs));
118}
119
120#endif
121