aboutsummaryrefslogtreecommitdiffhomepage
path: root/tests/ApplyGammaTest.cpp
blob: 4147be7f41fec75f1b48001bee41bcde5729a301 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include <initializer_list>
#include "Test.h"

#if SK_SUPPORT_GPU
#include "GrContext.h"

#include "SkCanvas.h"
#include "SkColorFilter.h"
#include "SkSurface.h"
#include "SkUtils.h"

/** convert 0..1 linear value to 0..1 srgb */
static float linear_to_srgb(float linear) {
    if (linear <= 0.0031308) {
        return linear * 12.92f;
    } else {
        return 1.055f * powf(linear, 1.f / 2.4f) - 0.055f;
    }
}

/** convert 0..1 srgb value to 0..1 linear */
static float srgb_to_linear(float srgb) {
    if (srgb <= 0.04045f) {
        return srgb / 12.92f;
    } else {
        return powf((srgb + 0.055f) / 1.055f, 2.4f);
    }
}

bool check_gamma(uint32_t src, uint32_t dst, bool toSRGB, float error,
                 uint32_t* expected) {
    bool result = true;
    uint32_t expectedColor = src & 0xff000000;

    // Alpha should always be exactly preserved.
    if ((src & 0xff000000) != (dst & 0xff000000)) {
        result = false;
    }

    // need to unpremul before we can perform srgb magic
    float invScale = 0;
    float alpha = SkGetPackedA32(src);
    if (alpha) {
        invScale = 255.0f / alpha;
    }

    for (int c = 0; c < 3; ++c) {
        float srcComponent = ((src & (0xff << (c * 8))) >> (c * 8)) * invScale;
        float lower = SkTMax(0.f, srcComponent - error);
        float upper = SkTMin(255.f, srcComponent + error);
        if (toSRGB) {
            lower = linear_to_srgb(lower / 255.f);
            upper = linear_to_srgb(upper / 255.f);
        } else {
            lower = srgb_to_linear(lower / 255.f);
            upper = srgb_to_linear(upper / 255.f);
        }
        lower *= alpha;
        upper *= alpha;
        SkASSERT(lower >= 0.f && lower <= 255.f);
        SkASSERT(upper >= 0.f && upper <= 255.f);
        uint8_t dstComponent = (dst & (0xff << (c * 8))) >> (c * 8);
        if (dstComponent < SkScalarFloorToInt(lower) ||
            dstComponent > SkScalarCeilToInt(upper)) {
            result = false;
        }
        uint8_t expectedComponent = SkScalarRoundToInt((lower + upper) * 0.5f);
        expectedColor |= expectedComponent << (c * 8);
    }

    *expected = expectedColor;
    return result;
}

DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ApplyGamma, reporter, ctxInfo) {
    GrContext* context = ctxInfo.grContext();
    static const int kW = 256;
    static const int kH = 256;
    static const size_t kRowBytes = sizeof(uint32_t) * kW;

    GrSurfaceDesc baseDesc;
    baseDesc.fConfig = kRGBA_8888_GrPixelConfig;
    baseDesc.fWidth = kW;
    baseDesc.fHeight = kH;

    const SkImageInfo ii = SkImageInfo::MakeN32Premul(kW, kH);

    SkAutoTMalloc<uint32_t> srcPixels(kW * kH);
    for (int y = 0; y < kH; ++y) {
        for (int x = 0; x < kW; ++x) {
            srcPixels.get()[y*kW+x] = SkPreMultiplyARGB(x, y, x, 0xFF);
        }
    }

    SkBitmap bm;
    bm.installPixels(ii, srcPixels.get(), kRowBytes);

    SkAutoTMalloc<uint32_t> read(kW * kH);

    // We allow more error on GPUs with lower precision shader variables.
    float error = context->caps()->shaderCaps()->halfIs32Bits() ? 0.5f : 1.2f;

    for (auto toSRGB : { false, true }) {
        sk_sp<SkSurface> dst(SkSurface::MakeRenderTarget(context, SkBudgeted::kNo, ii));

        if (!dst) {
            ERRORF(reporter, "Could not create surfaces for copy surface test.");
            continue;
        }

        SkCanvas* dstCanvas = dst->getCanvas();

        dstCanvas->clear(SK_ColorRED);
        dstCanvas->flush();

        SkPaint gammaPaint;
        gammaPaint.setBlendMode(SkBlendMode::kSrc);
        gammaPaint.setColorFilter(toSRGB ? SkColorFilter::MakeLinearToSRGBGamma()
                                         : SkColorFilter::MakeSRGBToLinearGamma());

        dstCanvas->drawBitmap(bm, 0, 0, &gammaPaint);
        dstCanvas->flush();

        sk_memset32(read.get(), 0, kW * kH);
        if (!dst->readPixels(ii, read.get(), kRowBytes, 0, 0)) {
            ERRORF(reporter, "Error calling readPixels");
            continue;
        }

        bool abort = false;
        // Validate that pixels were copied/transformed correctly.
        for (int y = 0; y < kH && !abort; ++y) {
            for (int x = 0; x < kW && !abort; ++x) {
                uint32_t r = read.get()[y * kW + x];
                uint32_t s = srcPixels.get()[y * kW + x];
                uint32_t expected;
                if (!check_gamma(s, r, toSRGB, error, &expected)) {
                    ERRORF(reporter, "Expected dst %d,%d to contain 0x%08x "
                           "from src 0x%08x and mode %s. Got %08x", x, y, expected, s,
                           toSRGB ? "ToSRGB" : "ToLinear", r);
                    abort = true;
                    break;
                }
            }
        }
    }
}
#endif