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      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 <initializer_list>
      9 #include "Test.h"
     10 
     11 #if SK_SUPPORT_GPU
     12 #include "GrContext.h"
     13 
     14 #include "SkCanvas.h"
     15 #include "SkColorFilter.h"
     16 #include "SkSurface.h"
     17 #include "SkUtils.h"
     18 
     19 /** convert 0..1 linear value to 0..1 srgb */
     20 static float linear_to_srgb(float linear) {
     21     if (linear <= 0.0031308) {
     22         return linear * 12.92f;
     23     } else {
     24         return 1.055f * powf(linear, 1.f / 2.4f) - 0.055f;
     25     }
     26 }
     27 
     28 /** convert 0..1 srgb value to 0..1 linear */
     29 static float srgb_to_linear(float srgb) {
     30     if (srgb <= 0.04045f) {
     31         return srgb / 12.92f;
     32     } else {
     33         return powf((srgb + 0.055f) / 1.055f, 2.4f);
     34     }
     35 }
     36 
     37 bool check_gamma(uint32_t src, uint32_t dst, bool toSRGB, float error,
     38                  uint32_t* expected) {
     39     bool result = true;
     40     uint32_t expectedColor = src & 0xff000000;
     41 
     42     // Alpha should always be exactly preserved.
     43     if ((src & 0xff000000) != (dst & 0xff000000)) {
     44         result = false;
     45     }
     46 
     47     // need to unpremul before we can perform srgb magic
     48     float invScale = 0;
     49     float alpha = SkGetPackedA32(src);
     50     if (alpha) {
     51         invScale = 255.0f / alpha;
     52     }
     53 
     54     for (int c = 0; c < 3; ++c) {
     55         float srcComponent = ((src & (0xff << (c * 8))) >> (c * 8)) * invScale;
     56         float lower = SkTMax(0.f, srcComponent - error);
     57         float upper = SkTMin(255.f, srcComponent + error);
     58         if (toSRGB) {
     59             lower = linear_to_srgb(lower / 255.f);
     60             upper = linear_to_srgb(upper / 255.f);
     61         } else {
     62             lower = srgb_to_linear(lower / 255.f);
     63             upper = srgb_to_linear(upper / 255.f);
     64         }
     65         lower *= alpha;
     66         upper *= alpha;
     67         SkASSERT(lower >= 0.f && lower <= 255.f);
     68         SkASSERT(upper >= 0.f && upper <= 255.f);
     69         uint8_t dstComponent = (dst & (0xff << (c * 8))) >> (c * 8);
     70         if (dstComponent < SkScalarFloorToInt(lower) ||
     71             dstComponent > SkScalarCeilToInt(upper)) {
     72             result = false;
     73         }
     74         uint8_t expectedComponent = SkScalarRoundToInt((lower + upper) * 0.5f);
     75         expectedColor |= expectedComponent << (c * 8);
     76     }
     77 
     78     *expected = expectedColor;
     79     return result;
     80 }
     81 
     82 DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ApplyGamma, reporter, ctxInfo) {
     83     GrContext* context = ctxInfo.grContext();
     84     static const int kW = 256;
     85     static const int kH = 256;
     86     static const size_t kRowBytes = sizeof(uint32_t) * kW;
     87 
     88     GrSurfaceDesc baseDesc;
     89     baseDesc.fConfig = kRGBA_8888_GrPixelConfig;
     90     baseDesc.fWidth = kW;
     91     baseDesc.fHeight = kH;
     92 
     93     const SkImageInfo ii = SkImageInfo::MakeN32Premul(kW, kH);
     94 
     95     SkAutoTMalloc<uint32_t> srcPixels(kW * kH);
     96     for (int y = 0; y < kH; ++y) {
     97         for (int x = 0; x < kW; ++x) {
     98             srcPixels.get()[y*kW+x] = SkPreMultiplyARGB(x, y, x, 0xFF);
     99         }
    100     }
    101 
    102     SkBitmap bm;
    103     bm.installPixels(ii, srcPixels.get(), kRowBytes);
    104 
    105     SkAutoTMalloc<uint32_t> read(kW * kH);
    106 
    107     // We allow more error on GPUs with lower precision shader variables.
    108     float error = context->caps()->shaderCaps()->halfIs32Bits() ? 0.5f : 1.2f;
    109 
    110     for (auto toSRGB : { false, true }) {
    111         sk_sp<SkSurface> dst(SkSurface::MakeRenderTarget(context, SkBudgeted::kNo, ii));
    112 
    113         if (!dst) {
    114             ERRORF(reporter, "Could not create surfaces for copy surface test.");
    115             continue;
    116         }
    117 
    118         SkCanvas* dstCanvas = dst->getCanvas();
    119 
    120         dstCanvas->clear(SK_ColorRED);
    121         dstCanvas->flush();
    122 
    123         SkPaint gammaPaint;
    124         gammaPaint.setBlendMode(SkBlendMode::kSrc);
    125         gammaPaint.setColorFilter(toSRGB ? SkColorFilter::MakeLinearToSRGBGamma()
    126                                          : SkColorFilter::MakeSRGBToLinearGamma());
    127 
    128         dstCanvas->drawBitmap(bm, 0, 0, &gammaPaint);
    129         dstCanvas->flush();
    130 
    131         sk_memset32(read.get(), 0, kW * kH);
    132         if (!dst->readPixels(ii, read.get(), kRowBytes, 0, 0)) {
    133             ERRORF(reporter, "Error calling readPixels");
    134             continue;
    135         }
    136 
    137         bool abort = false;
    138         // Validate that pixels were copied/transformed correctly.
    139         for (int y = 0; y < kH && !abort; ++y) {
    140             for (int x = 0; x < kW && !abort; ++x) {
    141                 uint32_t r = read.get()[y * kW + x];
    142                 uint32_t s = srcPixels.get()[y * kW + x];
    143                 uint32_t expected;
    144                 if (!check_gamma(s, r, toSRGB, error, &expected)) {
    145                     ERRORF(reporter, "Expected dst %d,%d to contain 0x%08x "
    146                            "from src 0x%08x and mode %s. Got %08x", x, y, expected, s,
    147                            toSRGB ? "ToSRGB" : "ToLinear", r);
    148                     abort = true;
    149                     break;
    150                 }
    151             }
    152         }
    153     }
    154 }
    155 #endif
    156