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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "Color.h"
     18 
     19 
     20 #include <utils/Log.h>
     21 #include <cmath>
     22 
     23 namespace android {
     24 namespace uirenderer {
     25 
     26 static inline bool almostEqual(float a, float b) {
     27     return std::abs(a - b) < 1e-2f;
     28 }
     29 
     30 bool transferFunctionCloseToSRGB(const SkColorSpace* colorSpace) {
     31     if (colorSpace == nullptr) return true;
     32     if (colorSpace->isSRGB()) return true;
     33 
     34     SkColorSpaceTransferFn transferFunction;
     35     if (colorSpace->isNumericalTransferFn(&transferFunction)) {
     36         // sRGB transfer function params:
     37         const float sRGBParamA = 1 / 1.055f;
     38         const float sRGBParamB = 0.055f / 1.055f;
     39         const float sRGBParamC = 1 / 12.92f;
     40         const float sRGBParamD = 0.04045f;
     41         const float sRGBParamE = 0.0f;
     42         const float sRGBParamF = 0.0f;
     43         const float sRGBParamG = 2.4f;
     44 
     45         // This comparison will catch Display P3
     46         return almostEqual(sRGBParamA, transferFunction.fA) &&
     47                almostEqual(sRGBParamB, transferFunction.fB) &&
     48                almostEqual(sRGBParamC, transferFunction.fC) &&
     49                almostEqual(sRGBParamD, transferFunction.fD) &&
     50                almostEqual(sRGBParamE, transferFunction.fE) &&
     51                almostEqual(sRGBParamF, transferFunction.fF) &&
     52                almostEqual(sRGBParamG, transferFunction.fG);
     53     }
     54 
     55     return false;
     56 }
     57 
     58 sk_sp<SkColorSpace> DataSpaceToColorSpace(android_dataspace dataspace) {
     59 
     60     SkColorSpace::Gamut gamut;
     61     switch (dataspace & HAL_DATASPACE_STANDARD_MASK) {
     62         case HAL_DATASPACE_STANDARD_BT709:
     63             gamut = SkColorSpace::kSRGB_Gamut;
     64             break;
     65         case HAL_DATASPACE_STANDARD_BT2020:
     66             gamut = SkColorSpace::kRec2020_Gamut;
     67             break;
     68         case HAL_DATASPACE_STANDARD_DCI_P3:
     69             gamut = SkColorSpace::kDCIP3_D65_Gamut;
     70             break;
     71         case HAL_DATASPACE_STANDARD_ADOBE_RGB:
     72             gamut = SkColorSpace::kAdobeRGB_Gamut;
     73             break;
     74         case HAL_DATASPACE_STANDARD_UNSPECIFIED:
     75             return nullptr;
     76         case HAL_DATASPACE_STANDARD_BT601_625:
     77         case HAL_DATASPACE_STANDARD_BT601_625_UNADJUSTED:
     78         case HAL_DATASPACE_STANDARD_BT601_525:
     79         case HAL_DATASPACE_STANDARD_BT601_525_UNADJUSTED:
     80         case HAL_DATASPACE_STANDARD_BT2020_CONSTANT_LUMINANCE:
     81         case HAL_DATASPACE_STANDARD_BT470M:
     82         case HAL_DATASPACE_STANDARD_FILM:
     83         default:
     84             ALOGW("Unsupported Gamut: %d", dataspace);
     85             return nullptr;
     86     }
     87 
     88     switch (dataspace & HAL_DATASPACE_TRANSFER_MASK) {
     89         case HAL_DATASPACE_TRANSFER_LINEAR:
     90             return SkColorSpace::MakeRGB(SkColorSpace::kLinear_RenderTargetGamma, gamut);
     91         case HAL_DATASPACE_TRANSFER_SRGB:
     92             return SkColorSpace::MakeRGB(SkColorSpace::kSRGB_RenderTargetGamma, gamut);
     93         case HAL_DATASPACE_TRANSFER_GAMMA2_2:
     94             return SkColorSpace::MakeRGB({2.2f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f}, gamut);
     95         case HAL_DATASPACE_TRANSFER_GAMMA2_6:
     96             return SkColorSpace::MakeRGB({2.6f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f}, gamut);
     97         case HAL_DATASPACE_TRANSFER_GAMMA2_8:
     98             return SkColorSpace::MakeRGB({2.8f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f}, gamut);
     99         case HAL_DATASPACE_TRANSFER_UNSPECIFIED:
    100             return nullptr;
    101         case HAL_DATASPACE_TRANSFER_SMPTE_170M:
    102         case HAL_DATASPACE_TRANSFER_ST2084:
    103         case HAL_DATASPACE_TRANSFER_HLG:
    104         default:
    105             ALOGW("Unsupported Gamma: %d", dataspace);
    106             return nullptr;
    107     }
    108 }
    109 
    110 };  // namespace uirenderer
    111 };  // namespace android
    112