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 #include <cmath>
20
21 namespace android {
22 namespace uirenderer {
23
almostEqual(float a,float b)24 static inline bool almostEqual(float a, float b) {
25 return std::abs(a - b) < 1e-2f;
26 }
27
transferFunctionCloseToSRGB(const SkColorSpace * colorSpace)28 bool transferFunctionCloseToSRGB(const SkColorSpace* colorSpace) {
29 if (colorSpace == nullptr) return true;
30 if (colorSpace->isSRGB()) return true;
31
32 SkColorSpaceTransferFn transferFunction;
33 if (colorSpace->isNumericalTransferFn(&transferFunction)) {
34 // sRGB transfer function params:
35 const float sRGBParamA = 1 / 1.055f;
36 const float sRGBParamB = 0.055f / 1.055f;
37 const float sRGBParamC = 1 / 12.92f;
38 const float sRGBParamD = 0.04045f;
39 const float sRGBParamE = 0.0f;
40 const float sRGBParamF = 0.0f;
41 const float sRGBParamG = 2.4f;
42
43 // This comparison will catch Display P3
44 return
45 almostEqual(sRGBParamA, transferFunction.fA)
46 && almostEqual(sRGBParamB, transferFunction.fB)
47 && almostEqual(sRGBParamC, transferFunction.fC)
48 && almostEqual(sRGBParamD, transferFunction.fD)
49 && almostEqual(sRGBParamE, transferFunction.fE)
50 && almostEqual(sRGBParamF, transferFunction.fF)
51 && almostEqual(sRGBParamG, transferFunction.fG);
52 }
53
54 return false;
55 }
56
57 }; // namespace uirenderer
58 }; // namespace android
59