| /* |
| * Copyright 2016 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #define SkColorSpacePrintf(...) |
| |
| static inline bool color_space_almost_equal(float a, float b) { |
| return SkTAbs(a - b) < 0.01f; |
| } |
| |
| static inline bool is_zero_to_one(float v) { |
| return (0.0f <= v) && (v <= 1.0f); |
| } |
| |
| static inline bool is_valid_transfer_fn(const SkColorSpaceTransferFn& coeffs) { |
| if (SkScalarIsNaN(coeffs.fA) || SkScalarIsNaN(coeffs.fB) || |
| SkScalarIsNaN(coeffs.fC) || SkScalarIsNaN(coeffs.fD) || |
| SkScalarIsNaN(coeffs.fE) || SkScalarIsNaN(coeffs.fF) || |
| SkScalarIsNaN(coeffs.fG)) |
| { |
| return false; |
| } |
| |
| if (!is_zero_to_one(coeffs.fD)) { |
| return false; |
| } |
| |
| if (coeffs.fD == 0.0f) { |
| // Y = (aX + b)^g + c for always |
| if (0.0f == coeffs.fA || 0.0f == coeffs.fG) { |
| SkColorSpacePrintf("A or G is zero, constant transfer function " |
| "is nonsense"); |
| return false; |
| } |
| } |
| |
| if (coeffs.fD == 1.0f) { |
| // Y = eX + f for always |
| if (0.0f == coeffs.fE) { |
| SkColorSpacePrintf("E is zero, constant transfer function is " |
| "nonsense"); |
| return false; |
| } |
| } |
| |
| if ((0.0f == coeffs.fA || 0.0f == coeffs.fG) && 0.0f == coeffs.fE) { |
| SkColorSpacePrintf("A or G, and E are zero, constant transfer function " |
| "is nonsense"); |
| return false; |
| } |
| |
| if (coeffs.fE < 0.0f) { |
| SkColorSpacePrintf("Transfer function must be increasing"); |
| return false; |
| } |
| |
| if (coeffs.fA < 0.0f || coeffs.fG < 0.0f) { |
| SkColorSpacePrintf("Transfer function must be positive or increasing"); |
| return false; |
| } |
| |
| return true; |
| } |
| |
| static inline bool is_almost_srgb(const SkColorSpaceTransferFn& coeffs) { |
| return color_space_almost_equal(0.9479f, coeffs.fA) && |
| color_space_almost_equal(0.0521f, coeffs.fB) && |
| color_space_almost_equal(0.0000f, coeffs.fC) && |
| color_space_almost_equal(0.0405f, coeffs.fD) && |
| color_space_almost_equal(0.0774f, coeffs.fE) && |
| color_space_almost_equal(0.0000f, coeffs.fF) && |
| color_space_almost_equal(2.4000f, coeffs.fG); |
| } |
| |
| static inline bool is_almost_2dot2(const SkColorSpaceTransferFn& coeffs) { |
| return color_space_almost_equal(1.0f, coeffs.fA) && |
| color_space_almost_equal(0.0f, coeffs.fB) && |
| color_space_almost_equal(0.0f, coeffs.fC) && |
| color_space_almost_equal(0.0f, coeffs.fD) && |
| color_space_almost_equal(0.0f, coeffs.fE) && |
| color_space_almost_equal(0.0f, coeffs.fF) && |
| color_space_almost_equal(2.2f, coeffs.fG); |
| } |