| /* |
| * Copyright 2016 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| #ifndef SkColorSpacePriv_DEFINED |
| #define SkColorSpacePriv_DEFINED |
| |
| #include <math.h> |
| |
| #include "SkColorSpace.h" |
| #include "SkFixed.h" |
| |
| #define SkColorSpacePrintf(...) |
| |
| // A gamut narrower than sRGB, useful for testing. |
| static constexpr skcms_Matrix3x3 gNarrow_toXYZD50 = {{ |
| { 0.190974f, 0.404865f, 0.368380f }, |
| { 0.114746f, 0.582937f, 0.302318f }, |
| { 0.032925f, 0.153615f, 0.638669f }, |
| }}; |
| |
| static inline bool color_space_almost_equal(float a, float b) { |
| return SkTAbs(a - b) < 0.01f; |
| } |
| |
| // Let's use a stricter version for transfer functions. Worst case, these are encoded |
| // in ICC format, which offers 16-bits of fractional precision. |
| static inline bool transfer_fn_almost_equal(float a, float b) { |
| return SkTAbs(a - b) < 0.001f; |
| } |
| |
| 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 (coeffs.fD < 0.0f) { |
| return false; |
| } |
| |
| if (coeffs.fD == 0.0f) { |
| // Y = (aX + b)^g + e 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 = cX + f for always |
| if (0.0f == coeffs.fC) { |
| SkColorSpacePrintf("C is zero, constant transfer function is " |
| "nonsense"); |
| return false; |
| } |
| } |
| |
| if ((0.0f == coeffs.fA || 0.0f == coeffs.fG) && 0.0f == coeffs.fC) { |
| SkColorSpacePrintf("A or G, and C are zero, constant transfer function " |
| "is nonsense"); |
| return false; |
| } |
| |
| if (coeffs.fC < 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 skcms_TransferFunction& coeffs) { |
| return transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.a, coeffs.a) && |
| transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.b, coeffs.b) && |
| transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.c, coeffs.c) && |
| transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.d, coeffs.d) && |
| transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.e, coeffs.e) && |
| transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.f, coeffs.f) && |
| transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.g, coeffs.g); |
| } |
| |
| static inline bool is_almost_2dot2(const skcms_TransferFunction& coeffs) { |
| return transfer_fn_almost_equal(1.0f, coeffs.a) && |
| transfer_fn_almost_equal(0.0f, coeffs.b) && |
| transfer_fn_almost_equal(0.0f, coeffs.e) && |
| transfer_fn_almost_equal(2.2f, coeffs.g) && |
| coeffs.d <= 0.0f; |
| } |
| |
| static inline bool is_almost_linear(const skcms_TransferFunction& coeffs) { |
| // OutputVal = InputVal ^ 1.0f |
| const bool linearExp = |
| transfer_fn_almost_equal(1.0f, coeffs.a) && |
| transfer_fn_almost_equal(0.0f, coeffs.b) && |
| transfer_fn_almost_equal(0.0f, coeffs.e) && |
| transfer_fn_almost_equal(1.0f, coeffs.g) && |
| coeffs.d <= 0.0f; |
| |
| // OutputVal = 1.0f * InputVal |
| const bool linearFn = |
| transfer_fn_almost_equal(1.0f, coeffs.c) && |
| transfer_fn_almost_equal(0.0f, coeffs.f) && |
| coeffs.d >= 1.0f; |
| |
| return linearExp || linearFn; |
| } |
| |
| // Return raw pointers to commonly used SkColorSpaces. |
| // No need to ref/unref these, but if you do, do it in pairs. |
| SkColorSpace* sk_srgb_singleton(); |
| SkColorSpace* sk_srgb_linear_singleton(); |
| |
| #endif // SkColorSpacePriv_DEFINED |