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/*
* 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
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