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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 "include/core/SkColorSpace.h"
#include "include/private/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;
}
// NOTE: All of this logic is copied from skcms.cc, and needs to be kept in sync.
// Most transfer functions we work with are sRGBish.
// For exotic HDR transfer functions, we encode them using a tf.g that makes no sense,
// and repurpose the other fields to hold the parameters of the HDR functions.
enum TFKind { Bad_TF, sRGBish_TF, PQish_TF, HLGish_TF, HLGinvish_TF };
static inline TFKind classify_transfer_fn(const skcms_TransferFunction& tf) {
if (tf.g < 0 && (int)tf.g == tf.g) {
// TODO: sanity checks for PQ/HLG like we do for sRGBish.
switch (-(int)tf.g) {
case PQish_TF: return PQish_TF;
case HLGish_TF: return HLGish_TF;
case HLGinvish_TF: return HLGinvish_TF;
}
return Bad_TF;
}
// Basic sanity checks for sRGBish transfer functions.
if (sk_float_isfinite(tf.a + tf.b + tf.c + tf.d + tf.e + tf.f + tf.g)
// a,c,d,g should be non-negative to make any sense.
&& tf.a >= 0
&& tf.c >= 0
&& tf.d >= 0
&& tf.g >= 0
// Raising a negative value to a fractional tf->g produces complex numbers.
&& tf.a * tf.d + tf.b >= 0) {
return sRGBish_TF;
}
return Bad_TF;
}
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