1 /*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7 #ifndef SkColorSpacePriv_DEFINED
8 #define SkColorSpacePriv_DEFINED
9
10 #include "include/core/SkColorSpace.h"
11 #include "include/private/base/SkTemplates.h"
12 #include "modules/skcms/skcms.h"
13
14 namespace skvm {
15 class Builder;
16 struct Color;
17 struct F32;
18 struct Uniforms;
19 }
20
21 // A gamut narrower than sRGB, useful for testing.
22 static constexpr skcms_Matrix3x3 gNarrow_toXYZD50 = {{
23 { 0.190974f, 0.404865f, 0.368380f },
24 { 0.114746f, 0.582937f, 0.302318f },
25 { 0.032925f, 0.153615f, 0.638669f },
26 }};
27
color_space_almost_equal(float a,float b)28 static inline bool color_space_almost_equal(float a, float b) {
29 return SkTAbs(a - b) < 0.01f;
30 }
31
32 // Let's use a stricter version for transfer functions. Worst case, these are encoded
33 // in ICC format, which offers 16-bits of fractional precision.
transfer_fn_almost_equal(float a,float b)34 static inline bool transfer_fn_almost_equal(float a, float b) {
35 return SkTAbs(a - b) < 0.001f;
36 }
37
is_almost_srgb(const skcms_TransferFunction & coeffs)38 static inline bool is_almost_srgb(const skcms_TransferFunction& coeffs) {
39 return transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.a, coeffs.a) &&
40 transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.b, coeffs.b) &&
41 transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.c, coeffs.c) &&
42 transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.d, coeffs.d) &&
43 transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.e, coeffs.e) &&
44 transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.f, coeffs.f) &&
45 transfer_fn_almost_equal(SkNamedTransferFn::kSRGB.g, coeffs.g);
46 }
47
is_almost_2dot2(const skcms_TransferFunction & coeffs)48 static inline bool is_almost_2dot2(const skcms_TransferFunction& coeffs) {
49 return transfer_fn_almost_equal(1.0f, coeffs.a) &&
50 transfer_fn_almost_equal(0.0f, coeffs.b) &&
51 transfer_fn_almost_equal(0.0f, coeffs.e) &&
52 transfer_fn_almost_equal(2.2f, coeffs.g) &&
53 coeffs.d <= 0.0f;
54 }
55
is_almost_linear(const skcms_TransferFunction & coeffs)56 static inline bool is_almost_linear(const skcms_TransferFunction& coeffs) {
57 // OutputVal = InputVal ^ 1.0f
58 const bool linearExp =
59 transfer_fn_almost_equal(1.0f, coeffs.a) &&
60 transfer_fn_almost_equal(0.0f, coeffs.b) &&
61 transfer_fn_almost_equal(0.0f, coeffs.e) &&
62 transfer_fn_almost_equal(1.0f, coeffs.g) &&
63 coeffs.d <= 0.0f;
64
65 // OutputVal = 1.0f * InputVal
66 const bool linearFn =
67 transfer_fn_almost_equal(1.0f, coeffs.c) &&
68 transfer_fn_almost_equal(0.0f, coeffs.f) &&
69 coeffs.d >= 1.0f;
70
71 return linearExp || linearFn;
72 }
73
74 skvm::F32 sk_program_transfer_fn(
75 skvm::F32 v, skcms_TFType,
76 skvm::F32 G, skvm::F32 A, skvm::F32 B, skvm::F32 C, skvm::F32 D, skvm::F32 E, skvm::F32 F);
77
78 skvm::Color sk_program_transfer_fn(skvm::Builder*, skvm::Uniforms*,
79 const skcms_TransferFunction&, skvm::Color);
80
81 // Return raw pointers to commonly used SkColorSpaces.
82 // No need to ref/unref these, but if you do, do it in pairs.
83 SkColorSpace* sk_srgb_singleton();
84 SkColorSpace* sk_srgb_linear_singleton();
85
86 #endif // SkColorSpacePriv_DEFINED
87