1 /*
2 * Copyright 2017 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
8 #ifndef SkImageInfoPriv_DEFINED
9 #define SkImageInfoPriv_DEFINED
10
11 #include "SkImageInfo.h"
12
13 /**
14 * Returns true if |info| contains a valid combination of width, height, colorType, alphaType,
15 * colorSpace. Returns false otherwise.
16 */
SkImageInfoIsValid(const SkImageInfo & info)17 static inline bool SkImageInfoIsValid(const SkImageInfo& info) {
18 if (info.width() <= 0 || info.height() <= 0) {
19 return false;
20 }
21
22 const int kMaxDimension = SK_MaxS32 >> 2;
23 if (info.width() > kMaxDimension || info.height() > kMaxDimension) {
24 return false;
25 }
26
27 if (kUnknown_SkColorType == info.colorType() || kUnknown_SkAlphaType == info.alphaType()) {
28 return false;
29 }
30
31 if (kOpaque_SkAlphaType != info.alphaType() &&
32 (kRGB_565_SkColorType == info.colorType() || kGray_8_SkColorType == info.colorType())) {
33 return false;
34 }
35
36 if (kRGBA_F16_SkColorType == info.colorType() &&
37 (!info.colorSpace() || !info.colorSpace()->gammaIsLinear())) {
38 return false;
39 }
40
41 if (info.colorSpace() &&
42 (!info.colorSpace()->gammaCloseToSRGB() && !info.colorSpace()->gammaIsLinear())) {
43 return false;
44 }
45
46 return true;
47 }
48
49 /**
50 * Returns true if Skia has defined a pixel conversion from the |src| to the |dst|.
51 * Returns false otherwise. Some discussion of false cases:
52 * We will not convert to kIndex8 unless it exactly matches the src, since color tables
53 * are immutable.
54 * We do not convert to kGray8 when the |src| is not kGray8 in the same color space.
55 * We may add this feature - it just requires some work to convert to luminance while
56 * handling color spaces correctly. Currently no one is asking for this.
57 * We will not convert from kAlpha8 when the |dst| is not kAlpha8. This would require
58 * inventing color information.
59 * We will not convert to kOpaque when the |src| is not kOpaque. This could be
60 * implemented to set all the alpha values to 1, but there is still some ambiguity -
61 * should we use kPremul or kUnpremul color values with the opaque alphas? Or should
62 * we just use whatever the |src| alpha is? In the future, we could choose to clearly
63 * define this, but currently no one is asking for this feature.
64 * We will not convert to a particular color space if |src| is nullptr. The color space
65 * conversion is not well-defined.
66 */
SkImageInfoValidConversion(const SkImageInfo & dst,const SkImageInfo & src)67 static inline bool SkImageInfoValidConversion(const SkImageInfo& dst, const SkImageInfo& src) {
68 if (!SkImageInfoIsValid(dst) || !SkImageInfoIsValid(src)) {
69 return false;
70 }
71
72 if (kIndex_8_SkColorType == dst.colorType()) {
73 if (kIndex_8_SkColorType != src.colorType()) {
74 return false;
75 }
76
77 if ((kPremul_SkAlphaType == dst.alphaType() && kUnpremul_SkAlphaType == src.alphaType()) ||
78 (kUnpremul_SkAlphaType == dst.alphaType() && kPremul_SkAlphaType == src.alphaType()))
79 {
80 return false;
81 }
82
83 if (dst.colorSpace() && !SkColorSpace::Equals(dst.colorSpace(), src.colorSpace())) {
84 return false;
85 }
86 }
87
88 if (kGray_8_SkColorType == dst.colorType()) {
89 if (kGray_8_SkColorType != src.colorType()) {
90 return false;
91 }
92
93 if (dst.colorSpace() && !SkColorSpace::Equals(dst.colorSpace(), src.colorSpace())) {
94 return false;
95 }
96 }
97
98 if (kAlpha_8_SkColorType != dst.colorType() && kAlpha_8_SkColorType == src.colorType()) {
99 return false;
100 }
101
102 if (kOpaque_SkAlphaType == dst.alphaType() && kOpaque_SkAlphaType != src.alphaType()) {
103 return false;
104 }
105
106 if (dst.colorSpace() && !src.colorSpace()) {
107 return false;
108 }
109
110 return true;
111 }
112 #endif // SkImageInfoPriv_DEFINED
113