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
8 #include "GrColorSpaceXform.h"
9 #include "SkColorSpace.h"
10 #include "SkColorSpace_Base.h"
11 #include "SkMatrix44.h"
12 #include "SkSpinlock.h"
13
14 class GrColorSpaceXformCache {
15 public:
16 using NewValueFn = std::function<sk_sp<GrColorSpaceXform>(void)>;
17
GrColorSpaceXformCache()18 GrColorSpaceXformCache() : fSequence(0) {}
19
findOrAdd(uint64_t key,NewValueFn newValue)20 sk_sp<GrColorSpaceXform> findOrAdd(uint64_t key, NewValueFn newValue) {
21 int oldest = 0;
22 for (int i = 0; i < kEntryCount; ++i) {
23 if (fEntries[i].fKey == key) {
24 fEntries[i].fLastUse = fSequence++;
25 return fEntries[i].fXform;
26 }
27 if (fEntries[i].fLastUse < fEntries[oldest].fLastUse) {
28 oldest = i;
29 }
30 }
31 fEntries[oldest].fKey = key;
32 fEntries[oldest].fXform = newValue();
33 fEntries[oldest].fLastUse = fSequence++;
34 return fEntries[oldest].fXform;
35 }
36
37 private:
38 enum { kEntryCount = 32 };
39
40 struct Entry {
41 // The default Entry is "valid". Any 64-bit key that is the same 32-bit value repeated
42 // implies no xform is necessary, so nullptr should be returned. This particular case should
43 // never happen, but by initializing all entries with this data, we can avoid special cases
44 // for the array not yet being full.
EntryGrColorSpaceXformCache::Entry45 Entry() : fKey(0), fXform(nullptr), fLastUse(0) {}
46
47 uint64_t fKey;
48 sk_sp<GrColorSpaceXform> fXform;
49 uint64_t fLastUse;
50 };
51
52 Entry fEntries[kEntryCount];
53 uint64_t fSequence;
54 };
55
GrColorSpaceXform(const SkMatrix44 & srcToDst)56 GrColorSpaceXform::GrColorSpaceXform(const SkMatrix44& srcToDst)
57 : fSrcToDst(srcToDst) {}
58
59 static SkSpinlock gColorSpaceXformCacheSpinlock;
60
Make(const SkColorSpace * src,const SkColorSpace * dst)61 sk_sp<GrColorSpaceXform> GrColorSpaceXform::Make(const SkColorSpace* src, const SkColorSpace* dst) {
62 if (!src || !dst) {
63 // Invalid
64 return nullptr;
65 }
66
67 if (src == dst) {
68 // Quick equality check - no conversion needed in this case
69 return nullptr;
70 }
71
72 const SkMatrix44* toXYZD50 = as_CSB(src)->toXYZD50();
73 const SkMatrix44* fromXYZD50 = as_CSB(dst)->fromXYZD50();
74 if (!toXYZD50 || !fromXYZD50) {
75 // unsupported colour spaces -- cannot specify gamut as a matrix
76 return nullptr;
77 }
78
79 uint32_t srcHash = as_CSB(src)->toXYZD50Hash();
80 uint32_t dstHash = as_CSB(dst)->toXYZD50Hash();
81 if (srcHash == dstHash) {
82 // Identical gamut - no conversion needed in this case
83 SkASSERT(*toXYZD50 == *as_CSB(dst)->toXYZD50() && "Hash collision");
84 return nullptr;
85 }
86
87 auto deferredResult = [fromXYZD50, toXYZD50]() {
88 SkMatrix44 srcToDst(SkMatrix44::kUninitialized_Constructor);
89 srcToDst.setConcat(*fromXYZD50, *toXYZD50);
90 return sk_make_sp<GrColorSpaceXform>(srcToDst);
91 };
92
93 if (gColorSpaceXformCacheSpinlock.tryAcquire()) {
94 static GrColorSpaceXformCache* gCache;
95 if (nullptr == gCache) {
96 gCache = new GrColorSpaceXformCache();
97 }
98
99 uint64_t key = static_cast<uint64_t>(srcHash) << 32 | static_cast<uint64_t>(dstHash);
100 sk_sp<GrColorSpaceXform> xform = gCache->findOrAdd(key, deferredResult);
101 gColorSpaceXformCacheSpinlock.release();
102 return xform;
103 } else {
104 // Rather than wait for the spin lock, just bypass the cache
105 return deferredResult();
106 }
107 }
108
Equals(const GrColorSpaceXform * a,const GrColorSpaceXform * b)109 bool GrColorSpaceXform::Equals(const GrColorSpaceXform* a, const GrColorSpaceXform* b) {
110 if (a == b) {
111 return true;
112 }
113
114 if (!a || !b) {
115 return false;
116 }
117
118 return a->fSrcToDst == b->fSrcToDst;
119 }
120
apply(const GrColor4f & srcColor)121 GrColor4f GrColorSpaceXform::apply(const GrColor4f& srcColor) {
122 GrColor4f result;
123 fSrcToDst.mapScalars(srcColor.fRGBA, result.fRGBA);
124 // We always operate on unpremul colors, so clamp to [0,1].
125 for (int i = 0; i < 4; ++i) {
126 result.fRGBA[i] = SkTPin(result.fRGBA[i], 0.0f, 1.0f);
127 }
128 return result;
129 }
130