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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.
*/
#include "GrColorSpaceXform.h"
#include "SkColorSpace.h"
#include "SkColorSpace_Base.h"
#include "SkMatrix44.h"
#include "SkSpinlock.h"
class GrColorSpaceXformCache {
public:
using NewValueFn = std::function<sk_sp<GrColorSpaceXform>(void)>;
GrColorSpaceXformCache() : fSequence(0) {}
sk_sp<GrColorSpaceXform> findOrAdd(uint64_t key, NewValueFn newValue) {
int oldest = 0;
for (int i = 0; i < kEntryCount; ++i) {
if (fEntries[i].fKey == key) {
fEntries[i].fLastUse = fSequence++;
return fEntries[i].fXform;
}
if (fEntries[i].fLastUse < fEntries[oldest].fLastUse) {
oldest = i;
}
}
fEntries[oldest].fKey = key;
fEntries[oldest].fXform = newValue();
fEntries[oldest].fLastUse = fSequence++;
return fEntries[oldest].fXform;
}
private:
enum { kEntryCount = 32 };
struct Entry {
// The default Entry is "valid". Any 64-bit key that is the same 32-bit value repeated
// implies no xform is necessary, so nullptr should be returned. This particular case should
// never happen, but by initializing all entries with this data, we can avoid special cases
// for the array not yet being full.
Entry() : fKey(0), fXform(nullptr), fLastUse(0) {}
uint64_t fKey;
sk_sp<GrColorSpaceXform> fXform;
uint64_t fLastUse;
};
Entry fEntries[kEntryCount];
uint64_t fSequence;
};
GrColorSpaceXform::GrColorSpaceXform(const SkMatrix44& srcToDst)
: fSrcToDst(srcToDst) {}
static SkSpinlock gColorSpaceXformCacheSpinlock;
sk_sp<GrColorSpaceXform> GrColorSpaceXform::Make(SkColorSpace* src, SkColorSpace* dst) {
if (!src || !dst) {
// Invalid
return nullptr;
}
if (src == dst) {
// Quick equality check - no conversion needed in this case
return nullptr;
}
const SkMatrix44* toXYZD50 = as_CSB(src)->toXYZD50();
const SkMatrix44* fromXYZD50 = as_CSB(dst)->fromXYZD50();
if (!toXYZD50 || !fromXYZD50) {
// unsupported colour spaces -- cannot specify gamut as a matrix
return nullptr;
}
uint32_t srcHash = as_CSB(src)->toXYZD50Hash();
uint32_t dstHash = as_CSB(dst)->toXYZD50Hash();
if (srcHash == dstHash) {
// Identical gamut - no conversion needed in this case
SkASSERT(*toXYZD50 == *as_CSB(dst)->toXYZD50() && "Hash collision");
return nullptr;
}
auto deferredResult = [fromXYZD50, toXYZD50]() {
SkMatrix44 srcToDst(SkMatrix44::kUninitialized_Constructor);
srcToDst.setConcat(*fromXYZD50, *toXYZD50);
return sk_make_sp<GrColorSpaceXform>(srcToDst);
};
if (gColorSpaceXformCacheSpinlock.tryAcquire()) {
static GrColorSpaceXformCache* gCache;
if (nullptr == gCache) {
gCache = new GrColorSpaceXformCache();
}
uint64_t key = static_cast<uint64_t>(srcHash) << 32 | static_cast<uint64_t>(dstHash);
sk_sp<GrColorSpaceXform> xform = gCache->findOrAdd(key, deferredResult);
gColorSpaceXformCacheSpinlock.release();
return xform;
} else {
// Rather than wait for the spin lock, just bypass the cache
return deferredResult();
}
}
bool GrColorSpaceXform::Equals(const GrColorSpaceXform* a, const GrColorSpaceXform* b) {
if (a == b) {
return true;
}
if (!a || !b) {
return false;
}
return a->fSrcToDst == b->fSrcToDst;
}
GrColor4f GrColorSpaceXform::apply(const GrColor4f& srcColor) {
GrColor4f result;
fSrcToDst.mapScalars(srcColor.fRGBA, result.fRGBA);
return result;
}
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