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Unified Diff: src/core/SkColorSpace.cpp

Issue 1928123002: Introduce SkGammas type to represent ICC gamma curves (Closed) Base URL: https://skia.googlesource.com/skia.git@delcolorspace
Patch Set: Fix Mac clang again Created 4 years, 8 months ago
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Index: src/core/SkColorSpace.cpp
diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp
index 43c424f1dca8b0cf9b004f29b22ffd1b4d1585a0..54495de9407e62d41d9c556e557c7060297f4a3b 100644
--- a/src/core/SkColorSpace.cpp
+++ b/src/core/SkColorSpace.cpp
@@ -23,29 +23,28 @@ void SkFloat3x3::dump() const {
static int32_t gUniqueColorSpaceID;
-SkColorSpace::SkColorSpace(const SkFloat3& gamma, const SkFloat3x3& toXYZD50, Named named)
- : fGamma(gamma)
+SkColorSpace::SkColorSpace(SkGammas gammas, const SkFloat3x3& toXYZD50, Named named)
+ : fGammas(std::move(gammas))
, fToXYZD50(toXYZD50)
, fToXYZOffset({{ 0.0f, 0.0f, 0.0f }})
, fUniqueID(sk_atomic_inc(&gUniqueColorSpaceID))
, fNamed(named)
{}
-SkColorSpace::SkColorSpace(SkColorLookUpTable colorLUT, const SkFloat3& gamma,
+SkColorSpace::SkColorSpace(SkColorLookUpTable colorLUT, SkGammas gammas,
const SkFloat3x3& toXYZD50, const SkFloat3& toXYZOffset)
: fColorLUT(std::move(colorLUT))
- , fGamma(gamma)
+ , fGammas(std::move(gammas))
, fToXYZD50(toXYZD50)
, fToXYZOffset(toXYZOffset)
, fUniqueID(sk_atomic_inc(&gUniqueColorSpaceID))
, fNamed(kUnknown_Named)
{}
-sk_sp<SkColorSpace> SkColorSpace::NewRGB(const SkFloat3x3& toXYZD50, const SkFloat3& gamma) {
- return sk_sp<SkColorSpace>(new SkColorSpace(gamma, toXYZD50, kUnknown_Named));
+sk_sp<SkColorSpace> SkColorSpace::NewRGB(const SkFloat3x3& toXYZD50, SkGammas gammas) {
+ return sk_sp<SkColorSpace>(new SkColorSpace(std::move(gammas), toXYZD50, kUnknown_Named));
}
-const SkFloat3 gSRGB_gamma {{ 2.2f, 2.2f, 2.2f }};
const SkFloat3x3 gSRGB_toXYZD50 {{
0.4358f, 0.2224f, 0.0139f, // * R
0.3853f, 0.7170f, 0.0971f, // * G
@@ -55,7 +54,8 @@ const SkFloat3x3 gSRGB_toXYZD50 {{
sk_sp<SkColorSpace> SkColorSpace::NewNamed(Named named) {
switch (named) {
case kSRGB_Named:
- return sk_sp<SkColorSpace>(new SkColorSpace(gSRGB_gamma, gSRGB_toXYZD50, kSRGB_Named));
+ return sk_sp<SkColorSpace>(new SkColorSpace(SkGammas(2.2f, 2.2f, 2.2f), gSRGB_toXYZD50,
+ kSRGB_Named));
default:
break;
}
@@ -264,9 +264,8 @@ bool load_xyz(float dst[3], const uint8_t* src, size_t len) {
static const uint32_t kTAG_CurveType = SkSetFourByteTag('c', 'u', 'r', 'v');
static const uint32_t kTAG_ParaCurveType = SkSetFourByteTag('p', 'a', 'r', 'a');
-// FIXME (msarett):
-// We need to handle the possibility that the gamma curve does not correspond to 2.2f.
-static bool load_gammas(float* gammas, uint32_t numGammas, const uint8_t* src, size_t len) {
+bool SkColorSpace::LoadGammas(SkGammaCurve* gammas, uint32_t numGammas, const uint8_t* src,
+ size_t len) {
for (uint32_t i = 0; i < numGammas; i++) {
if (len < 12) {
// FIXME (msarett):
@@ -289,7 +288,7 @@ static bool load_gammas(float* gammas, uint32_t numGammas, const uint8_t* src, s
// Some tags require a gamma curve, but the author doesn't actually want
// to transform the data. In this case, it is common to see a curve with
// a count of 0.
- gammas[i] = 1.0f;
+ gammas[i].fValue = 1.0f;
break;
} else if (len < 12 + 2 * count) {
SkColorSpacePrintf("gamma tag is too small (%d bytes)", len);
@@ -298,27 +297,31 @@ static bool load_gammas(float* gammas, uint32_t numGammas, const uint8_t* src, s
const uint16_t* table = (const uint16_t*) (src + 12);
if (1 == count) {
- // Table entry is the exponent (bias 256).
+ // The table entry is the gamma (with a bias of 256).
uint16_t value = read_big_endian_short((const uint8_t*) table);
- gammas[i] = value / 256.0f;
+ gammas[i].fValue = value / 256.0f;
SkColorSpacePrintf("gamma %d %g\n", value, *gamma);
break;
}
- // Print the interpolation table. For now, we ignore this and guess 2.2f.
+ // Fill in the interpolation table.
+ // FIXME (msarett):
+ // We should recognize commonly occurring tables and just set gamma to 2.2f.
+ gammas[i].fTableSize = count;
+ gammas[i].fTable = std::unique_ptr<float[]>(new float[count]);
for (uint32_t j = 0; j < count; j++) {
- SkColorSpacePrintf("curve[%d] %d\n", j,
- read_big_endian_short((const uint8_t*) &table[j]));
+ gammas[i].fTable[j] =
+ (read_big_endian_short((const uint8_t*) &table[j])) / 65535.0f;
}
-
- gammas[i] = 2.2f;
break;
}
case kTAG_ParaCurveType:
// Guess 2.2f.
+ // FIXME (msarett): Handle parametric curves.
SkColorSpacePrintf("parametric curve\n");
- gammas[i] = 2.2f;
+ gammas[i].fValue = 2.2f;
+ // Determine the size of the parametric curve tag.
switch(read_big_endian_short(src + 8)) {
case 0:
tagBytes = 12 + 4;
@@ -358,28 +361,19 @@ static bool load_gammas(float* gammas, uint32_t numGammas, const uint8_t* src, s
}
}
- // If all of the gammas we encounter are 1.0f, indicate that we failed to load gammas.
- // There is no need to apply a gamma of 1.0f.
- for (uint32_t i = 0; i < numGammas; i++) {
- if (1.0f != gammas[i]) {
- return true;
- }
- }
-
- return false;
+ return true;
}
static const uint32_t kTAG_AtoBType = SkSetFourByteTag('m', 'A', 'B', ' ');
-bool load_color_lut(SkColorLookUpTable* colorLUT, uint32_t inputChannels, uint32_t outputChannels,
- const uint8_t* src, size_t len) {
+bool SkColorSpace::LoadColorLUT(SkColorLookUpTable* colorLUT, uint32_t inputChannels,
+ uint32_t outputChannels, const uint8_t* src, size_t len) {
if (len < 20) {
SkColorSpacePrintf("Color LUT tag is too small (%d bytes).", len);
return false;
}
- SkASSERT(inputChannels <= SkColorLookUpTable::kMaxChannels &&
- outputChannels <= SkColorLookUpTable::kMaxChannels);
+ SkASSERT(inputChannels <= SkColorLookUpTable::kMaxChannels && 3 == outputChannels);
colorLUT->fInputChannels = inputChannels;
colorLUT->fOutputChannels = outputChannels;
uint32_t numEntries = 1;
@@ -441,8 +435,8 @@ bool load_matrix(SkFloat3x3* toXYZ, SkFloat3* toXYZOffset, const uint8_t* src, s
return true;
}
-bool load_a2b0(SkColorLookUpTable* colorLUT, SkFloat3* gamma, SkFloat3x3* toXYZ,
- SkFloat3* toXYZOffset, const uint8_t* src, size_t len) {
+bool SkColorSpace::LoadA2B0(SkColorLookUpTable* colorLUT, SkGammas* gammas, SkFloat3x3* toXYZ,
+ SkFloat3* toXYZOffset, const uint8_t* src, size_t len) {
if (len < 32) {
SkColorSpacePrintf("A to B tag is too small (%d bytes).", len);
return false;
@@ -460,7 +454,7 @@ bool load_a2b0(SkColorLookUpTable* colorLUT, SkFloat3* gamma, SkFloat3x3* toXYZ,
uint8_t inputChannels = src[8];
uint8_t outputChannels = src[9];
if (0 == inputChannels || inputChannels > SkColorLookUpTable::kMaxChannels ||
- 0 < outputChannels || outputChannels > SkColorLookUpTable::kMaxChannels) {
+ 3 != outputChannels) {
// The color LUT assumes that there are at most 16 input channels. For RGB
// profiles, output channels should be 3.
SkColorSpacePrintf("Too many input or output channels in A to B tag.\n");
@@ -483,16 +477,16 @@ bool load_a2b0(SkColorLookUpTable* colorLUT, SkFloat3* gamma, SkFloat3x3* toXYZ,
uint32_t offsetToColorLUT = read_big_endian_int(src + 24);
if (0 != offsetToColorLUT && offsetToColorLUT < len) {
- if (!load_color_lut(colorLUT, inputChannels, outputChannels, src + offsetToColorLUT,
- len - offsetToColorLUT)) {
+ if (!SkColorSpace::LoadColorLUT(colorLUT, inputChannels, outputChannels,
+ src + offsetToColorLUT, len - offsetToColorLUT)) {
SkColorSpacePrintf("Failed to read color LUT from A to B tag.\n");
}
}
uint32_t offsetToMCurves = read_big_endian_int(src + 20);
if (0 != offsetToMCurves && offsetToMCurves < len) {
- if (!load_gammas(gamma->fVec, outputChannels, src + offsetToMCurves, len - offsetToMCurves))
- {
+ if (!SkColorSpace::LoadGammas(&gammas->fRed, outputChannels, src + offsetToMCurves,
+ len - offsetToMCurves)) {
SkColorSpacePrintf("Failed to read M curves from A to B tag.\n");
}
}
@@ -567,42 +561,39 @@ sk_sp<SkColorSpace> SkColorSpace::NewICC(const void* base, size_t len) {
// It is not uncommon to see missing or empty gamma tags. This indicates
// that we should use unit gamma.
- SkFloat3 gamma {{ 1.0f, 1.0f, 1.0f }};
+ SkGammas gammas;
r = ICCTag::Find(tags.get(), tagCount, kTAG_rTRC);
g = ICCTag::Find(tags.get(), tagCount, kTAG_gTRC);
b = ICCTag::Find(tags.get(), tagCount, kTAG_bTRC);
- if (!r ||
- !load_gammas(&gamma.fVec[0], 1, r->addr((const uint8_t*) base), r->fLength))
- {
+ if (!r || !SkColorSpace::LoadGammas(&gammas.fRed, 1,
+ r->addr((const uint8_t*) base), r->fLength)) {
SkColorSpacePrintf("Failed to read R gamma tag.\n");
}
- if (!g ||
- !load_gammas(&gamma.fVec[1], 1, g->addr((const uint8_t*) base), g->fLength))
- {
+ if (!g || !SkColorSpace::LoadGammas(&gammas.fGreen, 1,
+ g->addr((const uint8_t*) base), g->fLength)) {
SkColorSpacePrintf("Failed to read G gamma tag.\n");
}
- if (!b ||
- !load_gammas(&gamma.fVec[2], 1, b->addr((const uint8_t*) base), b->fLength))
- {
+ if (!b || !SkColorSpace::LoadGammas(&gammas.fBlue, 1,
+ b->addr((const uint8_t*) base), b->fLength)) {
SkColorSpacePrintf("Failed to read B gamma tag.\n");
}
- return SkColorSpace::NewRGB(toXYZ, gamma);
+ return SkColorSpace::NewRGB(toXYZ, std::move(gammas));
}
// Recognize color profile specified by A2B0 tag.
const ICCTag* a2b0 = ICCTag::Find(tags.get(), tagCount, kTAG_A2B0);
if (a2b0) {
SkColorLookUpTable colorLUT;
- SkFloat3 gamma;
+ SkGammas gammas;
SkFloat3x3 toXYZ;
SkFloat3 toXYZOffset;
- if (!load_a2b0(&colorLUT, &gamma, &toXYZ, &toXYZOffset,
- a2b0->addr((const uint8_t*) base), a2b0->fLength)) {
+ if (!SkColorSpace::LoadA2B0(&colorLUT, &gammas, &toXYZ, &toXYZOffset,
+ a2b0->addr((const uint8_t*) base), a2b0->fLength)) {
return_null("Failed to parse A2B0 tag");
}
- return sk_sp<SkColorSpace>(new SkColorSpace(std::move(colorLUT), gamma, toXYZ,
- toXYZOffset));
+ return sk_sp<SkColorSpace>(new SkColorSpace(std::move(colorLUT), std::move(gammas),
+ toXYZ, toXYZOffset));
}
}
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