Drafts and half ideas

src/core/SkColorSpace.cpp

Index: src/core/SkColorSpace.cpp
diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp
index be27a49c0ff8fff9bac63e8fa2bd40df5be69a87..381aa21de9df48894eee6e41f4a93267d913e150 100644
--- a/src/core/SkColorSpace.cpp
+++ b/src/core/SkColorSpace.cpp
@@ -88,36 +88,32 @@ 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)
 {
     for (int i = 0; i < 3; ++i) {
-        SkASSERT(SkFloatIsFinite(gamma.fVec[i]));
         for (int j = 0; j < 3; ++j) {
             SkASSERT(SkFloatIsFinite(toXYZD50.fMat[3*i + j]));
         }
     }
 }
 
-SkColorSpace::SkColorSpace(SkColorLookUpTable colorLUT, const SkFloat3& gamma, const SkFloat3x3& toXYZD50,
+SkColorSpace::SkColorSpace(SkColorLookUpTable colorLUT, SkGammas gammas, const SkFloat3x3& toXYZD50,
                            const SkFloat3& toXYZOffset)
     : fColorLUT(std::move(colorLUT))
-    , fGamma(gamma)
+    , fGammas(gammas)
     , fToXYZD50(toXYZD50)
     , fToXYZOffset(toXYZOffset)
     , fUniqueID(sk_atomic_inc(&gUniqueColorSpaceID))
     , fNamed(kUnknown_Named)
 {}
 
-sk_sp<SkColorSpace> SkColorSpace::NewRGB(const SkFloat3x3& toXYZD50, const SkFloat3& gamma) {
+sk_sp<SkColorSpace> SkColorSpace::NewRGB(const SkFloat3x3& toXYZD50, SkGammas gammas) {
     for (int i = 0; i < 3; ++i) {
-        if (!SkFloatIsFinite(gamma.fVec[i]) || gamma.fVec[i] < 0) {
-            return nullptr;
-        }
         for (int j = 0; j < 3; ++j) {
             if (!SkFloatIsFinite(toXYZD50.fMat[3*i + j])) {
                 return nullptr;
@@ -131,24 +127,21 @@ sk_sp<SkColorSpace> SkColorSpace::NewRGB(const SkFloat3x3& toXYZD50, const SkFlo
         return nullptr;
     }
 
-    return sk_sp<SkColorSpace>(new SkColorSpace(gamma, toXYZD50, kUnknown_Named));
+    return sk_sp<SkColorSpace>(new SkColorSpace(std::move(gammas), toXYZD50, kUnknown_Named));
 }
 
 void SkColorSpace::dump() const {
     fToXYZD50.dump();
-    fGamma.dump();
 }
 
 //////////////////////////////////////////////////////////////////////////////////////////////////
 
-const SkFloat3   gDevice_gamma {{ 0, 0, 0 }};
 const SkFloat3x3 gDevice_toXYZD50 {{
     1, 0, 0,
     0, 1, 0,
     0, 0, 1
 }};
 
-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
@@ -158,10 +151,11 @@ const SkFloat3x3 gSRGB_toXYZD50 {{
 sk_sp<SkColorSpace> SkColorSpace::NewNamed(Named named) {
     switch (named) {
         case kDevice_Named:
-            return sk_sp<SkColorSpace>(new SkColorSpace(gDevice_gamma, gDevice_toXYZD50,
+            return sk_sp<SkColorSpace>(new SkColorSpace(std::move(SkGammas()), gDevice_toXYZD50,
                                                         kDevice_Named));
         case kSRGB_Named:
-            return sk_sp<SkColorSpace>(new SkColorSpace(gSRGB_gamma, gSRGB_toXYZD50, kSRGB_Named));
+            return sk_sp<SkColorSpace>(new SkColorSpace(std::move(SkGammas::sRGB()), gSRGB_toXYZD50,
+                                                        kSRGB_Named));
         default:
             break;
     }
@@ -372,7 +366,7 @@ 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) {
+static bool load_gammas(SkGamma* gammas, uint32_t numGammas, const uint8_t* src, size_t len) {
     for (uint32_t i = 0; i < numGammas; i++) {
         if (len < 12) {
             // FIXME (msarett):
@@ -395,7 +389,8 @@ 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].fFlag = SkGamma::kGammaUseValueFlag;
+                    gammas[i].fValue = 1.0f;
                     break;
                 } else if (len < 12 + 2 * count) {
                     SkColorSpacePrintf("gamma tag is too small (%d bytes)", len);
@@ -406,24 +401,29 @@ static bool load_gammas(float* gammas, uint32_t numGammas, const uint8_t* src, s
                 if (1 == count) {
                     // Table entry is the exponent (bias 256).
                     uint16_t value = read_big_endian_short((const uint8_t*) table);
-                    gammas[i] = value / 256.0f;
+                    gammas[i].fFlag = SkGamma::kGammaUseValueFlag;
+                    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.
-                for (uint32_t i = 0; i < count; i++) {
-                    SkColorSpacePrintf("curve[%d] %d\n", i,
-                            read_big_endian_short((const uint8_t*) &table[i]));
+                // Fill in the interpolation table.
+                // FIXME (msarett):
+                // We should recognize commonly occurring tables and just set gamma to 2.2f.
+                gammas[i].fFlag = SkGamma::kGammaUseTableFlag;
+                gammas[i].fTableSize = count;
+                gammas[i].fTable = std::unique_ptr(new float[count]);
+                for (uint32_t j = 0; j < count; 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.
                 SkColorSpacePrintf("parametric curve\n");
-                gammas[i] = 2.2f;
+                gammas[i].fFlag = SkGamma::kGammaUseValueFlag;
+                gammas[i].fValue = 2.2f;
 
                 switch(read_big_endian_short(src + 8)) {
                     case 0: