Introduce SkGammas type to represent ICC gamma curves

src/core/SkColorSpace.h

Index: src/core/SkColorSpace.h
diff --git a/src/core/SkColorSpace.h b/src/core/SkColorSpace.h
index 2b3b15fe95576c33f5def8e4a341c5797a9bac30..9bbc20826dccecb4be8408b7d6fa58793a06cbcb 100644
--- a/src/core/SkColorSpace.h
+++ b/src/core/SkColorSpace.h
@@ -22,6 +22,7 @@
 //
 
 #include "SkRefCnt.h"
+#include "SkTArray.h"
 
 struct SkFloat3 {
     float fVec[3];
@@ -35,6 +36,39 @@ struct SkFloat3x3 {
     void dump() const;
 };
 
+struct SkGammaCurve {
+    bool isValue() const { return 0.0f != fValue; }
+    bool isTable() const { return 0 != fTableSize; }
+    bool isParametric() const { return false; }
+
+    // We have three different ways to represent gamma.
+    // (1) A single value:
+    float                    fValue;
+
+    // (2) A lookup table:
+    uint32_t                 fTableSize;
+    std::unique_ptr<float[]> fTable;
+
+    // (3) Parameters for a curve:
+    // FIXME (msarett): Handle parametric curves.
+
+    SkGammaCurve() {
+        memset(this, 0, sizeof(struct SkGammaCurve));
+    }
+
+    SkGammaCurve(float value)
+        : fValue(value)
+        , fTableSize(0)
+        , fTable(nullptr)
+    {}
+};
+
+struct SkGammas {
+    SkGammaCurve fRed;
+    SkGammaCurve fGreen;
+    SkGammaCurve fBlue;
+};
+
 struct SkColorLookUpTable {
     static const uint8_t kMaxChannels = 16;
 
@@ -46,14 +80,6 @@ struct SkColorLookUpTable {
     SkColorLookUpTable() {
         memset(this, 0, sizeof(struct SkColorLookUpTable));
     }
-
-    SkColorLookUpTable(SkColorLookUpTable&& that)

[msarett, 2016/04/28 21:26:48]

Now that we are on VS 2015, I think that this is no longer necessary.  Should be
implicit.

-        : fInputChannels(that.fInputChannels)
-        , fOutputChannels(that.fOutputChannels)
-        , fTable(std::move(that.fTable))
-    {
-        memcpy(fGridPoints, that.fGridPoints, kMaxChannels);
-    }
 };
 
 class SkColorSpace : public SkRefCnt {
@@ -67,25 +93,25 @@ public:
      *  Return a colorspace instance, given a 3x3 transform from linear_RGB to D50_XYZ
      *  and the src-gamma, return a ColorSpace
      */
-    static sk_sp<SkColorSpace> NewRGB(const SkFloat3x3& toXYZD50, const SkFloat3& gamma);
+    static sk_sp<SkColorSpace> NewRGB(const SkFloat3x3& toXYZD50, SkGammas gammas);
 
     static sk_sp<SkColorSpace> NewNamed(Named);
     static sk_sp<SkColorSpace> NewICC(const void*, size_t);
 
-    SkFloat3 gamma() const { return fGamma; }
+    const SkGammas& gammas() const { return fGammas; }
     SkFloat3x3 xyz() const { return fToXYZD50; }
     SkFloat3 xyzOffset() const { return fToXYZOffset; }
     Named named() const { return fNamed; }
     uint32_t uniqueID() const { return fUniqueID; }
 
 private:
-    SkColorSpace(const SkFloat3& gamma, const SkFloat3x3& toXYZ, Named);
+    SkColorSpace(SkGammas gammas, const SkFloat3x3& toXYZ, Named);
 
-    SkColorSpace(SkColorLookUpTable colorLUT, const SkFloat3& gamma, const SkFloat3x3& toXYZ,
-                 const SkFloat3& toXYZOffset);
+    SkColorSpace(SkColorLookUpTable colorLUT, SkGammas gammas,
+                 const SkFloat3x3& toXYZ, const SkFloat3& toXYZOffset);
 
     const SkColorLookUpTable fColorLUT;
-    const SkFloat3           fGamma;
+    const SkGammas           fGammas;
     const SkFloat3x3         fToXYZD50;
     const SkFloat3           fToXYZOffset;