Drafts and half ideas

src/core/SkColorSpace.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkColorSpace_DEFINED
 #define SkColorSpace_DEFINED
 
@@ skipping 17 matching lines @@
 
     void dump() const;
 };
 
 struct SkFloat3x3 {
     float fMat[9];
 
     void dump() const;
 };
 
+struct SkGamma {
+    static const uint32_t kGammaUseValueFlag =      0x1;
+    static const uint32_t kGammaUseTableFlag =      0x2;
+    static const uint32_t kGammaUseParametricFlag = 0x4;
+
+    bool isValue() const { return kGammaUseValueFlag & fFlag; }
+    bool isTable() const { return kGammaUseTableFlag & fFlag; }
+    bool isParametric() const { return kGammaUseParametricFlag & fFlag; }
+
+    uint32_t                 fFlag;
+
+    // Values
+    float                    fValue;
+
+    // Table
+    uint32_t                 fTableSize;
+    std::unique_ptr<float[]> fTable;
+
+    // Parametric
+    // FIXME (msarett): Handle parametric curves.
+
+    SkGamma() {
+        memset(this, 0, sizeof(struct SkGamma));
+    }
+
+    static SkGamma sRGB() {
+        SkGamma gamma;
+        gamma.fFlag = kGammaUseValueFlag;
+        gamma.fValue = 2.2f;
+        return std::move(gamma);
+    }
+};
+
+struct SkGammas {
+    SkGamma fGammas[3];
+
+    static SkGammas sRGB() {
+        SkGammas gammas;
+        gammas.fGammas[0] = std::move(SkGamma::sRGB());
+        gammas.fGammas[1] = std::move(SkGamma::sRGB());
+        gammas.fGammas[2] = std::move(SkGamma::sRGB());
+        return std::move(gammas);
+    }
+};
+
 struct SkColorLookUpTable {
     static const uint8_t kMaxChannels = 16;
 
     uint8_t                  fInputChannels;
     uint8_t                  fOutputChannels;
     uint8_t                  fGridPoints[kMaxChannels];
     std::unique_ptr<float[]> fTable;
 
     SkColorLookUpTable() {
         memset(this, 0, sizeof(struct SkColorLookUpTable));
     }
 };
 
 struct SkPM4f;
 void SkApply3x3ToPM4f(const SkFloat3x3&, const SkPM4f src[], SkPM4f dst[], int count);
 
 class SkColorSpace : public SkRefCnt {
 public:
     enum Named {
         kUnknown_Named,
         kDevice_Named,
         kSRGB_Named,
     };
 
     /**
      *  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; }
     Named named() const { return fNamed; }
     uint32_t uniqueID() const { return fUniqueID; }
 
     enum Result {
         kFailure_Result,
         kIdentity_Result,
         kNormal_Result,
     };
 
     /**
      *  Given a src and dst colorspace, return the 3x3 matrix that will convert src_linear_RGB
      *  values into dst_linear_RGB values.
      */
     static Result Concat(const SkColorSpace* src, const SkColorSpace* dst, SkFloat3x3* result);
 
     static void Test();
     void dump() const;
 
 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,
+    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;
 
     const uint32_t           fUniqueID;
     const Named              fNamed;
 };
 
 #endif