Prepare SkColorSpace to be a public API

src/core/SkColorSpacePriv.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 SkColorSpacePriv_DEFINED
+#define SkColorSpacePriv_DEFINED
+
+struct SkGammaCurve {
+    bool isValue() const {
+        bool result = (0.0f != fValue);
+        SkASSERT(!result || (0 == fTableSize));
+        return result;
+    }
+
+    bool isTable() const {
+        bool result = (0 != fTableSize);
+        SkASSERT(!result || (0.0f == fValue));
+        SkASSERT(!result || fTable);
+        return result;
+    }
+
+    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 : public SkRefCnt {

[scroggo, 2016/05/17 16:54:27]

Why is gamma ref counted? I guess it's because of SkGammaCurve::fTable that you
don't want to worry about copying?

It seems potentially problematic because it has public members that can be
modified.

[msarett, 2016/05/17 17:27:13]

A couple reasons:
(1) As you say, it's nice to not have to std::move all the time.
(2) Now that it's a malloced ptr, it's nice to share a ref [ 2.2f, 2.2f, 2.2f ]
for the many images with standard gamma.
Ahh yes that's bad.  I think I can make these const, I'll follow up.

+public:
+    bool isValues() const {
+        return fRed.isValue() && fGreen.isValue() && fBlue.isValue();
+    }
+
+    SkGammaCurve fRed;
+    SkGammaCurve fGreen;
+    SkGammaCurve fBlue;
+
+    SkGammas(float red, float green, float blue)
+        : fRed(red)
+        , fGreen(green)
+        , fBlue(blue)
+    {}
+
+    SkGammas() {}
+
+    friend class SkColorSpace;
+};
+
+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));
+    }
+};
+
+#endif