Initial implementation of a SkColorSpace_A2B xform

src/core/SkColorSpaceXform_A2B.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 SkColorSpaceXform_A2B_DEFINED
+#define SkColorSpaceXform_A2B_DEFINED
+
+#include "SkColorSpace_Base.h"
+#include "SkColorSpaceXform_Base.h"
+#include "SkRasterPipeline.h"
+
+#include <forward_list>
+#include <functional>
+#include <vector>
+
+class SkColorSpace_A2B;
+class SkColorSpace_XYZ;
+
+
+class SkColorSpaceXform_A2B : public SkColorSpaceXform_Base {
+public:
+    bool onApply(ColorFormat dstFormat, void* dst, ColorFormat srcFormat, const void* src,
+                 int count, SkAlphaType alphaType) const override;
+
+private:
+    SkColorSpaceXform_A2B(SkColorSpace_A2B* srcSpace, SkColorSpace_XYZ* dstSpace);
+
+    enum Channels {
+        kRGB_Channels = -1,
+        kR_Channels   =  0,
+        kG_Channels   =  1,
+        kB_Channels   =  2
+    };
+    void addGamma(std::function<float(float)> fn, Channels channels);
+
+    void addMatrix(const SkMatrix44& matrix);
+
+    SkRasterPipeline                               fElementsPipeline;
+    bool                                           fLinearDstGamma;
+    // storage used by the pipeline
+    std::forward_list<std::function<float(float)>> fGammaFunctions;
+    std::forward_list<std::vector<float>>          fMatrices;
+    std::forward_list<std::vector<float>>          fGammaTables;
+    std::vector<sk_sp<const SkColorLookUpTable>>   fCLUTs;
+    // these are here to maintain ownership of tables used in the pipeline
+    std::vector<sk_sp<const SkGammas>>             fGammaRefs;
+
+    friend class SkColorSpaceXform;
+};
+
+#endif