color: Towards ColorTransform optimizations and code generation

ui/gfx/color_transform.h

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_COLOR_TRANSFORM_H_
 #define UI_GFX_COLOR_TRANSFORM_H_
 
+#include <list>
 #include <memory>
-#include <stdint.h>
 
 #include "build/build_config.h"
 #include "ui/gfx/color_space.h"
 #include "ui/gfx/geometry/point3_f.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 class GFX_EXPORT ColorTransform {
  public:
   enum class Intent { INTENT_ABSOLUTE, INTENT_PERCEPTUAL, TEST_NO_OPT };
+  class Step;
 
   // TriStimulus is a color coordinate in any color space.
   // Channel order is XYZ, RGB or YUV.
   typedef Point3F TriStim;
 
-  virtual ~ColorTransform() {}
+  ~ColorTransform();
 
   // Perform transformation of colors, |colors| is both input and output.
-  virtual void transform(TriStim* colors, size_t num) = 0;
+  void transform(TriStim* colors, size_t num);

[hubbe, 2017/02/13 22:03:18]

I'm not a big fan of this, because it makes it impossible to extend the
ColorTransform class.

 
   static std::unique_ptr<ColorTransform> NewColorTransform(
       const ColorSpace& from,
       const ColorSpace& to,
       Intent intent);
 
-  static float ToLinearForTesting(ColorSpace::TransferID id, float v);
-  static float FromLinearForTesting(ColorSpace::TransferID id, float v);
+  size_t NumberOfStepsForTesting() { return steps_.size(); }
+
+ private:
+  typedef std::list<std::unique_ptr<Step>> StepList;
+  StepList steps_;
+
+  ColorTransform(StepList);
+  static void Append(ColorSpace from,
+                     const ColorSpace& to,
+                     ColorTransform::Intent intent,
+                     StepList* builder);
+  static void Simplify(StepList* steps);
 };
+
 }  // namespace gfx
 
 #endif  // UI_GFX_COLOR_TRANSFORM_H_