Towards deleting YUV to RGB computation redundancy

ui/gfx/color_space.h

 // Copyright (c) 2012 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_SPACE_H_
 #define UI_GFX_COLOR_SPACE_H_
 
 #include <stdint.h>
 
 #include "base/gtest_prod_util.h"
@@ skipping 160 matching lines @@
   bool IsHDR() const;
 
   // Note that this may return nullptr.
   sk_sp<SkColorSpace> ToSkColorSpace() const;
   static ColorSpace FromSkColorSpace(const sk_sp<SkColorSpace>& sk_color_space);
 
   void GetPrimaryMatrix(SkMatrix44* to_XYZD50) const;
   bool GetTransferFunction(SkColorSpaceTransferFn* fn) const;
   bool GetInverseTransferFunction(SkColorSpaceTransferFn* fn) const;
 
+  // For most formats, this is the RGB to YUV matrix.
+  void GetTransferMatrix(SkMatrix44* matrix) const;

[hubbe, 2017/02/02 04:51:37]

Maybe return a bool since this is not always possible?

[ccameron, 2017/02/02 17:33:52]

I was going back-and-forth on this, but in the end felt that it was more
appropriate to leave this together, since that's the structure that was already
present.

If we were to separate it out, I'd prefer that we put the full BT2020_CL
conversion in its own distinct function.

[hubbe, 2017/02/02 18:35:25]

Doing so would make the implementation a lot bigger and harder to optimize.

+  void GetRangeAdjustMatrix(SkMatrix44* matrix) const;
+
  private:
   PrimaryID primaries_ = PrimaryID::UNSPECIFIED;
   TransferID transfer_ = TransferID::UNSPECIFIED;
   MatrixID matrix_ = MatrixID::UNSPECIFIED;
   RangeID range_ = RangeID::LIMITED;
 
   // Only used if primaries_ is PrimaryID::CUSTOM.
   float custom_primary_matrix_[9] = {0, 0, 0, 0, 0, 0, 0, 0};
 
   // Only used if transfer_ is TransferID::CUSTOM. This array consists of the A
   // through G entries of the SkColorSpaceTransferFn structure in alphabetical
   // order.
   float custom_transfer_params_[7] = {0, 0, 0, 0, 0, 0, 0};
 
   // This is used to look up the ICCProfile from which this ColorSpace was
   // created, if possible.
   uint64_t icc_profile_id_ = 0;
   sk_sp<SkColorSpace> icc_profile_sk_color_space_;
 
   friend class ICCProfile;
   friend class ColorSpaceToColorSpaceTransform;
   friend class ColorSpaceWin;
   friend struct IPC::ParamTraits<gfx::ColorSpace>;
   FRIEND_TEST_ALL_PREFIXES(SimpleColorSpace, GetColorSpace);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_COLOR_SPACE_H_