color: Towards ColorTransform optimizations and code generation

ui/gfx/color_space.cc

 // 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.
 
 #include "ui/gfx/color_space.h"
 
 #include <map>
 
 #include "base/lazy_instance.h"
 #include "base/synchronization/lock.h"
 #include "third_party/skia/include/core/SkColorSpace.h"
 #include "ui/gfx/icc_profile.h"
+#include "ui/gfx/skia_color_space_util.h"
 #include "ui/gfx/transform.h"
 
 namespace gfx {
 
-namespace {
-
-SkColorSpaceTransferFn InvertTransferFn(SkColorSpaceTransferFn fn) {
-  SkColorSpaceTransferFn fn_inv = {0};
-  if (fn.fA > 0 && fn.fG > 0) {
-    double a_to_the_g = pow(fn.fA, fn.fG);
-    fn_inv.fA = 1.f / a_to_the_g;
-    fn_inv.fB = -fn.fE / a_to_the_g;
-    fn_inv.fG = 1.f / fn.fG;
-  }
-  fn_inv.fD = fn.fC * fn.fD + fn.fF;
-  fn_inv.fE = -fn.fB / fn.fA;
-  if (fn.fC != 0) {
-    fn_inv.fC = 1.f / fn.fC;
-    fn_inv.fF = -fn.fF / fn.fC;
-  }
-  return fn_inv;
-}
-};
-
 ColorSpace::PrimaryID ColorSpace::PrimaryIDFromInt(int primary_id) {
   if (primary_id < 0 || primary_id > static_cast<int>(PrimaryID::LAST))
     return PrimaryID::UNKNOWN;
   if (primary_id > static_cast<int>(PrimaryID::LAST_STANDARD_VALUE) &&
       primary_id < 1000)
     return PrimaryID::UNKNOWN;
   return static_cast<PrimaryID>(primary_id);
 }
 
 ColorSpace::TransferID ColorSpace::TransferIDFromInt(int transfer_id) {
@@ skipping 432 matching lines @@
     case ColorSpace::TransferID::SMPTEST2084_NON_HDR:
       break;
   }
 
   return false;
 }
 
 bool ColorSpace::GetInverseTransferFunction(SkColorSpaceTransferFn* fn) const {
   if (!GetTransferFunction(fn))
     return false;
-  *fn = InvertTransferFn(*fn);
+  *fn = SkTransferFnInverse(*fn);
   return true;
 }
 
 void ColorSpace::GetTransferMatrix(SkMatrix44* matrix) const {
   float Kr = 0;
   float Kb = 0;
   switch (matrix_) {
     case ColorSpace::MatrixID::RGB:
       matrix->setIdentity();
       return;
@@ skipping 107 matching lines @@
     case MatrixID::BT2020_CL:
     case MatrixID::YDZDX:
     case MatrixID::UNKNOWN:
       matrix->setScale(255.0f/219.0f, 255.0f/224.0f, 255.0f/224.0f);
       matrix->postTranslate(-16.0f/219.0f, -15.5f/224.0f, -15.5f/224.0f);
       break;
   }
 }
 
 }  // namespace gfx