color: Use named gamuts in ToSkColorSpace

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 <sstream>
 
 #include "base/lazy_instance.h"
@@ skipping 409 matching lines @@
   }
 
   // Use the named SRGB and linear-SRGB instead of the generic constructors.
   if (primaries_ == PrimaryID::BT709) {
     if (transfer_ == TransferID::IEC61966_2_1)
       return SkColorSpace::MakeSRGB();
     if (transfer_ == TransferID::LINEAR || transfer_ == TransferID::LINEAR_HDR)
       return SkColorSpace::MakeSRGBLinear();
   }
 
+  // Prefer to used the named gamma and gamut, if possible.
+  bool has_named_gamma = true;
+  SkColorSpace::RenderTargetGamma named_gamma =
+      SkColorSpace::kSRGB_RenderTargetGamma;
+  switch (transfer_) {
+    case TransferID::IEC61966_2_1:
+      break;
+    case TransferID::LINEAR:
+    case TransferID::LINEAR_HDR:
+      named_gamma = SkColorSpace::kLinear_RenderTargetGamma;
+      break;
+    default:
+      has_named_gamma = false;
+      break;
+  }
+  bool has_named_gamut = true;
+  SkColorSpace::Gamut named_gamut = SkColorSpace::kSRGB_Gamut;
+  switch (primaries_) {
+    case PrimaryID::BT709:
+      break;
+    case PrimaryID::ADOBE_RGB:
+      named_gamut = SkColorSpace::kAdobeRGB_Gamut;
+      break;
+    case PrimaryID::SMPTEST432_1:
+      named_gamut = SkColorSpace::kDCIP3_D65_Gamut;
+      break;
+    case PrimaryID::BT2020:
+      named_gamut = SkColorSpace::kRec2020_Gamut;
+      break;
+    default:
+      has_named_gamut = false;
+      break;
+  }
+  if (has_named_gamut && has_named_gamma)
+    return SkColorSpace::MakeRGB(named_gamma, named_gamut);
+
+  // Use named gamma with custom primaries, if possible.
   SkMatrix44 to_xyz_d50;
   GetPrimaryMatrix(&to_xyz_d50);
-
-  // Use the named sRGB and linear transfer functions.
-  if (transfer_ == TransferID::IEC61966_2_1) {
-    return SkColorSpace::MakeRGB(SkColorSpace::kSRGB_RenderTargetGamma,
-                                 to_xyz_d50);
-  }
-  if (transfer_ == TransferID::LINEAR || transfer_ == TransferID::LINEAR_HDR) {
-    return SkColorSpace::MakeRGB(SkColorSpace::kLinear_RenderTargetGamma,
-                                 to_xyz_d50);
-  }
+  if (has_named_gamma)
+    return SkColorSpace::MakeRGB(named_gamma, to_xyz_d50);

[msarett1, 2017/04/17 21:30:43]

Is there ever a case where has_named_gamut is true, but has_named_gamma is not?

[ccameron, 2017/04/17 23:08:05]

Good point -- added that case.

 
   // Use the parametric transfer function if no other option is available.
   SkColorSpaceTransferFn fn;
   if (!GetTransferFunction(&fn)) {
     DLOG(ERROR) << "Failed to parameterize transfer function for SkColorSpace";
     return nullptr;
   }
   return SkColorSpace::MakeRGB(fn, to_xyz_d50);
 }
 
@@ skipping 385 matching lines @@
       matrix->postTranslate(-16.0f/219.0f, -15.5f/224.0f, -15.5f/224.0f);
       break;
   }
 }
 
 std::ostream& operator<<(std::ostream& out, const ColorSpace& color_space) {
   return out << color_space.ToString();
 }
 
 }  // namespace gfx