color: Use named gamuts in ToSkColorSpace

ui/gfx/color_space.cc

Index: ui/gfx/color_space.cc
diff --git a/ui/gfx/color_space.cc b/ui/gfx/color_space.cc
index 27a0f54364ac73b8e6a28919253bb1cf5f783e99..042900e0c49159652512c024fa4b2838c219bdb5 100644
--- a/ui/gfx/color_space.cc
+++ b/ui/gfx/color_space.cc
@@ -427,18 +427,47 @@ sk_sp<SkColorSpace> ColorSpace::ToSkColorSpace() const {
       return SkColorSpace::MakeSRGBLinear();
   }
 
-  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);
+  // 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;
   }
-  if (transfer_ == TransferID::LINEAR || transfer_ == TransferID::LINEAR_HDR) {
-    return SkColorSpace::MakeRGB(SkColorSpace::kLinear_RenderTargetGamma,
-                                 to_xyz_d50);
+  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);
+  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;