[YUV AHB] Add PredefinedColorSpace::Rec2020Linear

Fixed: 521496029
Change-Id: Ifcb9f95d7c00ba2ba707ae996d7ade369d859f0f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/314875
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>

src/dawn/common/ExternalTextureParams.cpp

diff --git a/src/dawn/common/ExternalTextureParams.cpp b/src/dawn/common/ExternalTextureParams.cpp
index cf62975..3517345 100644
--- a/src/dawn/common/ExternalTextureParams.cpp
+++ b/src/dawn/common/ExternalTextureParams.cpp
@@ -40,7 +40,7 @@
 //   }
 //   return (B + exp((v - C) / A)) / F
 constexpr TransferFunction kEOTF_HLG = {
-    .g = -1,  // Mode HLG see XXX
+    .g = -1,  // Mode HLG see src/dawn/native/ExternalTexture.cpp
     .a = 0.17883277,
     .b = 0.28466892,
     .c = 0.55991073,
@@ -57,7 +57,7 @@
 //   v = max(v - C, 0) / (D - E * v)
 //   return pow(v, 1.0 / A)
 constexpr TransferFunction kEOTF_PQ = {
-    .g = -2,  // Mode HLG see XXX
+    .g = -2,  // Mode PQ see src/dawn/native/ExternalTexture.cpp
     .a = (2610.0 / 16384.0),
     .b = (2523.0 / 4096.0) * 128.0,
     .c = (3424.0 / 4096.0),
@@ -172,6 +172,10 @@
             dstXYZToRGB = kXYZToRGB_DisplayP3;
             dstOETF = kEOTF_Identity;
             break;
+        case wgpu::PredefinedColorSpace::Rec2020Linear:
+            dstXYZToRGB = kXYZToRGB_Rec2020;
+            dstOETF = kEOTF_Identity;
+            break;
         default:
             return wgpu::Status::Error;
     }

src/dawn/dawn.json

diff --git a/src/dawn/dawn.json b/src/dawn/dawn.json
index b5ec9a2..038434f 100644
--- a/src/dawn/dawn.json
+++ b/src/dawn/dawn.json
@@ -4045,7 +4045,8 @@
             {"value": 1, "name": "sRGB"},
             {"value": 2, "name": "display p3"},
             {"value": 3, "name": "sRGB linear", "tags": ["dawn", "art"]},
-            {"value": 4, "name": "display p3 linear", "tags": ["dawn", "art"]}
+            {"value": 4, "name": "display p3 linear", "tags": ["dawn", "art"]},
+            {"value": 5, "name": "rec 2020 linear", "tags": ["dawn", "art"]}
         ]
     },
     "tone mapping mode": {

src/dawn/tests/end2end/ExternalTextureTests.cpp

diff --git a/src/dawn/tests/end2end/ExternalTextureTests.cpp b/src/dawn/tests/end2end/ExternalTextureTests.cpp
index 0d2538f..6db09a0 100644
--- a/src/dawn/tests/end2end/ExternalTextureTests.cpp
+++ b/src/dawn/tests/end2end/ExternalTextureTests.cpp
@@ -2046,6 +2046,17 @@
         wgpu::PredefinedColorSpace::SRGBLinear, {0.75, 0.75, 0.75, 1}, {1, 1, 1});
 }
 
+// Test that PredefinedColorSpace::Rec2020Linear is the same color space as using primaries of
+// Rec2020 and an identity transfer function. (the Rec2020 primaries are tested as part of the PQ
+// and HLG tests above).
+TEST_P(ExternalTextureTests, ColorSpaceConversion_Rec2020_Rec2020Linear) {
+    CheckColorSpaceConversion(
+        {
+            .primaries = wgpu::ColorSpacePrimariesDawn::Rec2020,
+        },
+        wgpu::PredefinedColorSpace::Rec2020Linear, {0.4, 0.2, 0.1, 1}, {0.4, 0.2, 0.1});
+}
+
 // TODO(https://crbug.com/468988322): Add tests of ExternalTextures being used with a resource table
 // and with Vulkan's extended dynamic state as these are other interactions that could easily break.