Use the correct dataspace in shaders.cpp

This improves the quality of HDR->SDR tone-mapping in TextureView by
removing an incorrect gamut mapping which was causing undesired hue
shift.

The technical detail is that in TextureView, skia will color manage the
input image to the destination colorspace prior to tone-mapping. The
tone-mapping shader library compensates when authoring the shader to use
the correct EOTF when re-decoding the image, but did not compensate when
binding uniforms. This patch compensates accordingly so that the correct
gamut->gamut mapping is applied.

This patch adds a brief test suite for libshaders to verify that the
correct color gamut matrices are being selected.

Bug: 234355355
Test: Observe accurate HLG colors in Photos and Instagram where
TextureView is used for media playback.
Test: libshaders_test

Change-Id: I801349cfe1780880a55528fd7e91ff1ac553281b

4 files changed, 163 insertions, 2 deletions

diff --git a/libs/shaders/TEST_MAPPING b/libs/shaders/TEST_MAPPING
new file mode 100644
index 0000000000..ad6514d201
--- /dev/null
+++ b/libs/shaders/TEST_MAPPING
@@ -0,0 +1,10 @@
+{
+  "presubmit": [
+    {
+      "name": "librenderengine_test"
+    },
+    {
+      "name": "libshaders_test"
+    }
+  ]
+}
diff --git a/libs/shaders/shaders.cpp b/libs/shaders/shaders.cpp
index 62745dc8d5..f80e93f6f8 100644
--- a/libs/shaders/shaders.cpp
+++ b/libs/shaders/shaders.cpp
@@ -469,12 +469,17 @@ std::vector<tonemap::ShaderUniform> buildLinearEffectUniforms(
         float currentDisplayLuminanceNits, float maxLuminance, AHardwareBuffer* buffer,
         aidl::android::hardware::graphics::composer3::RenderIntent renderIntent) {
     std::vector<tonemap::ShaderUniform> uniforms;
-    if (linearEffect.inputDataspace == linearEffect.outputDataspace) {
+
+    const ui::Dataspace inputDataspace = linearEffect.fakeInputDataspace == ui::Dataspace::UNKNOWN
+            ? linearEffect.inputDataspace
+            : linearEffect.fakeInputDataspace;
+
+    if (inputDataspace == linearEffect.outputDataspace) {
         uniforms.push_back({.name = "in_rgbToXyz", .value = buildUniformValue<mat4>(mat4())});
         uniforms.push_back(
                 {.name = "in_xyzToRgb", .value = buildUniformValue<mat4>(colorTransform)});
     } else {
-        ColorSpace inputColorSpace = toColorSpace(linearEffect.inputDataspace);
+        ColorSpace inputColorSpace = toColorSpace(inputDataspace);
         ColorSpace outputColorSpace = toColorSpace(linearEffect.outputDataspace);
         uniforms.push_back({.name = "in_rgbToXyz",
                             .value = buildUniformValue<mat4>(mat4(inputColorSpace.getRGBtoXYZ()))});
diff --git a/libs/shaders/tests/Android.bp b/libs/shaders/tests/Android.bp
new file mode 100644
index 0000000000..cf671bcb7a
--- /dev/null
+++ b/libs/shaders/tests/Android.bp
@@ -0,0 +1,48 @@
+// Copyright 2022 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package {
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "frameworks_native_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-Apache-2.0
+    default_applicable_licenses: ["frameworks_native_license"],
+}
+
+cc_test {
+    name: "libshaders_test",
+    test_suites: ["device-tests"],
+    srcs: [
+        "shaders_test.cpp",
+    ],
+    header_libs: [
+        "libtonemap_headers",
+    ],
+    shared_libs: [
+        "android.hardware.graphics.common-V3-ndk",
+        "android.hardware.graphics.composer3-V1-ndk",
+        "android.hardware.graphics.common@1.2",
+        "libnativewindow",
+    ],
+    static_libs: [
+        "libarect",
+        "libgmock",
+        "libgtest",
+        "libmath",
+        "libshaders",
+        "libtonemap",
+        "libui-types",
+    ],
+}
diff --git a/libs/shaders/tests/shaders_test.cpp b/libs/shaders/tests/shaders_test.cpp
new file mode 100644
index 0000000000..d45fb246c7
--- /dev/null
+++ b/libs/shaders/tests/shaders_test.cpp
@@ -0,0 +1,98 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "shaders/shaders.h"
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <math/mat4.h>
+#include <tonemap/tonemap.h>
+#include <ui/ColorSpace.h>
+#include <cmath>
+
+namespace android {
+
+using testing::Contains;
+using testing::HasSubstr;
+
+struct ShadersTest : public ::testing::Test {};
+
+namespace {
+
+MATCHER_P2(UniformEq, name, value, "") {
+    return arg.name == name && arg.value == value;
+}
+
+template <typename T, std::enable_if_t<std::is_trivially_copyable<T>::value, bool> = true>
+std::vector<uint8_t> buildUniformValue(T value) {
+    std::vector<uint8_t> result;
+    result.resize(sizeof(value));
+    std::memcpy(result.data(), &value, sizeof(value));
+    return result;
+}
+
+} // namespace
+
+TEST_F(ShadersTest, buildLinearEffectUniforms_selectsNoOpGamutMatrices) {
+    shaders::LinearEffect effect =
+            shaders::LinearEffect{.inputDataspace = ui::Dataspace::V0_SRGB_LINEAR,
+                                  .outputDataspace = ui::Dataspace::V0_SRGB_LINEAR,
+                                  .fakeInputDataspace = ui::Dataspace::UNKNOWN};
+
+    mat4 colorTransform = mat4::scale(vec4(.9, .9, .9, 1.));
+    auto uniforms =
+            shaders::buildLinearEffectUniforms(effect, colorTransform, 1.f, 1.f, 1.f, nullptr,
+                                               aidl::android::hardware::graphics::composer3::
+                                                       RenderIntent::COLORIMETRIC);
+    EXPECT_THAT(uniforms, Contains(UniformEq("in_rgbToXyz", buildUniformValue<mat4>(mat4()))));
+    EXPECT_THAT(uniforms,
+                Contains(UniformEq("in_xyzToRgb", buildUniformValue<mat4>(colorTransform))));
+}
+
+TEST_F(ShadersTest, buildLinearEffectUniforms_selectsGamutTransformMatrices) {
+    shaders::LinearEffect effect =
+            shaders::LinearEffect{.inputDataspace = ui::Dataspace::V0_SRGB,
+                                  .outputDataspace = ui::Dataspace::DISPLAY_P3,
+                                  .fakeInputDataspace = ui::Dataspace::UNKNOWN};
+
+    ColorSpace inputColorSpace = ColorSpace::sRGB();
+    ColorSpace outputColorSpace = ColorSpace::DisplayP3();
+    auto uniforms =
+            shaders::buildLinearEffectUniforms(effect, mat4(), 1.f, 1.f, 1.f, nullptr,
+                                               aidl::android::hardware::graphics::composer3::
+                                                       RenderIntent::COLORIMETRIC);
+    EXPECT_THAT(uniforms,
+                Contains(UniformEq("in_rgbToXyz",
+                                   buildUniformValue<mat4>(mat4(inputColorSpace.getRGBtoXYZ())))));
+    EXPECT_THAT(uniforms,
+                Contains(UniformEq("in_xyzToRgb",
+                                   buildUniformValue<mat4>(mat4(outputColorSpace.getXYZtoRGB())))));
+}
+
+TEST_F(ShadersTest, buildLinearEffectUniforms_respectsFakeInputDataspace) {
+    shaders::LinearEffect effect =
+            shaders::LinearEffect{.inputDataspace = ui::Dataspace::V0_SRGB,
+                                  .outputDataspace = ui::Dataspace::DISPLAY_P3,
+                                  .fakeInputDataspace = ui::Dataspace::DISPLAY_P3};
+
+    auto uniforms =
+            shaders::buildLinearEffectUniforms(effect, mat4(), 1.f, 1.f, 1.f, nullptr,
+                                               aidl::android::hardware::graphics::composer3::
+                                                       RenderIntent::COLORIMETRIC);
+    EXPECT_THAT(uniforms, Contains(UniformEq("in_rgbToXyz", buildUniformValue<mat4>(mat4()))));
+    EXPECT_THAT(uniforms, Contains(UniformEq("in_xyzToRgb", buildUniformValue<mat4>(mat4()))));
+}
+
+} // namespace android