autotests: add very basic ColorDescription mapping test

autotests/CMakeLists.txt

@@ -242,3 +242,14 @@ target_link_libraries(testOutputTransform
 )
 add_test(NAME kwin-testOutputTransform COMMAND testOutputTransform)
 ecm_mark_as_test(testOutputTransform)
+
+########################################################
+# Test Colorspace
+########################################################
+add_executable(testColorspaces test_colorspaces.cpp)
+target_link_libraries(testColorspaces
+    Qt::Test
+    kwin
+)
+add_test(NAME kwin-testColorspaces COMMAND testColorspaces)
+ecm_mark_as_test(testColorspaces)

autotests/test_colorspaces.cpp

@@ -0,0 +1,76 @@
+/*
+    SPDX-FileCopyrightText: 2023 Xaver Hugl <xaver.hugl@gmail.com>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+#include <QTest>
+
+#include "core/colorspace.h"
+
+using namespace KWin;
+
+class TestColorspaces : public QObject
+{
+    Q_OBJECT
+
+public:
+    TestColorspaces() = default;
+
+private Q_SLOTS:
+    void roundtripConversion_data();
+    void roundtripConversion();
+};
+
+static bool compareVectors(const QVector3D &one, const QVector3D &two, float maxDifference)
+{
+    const bool ret = std::abs(one.x() - two.x()) <= maxDifference
+        && std::abs(one.y() - two.y()) <= maxDifference
+        && std::abs(one.z() - two.z()) <= maxDifference;
+    if (!ret) {
+        qWarning() << one << "!=" << two << "within" << maxDifference;
+    }
+    return ret;
+}
+
+void TestColorspaces::roundtripConversion_data()
+{
+    QTest::addColumn<NamedColorimetry>("srcColorimetry");
+    QTest::addColumn<NamedTransferFunction>("srcTransferFunction");
+    QTest::addColumn<NamedColorimetry>("dstColorimetry");
+    QTest::addColumn<NamedTransferFunction>("dstTransferFunction");
+    QTest::addColumn<double>("requiredAccuracy");
+
+    const double resolution10bit = std::pow(1.0 / 2.0, 10);
+    QTest::addRow("BT709 (sRGB) <-> BT2020 (linear)") << NamedColorimetry::BT709 << NamedTransferFunction::sRGB << NamedColorimetry::BT2020 << NamedTransferFunction::linear << resolution10bit;
+    QTest::addRow("BT709 (gamma 2.2) <-> BT2020 (linear)") << NamedColorimetry::BT709 << NamedTransferFunction::gamma22 << NamedColorimetry::BT2020 << NamedTransferFunction::linear << resolution10bit;
+    QTest::addRow("BT709 (scRGB) <-> BT2020 (linear)") << NamedColorimetry::BT709 << NamedTransferFunction::scRGB << NamedColorimetry::BT2020 << NamedTransferFunction::linear << resolution10bit;
+    QTest::addRow("BT709 (linear) <-> BT2020 (linear)") << NamedColorimetry::BT709 << NamedTransferFunction::linear << NamedColorimetry::BT2020 << NamedTransferFunction::linear << resolution10bit;
+    QTest::addRow("BT709 (PQ) <-> BT2020 (linear)") << NamedColorimetry::BT709 << NamedTransferFunction::PerceptualQuantizer << NamedColorimetry::BT2020 << NamedTransferFunction::linear << 3 * resolution10bit;
+}
+
+void TestColorspaces::roundtripConversion()
+{
+    QFETCH(NamedColorimetry, srcColorimetry);
+    QFETCH(NamedTransferFunction, srcTransferFunction);
+    QFETCH(NamedColorimetry, dstColorimetry);
+    QFETCH(NamedTransferFunction, dstTransferFunction);
+    QFETCH(double, requiredAccuracy);
+
+    const auto src = ColorDescription(srcColorimetry, srcTransferFunction, 100, 0, 100, 100, 0);
+    const auto dst = ColorDescription(dstColorimetry, dstTransferFunction, 100, 0, 100, 100, 0);
+
+    const QVector3D red(1, 0, 0);
+    const QVector3D green(0, 1, 0);
+    const QVector3D blue(0, 0, 1);
+    const QVector3D white(1, 1, 1);
+
+    QVERIFY(compareVectors(dst.mapTo(src.mapTo(red, dst), src), red, requiredAccuracy));
+    QVERIFY(compareVectors(dst.mapTo(src.mapTo(green, dst), src), green, requiredAccuracy));
+    QVERIFY(compareVectors(dst.mapTo(src.mapTo(blue, dst), src), blue, requiredAccuracy));
+    QVERIFY(compareVectors(dst.mapTo(src.mapTo(white, dst), src), white, requiredAccuracy));
+}
+
+QTEST_MAIN(TestColorspaces)
+
+#include "test_colorspaces.moc"