core/colorspace: move Colorimetry::toOther to ColorDescription

With some rendering intents we need to apply behavior based on brightness levels
or the SDR colorimetry

autotests/test_colorspaces.cpp

@@ -85,8 +85,8 @@ void TestColorspaces::roundtripConversion()
 void TestColorspaces::nonNormalizedPrimaries()
 {
     // this test ensures that non-normalized primaries don't mess up the transformations between color spaces
-    const auto from = Colorimetry::fromName(NamedColorimetry::BT709);
-    const auto to = Colorimetry(Colorimetry::xyToXYZ(from.red()) * 2, Colorimetry::xyToXYZ(from.green()) * 2, Colorimetry::xyToXYZ(from.blue()) * 2, Colorimetry::xyToXYZ(from.white()) * 2);
+    const auto &from = ColorDescription::sRGB;
+    const ColorDescription to(Colorimetry(Colorimetry::xyToXYZ(from.containerColorimetry().red()) * 2, Colorimetry::xyToXYZ(from.containerColorimetry().green()) * 2, Colorimetry::xyToXYZ(from.containerColorimetry().blue()) * 2, Colorimetry::xyToXYZ(from.containerColorimetry().white()) * 2), from.transferFunction(), from.referenceLuminance(), from.minLuminance(), from.maxAverageLuminance(), from.maxHdrLuminance());
 
     const auto convertedWhite = from.toOther(to, RenderingIntent::RelativeColorimetric) * QVector3D(1, 1, 1);
     QCOMPARE_LE(std::abs(1 - convertedWhite.x()), s_resolution10bit);

src/backends/drm/drm_output.cpp

@@ -517,7 +517,7 @@ bool DrmOutput::needsChannelFactorFallback() const
 
 QVector3D DrmOutput::effectiveChannelFactors() const
 {
-    QVector3D adaptedChannelFactors = Colorimetry::fromName(NamedColorimetry::BT709).toOther(m_state.colorDescription.containerColorimetry(), RenderingIntent::RelativeColorimetric) * m_channelFactors;
+    QVector3D adaptedChannelFactors = ColorDescription::sRGB.toOther(colorDescription(), RenderingIntent::RelativeColorimetric) * m_channelFactors;
     // normalize red to be the original brightness value again
     adaptedChannelFactors *= m_channelFactors.x() / adaptedChannelFactors.x();
     if (m_state.highDynamicRange || !m_brightnessDevice) {

src/core/colorpipeline.cpp

@@ -23,7 +23,7 @@ ColorPipeline ColorPipeline::create(const ColorDescription &from, const ColorDes
 
     // FIXME this assumes that the range stays the same with matrix multiplication
     // that's not necessarily true, and figuring out the actual range could be complicated..
-    ret.addMatrix(from.containerColorimetry().toOther(to.containerColorimetry(), intent), ret.currentOutputRange());
+    ret.addMatrix(from.toOther(to, intent), ret.currentOutputRange());
 
     ret.addInverseTransferFunction(to.transferFunction());
     return ret;

src/core/colorspace.cpp

@@ -126,18 +126,6 @@ const QMatrix4x4 &Colorimetry::fromXYZ() const
     return m_fromXYZ;
 }
 
-QMatrix4x4 Colorimetry::toOther(const Colorimetry &other, RenderingIntent intent) const
-{
-    switch (intent) {
-    case RenderingIntent::Perceptual:
-    case RenderingIntent::RelativeColorimetric:
-        return other.fromXYZ() * chromaticAdaptationMatrix(this->white(), other.white()) * toXYZ();
-    case RenderingIntent::AbsoluteColorimetric:
-        return other.fromXYZ() * toXYZ();
-    }
-    Q_UNREACHABLE();
-}
-
 Colorimetry Colorimetry::adaptedTo(QVector2D newWhitepoint) const
 {
     const auto mat = chromaticAdaptationMatrix(this->white(), newWhitepoint);
@@ -273,11 +261,26 @@ std::optional<double> ColorDescription::maxHdrLuminance() const
     return m_maxHdrLuminance;
 }
 
+QMatrix4x4 ColorDescription::toOther(const ColorDescription &other, RenderingIntent intent) const
+{
+    switch (intent) {
+    case RenderingIntent::Perceptual: {
+        const Colorimetry &srcContainer = containerColorimetry() == NamedColorimetry::BT709 ? other.sdrColorimetry() : containerColorimetry();
+        return other.containerColorimetry().fromXYZ() * Colorimetry::chromaticAdaptationMatrix(srcContainer.white(), other.containerColorimetry().white()) * srcContainer.toXYZ();
+    }
+    case RenderingIntent::RelativeColorimetric:
+        return other.containerColorimetry().fromXYZ() * Colorimetry::chromaticAdaptationMatrix(containerColorimetry().white(), other.containerColorimetry().white()) * containerColorimetry().toXYZ();
+    case RenderingIntent::AbsoluteColorimetric:
+        return other.containerColorimetry().fromXYZ() * containerColorimetry().toXYZ();
+    }
+    Q_UNREACHABLE();
+}
+
 QVector3D ColorDescription::mapTo(QVector3D rgb, const ColorDescription &dst, RenderingIntent intent) const
 {
     rgb = m_transferFunction.encodedToNits(rgb);
     rgb *= dst.referenceLuminance() / m_referenceLuminance;
-    rgb = m_containerColorimetry.toOther(dst.containerColorimetry(), intent) * rgb;
+    rgb = toOther(dst, intent) * rgb;
     return dst.transferFunction().nitsToEncoded(rgb);
 }
 

src/core/colorspace.h

@@ -70,10 +70,6 @@ public:
      * @returns a matrix that transforms from the XYZ representation to the linear RGB representation of colors in this colorimetry
      */
     const QMatrix4x4 &fromXYZ() const;
-    /**
-     * @returns a matrix that transforms from linear RGB in this colorimetry to linear RGB in the other colorimetry
-     */
-    QMatrix4x4 toOther(const Colorimetry &colorimetry, RenderingIntent intent) const;
     bool operator==(const Colorimetry &other) const;
     bool operator==(NamedColorimetry name) const;
     /**
@@ -179,9 +175,14 @@ public:
 
     bool operator==(const ColorDescription &other) const = default;
 
-    QVector3D mapTo(QVector3D rgb, const ColorDescription &other, RenderingIntent intent) const;
     ColorDescription withTransferFunction(const TransferFunction &func) const;
 
+    /**
+     * @returns a matrix that transforms from linear RGB in this color description to linear RGB in the other one
+     */
+    QMatrix4x4 toOther(const ColorDescription &other, RenderingIntent intent) const;
+    QVector3D mapTo(QVector3D rgb, const ColorDescription &other, RenderingIntent intent) const;
+
     /**
      * This color description describes display-referred sRGB, with a gamma22 transfer function
      */

src/opengl/glshader.cpp

@@ -471,8 +471,7 @@ QMatrix4x4 GLShader::getUniformMatrix4x4(const char *name)
 
 bool GLShader::setColorspaceUniforms(const ColorDescription &src, const ColorDescription &dst, RenderingIntent intent)
 {
-    const auto &srcColorimetry = intent == RenderingIntent::Perceptual && src.containerColorimetry() == NamedColorimetry::BT709 ? dst.sdrColorimetry() : src.containerColorimetry();
-    return setUniform(Mat4Uniform::ColorimetryTransformation, srcColorimetry.toOther(dst.containerColorimetry(), intent))
+    return setUniform(Mat4Uniform::ColorimetryTransformation, src.toOther(dst, intent))
         && setUniform(IntUniform::SourceNamedTransferFunction, src.transferFunction().type)
         && setUniform(Vec2Uniform::SourceTransferFunctionParams, QVector2D(src.transferFunction().minLuminance, src.transferFunction().maxLuminance - src.transferFunction().minLuminance))
         && setUniform(FloatUniform::SourceReferenceLuminance, src.referenceLuminance())