Add support for setting the color model to use when interpolating a

gradient ramp Some gradients will pass through murky grey mid-tones when interpolating using red/green/blue channels. Interpolating via hue/saturation/lightness/value channels can avoid these desaturated mid tones, resulting in more visually pleasing gradients. The color spec can be set per stop in a multi-stop gradient, and there's also an option to control the direction which interpolation should follow for the Hue component of a HSL/HSV color spec interpolation. Sponsored by North Road, thanks to SLYR
qgis · Nov 10, 2021 · acabfb3 · acabfb3
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diff --git a/python/core/auto_generated/qgscolorrampimpl.sip.in b/python/core/auto_generated/qgscolorrampimpl.sip.in
@@ -8,6 +8,7 @@
 
 
 
+
 class QgsGradientStop
 {
 %Docstring(signature="appended")
@@ -33,6 +34,61 @@ Constructor for QgsGradientStop
     QColor color;
 
     bool operator==( const QgsGradientStop &other ) const;
+
+    bool operator!=( const QgsGradientStop &other ) const;
+
+    QColor::Spec colorSpec() const;
+%Docstring
+Returns the color specification in which the color component interpolation will occur.
+
+For multi-stop gradients this color spec will be used for the portion of the color ramp
+leading into the current stop.
+
+.. seealso:: :py:func:`setColorSpec`
+
+.. versionadded:: 3.24
+%End
+
+    void setColorSpec( QColor::Spec spec );
+%Docstring
+Sets the color specification in which the color component interpolation will occur.
+
+Only QColor.Spec.Rgb, QColor.Spec.Hsv and QColor.Spec.Hsl are currently supported.
+
+For multi-stop gradients this color spec will be used for the portion of the color ramp
+leading into the current stop.
+
+.. seealso:: :py:func:`colorSpec`
+
+.. versionadded:: 3.24
+%End
+
+    Qgis::AngularDirection direction() const;
+%Docstring
+Returns the direction to traverse the color wheel using when interpolating hue-based color
+specifications.
+
+For multi-stop gradients this direction will be used for the portion of the color ramp
+leading into the current stop.
+
+.. seealso:: :py:func:`setDirection`
+
+.. versionadded:: 3.24
+%End
+
+    void setDirection( Qgis::AngularDirection direction );
+%Docstring
+Sets the ``direction`` to traverse the color wheel using when interpolating hue-based color
+specifications.
+
+For multi-stop gradients this direction will be used for the portion of the color ramp
+leading into the current stop.
+
+.. seealso:: :py:func:`direction`
+
+.. versionadded:: 3.24
+%End
+
 };
 
 typedef QList<QgsGradientStop> QgsGradientStopsList;
@@ -207,9 +263,62 @@ Copy color ramp stops to a QGradient
                 by this factor before adding to the gradient.
 
 .. versionadded:: 2.1
+%End
+
+    QColor::Spec colorSpec() const;
+%Docstring
+Returns the color specification in which the color component interpolation will occur.
+
+For multi-stop gradients this color spec will be used for the portion of the color ramp
+leading into the final stop (i.e. :py:func:`~QgsGradientColorRamp.color2`).
+
+.. seealso:: :py:func:`setColorSpec`
+
+.. versionadded:: 3.24
+%End
+
+    void setColorSpec( QColor::Spec spec );
+%Docstring
+Sets the color specification in which the color component interpolation will occur.
+
+Only QColor.Spec.Rgb, QColor.Spec.Hsv and QColor.Spec.Hsl are currently supported.
+
+For multi-stop gradients this color spec will be used for the portion of the color ramp
+leading into the final stop (i.e. :py:func:`~QgsGradientColorRamp.color2`).
+
+.. seealso:: :py:func:`colorSpec`
+
+.. versionadded:: 3.24
+%End
+
+    Qgis::AngularDirection direction() const;
+%Docstring
+Returns the direction to traverse the color wheel using when interpolating hue-based color
+specifications.
+
+For multi-stop gradients this direction will be used for the portion of the color ramp
+leading into the final stop (i.e. :py:func:`~QgsGradientColorRamp.color2`).
+
+.. seealso:: :py:func:`setDirection`
+
+.. versionadded:: 3.24
+%End
+
+    void setDirection( Qgis::AngularDirection direction );
+%Docstring
+Sets the ``direction`` to traverse the color wheel using when interpolating hue-based color
+specifications.
+
+For multi-stop gradients this direction will be used for the portion of the color ramp
+leading into the final stop (i.e. :py:func:`~QgsGradientColorRamp.color2`).
+
+.. seealso:: :py:func:`direction`
+
+.. versionadded:: 3.24
 %End
 
   protected:
+
 };
 
 

diff --git a/python/gui/auto_generated/qgsgradientstopeditor.sip.in b/python/gui/auto_generated/qgsgradientstopeditor.sip.in
@@ -96,6 +96,20 @@ first or last stop is selected, as they cannot be repositioned.
 .. seealso:: :py:func:`setSelectedStopColor`
 
 .. seealso:: :py:func:`setSelectedStopDetails`
+%End
+
+    void setSelectedStopColorSpec( QColor::Spec spec );
+%Docstring
+Sets the color ``spec`` for the current selected stop.
+
+.. versionadded:: 3.24
+%End
+
+    void setSelectedStopDirection( Qgis::AngularDirection direction );
+%Docstring
+Sets the hue angular direction for the current selected stop.
+
+.. versionadded:: 3.24
 %End
 
     void setSelectedStopDetails( const QColor &color, double offset );