[ColorWidget] Synchronize color model with color ramp one

python/PyQt6/gui/auto_generated/qgscompoundcolorwidget.sip.in

@@ -52,6 +52,16 @@ Sets whether opacity modification (transparency) is permitted
 for the color dialog. Defaults to ``True``.
 
 :param allowOpacity: set to ``False`` to disable opacity modification
+%End
+
+    void setColorModelEditable( bool colorModelEditable );
+%Docstring
+Sets whether color model is editable or not
+
+:param colorModelEditable: set to ``False`` to disable color model modification
+                           Defaults to ``True``.
+
+.. versionadded:: 3.40
 %End
 
     void setDiscarded( bool discarded );

python/gui/auto_generated/qgscompoundcolorwidget.sip.in

@@ -52,6 +52,16 @@ Sets whether opacity modification (transparency) is permitted
 for the color dialog. Defaults to ``True``.
 
 :param allowOpacity: set to ``False`` to disable opacity modification
+%End
+
+    void setColorModelEditable( bool colorModelEditable );
+%Docstring
+Sets whether color model is editable or not
+
+:param colorModelEditable: set to ``False`` to disable color model modification
+                           Defaults to ``True``.
+
+.. versionadded:: 3.40
 %End
 
     void setDiscarded( bool discarded );

src/gui/qgscompoundcolorwidget.cpp

@@ -346,6 +346,11 @@ void QgsCompoundColorWidget::setAllowOpacity( const bool allowOpacity )
   }
 }
 
+void QgsCompoundColorWidget::setColorModelEditable( bool colorModelEditable )
+{
+  mColorModel->setVisible( colorModelEditable );
+}
+
 void QgsCompoundColorWidget::refreshSchemeComboBox()
 {
   mSchemeComboBox->blockSignals( true );

src/gui/qgscompoundcolorwidget.h

@@ -20,6 +20,7 @@
 #include "qgspanelwidget.h"
 #include "ui_qgscompoundcolorwidget.h"
 #include "qgis_gui.h"
+#include "qgis.h"
 
 class QgsScreenHelper;
 
@@ -67,6 +68,14 @@ class GUI_EXPORT QgsCompoundColorWidget : public QgsPanelWidget, private Ui::Qgs
      */
     void setAllowOpacity( bool allowOpacity );
 
+    /**
+     * Sets whether color model is editable or not
+     * \param colorModelEditable set to FALSE to disable color model modification
+     * Defaults to TRUE.
+     * \since QGIS 3.40
+     */
+    void setColorModelEditable( bool colorModelEditable );
+
     /**
      * Sets whether the widget's color has been "discarded" and the selected color should not
      * be stored in the recent color list.

src/gui/qgsgradientcolorrampdialog.cpp

@@ -53,9 +53,12 @@ QgsGradientColorRampDialog::QgsGradientColorRampDialog( const QgsGradientColorRa
   setupUi( this );
   QgsGui::enableAutoGeometryRestore( this );
 
+  mColorWidget->setColorModelEditable( false );
+
   mStopColorSpec->addItem( tr( "RGB" ), static_cast< int >( QColor::Spec::Rgb ) );
   mStopColorSpec->addItem( tr( "HSV" ), static_cast< int >( QColor::Spec::Hsv ) );
   mStopColorSpec->addItem( tr( "HSL" ), static_cast< int >( QColor::Spec::Hsl ) );
+  mStopColorSpec->addItem( tr( "CMYK" ), static_cast< int >( QColor::Spec::Cmyk ) );
   mStopColorSpec->setCurrentIndex( mStopColorSpec->findData( static_cast< int >( ramp.colorSpec() ) ) );
 
   mStopDirection->addItem( tr( "Clockwise" ), static_cast< int >( Qgis::AngularDirection::Clockwise ) );
@@ -66,11 +69,18 @@ QgsGradientColorRampDialog::QgsGradientColorRampDialog( const QgsGradientColorRa
 
   connect( mStopColorSpec, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, [ = ]
   {
-    mStopDirection->setEnabled( static_cast< QColor::Spec>( mStopColorSpec->currentData().toInt() ) != QColor::Spec::Rgb );
+    const QColor::Spec colorSpec = static_cast< QColor::Spec>( mStopColorSpec->currentData().toInt() );
+    mStopDirection->setEnabled( colorSpec != QColor::Spec::Rgb );
+
+    if ( colorSpec != mColorWidget->color().spec() )
+    {
+      mColorWidget->setColor( mColorWidget->color().convertTo( colorSpec ) );
+    }
 
     if ( mBlockChanges )
       return;
-    mStopEditor->setSelectedStopColorSpec( static_cast< QColor::Spec>( mStopColorSpec->currentData().toInt() ) );
+
+    mStopEditor->setSelectedStopColorSpec( colorSpec );
   } );
 
   connect( mStopDirection, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, [ = ]

tests/src/gui/testqgscompoundcolorwidget.cpp

@@ -201,6 +201,18 @@ void TestQgsCompoundColorWidget::testModelChange()
 
   w.setColor( QColor( 1, 2, 3 ) );
   QCOMPARE( w.mColorModel->currentData(), QColor::Rgb );
+
+  w.setColor( QColor::fromCmykF( 0.5, 0.1, 0.2, 0.3 ) );
+  QCOMPARE( w.mColorModel->currentData(), QColor::Cmyk );
+
+  w.setColor( QColor::fromHsvF( 0.5, 0.1, 0.2 ) );
+  QCOMPARE( w.mColorModel->currentData(), QColor::Rgb );
+
+  QVERIFY( w.mColorModel->isVisible() );
+  w.setColorModelEditable( false );
+  QVERIFY( !w.mColorModel->isVisible() );
+  w.setColorModelEditable( true );
+  QVERIFY( w.mColorModel->isVisible() );
 }
 
 void TestQgsCompoundColorWidget::testTabChange()