[Backport release-3_40] Fix data-defined overrides ignored in legend text format

python/PyQt6/core/auto_generated/qgslegendsettings.sip.in

@@ -26,6 +26,14 @@ The content of the legend is driven by the :py:class:`QgsLegendModel` class.
   public:
     QgsLegendSettings();
 
+    void updateDataDefinedProperties( QgsRenderContext &context );
+%Docstring
+Updates any data-defined properties in the settings, using the specified
+render ``context``.
+
+.. versionadded:: 3.42
+%End
+
     void setTitle( const QString &t );
 %Docstring
 Sets the title for the legend, which will be rendered above all legend items.

python/PyQt6/core/auto_generated/qgslegendstyle.sip.in

@@ -161,6 +161,14 @@ Writes the component's style definition to an XML element.
 Reads the component's style definition from an XML element.
 
 .. seealso:: :py:func:`writeXml`
+%End
+
+    void updateDataDefinedProperties( QgsRenderContext &context );
+%Docstring
+Updates any data-defined properties in the style, using the specified
+render ``context``.
+
+.. versionadded:: 3.42
 %End
 
     static QString styleName( Style s );

python/core/auto_generated/qgslegendsettings.sip.in

@@ -26,6 +26,14 @@ The content of the legend is driven by the :py:class:`QgsLegendModel` class.
   public:
     QgsLegendSettings();
 
+    void updateDataDefinedProperties( QgsRenderContext &context );
+%Docstring
+Updates any data-defined properties in the settings, using the specified
+render ``context``.
+
+.. versionadded:: 3.42
+%End
+
     void setTitle( const QString &t );
 %Docstring
 Sets the title for the legend, which will be rendered above all legend items.

python/core/auto_generated/qgslegendstyle.sip.in

@@ -161,6 +161,14 @@ Writes the component's style definition to an XML element.
 Reads the component's style definition from an XML element.
 
 .. seealso:: :py:func:`writeXml`
+%End
+
+    void updateDataDefinedProperties( QgsRenderContext &context );
+%Docstring
+Updates any data-defined properties in the style, using the specified
+render ``context``.
+
+.. versionadded:: 3.42
 %End
 
     static QString styleName( Style s );

src/core/qgslegendrenderer.cpp

@@ -206,6 +206,8 @@ QSizeF QgsLegendRenderer::paintAndDetermineSize( QgsRenderContext &context )
   if ( !rootGroup )
     return size;
 
+  mSettings.updateDataDefinedProperties( context );
+
   // temporarily remove painter from context -- we don't need to actually draw anything yet. But we DO need
   // to send the full render context so that an expression context is available during the size calculation
   QgsScopedRenderContextPainterSwap noPainter( context, nullptr );

src/core/qgslegendsettings.cpp

@@ -64,6 +64,14 @@ QgsLegendSettings::QgsLegendSettings()
   rstyle( QgsLegendStyle::SymbolLabel ).setTextFormat( f );
 }
 
+void QgsLegendSettings::updateDataDefinedProperties( QgsRenderContext &context )
+{
+  rstyle( QgsLegendStyle::Title ).updateDataDefinedProperties( context );
+  rstyle( QgsLegendStyle::Group ).updateDataDefinedProperties( context );
+  rstyle( QgsLegendStyle::Subgroup ).updateDataDefinedProperties( context );
+  rstyle( QgsLegendStyle::SymbolLabel ).updateDataDefinedProperties( context );
+}
+
 QColor QgsLegendSettings::fontColor() const
 {
   return style( QgsLegendStyle::SymbolLabel ).textFormat().color();

src/core/qgslegendsettings.h

@@ -39,6 +39,14 @@ class CORE_EXPORT QgsLegendSettings
   public:
     QgsLegendSettings();
 
+    /**
+     * Updates any data-defined properties in the settings, using the specified
+     * render \a context.
+     *
+     * \since QGIS 3.42
+     */
+    void updateDataDefinedProperties( QgsRenderContext &context );
+
     /**
      * Sets the title for the legend, which will be rendered above all legend items.
      *

src/core/qgslegendstyle.cpp

@@ -19,6 +19,7 @@
 #include "qgsfontutils.h"
 #include "qgis.h"
 #include "qgsreadwritecontext.h"
+#include "qgspropertycollection.h"
 
 #include <QFont>
 #include <QMap>
@@ -110,6 +111,13 @@ void QgsLegendStyle::readXml( const QDomElement &elem, const QDomDocument &doc,
   mIndent = elem.attribute( QStringLiteral( "indent" ), QStringLiteral( "0" ) ).toDouble();
 }
 
+void QgsLegendStyle::updateDataDefinedProperties( QgsRenderContext &context )
+{
+  if ( mTextFormat.dataDefinedProperties().hasActiveProperties() ) // note, we use format instead of tmpFormat here, it's const and potentially avoids a detach
+    mTextFormat.updateDataDefinedProperties( context );
+
+}
+
 QString QgsLegendStyle::styleName( Style s )
 {
   switch ( s )

src/core/qgslegendstyle.h

@@ -165,6 +165,14 @@ class CORE_EXPORT QgsLegendStyle
      */
     void readXml( const QDomElement &elem, const QDomDocument &doc, const QgsReadWriteContext &context = QgsReadWriteContext() );
 
+    /**
+     * Updates any data-defined properties in the style, using the specified
+     * render \a context.
+     *
+     * \since QGIS 3.42
+     */
+    void updateDataDefinedProperties( QgsRenderContext &context );
+
     /**
      * Returns the name for a style component as a string.
      *

tests/src/core/testqgslegendrenderer.cpp

@@ -108,6 +108,7 @@ class TestQgsLegendRenderer : public QgsTest
     void testLeftAlignTextRightAlignSymbol();
     void testCenterAlignTextRightAlignSymbol();
     void testRightAlignTextRightAlignSymbol();
+    void testDataDefinedTextFormat();
 
     void testGroupHeadingSpacing();
     void testGroupIndentSetup();
@@ -739,6 +740,46 @@ void TestQgsLegendRenderer::testRightAlignTextRightAlignSymbol()
   QVERIFY( _verifyImage( res, QStringLiteral( "legend_two_cols_right_align_symbol_right_align_text" ) ) );
 }
 
+void TestQgsLegendRenderer::testDataDefinedTextFormat()
+{
+  QgsMarkerSymbol *sym = new QgsMarkerSymbol();
+  sym->setColor( Qt::red );
+  sym->setSize( sym->size() * 6 );
+  QgsCategorizedSymbolRenderer *catRenderer = dynamic_cast<QgsCategorizedSymbolRenderer *>( mVL3->renderer() );
+  QVERIFY( catRenderer );
+  catRenderer->updateCategorySymbol( 0, sym );
+
+  QgsLayerTreeModel legendModel( mRoot );
+  QgsLegendSettings settings;
+
+  setStandardTestFont( settings, QStringLiteral( "Bold" ) );
+  QgsTextFormat format = settings.style( QgsLegendStyle::Group ).textFormat();
+  format.dataDefinedProperties().setProperty( QgsPalLayerSettings::Property::Color, QgsProperty::fromExpression( "@text_color_group" ) );
+  settings.rstyle( QgsLegendStyle::Group ).setTextFormat( format );
+
+  format = settings.style( QgsLegendStyle::Subgroup ).textFormat();
+  format.dataDefinedProperties().setProperty( QgsPalLayerSettings::Property::Color, QgsProperty::fromExpression( "@text_color_subgroup" ) );
+  settings.rstyle( QgsLegendStyle::Subgroup ).setTextFormat( format );
+
+  format = settings.style( QgsLegendStyle::SymbolLabel ).textFormat();
+  format.dataDefinedProperties().setProperty( QgsPalLayerSettings::Property::Color, QgsProperty::fromExpression( "@text_color_symbol_label" ) );
+  settings.rstyle( QgsLegendStyle::SymbolLabel ).setTextFormat( format );
+
+  QgsExpressionContext context;
+  QgsExpressionContextScope *scope = new QgsExpressionContextScope();
+  scope->setVariable( QStringLiteral( "text_color_group" ), QStringLiteral( "255,0,0" ) );
+  scope->setVariable( QStringLiteral( "text_color_subgroup" ), QStringLiteral( "0,255,255" ) );
+  scope->setVariable( QStringLiteral( "text_color_symbol_label" ), QStringLiteral( "255,0,255" ) );
+  context.appendScope( scope );
+
+  QgsRenderContext rc;
+  rc.setExpressionContext( context );
+  settings.updateDataDefinedProperties( rc );
+
+  QImage res = renderLegend( &legendModel, settings );
+  QVERIFY( _verifyImage( res, QStringLiteral( "data_defined_text_format" ) ) );
+}
+
 void TestQgsLegendRenderer::testGroupHeadingSpacing()
 {
   QgsMarkerSymbol *sym = new QgsMarkerSymbol();

tests/src/python/CMakeLists.txt

@@ -161,6 +161,8 @@ ADD_PYTHON_TEST(PyQgsLayoutSnapper test_qgslayoutsnapper.py)
 ADD_PYTHON_TEST(PyQgsLayoutTable test_qgslayouttable.py)
 ADD_PYTHON_TEST(PyQgsLegendPatchShape test_qgslegendpatchshape.py)
 ADD_PYTHON_TEST(PyQgsLegendRenderer test_qgslegendrenderer.py)
+ADD_PYTHON_TEST(PyQgsLegendSettings test_qgslegendsettings.py)
+ADD_PYTHON_TEST(PyQgsLegendStyle test_qgslegendstyle.py)
 ADD_PYTHON_TEST(PyQgsLinearReferencingSymbolLayer test_qgslinearreferencingsymbollayer.py)
 ADD_PYTHON_TEST(PyQgsLineSegment test_qgslinesegment.py)
 ADD_PYTHON_TEST(PyQgsLineString test_qgslinestring.py)

tests/src/python/test_qgslegendsettings.py

@@ -0,0 +1,188 @@
+""""Test QgsLegendSettings
+
+.. note:: This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+Run with ctest -V -R PyQgsLegendSettings
+
+"""
+
+from qgis.PyQt.QtCore import Qt, QSizeF
+from qgis.PyQt.QtGui import QColor
+
+from qgis.core import (
+    Qgis,
+    QgsLegendStyle,
+    QgsLegendSettings,
+    QgsExpressionContext,
+    QgsExpressionContextScope,
+    QgsTextFormat,
+    QgsRenderContext,
+    QgsPalLayerSettings,
+    QgsProperty,
+)
+import unittest
+from qgis.testing import start_app, QgisTestCase
+
+from utilities import unitTestDataPath
+
+QGISAPP = start_app()
+TEST_DATA_DIR = unitTestDataPath()
+
+
+class TestPyQgsLegendSettings(QgisTestCase):
+
+    def test_getters_setters(self):
+        settings = QgsLegendSettings()
+
+        title = "Test Legend"
+        settings.setTitle(title)
+        self.assertEqual(settings.title(), title)
+
+        settings.setTitleAlignment(Qt.AlignmentFlag.AlignRight)
+        self.assertEqual(settings.titleAlignment(), Qt.AlignmentFlag.AlignRight)
+
+        test_style = QgsLegendStyle()
+        test_style.setIndent(33)
+        settings.setStyle(QgsLegendStyle.Style.Symbol, test_style)
+        self.assertEqual(settings.style(QgsLegendStyle.Style.Symbol).indent(), 33)
+
+        test_style2 = QgsLegendStyle()
+        test_style2.setIndent(35)
+        settings.setStyle(QgsLegendStyle.Style.SymbolLabel, test_style2)
+        self.assertEqual(settings.style(QgsLegendStyle.Style.Symbol).indent(), 33)
+        self.assertEqual(settings.style(QgsLegendStyle.Style.SymbolLabel).indent(), 35)
+
+        settings.setBoxSpace(5.0)
+        self.assertEqual(settings.boxSpace(), 5.0)
+
+        settings.setWrapChar("\n")
+        self.assertEqual(settings.wrapChar(), "\n")
+
+        settings.setColumnSpace(5.0)
+        self.assertEqual(settings.columnSpace(), 5.0)
+
+        settings.setColumnCount(3)
+        self.assertEqual(settings.columnCount(), 3)
+
+        settings.setSplitLayer(True)
+        self.assertTrue(settings.splitLayer())
+        settings.setSplitLayer(False)
+        self.assertFalse(settings.splitLayer())
+
+        settings.setEqualColumnWidth(True)
+        self.assertTrue(settings.equalColumnWidth())
+        settings.setEqualColumnWidth(False)
+        self.assertFalse(settings.equalColumnWidth())
+
+        settings.setSymbolSize(QSizeF(10.0, 10.0))
+        self.assertEqual(settings.symbolSize(), QSizeF(10.0, 10.0))
+        settings.setMaximumSymbolSize(20.0)
+        settings.setMinimumSymbolSize(5.0)
+        self.assertEqual(settings.maximumSymbolSize(), 20.0)
+        self.assertEqual(settings.minimumSymbolSize(), 5.0)
+
+        settings.setSymbolAlignment(Qt.AlignmentFlag.AlignRight)
+        self.assertEqual(settings.symbolAlignment(), Qt.AlignmentFlag.AlignRight)
+
+        settings.setDrawRasterStroke(True)
+        self.assertTrue(settings.drawRasterStroke())
+
+        settings.setRasterStrokeColor(QColor(255, 0, 0))
+        self.assertEqual(settings.rasterStrokeColor(), QColor(255, 0, 0))
+
+        settings.setRasterStrokeWidth(2.0)
+        self.assertEqual(settings.rasterStrokeWidth(), 2.0)
+
+        settings.setWmsLegendSize(QSizeF(50.0, 150.0))
+        self.assertEqual(settings.wmsLegendSize(), QSizeF(50.0, 150.0))
+
+        settings.setSynchronousLegendRequests(True)
+        self.assertTrue(settings.synchronousLegendRequests())
+        settings.setSynchronousLegendRequests(False)
+        self.assertFalse(settings.synchronousLegendRequests())
+
+        settings.setJsonRenderFlags(Qgis.LegendJsonRenderFlag.ShowRuleDetails)
+        self.assertEqual(
+            settings.jsonRenderFlags(), Qgis.LegendJsonRenderFlag.ShowRuleDetails
+        )
+
+    def test_split_string_for_wrapping(self):
+        settings = QgsLegendSettings()
+        settings.setWrapChar("|")
+        self.assertEqual(
+            settings.splitStringForWrapping("Test|String|Wrapping"),
+            ["Test", "String", "Wrapping"],
+        )
+
+    def test_evaluate_item_text(self):
+        settings = QgsLegendSettings()
+        settings.setWrapChar("|")
+
+        expression_context_scope = QgsExpressionContextScope()
+        expression_context_scope.setVariable("test_string", "Test|String")
+        expression_context = QgsExpressionContext()
+        expression_context.appendScope(expression_context_scope)
+
+        self.assertEqual(
+            settings.evaluateItemText(
+                "[% @test_string %]|Wrapping", expression_context
+            ),
+            ["Test", "String", "Wrapping"],
+        )
+
+    def test_update_data_defined_properties(self):
+        style = QgsLegendStyle()
+        text_format = QgsTextFormat()
+        text_format.setColor(QColor(255, 0, 0, 255))
+        text_format.dataDefinedProperties().setProperty(
+            QgsPalLayerSettings.Property.Color,
+            QgsProperty.fromExpression("@text_color"),
+        )
+        style.setTextFormat(text_format)
+        settings = QgsLegendSettings()
+        settings.setStyle(QgsLegendStyle.Style.Group, style)
+
+        style2 = QgsLegendStyle()
+        text_format = QgsTextFormat()
+        text_format.setColor(QColor(255, 0, 255, 255))
+        text_format.dataDefinedProperties().setProperty(
+            QgsPalLayerSettings.Property.Color,
+            QgsProperty.fromExpression("@text_color2"),
+        )
+        style2.setTextFormat(text_format)
+        settings.setStyle(QgsLegendStyle.Style.Subgroup, style2)
+
+        self.assertEqual(
+            settings.style(QgsLegendStyle.Style.Group).textFormat().color(),
+            QColor(255, 0, 0, 255),
+        )
+        self.assertEqual(
+            settings.style(QgsLegendStyle.Style.Subgroup).textFormat().color(),
+            QColor(255, 0, 255, 255),
+        )
+
+        # apply data defined properties
+        rc = QgsRenderContext()
+        expression_context_scope = QgsExpressionContextScope()
+        expression_context_scope.setVariable("text_color", "0,255,0")
+        expression_context_scope.setVariable("text_color2", "255,255,255")
+        expression_context = QgsExpressionContext()
+        expression_context.appendScope(expression_context_scope)
+        rc.setExpressionContext(expression_context)
+        settings.updateDataDefinedProperties(rc)
+
+        self.assertEqual(
+            settings.style(QgsLegendStyle.Style.Group).textFormat().color(),
+            QColor(0, 255, 0, 255),
+        )
+        self.assertEqual(
+            settings.style(QgsLegendStyle.Style.Subgroup).textFormat().color(),
+            QColor(255, 255, 255, 255),
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()