Address review

Author: JuhoErvasti

python/PyQt6/core/auto_generated/symbology/qgssymbol.sip.in

@@ -870,7 +870,7 @@ Internally, this notifies all symbol layers which were used via a call to
 %Docstring
 Returns the symbol's extent buffer.
 
-:return: The symbol's extent buffer
+Units are retrieved via :py:func:`~QgsSymbol.extentBufferSizeUnit`.
 
 .. versionadded:: 3.42
 %End
@@ -879,6 +879,8 @@ Returns the symbol's extent buffer.
 %Docstring
 Sets the symbol's extent buffer.
 
+Units are set via :py:func:`~QgsSymbol.setExtentBufferSizeUnit`.
+
 :param extentBuffer: buffer distance.
 
 .. seealso:: :py:func:`extentBuffer`
@@ -894,13 +896,17 @@ Sets the symbol's extent buffer.
 %Docstring
 Returns the units for the buffer size.
 
+.. seealso:: :py:func:`extentBuffer`
+
 .. seealso:: :py:func:`setExtentBufferSizeUnit`
 %End
 
     void setExtentBufferSizeUnit( Qgis::RenderUnit unit );
 %Docstring
 Sets the ``unit`` used for the extent buffer.
 
+.. seealso:: :py:func:`setExtentBuffer`
+
 .. seealso:: :py:func:`extentBufferSizeUnit`
 %End
 

python/core/auto_generated/symbology/qgssymbol.sip.in

@@ -870,7 +870,7 @@ Internally, this notifies all symbol layers which were used via a call to
 %Docstring
 Returns the symbol's extent buffer.
 
-:return: The symbol's extent buffer
+Units are retrieved via :py:func:`~QgsSymbol.extentBufferSizeUnit`.
 
 .. versionadded:: 3.42
 %End
@@ -879,6 +879,8 @@ Returns the symbol's extent buffer.
 %Docstring
 Sets the symbol's extent buffer.
 
+Units are set via :py:func:`~QgsSymbol.setExtentBufferSizeUnit`.
+
 :param extentBuffer: buffer distance.
 
 .. seealso:: :py:func:`extentBuffer`
@@ -894,13 +896,17 @@ Sets the symbol's extent buffer.
 %Docstring
 Returns the units for the buffer size.
 
+.. seealso:: :py:func:`extentBuffer`
+
 .. seealso:: :py:func:`setExtentBufferSizeUnit`
 %End
 
     void setExtentBufferSizeUnit( Qgis::RenderUnit unit );
 %Docstring
 Sets the ``unit`` used for the extent buffer.
 
+.. seealso:: :py:func:`setExtentBuffer`
+
 .. seealso:: :py:func:`extentBufferSizeUnit`
 %End
 

src/core/symbology/qgsrenderer.cpp

@@ -425,7 +425,7 @@ double QgsFeatureRenderer::maximumExtentBuffer( QgsRenderContext &context ) cons
   if ( symbolList.empty() )
     return 0;
 
-  const QgsExpressionContext &expContext = context.expressionContext();
+  QgsExpressionContext &expContext = context.expressionContext();
 
   auto getValueFromSymbol = [ &expContext, &context ]( const QgsSymbol * sym ) -> double
   {
@@ -435,7 +435,11 @@ double QgsFeatureRenderer::maximumExtentBuffer( QgsRenderContext &context ) cons
 
     if ( property.isActive() )
     {
+      expContext.setOriginalValueVariable( sym->extentBuffer() );
+
       value = sym->dataDefinedProperties().valueAsDouble( QgsSymbol::Property::ExtentBuffer, expContext, sym->extentBuffer() );
+      if ( value < 0 )
+        value = 0;
     }
     else
     {

src/core/symbology/qgssymbol.cpp

@@ -2254,7 +2254,7 @@ void QgsSymbol::initPropertyDefinitions()
   sPropertyDefinitions = QgsPropertiesDefinition
   {
     { static_cast< int >( QgsSymbol::Property::Opacity ), QgsPropertyDefinition( "alpha", QObject::tr( "Opacity" ), QgsPropertyDefinition::Opacity, origin )},
-    { static_cast< int >( QgsSymbol::Property::ExtentBuffer ), QgsPropertyDefinition( "extent_buffer", QObject::tr( "Extent buffer" ), QgsPropertyDefinition::Double, origin )},
+    { static_cast< int >( QgsSymbol::Property::ExtentBuffer ), QgsPropertyDefinition( "extent_buffer", QObject::tr( "Extent buffer" ), QgsPropertyDefinition::DoublePositive, origin )},
   };
 }
 

src/core/symbology/qgssymbol.h

@@ -871,14 +871,15 @@ class CORE_EXPORT QgsSymbol
     /**
      * Returns the symbol's extent buffer.
      *
-     * \returns The symbol's extent buffer
+     * Units are retrieved via extentBufferSizeUnit().
      * \since QGIS 3.42
      */
     double extentBuffer() const;
 
     /**
      * Sets the symbol's extent buffer.
      *
+     * Units are set via setExtentBufferSizeUnit().
      * \param extentBuffer buffer distance.
      * \see extentBuffer()
      * \note Negative values are not supported and will be changed to 0.
@@ -889,13 +890,15 @@ class CORE_EXPORT QgsSymbol
     /**
      * Returns the units for the buffer size.
      *
+     * \see extentBuffer()
      * \see setExtentBufferSizeUnit()
      */
     Qgis::RenderUnit extentBufferSizeUnit() const { return mExtentBufferSizeUnit; }
 
     /**
      * Sets the \a unit used for the extent buffer.
      *
+     * \see setExtentBuffer()
      * \see extentBufferSizeUnit()
      */
     void setExtentBufferSizeUnit( Qgis::RenderUnit unit ) { mExtentBufferSizeUnit = unit; }

src/core/vector/qgsvectorlayerrenderer.cpp

@@ -17,7 +17,6 @@
 
 #include "qgsmessagelog.h"
 #include "qgspallabeling.h"
-#include "qgsrectangle.h"
 #include "qgsrenderer.h"
 #include "qgsrendercontext.h"
 #include "qgssinglesymbolrenderer.h"

src/gui/symbology/qgsextentbufferdialog.cpp

@@ -17,8 +17,11 @@
 #include "moc_qgsextentbufferdialog.cpp"
 #include "qdialogbuttonbox.h"
 #include "qgsexpressioncontext.h"
+#include "qgsexpressioncontextutils.h"
 #include "qgshelp.h"
+#include "qgsmapcanvas.h"
 #include "qgspanelwidget.h"
+#include "qgsproject.h"
 #include "qgssymbol.h"
 #include "qgssymbolwidgetcontext.h"
 #include "qgsunittypes.h"
@@ -78,8 +81,28 @@ void QgsExtentBufferWidget::registerDataDefinedButton( QgsPropertyOverrideButton
 
 QgsExpressionContext QgsExtentBufferWidget::createExpressionContext() const
 {
-  QList<QgsExpressionContextScope *> scopes = mContext.globalProjectAtlasMapLayerScopes( mLayer );
-  QgsExpressionContext expContext( scopes );
+  if ( QgsExpressionContext *lExpressionContext = mContext.expressionContext() )
+    return *lExpressionContext;
+
+  QgsExpressionContext expContext;
+
+  if ( mContext.mapCanvas() )
+  {
+    expContext = mContext.mapCanvas()->createExpressionContext();
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::globalScope()
+               << QgsExpressionContextUtils::projectScope( QgsProject::instance() )
+               << QgsExpressionContextUtils::atlasScope( nullptr )
+               << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+
+  if ( mLayer )
+    expContext << QgsExpressionContextUtils::layerScope( mLayer );
+
+  expContext.setOriginalValueVariable( mExtentBufferSpinBox->value() );
+  expContext.setHighlightedVariables( QStringList() << QgsExpressionContext::EXPR_ORIGINAL_VALUE );
 
   return expContext;
 }
@@ -149,6 +172,12 @@ QgsExtentBufferWidget *QgsExtentBufferDialog::widget() const
   return mWidget;
 }
 
+void QgsExtentBufferDialog::setContext( const QgsSymbolWidgetContext &context )
+{
+  mWidget->setContext( context );
+}
+
+
 void QgsExtentBufferDialog::showHelp()
 {
   QgsHelp::openHelp( QStringLiteral( "working_with_vector/vector_properties.html#extent-buffer" ) );

src/gui/symbology/qgsextentbufferdialog.h

@@ -134,6 +134,13 @@ class GUI_EXPORT QgsExtentBufferDialog : public QDialog
     */
     QgsExtentBufferWidget *widget() const;
 
+    /**
+     * Sets the context in which widget is shown, e.g., the associated map canvas and expression contexts.
+     * \param context symbol widget context
+     * \see context()
+     */
+    void setContext( const QgsSymbolWidgetContext &context );
+
   private:
     QgsExtentBufferWidget *mWidget;
 

src/gui/symbology/qgssymbolslistwidget.cpp

@@ -331,7 +331,7 @@ void QgsSymbolsListWidget::showExtentBufferSettings()
 
     if ( dlg.widget() )
     {
-      dlg.widget()->setContext( mContext );
+      dlg.setContext( mContext );
     }
 
     if ( dlg.exec() == QDialog::Accepted )