Add configurable extent buffer to symbols

python/PyQt6/core/auto_additions/qgssymbol.py

@@ -4,6 +4,9 @@
 QgsSymbol.Property.PropertyOpacity = QgsSymbol.Property.Opacity
 QgsSymbol.PropertyOpacity.is_monkey_patched = True
 QgsSymbol.PropertyOpacity.__doc__ = "Opacity"
+QgsSymbol.ExtentBuffer = QgsSymbol.Property.ExtentBuffer
+QgsSymbol.ExtentBuffer.is_monkey_patched = True
+QgsSymbol.ExtentBuffer.__doc__ = "Extent buffer \n.. versionadded:: 3.42"
 QgsSymbol.Property.__doc__ = """Data definable properties.
 
 .. versionadded:: 3.18
@@ -12,6 +15,10 @@
 
   Available as ``QgsSymbol.PropertyOpacity`` in older QGIS releases.
 
+* ``ExtentBuffer``: Extent buffer
+
+  .. versionadded:: 3.42
+
 
 """
 # --

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

@@ -628,6 +628,17 @@ Currently clones
 :param destRenderer: destination renderer for copied effect
 
 .. versionadded:: 3.22
+%End
+
+    double maximumExtentBuffer( QgsRenderContext &context ) const;
+%Docstring
+Returns the maximum extent buffer found in this renderer's symbols.
+
+.. note::
+
+   Returns 0 if the renderer doesn't have any symbols.
+
+.. versionadded:: 3.42
 %End
 
   protected:

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

@@ -244,6 +244,7 @@ Returns the default symbol type required for the specified geometry ``type``.
     enum class Property /BaseType=IntEnum/
     {
       Opacity,
+      ExtentBuffer,
     };
 
     static const QgsPropertiesDefinition &propertyDefinitions();
@@ -863,6 +864,44 @@ Internally, this notifies all symbol layers which were used via a call to
 :py:func:`QgsSymbolLayer.stopFeatureRender()`.
 
 .. versionadded:: 3.20
+%End
+
+    double extentBuffer() const;
+%Docstring
+Returns the symbol's extent buffer.
+
+:return: The symbol's extent buffer
+
+.. versionadded:: 3.42
+%End
+
+    void setExtentBuffer( double extentBuffer );
+%Docstring
+Sets the symbol's extent buffer.
+
+:param extentBuffer: buffer distance.
+
+.. seealso:: :py:func:`extentBuffer`
+
+.. note::
+
+   Negative values are not supported and will be changed to 0.
+
+.. versionadded:: 3.42
+%End
+
+    Qgis::RenderUnit extentBufferSizeUnit() const;
+%Docstring
+Returns the units for the buffer size.
+
+.. seealso:: :py:func:`setExtentBufferSizeUnit`
+%End
+
+    void setExtentBufferSizeUnit( Qgis::RenderUnit unit );
+%Docstring
+Sets the ``unit`` used for the extent buffer.
+
+.. seealso:: :py:func:`extentBufferSizeUnit`
 %End
 
   protected:
@@ -934,6 +973,7 @@ Render editing vertex marker at specified point
 
 
 
+
   private:
     QgsSymbol( const QgsSymbol & );
 };

python/core/auto_additions/qgssymbol.py

@@ -4,6 +4,9 @@
 QgsSymbol.Property.PropertyOpacity = QgsSymbol.Property.Opacity
 QgsSymbol.PropertyOpacity.is_monkey_patched = True
 QgsSymbol.PropertyOpacity.__doc__ = "Opacity"
+QgsSymbol.ExtentBuffer = QgsSymbol.Property.ExtentBuffer
+QgsSymbol.ExtentBuffer.is_monkey_patched = True
+QgsSymbol.ExtentBuffer.__doc__ = "Extent buffer \n.. versionadded:: 3.42"
 QgsSymbol.Property.__doc__ = """Data definable properties.
 
 .. versionadded:: 3.18
@@ -12,6 +15,10 @@
 
   Available as ``QgsSymbol.PropertyOpacity`` in older QGIS releases.
 
+* ``ExtentBuffer``: Extent buffer
+
+  .. versionadded:: 3.42
+
 
 """
 # --

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

@@ -628,6 +628,17 @@ Currently clones
 :param destRenderer: destination renderer for copied effect
 
 .. versionadded:: 3.22
+%End
+
+    double maximumExtentBuffer( QgsRenderContext &context ) const;
+%Docstring
+Returns the maximum extent buffer found in this renderer's symbols.
+
+.. note::
+
+   Returns 0 if the renderer doesn't have any symbols.
+
+.. versionadded:: 3.42
 %End
 
   protected:

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

@@ -244,6 +244,7 @@ Returns the default symbol type required for the specified geometry ``type``.
     enum class Property
     {
       Opacity,
+      ExtentBuffer,
     };
 
     static const QgsPropertiesDefinition &propertyDefinitions();
@@ -863,6 +864,44 @@ Internally, this notifies all symbol layers which were used via a call to
 :py:func:`QgsSymbolLayer.stopFeatureRender()`.
 
 .. versionadded:: 3.20
+%End
+
+    double extentBuffer() const;
+%Docstring
+Returns the symbol's extent buffer.
+
+:return: The symbol's extent buffer
+
+.. versionadded:: 3.42
+%End
+
+    void setExtentBuffer( double extentBuffer );
+%Docstring
+Sets the symbol's extent buffer.
+
+:param extentBuffer: buffer distance.
+
+.. seealso:: :py:func:`extentBuffer`
+
+.. note::
+
+   Negative values are not supported and will be changed to 0.
+
+.. versionadded:: 3.42
+%End
+
+    Qgis::RenderUnit extentBufferSizeUnit() const;
+%Docstring
+Returns the units for the buffer size.
+
+.. seealso:: :py:func:`setExtentBufferSizeUnit`
+%End
+
+    void setExtentBufferSizeUnit( Qgis::RenderUnit unit );
+%Docstring
+Sets the ``unit`` used for the extent buffer.
+
+.. seealso:: :py:func:`extentBufferSizeUnit`
 %End
 
   protected:
@@ -934,6 +973,7 @@ Render editing vertex marker at specified point
 
 
 
+
   private:
     QgsSymbol( const QgsSymbol & );
 };

src/core/symbology/qgsrenderer.cpp

@@ -38,6 +38,7 @@
 #include <QDomDocument>
 #include <QPolygonF>
 #include <QThread>
+#include <algorithm>
 
 QgsPropertiesDefinition QgsFeatureRenderer::sPropertyDefinitions;
 
@@ -417,6 +418,49 @@ QgsLegendSymbolList QgsFeatureRenderer::legendSymbolItems() const
   return QgsLegendSymbolList();
 }
 
+double QgsFeatureRenderer::maximumExtentBuffer( QgsRenderContext &context ) const
+{
+  const QgsSymbolList symbolList = symbols( context );
+
+  if ( symbolList.empty() )
+    return 0;
+
+  const QgsExpressionContext &expContext = context.expressionContext();
+
+  auto getValueFromSymbol = [ &expContext, &context ]( const QgsSymbol * sym ) -> double
+  {
+    const QgsProperty property = sym->dataDefinedProperties().property( QgsSymbol::Property::ExtentBuffer );
+
+    double value = 0.0;
+
+    if ( property.isActive() )
+    {
+      value = sym->dataDefinedProperties().valueAsDouble( QgsSymbol::Property::ExtentBuffer, expContext, sym->extentBuffer() );
+    }
+    else
+    {
+      value = sym->extentBuffer();
+    }
+
+    if ( sym->extentBufferSizeUnit() != Qgis::RenderUnit::MapUnits )
+    {
+      value = context.convertToMapUnits( value, sym->extentBufferSizeUnit(), sym->mapUnitScale() );
+    }
+
+    return value;
+  };
+
+  if ( symbolList.size() == 1 )
+    return getValueFromSymbol( symbolList[0] );
+
+  auto it = std::max_element( symbolList.constBegin(), symbolList.constEnd(), [ &getValueFromSymbol ]( const QgsSymbol * a, const QgsSymbol * b ) -> bool
+  {
+    return getValueFromSymbol( a ) < getValueFromSymbol( b );
+  } );
+
+  return getValueFromSymbol( *it );
+}
+
 QList<QgsLayerTreeModelLegendNode *> QgsFeatureRenderer::createLegendNodes( QgsLayerTreeLayer *nodeLayer ) const
 {
   QList<QgsLayerTreeModelLegendNode *> nodes;
@@ -492,8 +536,9 @@ QgsSymbolList QgsFeatureRenderer::symbolsForFeature( const QgsFeature &feature,
 
 void QgsFeatureRenderer::modifyRequestExtent( QgsRectangle &extent, QgsRenderContext &context )
 {
-  Q_UNUSED( extent )
-  Q_UNUSED( context )
+  double extentBuffer = maximumExtentBuffer( context );
+
+  extent.grow( extentBuffer );
 }
 
 QgsSymbolList QgsFeatureRenderer::originalSymbolsForFeature( const QgsFeature &feature, QgsRenderContext &context ) const

src/core/symbology/qgsrenderer.h

@@ -653,6 +653,14 @@ class CORE_EXPORT QgsFeatureRenderer
      */
     void copyRendererData( QgsFeatureRenderer *destRenderer ) const;
 
+    /**
+     * Returns the maximum extent buffer found in this renderer's symbols.
+     *
+     * \note Returns 0 if the renderer doesn't have any symbols.
+     * \since QGIS 3.42
+     */
+    double maximumExtentBuffer( QgsRenderContext &context ) const;
+
   protected:
     QgsFeatureRenderer( const QString &type );
 

src/core/symbology/qgssymbol.cpp

@@ -26,6 +26,7 @@
 
 #include "qgssymbol.h"
 #include "qgspolyhedralsurface.h"
+#include "qgsrectangle.h"
 #include "qgssymbollayer.h"
 
 #include "qgsgeometrygeneratorsymbollayer.h"
@@ -2223,6 +2224,20 @@ QgsSymbolRenderContext *QgsSymbol::symbolRenderContext()
   return mSymbolRenderContext.get();
 }
 
+double QgsSymbol::extentBuffer() const
+{
+  return mExtentBuffer;
+}
+
+void QgsSymbol::setExtentBuffer( double extentBuffer )
+{
+  if ( extentBuffer < 0 )
+    mExtentBuffer = 0;
+  else
+    mExtentBuffer = extentBuffer;
+}
+
+
 void QgsSymbol::renderVertexMarker( QPointF pt, QgsRenderContext &context, Qgis::VertexMarkerType currentVertexMarkerType, double currentVertexMarkerSize )
 {
   int markerSize = context.convertToPainterUnits( currentVertexMarkerSize, Qgis::RenderUnit::Millimeters );
@@ -2239,6 +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 )},
   };
 }
 
@@ -2298,6 +2314,8 @@ void QgsSymbol::copyCommonProperties( const QgsSymbol *other )
   mDataDefinedProperties = other->mDataDefinedProperties;
   mSymbolFlags = other->mSymbolFlags;
   mAnimationSettings = other->mAnimationSettings;
+  mExtentBuffer = other->mExtentBuffer;
+  mExtentBufferSizeUnit = other->mExtentBufferSizeUnit;
   if ( other->mBufferSettings )
     mBufferSettings = std::make_unique< QgsSymbolBufferSettings >( *other->mBufferSettings );
   else

src/core/symbology/qgssymbol.h

@@ -269,6 +269,7 @@ class CORE_EXPORT QgsSymbol
     enum class Property SIP_MONKEYPATCH_SCOPEENUM_UNNEST( QgsSymbol, Property ) : int
     {
       Opacity SIP_MONKEYPATCH_COMPAT_NAME( PropertyOpacity ), //!< Opacity
+      ExtentBuffer, //!< Extent buffer \since QGIS 3.42
     };
     // *INDENT-ON*
 
@@ -867,6 +868,38 @@ class CORE_EXPORT QgsSymbol
      */
     void stopFeatureRender( const QgsFeature &feature, QgsRenderContext &context, int layer = -1 );
 
+    /**
+     * Returns the symbol's extent buffer.
+     *
+     * \returns The symbol's extent buffer
+     * \since QGIS 3.42
+     */
+    double extentBuffer() const;
+
+    /**
+     * Sets the symbol's extent buffer.
+     *
+     * \param extentBuffer buffer distance.
+     * \see extentBuffer()
+     * \note Negative values are not supported and will be changed to 0.
+     * \since QGIS 3.42
+     */
+    void setExtentBuffer( double extentBuffer );
+
+    /**
+     * Returns the units for the buffer size.
+     *
+     * \see setExtentBufferSizeUnit()
+     */
+    Qgis::RenderUnit extentBufferSizeUnit() const { return mExtentBufferSizeUnit; }
+
+    /**
+     * Sets the \a unit used for the extent buffer.
+     *
+     * \see extentBufferSizeUnit()
+     */
+    void setExtentBufferSizeUnit( Qgis::RenderUnit unit ) { mExtentBufferSizeUnit = unit; }
+
   protected:
 
     /**
@@ -955,6 +988,9 @@ class CORE_EXPORT QgsSymbol
     Qgis::SymbolType mType;
     QgsSymbolLayerList mLayers;
 
+    double mExtentBuffer = 0;
+    Qgis::RenderUnit mExtentBufferSizeUnit = Qgis::RenderUnit::MapUnits;
+
     //! Symbol opacity (in the range 0 - 1)
     qreal mOpacity = 1.0;