Add sourceExtent method to QgsFeatureSource

Author: nyalldawson

python/core/qgsfeaturesource.sip

@@ -78,6 +78,14 @@ class QgsFeatureSource
  :rtype: set of QVariant
 %End
 
+    virtual QgsRectangle sourceExtent() const;
+%Docstring
+ Returns the extent of all geometries from the source.
+ The base class implementation uses a non-optimised approach of looping through
+ all features in the source.
+ :rtype: QgsRectangle
+%End
+
 };
 
 

python/core/qgsvectordataprovider.sip

@@ -126,6 +126,8 @@ Bitmask of all provider's editing capabilities
 
     virtual QgsCoordinateReferenceSystem sourceCrs() const;
 
+    virtual QgsRectangle sourceExtent() const;
+
 
     virtual QString dataComment() const;
 %Docstring

python/core/qgsvectorlayer.sip

@@ -1103,10 +1103,8 @@ Synchronises with changes in the datasource
 
     virtual QgsRectangle extent() const;
 
-%Docstring
-Return the extent of the layer
- :rtype: QgsRectangle
-%End
+    virtual QgsRectangle sourceExtent() const;
+
 
     virtual QgsFields fields() const;
 %Docstring

src/core/qgsfeaturesource.cpp

@@ -40,3 +40,20 @@ QSet<QVariant> QgsFeatureSource::uniqueValues( int fieldIndex, int limit ) const
   return values;
 }
 
+QgsRectangle QgsFeatureSource::sourceExtent() const
+{
+  QgsRectangle r;
+
+  QgsFeatureRequest req;
+  req.setSubsetOfAttributes( QgsAttributeList() );
+
+  QgsFeatureIterator it = getFeatures( req );
+  QgsFeature f;
+  while ( it.nextFeature( f ) )
+  {
+    if ( f.hasGeometry() )
+      r.combineExtentWith( f.geometry().boundingBox() );
+  }
+  return r;
+}
+

src/core/qgsfeaturesource.h

@@ -87,6 +87,13 @@ class CORE_EXPORT QgsFeatureSource
      */
     virtual QSet<QVariant> uniqueValues( int fieldIndex, int limit = -1 ) const;
 
+    /**
+     * Returns the extent of all geometries from the source.
+     * The base class implementation uses a non-optimised approach of looping through
+     * all features in the source.
+     */
+    virtual QgsRectangle sourceExtent() const;
+
 };
 
 Q_DECLARE_METATYPE( QgsFeatureSource * )

src/core/qgsvectordataprovider.cpp

@@ -52,6 +52,11 @@ QgsCoordinateReferenceSystem QgsVectorDataProvider::sourceCrs() const
   return crs();
 }
 
+QgsRectangle QgsVectorDataProvider::sourceExtent() const
+{
+  return extent();
+}
+
 QString QgsVectorDataProvider::dataComment() const
 {
   return QString();

src/core/qgsvectordataprovider.h

@@ -159,6 +159,7 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider, public QgsFeat
     virtual QgsFields fields() const override = 0;
 
     QgsCoordinateReferenceSystem sourceCrs() const override;
+    QgsRectangle sourceExtent() const override;
 
     /**
      * Return a short comment for the data that this provider is

src/core/qgsvectorlayer.cpp

@@ -879,6 +879,11 @@ QgsRectangle QgsVectorLayer::extent() const
   return rect;
 }
 
+QgsRectangle QgsVectorLayer::sourceExtent() const
+{
+  return extent();
+}
+
 QString QgsVectorLayer::subsetString() const
 {
   if ( !mValid || !mDataProvider )

src/core/qgsvectorlayer.h

@@ -1077,8 +1077,8 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
      */
     virtual QgsMapLayerRenderer *createMapRenderer( QgsRenderContext &rendererContext ) override SIP_FACTORY;
 
-    //! Return the extent of the layer
     QgsRectangle extent() const override;
+    QgsRectangle sourceExtent() const override;
 
     /**
      * Returns the list of fields of this layer.