Fix point displacement renderer not ignoring features with no symbol

Previously, the renderer would incorrectly draw circles and
displace features which were proximal to features with no symbols.
This caused issues with the rule based renderer, were some
features should not be drawn.

Author: nyalldawson

src/core/symbology-ng/qgspointdisplacementrenderer.cpp

@@ -87,6 +87,12 @@ bool QgsPointDisplacementRenderer::renderFeature( QgsFeature& feature, QgsRender
   if ( !feature.constGeometry() )
     return false;
 
+  QgsSymbolV2* symbol = firstSymbolForFeature( mRenderer, feature );
+
+  //if the feature has no symbol (eg, no matching rule in a rule-based renderer), skip it
+  if ( !symbol )
+    return false;
+
   //point position in screen coords
   const QgsGeometry* geom = feature.constGeometry();
   QGis::WkbType geomType = geom->wkbType();
@@ -105,7 +111,7 @@ bool QgsPointDisplacementRenderer::renderFeature( QgsFeature& feature, QgsRender
     mSpatialIndex->insertFeature( feature );
     // create new group
     DisplacementGroup newGroup;
-    newGroup.insert( feature.id(), feature );
+    newGroup.insert( feature.id(), qMakePair( feature, symbol ) );
     mDisplacementGroups.push_back( newGroup );
     // add to group index
     mGroupIndex.insert( feature.id(), mDisplacementGroups.count() - 1 );
@@ -119,15 +125,15 @@ bool QgsPointDisplacementRenderer::renderFeature( QgsFeature& feature, QgsRender
   DisplacementGroup& group = mDisplacementGroups[groupIdx];
 
   // add to a group
-  group.insert( feature.id(), feature );
+  group.insert( feature.id(), qMakePair( feature, symbol ) );
   // add to group index
   mGroupIndex.insert( feature.id(), groupIdx );
   return true;
 }
 
 void QgsPointDisplacementRenderer::drawGroup( const DisplacementGroup& group, QgsRenderContext& context )
 {
-  const QgsFeature& feature = group.begin().value();
+  const QgsFeature& feature = group.begin().value().first;
   bool selected = mSelectedFeatures.contains( feature.id() ); // maybe we should highlight individual features instead of the whole group?
 
   QPointF pt;
@@ -139,9 +145,8 @@ void QgsPointDisplacementRenderer::drawGroup( const DisplacementGroup& group, Qg
 
   for ( DisplacementGroup::const_iterator attIt = group.constBegin(); attIt != group.constEnd(); ++attIt )
   {
-    labelAttributeList << ( mDrawLabels ? getLabel( attIt.value() ) : QString() );
-    QgsFeature& f = const_cast<QgsFeature&>( attIt.value() ); // other parts of API use non-const ref to QgsFeature :-/
-    symbolList << dynamic_cast<QgsMarkerSymbolV2*>( firstSymbolForFeature( mRenderer, f ) );
+    labelAttributeList << ( mDrawLabels ? getLabel( attIt.value().first ) : QString() );
+    symbolList << dynamic_cast<QgsMarkerSymbolV2*>( attIt.value().second );
   }
 
   //draw symbol
@@ -419,7 +424,7 @@ void QgsPointDisplacementRenderer::printInfoDisplacementGroups()
   for ( int i = 0; i < nGroups; ++i )
   {
     QgsDebugMsg( "***************displacement group " + QString::number( i ) );
-    QMap<QgsFeatureId, QgsFeature>::const_iterator it = mDisplacementGroups.at( i ).constBegin();
+    DisplacementGroup::const_iterator it = mDisplacementGroups.at( i ).constBegin();
     for ( ; it != mDisplacementGroups.at( i ).constEnd(); ++it )
     {
       QgsDebugMsg( FID_TO_STRING( it.key() ) );

src/core/symbology-ng/qgspointdisplacementrenderer.h

@@ -143,7 +143,7 @@ class CORE_EXPORT QgsPointDisplacementRenderer: public QgsFeatureRendererV2
     /**Maximum scale denominator for label display. Negative number means no scale limitation*/
     double mMaxLabelScaleDenominator;
 
-    typedef QMap<QgsFeatureId, QgsFeature> DisplacementGroup;
+    typedef QMap<QgsFeatureId, QPair< QgsFeature, QgsSymbolV2* > > DisplacementGroup;
     /**Groups of features that have the same position*/
     QList<DisplacementGroup> mDisplacementGroups;
     /**Mapping from feature ID to its group index*/