Fix issue with intents to rebuild index of an empty layer

With one or more empty layers, this would lead to a weird blinking due to progress dialog being opened when snapping to empty layers is active. The fix adds a flag in the point locator, so the index is not rebuilt unless there are some features in the layer
qgis · Feb 9, 2015 · 0386ed0 · 0386ed0
1 parent ee50520
commit 0386ed0
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Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/src/core/qgspointlocator.cpp b/src/core/qgspointlocator.cpp
@@ -564,6 +564,7 @@ class QgsPointLocator_DumpTree : public SpatialIndex::IQueryStrategy
 QgsPointLocator::QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateReferenceSystem* destCRS, const QgsRectangle* extent )
     : mStorage( 0 )
     , mRTree( 0 )
+    , mIsEmptyLayer( false )
     , mTransform( 0 )
     , mLayer( layer )
     , mExtent( 0 )
@@ -602,7 +603,7 @@ bool QgsPointLocator::init( int maxFeaturesToIndex )
 
 bool QgsPointLocator::hasIndex() const
 {
-  return mRTree != 0;
+  return mRTree != 0 || mIsEmptyLayer;
 }
 
 
@@ -658,7 +659,10 @@ bool QgsPointLocator::rebuildIndex( int maxFeaturesToIndex )
   SpatialIndex::id_type indexId;
 
   if ( dataList.isEmpty() )
+  {
+    mIsEmptyLayer = true;
     return true; // no features
+  }
 
   QgsPointLocator_Stream stream( dataList );
   mRTree = RTree::createAndBulkLoadNewRTree( RTree::BLM_STR, stream, *mStorage, fillFactor, indexCapacity,
@@ -672,6 +676,8 @@ void QgsPointLocator::destroyIndex()
   delete mRTree;
   mRTree = 0;
 
+  mIsEmptyLayer = false;
+
   foreach ( QgsGeometry* g, mGeoms )
     delete g;
   mGeoms.clear();
@@ -680,7 +686,11 @@ void QgsPointLocator::destroyIndex()
 void QgsPointLocator::onFeatureAdded( QgsFeatureId fid )
 {
   if ( !mRTree )
+  {
+    if ( mIsEmptyLayer )
+      rebuildIndex(); // first feature - let's built the index
     return; // nothing to do if we are not initialized yet
+  }
 
   QgsFeature f;
   if ( mLayer->getFeatures( QgsFeatureRequest( fid ) ).nextFeature( f ) )

diff --git a/src/core/qgspointlocator.h b/src/core/qgspointlocator.h
@@ -170,6 +170,9 @@ class CORE_EXPORT QgsPointLocator : public QObject
     QHash<QgsFeatureId, QgsGeometry*> mGeoms;
     SpatialIndex::ISpatialIndex* mRTree;
 
+    //! flag whether the layer is currently empty (i.e. mRTree is null but it is not necessary to rebuild it)
+    bool mIsEmptyLayer;
+
     /** R-tree containing spatial index */
     QgsCoordinateTransform* mTransform;
     QgsVectorLayer* mLayer;