Add ownership management to the MapLayerRegistry

Author: m-kuhn

src/core/qgsmaplayerregistry.cpp

@@ -73,7 +73,8 @@ QList<QgsMapLayer *> QgsMapLayerRegistry::mapLayersByName( QString layerName )
 //introduced in 1.8
 QList<QgsMapLayer *> QgsMapLayerRegistry::addMapLayers(
   QList<QgsMapLayer *> theMapLayers,
-  bool addToLegend )
+  bool addToLegend,
+  bool takeOwnership )
 {
   QList<QgsMapLayer *> myResultList;
   for ( int i = 0; i < theMapLayers.size(); ++i )
@@ -85,14 +86,12 @@ QList<QgsMapLayer *> QgsMapLayerRegistry::addMapLayers(
       continue;
     }
     //check the layer is not already registered!
-    QMap<QString, QgsMapLayer*>::iterator myIterator =
-      mMapLayers.find( myLayer->id() );
-    //if myIterator returns mMapLayers.end() then it
-    //does not exist in registry and its safe to add it
-    if ( myIterator == mMapLayers.end() )
+    if ( !mMapLayers.contains( myLayer->id() ) )
     {
       mMapLayers[myLayer->id()] = myLayer;
       myResultList << mMapLayers[myLayer->id()];
+      if ( takeOwnership )
+        mOwnedLayers << myLayer;
       emit layerWasAdded( myLayer );
     }
   }
@@ -109,10 +108,11 @@ QList<QgsMapLayer *> QgsMapLayerRegistry::addMapLayers(
 //this is just a thin wrapper for addMapLayers
 QgsMapLayer *
 QgsMapLayerRegistry::addMapLayer( QgsMapLayer* theMapLayer,
-                                  bool addToLegend )
+                                  bool addToLegend,
+                                  bool takeOwnership )
 {
   QList<QgsMapLayer *> addedLayers;
-  addedLayers = addMapLayers( QList<QgsMapLayer*>() << theMapLayer, addToLegend );
+  addedLayers = addMapLayers( QList<QgsMapLayer*>() << theMapLayer, addToLegend, takeOwnership );
   return addedLayers.isEmpty() ? 0 : addedLayers[0];
 }
 
@@ -124,17 +124,17 @@ void QgsMapLayerRegistry::removeMapLayers( QStringList theLayerIds )
 
   foreach ( const QString &myId, theLayerIds )
   {
+    QgsMapLayer* lyr = mMapLayers[myId];
     emit layerWillBeRemoved( myId );
-    delete mMapLayers[myId];
+    if ( mOwnedLayers.contains( lyr ) )
+    {
+      delete lyr;
+      mOwnedLayers.remove( lyr );
+    }
     mMapLayers.remove( myId );
   }
 }
 
-void QgsMapLayerRegistry::clearMapLayers()
-{
-  mMapLayers.clear();
-} // QgsMapLayerRegistry::clearMapLayers()
-
 void QgsMapLayerRegistry::removeMapLayer( const QString& theLayerId )
 {
   removeMapLayers( QStringList( theLayerId ) );

src/core/qgsmaplayerregistry.h

@@ -20,6 +20,7 @@
 #define QGSMAPLAYERREGISTRY_H
 
 #include <QMap>
+#include <QSet>
 #include <QObject>
 #include <QStringList>
 class QString;
@@ -58,10 +59,13 @@ class CORE_EXPORT QgsMapLayerRegistry : public QObject
      * The layersAdded() and layersWasAdded() signals will be emitted in any case.
      * The legendLayersAdded() signal only if addToLegend is true.
      *
-     * @param theMapLayers A list of layer which should be added to the registry
-     * @param addToLegend  If true (by default), the layers will be added to the
-     *                     legend and to the main canvas. If you have a private
-     *                     layer, you can set this parameter to false to hide it.
+     * @param theMapLayers  A list of layer which should be added to the registry
+     * @param addToLegend   If true (by default), the layers will be added to the
+     *                      legend and to the main canvas. If you have a private
+     *                      layer, you can set this parameter to false to hide it.
+     * @param takeOwnership Ownership will be transferred to the layer registry.
+     *                      If you specify false here, you have take care of deleting
+     *                      the layers yourself. Not available in python.
      *
      * @return QList<QgsMapLayer *> - a list of the map layers that were added
      *         successfully. If a layer is invalid, or already exists in the registry,
@@ -71,7 +75,8 @@ class CORE_EXPORT QgsMapLayerRegistry : public QObject
      * @note Added in QGIS 1.8
      */
     QList<QgsMapLayer *> addMapLayers( QList<QgsMapLayer *> theMapLayers,
-                                       bool addToLegend = true );
+                                       bool addToLegend = true,
+                                       bool takeOwnership = true );
 
     /**
      * @brief
@@ -86,6 +91,9 @@ class CORE_EXPORT QgsMapLayerRegistry : public QObject
      * @param addToLegend If true (by default), the layer will be added to the
      *                    legend and to the main canvas. If you have a private
      *                    you can set this parameter to false to hide it.
+     * @param takeOwnership Ownership will be transferred to the layer registry.
+     *                      If you specify false here, you have take care of deleting
+     *                      the layer yourself. Not available in python.
      *
      * @return NULL if unable to add layer, otherwise pointer to newly added layer
      *
@@ -94,17 +102,7 @@ class CORE_EXPORT QgsMapLayerRegistry : public QObject
      * @note As a side-effect QgsProject is made dirty.
      * @note Use addMapLayers if adding more than one layer at a time
      */
-    QgsMapLayer* addMapLayer( QgsMapLayer * theMapLayer, bool addToLegend = true );
-
-    /**
-     * @brief
-     * Clears the map layer registry silently. No signals are emitted,
-     * no layer is deleted. Whatever this is suitable for... The WMS
-     * server makes use of this.
-     *
-     * Not available in python
-     */
-    void clearMapLayers();
+    QgsMapLayer* addMapLayer( QgsMapLayer * theMapLayer, bool addToLegend = true, bool takeOwnership = true );
 
     /**
      * @brief
@@ -230,6 +228,7 @@ class CORE_EXPORT QgsMapLayerRegistry : public QObject
     static QgsMapLayerRegistry* mInstance;
 
     QMap<QString, QgsMapLayer*> mMapLayers;
+    QSet<QgsMapLayer*> mOwnedLayers;
 
     /** debugging member
         invoked when a connect() is made to this object

src/mapserver/qgswmsserver.cpp

@@ -373,7 +373,7 @@ QImage* QgsWMSServer::getLegendGraphics()
     currentY += layerSpace;
   }
 
-  QgsMapLayerRegistry::instance()->clearMapLayers();
+  QgsMapLayerRegistry::instance()->removeAllMapLayers();
   delete theImage;
   return paintImage;
 }
@@ -649,7 +649,7 @@ QImage* QgsWMSServer::getMap()
   clearFeatureSelections( selectedLayerIdList );
 
   QgsDebugMsg( "clearing filters" );
-  QgsMapLayerRegistry::instance()->clearMapLayers();
+  QgsMapLayerRegistry::instance()->removeAllMapLayers();
 
 #ifdef QGISDEBUG
   theImage->save( QDir::tempPath() + QDir::separator() + "lastrender.png" );
@@ -1447,7 +1447,7 @@ QStringList QgsWMSServer::layerSet( const QStringList &layersList,
         {
           layerKeys.push_front( theMapLayer->id() );
           QgsMapLayerRegistry::instance()->addMapLayers(
-            QList<QgsMapLayer *>() << theMapLayer, false );
+            QList<QgsMapLayer *>() << theMapLayer, false, false );
         }
       }
       else