Fix for crash if removing a layer with a related composer attribute table

git-svn-id: http://svn.osgeo.org/qgis/trunk@13537 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: mhugent

src/core/composer/qgscomposerattributetable.cpp

@@ -23,7 +23,7 @@
 QgsComposerAttributeTable::QgsComposerAttributeTable( QgsComposition* composition ): QgsComposerTable( composition ), mVectorLayer( 0 ), mComposerMap( 0 ), \
     mMaximumNumberOfFeatures( 5 ), mShowOnlyVisibleFeatures( true )
 {
-
+  connect( QgsMapLayerRegistry::instance(), SIGNAL( layerWillBeRemoved( QString ) ), this, SLOT( removeLayer( const QString& ) ) );
 }
 
 QgsComposerAttributeTable::~QgsComposerAttributeTable()
@@ -145,6 +145,17 @@ QString QgsComposerAttributeTable::attributeDisplayName( int attributeIndex, con
   }
 }
 
+void QgsComposerAttributeTable::removeLayer( QString layerId )
+{
+  if ( mVectorLayer )
+  {
+    if ( layerId == mVectorLayer->getLayerID() )
+    {
+      mVectorLayer = 0;
+    }
+  }
+}
+
 void QgsComposerAttributeTable::setSceneRect( const QRectF& rectangle )
 {
   double titleHeight =  2 * mGridStrokeWidth + 2 * mLineTextDistance + fontAscentMillimeters( mHeaderFont );

src/core/composer/qgscomposerattributetable.h

@@ -84,6 +84,10 @@ class CORE_EXPORT QgsComposerAttributeTable: public QgsComposerTable
     /**Returns the attribute name to display in the item (attribute name or an alias if present)*/
     QString attributeDisplayName( int attributeIndex, const QString& name ) const;
 
+  private slots:
+    /**Checks if this vector layer will be removed (and sets mVectorLayer to 0 if yes) */
+    void removeLayer( QString layerId );
+
   signals:
     /**This signal is emitted if the maximum number of feature changes (interactively)*/
     void maximumNumerOfFeaturesChanged( int n );