#9181: fix crash trying to resume node editing

Clears temporal objects to avoid crash trying to resume node editing and
disconnects signals to avoid repetitive connects

Author: ahuarte47

src/app/nodetool/qgsmaptoolnodetool.cpp

@@ -44,7 +44,7 @@ QgsMapToolNodeTool::QgsMapToolNodeTool( QgsMapCanvas* canvas )
 
 QgsMapToolNodeTool::~QgsMapToolNodeTool()
 {
-  removeRubberBands();
+  cleanTool();
 }
 
 void QgsMapToolNodeTool::createMovingRubberBands()
@@ -369,6 +369,7 @@ void QgsMapToolNodeTool::canvasPressEvent( QMouseEvent * e )
     mSelectedFeature = new QgsSelectedFeature( snapResults[0].snappedAtGeometry, vlayer, mCanvas );
     connect( QgisApp::instance()->legend(), SIGNAL( currentLayerChanged( QgsMapLayer* ) ), this, SLOT( currentLayerChanged( QgsMapLayer* ) ) );
     connect( mSelectedFeature, SIGNAL( destroyed() ), this, SLOT( selectedFeatureDestroyed() ) );
+    connect( vlayer, SIGNAL( editingStopped() ), this, SLOT( editingToggled() ) );
     mIsPoint = vlayer->geometryType() == QGis::Point;
   }
   else
@@ -485,20 +486,22 @@ void QgsMapToolNodeTool::canvasPressEvent( QMouseEvent * e )
 void QgsMapToolNodeTool::selectedFeatureDestroyed()
 {
   QgsDebugCall;
-  mSelectedFeature = 0;
+  cleanTool( false );
 }
 
 void QgsMapToolNodeTool::currentLayerChanged( QgsMapLayer *layer )
 {
   if ( mSelectedFeature && layer != mSelectedFeature->vlayer() )
   {
-    delete mSelectedFeature;
-    mSelectedFeature = 0;
-
-    removeRubberBands();
+    cleanTool();
   }
 }
 
+void QgsMapToolNodeTool::editingToggled()
+{
+  cleanTool();
+}
+
 void QgsMapToolNodeTool::canvasReleaseEvent( QMouseEvent * e )
 {
   if ( !mSelectedFeature )
@@ -605,10 +608,7 @@ void QgsMapToolNodeTool::canvasReleaseEvent( QMouseEvent * e )
 
 void QgsMapToolNodeTool::deactivate()
 {
-  removeRubberBands();
-
-  delete mSelectedFeature;
-  mSelectedFeature = 0;
+  cleanTool();
 
   mSelectionRubberBand = 0;
   mSelectAnother = false;
@@ -642,6 +642,23 @@ void QgsMapToolNodeTool::removeRubberBands()
     mSelectedFeature->cleanRubberBandsData();
 }
 
+void QgsMapToolNodeTool::cleanTool( bool deleteSelectedFeature )
+{
+  removeRubberBands();
+
+  if ( mSelectedFeature )
+  {
+    QgsVectorLayer *vlayer = mSelectedFeature->vlayer();
+    Q_ASSERT( vlayer );
+
+    disconnect( QgisApp::instance()->legend(), SIGNAL( currentLayerChanged( QgsMapLayer* ) ), this, SLOT( currentLayerChanged( QgsMapLayer* ) ) );
+    disconnect( mSelectedFeature, SIGNAL( destroyed() ), this, SLOT( selectedFeatureDestroyed() ) );
+    disconnect( vlayer, SIGNAL( editingStopped() ), this, SLOT( editingToggled() ) );
+
+    if ( deleteSelectedFeature ) delete mSelectedFeature;
+    mSelectedFeature = 0;
+  }
+}
 
 void QgsMapToolNodeTool::canvasDoubleClickEvent( QMouseEvent * e )
 {

src/app/nodetool/qgsmaptoolnodetool.h

@@ -60,12 +60,22 @@ class QgsMapToolNodeTool: public QgsMapToolVertexEdit
      */
     void currentLayerChanged( QgsMapLayer *layer );
 
+    /*
+     * the current edition state changed
+     */
+    void editingToggled();
+
   private:
     /**
      * Deletes the rubber band pointers and clears mRubberBands
      */
     void removeRubberBands();
 
+    /**
+     * Disconnects signals and clears objects
+     */
+    void cleanTool( bool deleteSelectedFeature = true );
+
     /**
      * Creating rubber band marker for movin of point
      * @param center coordinates of point to be moved