Applied patch #2492 provided by audun

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@13048 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: mhugent

src/app/legend/qgslegend.cpp

@@ -538,6 +538,17 @@ void QgsLegend::addLayer( QgsMapLayer * layer )
   doItemsLayout();
 }
 
+void QgsLegend::setMapCanvas( QgsMapCanvas * canvas )
+{
+  if( mMapCanvas ) 
+  {
+    disconnect( mMapCanvas, SIGNAL( layersChanged() ) );
+  }
+
+  mMapCanvas = canvas;
+  connect( mMapCanvas, SIGNAL( layersChanged() ), this, SLOT( refreshCheckStates() ) );
+}
+
 QgsLegendLayer* QgsLegend::currentLegendLayer()
 {
   QgsLegendItem* citem = dynamic_cast<QgsLegendItem *>( currentItem() );
@@ -1746,3 +1757,22 @@ QTreeWidgetItem * QgsLegend::lastVisibleItem()
   }
   return current;
 }
+
+void QgsLegend::refreshCheckStates()
+{
+  if( !mMapCanvas )
+  {
+    return;
+  }
+
+  QList<QgsMapLayer*> lst = mMapCanvas->layers();
+  for ( QTreeWidgetItem* item = firstItem(); item; item = nextItem( item ) ) 
+  {
+    QgsLegendLayer* ll = dynamic_cast<QgsLegendLayer *>( item );
+    if ( ll ) 
+    {
+      ll->setCheckState( 0, ( lst.contains( ll->layer() ) ? Qt::Checked : Qt::Unchecked ) );
+    }
+  }
+}
+

src/app/legend/qgslegend.h

@@ -187,7 +187,7 @@ class QgsLegend : public QTreeWidget
     /*!Adds a new layer group with the maplayer to the canvas*/
     void addLayer( QgsMapLayer * layer );
 
-    void setMapCanvas( QgsMapCanvas * canvas ) {mMapCanvas = canvas;}
+    void setMapCanvas( QgsMapCanvas * canvas );
 
     /**Updates symbology items for a layer*/
     void refreshLayerSymbology( QString key, bool expandItem = true );
@@ -265,6 +265,8 @@ class QgsLegend : public QTreeWidget
     /**Shows the property dialog of the first legend layer file in a legend layer*/
     void legendLayerShowProperties();
 
+    /**Updates check states when the map canvas layer set is changed */
+    void refreshCheckStates();
   protected:
 
     /*!Event handler for mouse movements.