Fix for bug 1090940 Zoom to all on empty map

Added a count function to the maplayer registry singelton


git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@2535 c8812cc2-4d05-0410-92ff-de0c093fc19c

src/qgisapp.cpp

@@ -2443,7 +2443,9 @@ void QgisApp::removeAllLayers()
 
 void QgisApp::zoomToLayerExtent()
 {
-
+// zoom only if one or more layers loaded
+  if(QgsMapLayerRegistry::instance()->count() > 0) 
+  {
     // get the selected item
     QListViewItem *li = mMapLegend->currentItem();
     QgsMapLayer *layer = ((QgsLegendItem *) li)->layer();
@@ -2453,6 +2455,7 @@ void QgisApp::zoomToLayerExtent()
 
     // notify the project we've made a change
     QgsProject::instance()->dirty(true);
+  }
 }
 
 void QgisApp::rightClickLegendMenu(QListViewItem * lvi, const QPoint & pt, int)

src/qgsmaplayerregistry.cpp

@@ -46,7 +46,11 @@ QgsMapLayerRegistry::QgsMapLayerRegistry(QObject *parent, const char *name) : QO
 #endif
   // constructor does nothing
 }
-
+// get the layer count (number of registered layers)
+const int QgsMapLayerRegistry::count()
+{
+  return mMapLayers.size();
+}
  //! Get a vector layer from the registry - the the requested key does not exist or
  //does not correspond to a vector layer, null returned!
  QgsVectorLayer * QgsMapLayerRegistry::getVectorLayer(QString theLayerId)

src/qgsmaplayerregistry.h

@@ -40,7 +40,11 @@ public:
 
  //! Returns the instance pointer, creating the object on the first call
  static QgsMapLayerRegistry * instance();
-
+/*! Return the number of registered layers.
+ *
+ * */
+ const int count();
+ 
  //! Retrieve a pointer to a loaded plugin by id
  QgsMapLayer * mapLayer(QString theLayerId);