Fix map layer combo box sometimes showing a selected layer which

is not applied

This could also have been fixed by changing from the activated
signal to currentIndexChanged for the indexChanged connection,
but it looks like activated was intentionally used here.

Author: nyalldawson

python/gui/qgsmaplayercombobox.sip

@@ -28,9 +28,18 @@ class QgsMapLayerComboBox : QComboBox
     //! returns the list of excepted layers
     QList<QgsMapLayer*> exceptedLayerList() const;
 
-    //! currentLayer returns the current layer selected in the combo box
+    /** Returns the current layer selected in the combo box.
+     * @see layer
+     */
     QgsMapLayer* currentLayer() const;
 
+    /** Return the layer currently shown at the specified index within the combo box.
+     * @param layerIndex position of layer to return
+     * @note added in QGIS 2.10
+     * @see currentLayer
+     */
+    QgsMapLayer* layer( int layerIndex ) const;
+
   public slots:
     //! setLayer set the current layer selected in the combo
     void setLayer( QgsMapLayer* layer );

src/gui/qgsmaplayercombobox.cpp

@@ -24,6 +24,8 @@ QgsMapLayerComboBox::QgsMapLayerComboBox( QWidget *parent ) :
   setModel( mProxyModel );
 
   connect( this, SIGNAL( activated( int ) ), this, SLOT( indexChanged( int ) ) );
+  connect( mProxyModel, SIGNAL( rowsInserted( QModelIndex, int, int ) ), this, SLOT( rowsChanged() ) );
+  connect( mProxyModel, SIGNAL( rowsRemoved( QModelIndex, int, int ) ), this, SLOT( rowsChanged() ) );
 }
 
 void QgsMapLayerComboBox::setLayer( QgsMapLayer *layer )
@@ -45,9 +47,12 @@ void QgsMapLayerComboBox::setLayer( QgsMapLayer *layer )
 
 QgsMapLayer* QgsMapLayerComboBox::currentLayer() const
 {
-  int i = currentIndex();
+  return layer( currentIndex() );
+}
 
-  const QModelIndex proxyIndex = mProxyModel->index( i, 0 );
+QgsMapLayer *QgsMapLayerComboBox::layer( int layerIndex ) const
+{
+  const QModelIndex proxyIndex = mProxyModel->index( layerIndex, 0 );
   if ( !proxyIndex.isValid() )
   {
     return 0;
@@ -74,3 +79,16 @@ void QgsMapLayerComboBox::indexChanged( int i )
   emit layerChanged( layer );
 }
 
+void QgsMapLayerComboBox::rowsChanged()
+{
+  if ( count() == 1 )
+  {
+    //currently selected layer item has changed
+    emit layerChanged( currentLayer() );
+  }
+  else if ( count() == 0 )
+  {
+    emit layerChanged( 0 );
+  }
+}
+

src/gui/qgsmaplayercombobox.h

@@ -52,9 +52,18 @@ class GUI_EXPORT QgsMapLayerComboBox : public QComboBox
     //! returns the list of excepted layers
     QList<QgsMapLayer*> exceptedLayerList() const {return mProxyModel->exceptedLayerList();}
 
-    //! currentLayer returns the current layer selected in the combo box
+    /** Returns the current layer selected in the combo box.
+     * @see layer
+     */
     QgsMapLayer* currentLayer() const;
 
+    /** Return the layer currently shown at the specified index within the combo box.
+     * @param layerIndex position of layer to return
+     * @note added in QGIS 2.10
+     * @see currentLayer
+     */
+    QgsMapLayer* layer( int layerIndex ) const;
+
   public slots:
     //! setLayer set the current layer selected in the combo
     void setLayer( QgsMapLayer* layer );
@@ -65,6 +74,7 @@ class GUI_EXPORT QgsMapLayerComboBox : public QComboBox
 
   protected slots:
     void indexChanged( int i );
+    void rowsChanged();
 
   private:
     QgsMapLayerProxyModel* mProxyModel;