Change default behaviour of field calculator dialog (fixes ticket #2542)

git-svn-id: http://svn.osgeo.org/qgis/trunk@13046 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: mhugent

src/app/qgsfieldcalculator.cpp

@@ -24,26 +24,37 @@ QgsFieldCalculator::QgsFieldCalculator( QgsVectorLayer* vl ): QDialog(), mVector
 {
   setupUi( this );
 
+  if ( !vl )
+  {
+    return;
+  }
+
   populateFields();
   populateOutputFieldTypes();
 
   //default values for field width and precision
   mOuputFieldWidthSpinBox->setValue( 10 );
   mOutputFieldPrecisionSpinBox->setValue( 3 );
 
-  mUpdateExistingFieldCheckBox->setCheckState( Qt::Checked );
+
 
   //disable ok button until there is text for output field and expression
   mButtonBox->button( QDialogButtonBox::Ok )->setEnabled( false );
 
   // disable creation of new fields if not supported by data provider
   if ( !( vl->dataProvider()->capabilities() & QgsVectorDataProvider::AddAttributes ) )
   {
+    mUpdateExistingFieldCheckBox->setCheckState( Qt::Checked );
     mUpdateExistingFieldCheckBox->setEnabled( false ); // must stay checked
     mNewFieldGroupBox->setEnabled( false );
     mNewFieldGroupBox->setTitle( mNewFieldGroupBox->title() + tr( " (not supported by provider)" ) );
   }
 
+  if ( vl->selectedFeaturesIds().size() > 0 )
+  {
+    mOnlyUpdateSelectedCheckBox->setChecked( true );
+  }
+
   if ( vl->geometryType() != QGis::Polygon )
   {
     mAreaButton->setEnabled( false );