add perimeter to derived attributes for polygonal geometries

Author: alexbruy

src/app/qgsmaptoolidentify.cpp

@@ -308,10 +308,14 @@ bool QgsMapToolIdentify::identifyVectorLayer( QgsVectorLayer *layer, int x, int
     else if ( layer->geometryType() == QGis::Polygon )
     {
       double area = calc.measure( f_it->geometry() );
+      double perimeter = calc.measurePerimeter( f_it->geometry() );
       QGis::UnitType myDisplayUnits;
       convertMeasurement( calc, area, myDisplayUnits, true );  // area and myDisplayUnits are out params
       QString str = calc.textUnit( area, 3, myDisplayUnits, true );
       derivedAttributes.insert( tr( "Area" ), str );
+      convertMeasurement( calc, perimeter, myDisplayUnits, false );  // area and myDisplayUnits are out params
+      str = calc.textUnit( perimeter, 3, myDisplayUnits, false );
+      derivedAttributes.insert( tr( "Perimeter" ), str );
     }
     else if ( layer->geometryType() == QGis::Point &&
               ( f_it->geometry()->wkbType() == QGis::WKBPoint ||