Best practices: Map interaction

When you are writing a tool that requires mouse interaction, use the Draw surface instead of listening for mouse clicks. With the Draw surface, you can easily capture geometries that are drawn by users of your application. Once you retrieve these geometries, you can add them to a Graphics layer or use them as input for other operations.

When you are writing a tool that captures map clicks, do the following:

The following code snippet creates a new Draw surface on the map, sets the DrawMode to Point, and listens for the IsEnabled property.

private Identify identifyDialog;
private IdentifyTask identifyTask;
private Draw draw;

public void Execute(object parameter)
    if (draw == null)
         draw = new Draw(MapApplication.Current.Map) { DrawMode = ESRI.ArcGIS.Client.DrawMode.Point };
         draw.DrawComplete += DrawComplete;

         // Listen to the IsEnabled property.  This is to detect cases where other tools have
         // disabled the Draw surface.
				     // Utils class shown below.
         Utils.RegisterForNotification("IsEnabled", draw, identifyDialog, OnDrawEnabledChanged);

     draw.IsEnabled = true;
     MapApplication.Current.ShowWindow("Identify", identifyDialog, false, null, IdentifyDialogHidden);

// Fires when the drawing action is complete.  Issues an identify operation using the drawn geometry.
private void DrawComplete(object sender, DrawEventArgs e)
    MapPoint clickPoint = e.Geometry as MapPoint;

    IdentifyParameters identifyParams = new IdentifyParameters()
        Geometry = clickPoint,
        MapExtent = MapApplication.Current.Map.Extent,
        LayerOption = LayerOption.visible,
        SpatialReference = MapApplication.Current.Map.SpatialReference

    if (identifyTask.IsBusy)

    GraphicsLayer graphicsLayer = MapApplication.Current.Map.Layers["IdentifyResultsLayer"] as GraphicsLayer;
    if (graphicsLayer == null)
        graphicsLayer = createResultsLayer();

    Graphic graphic = new Graphic() { Geometry = clickPoint };
public class Utils
   public static void RegisterForNotification(string propertyName, object source, FrameworkElement element, 
   PropertyChangedCallback callback)
       //Bind to a depedency property.
       Binding b = new Binding(propertyName) { Source = source };
       var prop = System.Windows.DependencyProperty.RegisterAttached(
            "ListenAttached" + propertyName,
            new PropertyMetadata(callback));

       element.SetBinding(prop, b);