Getting Directions

In the previous topic we added routing functionality to our application. In this topic we will extend the routing capabilities to generate driving directions for a given route.

In addition to adding a new directions method some of the existing methods must be modified to ensure that our application behaves in a logical and consistent manner.

Note
We need a Route object to generate directions, so it's important that you completed the previous topic: Creating and Optimizing a Route.

This is a straightforward process and you will notice that the code given here bears many similarities to previous topics.

In the Designer, add a menu item "Get directions" to the right-click context menu that we created in the previous topic. Add a Click event, switch to the Code View and add the following code:

 private void getDirectionsToolStripMenuItem_Click(object sender, EventArgs e) {
    try {
    // directions generation could take a while
    this.Cursor = Cursors.WaitCursor;

    // generate new directions and add them to the renderlist for display
    directions = route.GetDirections();
    renderList.Add(directions);

    // force the map to redraw to show our changes
    mapMain.Invalidate();
  } catch (Exception ex) {
    this.Cursor = Cursors.Default;
    MessageBox.Show(this, ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
  }
     this.Cursor = Cursors.Default;
}

Note
It is possible that an exception will be thrown if GeoBase could not generate directions. This could occur if, for example, route stops are on islands not joined by a bridge or ferry route. In this case the exception message is shown in a MessageBox.

You should now have a working application that demonstrates some of the built-in capabilities of GeoBase.