This sample demonstrates the use of the Geoprocessor (GP) task to calculate a viewshed within a five mile distance of an area of interest. It also illustrates how to use an Android AsyncTask to execute asynchronous GP tasks. The application prompts the user to add a point to the map with a single tap on the device, click the Play button to run a geoprocessing task that calculates the viewshed from the point location perspective.
- Geoprocessing
- Creating symbols on a Graphics Layer.
- Single Tap event listener.
A viewshed is an area visible from a specific location.
The onCreate() method is first called when the activity is created. It sets the content view to a MapView defined in the layout main.xml file. The mapType is set in the layout along with the zoom level and its center. The setOnSingleTapListener is set on the map such that when a user taps on the map it displays a point at the tapped location. It also removes any previous point if present.
The ActionBar displays the two icons Start and Delete. When Start is tapped, the viewshed analysis takes place using the point on the map as an AsyncTask running on the background thread. The results are displayed on a GraphicsLayer. When the Delete icon is tapped, any graphics are removed from the GraphicsLayer.