Mapping with Google APIs in Android, Page 2

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Panning, Zooming, and Toggling Map Modes

As was mentioned before, MapController is used to pan and zoom a map. You need to associate each button with a click listener. One example is as follows:

// Set up the button for "Pan East"

mPanE = (Button)findViewById(R.id.pane);    	



        




mPanE.setOnClickListener(new OnClickListener(){


	

		
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    // @Override

    public void onClick(View arg0) {

        panEast();

    }

}); 

The panEast() function is implemented to pan a quarter of the current screen width. Other panning functionalities are done in a similar fashion. Actually, the map itself is already draggable if the device is equipped with a touch screen input. For non-touch-screen devices, you use these buttons or the arrow keys of the rocker pad to pan the map.

public void panEast() {

    GeoPoint pt = new GeoPoint(

        mMapView.getMapCenter().getLatitudeE6(),

        mMapView.getMapCenter().getLongitudeE6()

            + mMapView.getLongitudeSpan() / 4);

    mOverlayController.setCenter(pt);

    mMapView.invalidate();

}

Zooming is done simply by increasing or decreasing the current zoom level through the controller.

public void zoomIn() {

    mOverlayController.setZoom(mMapView.getZoomLevel() + 1);

    mMapView.invalidate();

}

To toggle the map display for viewing satellite imagery or traffic, you can enable it directly from MapView.

public void toggleSatellite() {

    if (mMapView.isSatellite())

        mMapView.setSatellite(false);

    else

        mMapView.setSatellite(true);

    mMapView.invalidate();

}
 

public void toggleTraffic() {

    if (mMapView.isTraffic())

        mMapView.setTraffic(false);

    else

        mMapView.setTraffic(true);

    mMapView.invalidate();

}

Figures 2 and 3 show the results of toggling.

Click here for larger image
Figure 2. Satellite Imagery

Click here for larger image
Figure 3. Traffic on Satellite Imagery

 

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