我成功地将地图显示在屏幕上。现在用户可以在地图上移动并按压它。在按下一个点后,我需要在所按的位置在屏幕上添加一个推钉。如果用户决定选择另一个点,则在选择该点时,第一个推钉将消失,并在新位置上绘制一个新的推钉。
我是这样做的:
public class LocationSelectionActivity extends MapActivity
{
GeoPoint p;
List<Overlay> listOfOverlays;
MapOverlay mapOverlay;
private MapView mapView;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.locationselection);
mapView = (MapView) findViewById(R.id.mapView);
mapView.setSatellite(false);
final MapController mc = mapView.getController();
String coordinates[] = {"46.540606", "22.454542"};
double lat = Double.parseDouble(coordinates[0]);
double lng = Double.parseDouble(coordinates[1]);
p = new GeoPoint(
(int) (lat * 1E6),
(int) (lng * 1E6));
mc.animateTo(p);
mc.setZoom(10);
ZoomControls zoomControls = (ZoomControls) findViewById(R.id.zoomcontrols);
zoomControls.setOnZoomInClickListener(new View.OnClickListener() {
public void onClick(View v) {
mc.zoomIn();
}
});
zoomControls.setOnZoomOutClickListener(new View.OnClickListener() {
public void onClick(View v) {
mc.zoomOut();
}
});
//---Add a location marker---
mapOverlay = new MapOverlay();
listOfOverlays = mapView.getOverlays();
listOfOverlays.clear();
listOfOverlays.add(mapOverlay);
mapView.invalidate();
}
class MapOverlay extends com.google.android.maps.Overlay
{
@Override
public boolean draw(Canvas canvas, MapView mapView,
boolean shadow, long when)
{
super.draw(canvas, mapView, shadow);
//---translate the GeoPoint to screen pixels---
Point screenPts = new Point();
mapView.getProjection().toPixels(p, screenPts);
//---add the marker---
Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.map_flag);
canvas.drawBitmap(bmp, screenPts.x, screenPts.y-48, null);
return true;
}
@Override
public boolean onTouchEvent(MotionEvent event, MapView mapView)
{
//---when user lifts his finger---
if (event.getAction() == 1) {
GeoPoint p = mapView.getProjection().fromPixels(
(int) event.getX(),
(int) event.getY());
Toast.makeText(getBaseContext(),
p.getLatitudeE6() / 1E6 + "," +
p.getLongitudeE6() /1E6 ,
Toast.LENGTH_SHORT).show();
}
return false;
}
}
这绘制了初始的图钉(地图旗帜资源)。当在地图上点击时,我会得到一个包含坐标的Toast...剩下要做的就是在新的点击事件中擦除旧图钉并添加一个新图钉。
但是如何实现呢?