在Android上的地图活动中刷新叠加对象

Question

我必须建立一个地图活动,最重要的是,我需要显示一些位置点.这些位置从另一个类的哈希表中检索.此哈希表的内容始终会更改.所以我希望看到Map Activity上的那些位置点随着哈希表的修改而移动.代码如下所示:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mapview);

    MapView mapView = (MapView) this.findViewById(R.id.map);   
    mapView.setStreetView(true);
    mc = mapView.getController();


    mc.animateTo(...);
    mc.setZoom(12); 

    mapView.invalidate();

    List<Overlay> listOfOverlays = mapView.getOverlays();
    listOfOverlays.clear();

    MarkerOverlay mark = new MarkerOverlay(p);
     listOfOverlays.add(mark);

    for(Entry<Long,Pair> p: LQTManager.getInstance().ResultTable.entrySet())
    {

        GeoPoint point = new GeoPoint(
                    (int) (p.getValue().x * 1E6), 
                    (int) (p.getValue().y * 1E6));//some code is not shown
         MarkerOverlay markerOverlay = new MarkerOverlay(point);
         listOfOverlays.add(markerOverlay); 



    }

    mapView.postInvalidate();


}


class MarkerOverlay extends com.google.android.maps.Overlay
{
    public GeoPoint pt;

    public MarkerOverlay(GeoPoint pt){
        this.pt=pt;
        }

    @Override
    public boolean draw(Canvas canvas, MapView mapView, 
    boolean shadow, long when) 
    {
        super.draw(canvas, mapView, shadow);                   

        Point screenPts = new Point();
        mapView.getProjection().toPixels(pt, screenPts);

        Bitmap bmp = BitmapFactory.decodeResource(
            getResources(), R.drawable.pushpin);            

        canvas.drawBitmap(bmp, screenPts.x-16, screenPts.y-32, null); 

        return true;
    }
} 

如果我触摸屏幕,有没有办法刷新叠加对象.我正在考虑将一些函数放在MarkerOverlay的onTap覆盖方法中.但我认为如果我试图让Overlay尝试清除自己,那么逻辑上是不是？任何建议的想法？

Answer 1

mapView.postInvalidate()将更新地图视图并重新绘制叠加层.我正在使用Runnable来每秒刷新我的叠加层:

private Handler handler = new Handler();

private Runnable refreshTask = new Runnable()
{
  public void run()
  {
    handler.removeCallbacks(this);

    mapView.postInvalidate();

    handler.postDelayed(this, 1000);

  }
};