MapView在觸摸時添加圖釘

Question

我設法讓地圖顯示在屏幕上。現在用戶將在地圖上移動並按下它。按下一個點後，我需要在按下的位置上的屏幕上添加一個圖釘。如果用戶決定去另一點，所選擇的點壓接時，第一個圖釘將disapear和新的人會在新的位置

我不喜歡這樣可以得出：

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; 
     }   

    } 

這繪製初始圖釘（map_flag資源）。當點擊地圖時，我會收到Toast和coordonates ...所有剩下的工作就是點擊一下，抹掉舊的pin並添加一個新的pin。

但是怎麼做呢？

Answer 1

我會使用ItemizedOverlay，而不是一個普通的Overlay。然後，您只需更新OverlayItem對象的集合並在ItemizedOverlay上調用populate()即可。

這裏是a sample project顯示使用ItemizedOverlay拖放一個引腳。

Answer 2

@Override 
public boolean onTouchEvent(MotionEvent event, MapView mapView) 
{ 
    //---when user lifts his finger--- 
    if (event.getAction() == 1) {     
     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; 
}   

這將工作。使OnTouchEvent的GeoPoint Public ...

Answer 3

此代碼工作正常。

@Override 
     public boolean onTap(GeoPoint p, MapView mapView) { 
      Log.d("tap event ", "tap called"); 
      mapOverlays = mapView.getOverlays(); 
      drawable =getResources().getDrawable(R.drawable.marker); 
      itemizedOverlay = new SitesOverlay(drawable); 
      int lat=(int)p.getLatitudeE6(); 
      int lng=(int)p.getLongitudeE6(); 


      GeoPoint point = new GeoPoint(lat,lng); 
      Log.d("tap event ", "tapcalled"+lat+""+lng); 
      OverlayItem overlayitem = new OverlayItem(point, "", ""); 

      items.add(overlayitem); 
      populate(); 
      Log.d("tap event ", "populated"); 
      //  mapOverlays.add(itemizedOverlay); 


      return true; 
     }