Question

我很想在谷歌地图上添加多个标记。这是我的代码部分

public class GoogleMap extends MapView 
 {
     MapController mc;
     MapView mapView; 
     GeoPoint p; 

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
    ....

         double lat = Double.parseDouble(bundle.getString("paramLat"));
         double lng = Double.parseDouble(bundle.getString("paramLong"));

         mc = mapView.getController();
         p = new GeoPoint( (int) (lat * 1E6),  (int) (lng * 1E6));
         mc.animateTo(p);
         mc.setZoom(17);

         //---Add a location marker---
         MapOverlay mapOverlay = new MapOverlay();
         List<Overlay> 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.pushpin);            
                   canvas.drawBitmap(bmp, screenPts.x, screenPts.y-50, null);     


                   return true;



         }
}

我在这里有两个问题。当我试图只添加一个标记时，它可以工作但是多次调用draw方法。但为什么？什么时候被调用？

第二个问题是如何添加新标记。我创建了第二个名为p2的geoPoint，之后该怎么办？非常感谢你。

Answer 1

我在项目中实现了多个标记。这是示例代码;您需要更改的一些内容是标记图像，长度（您希望在for循环中定义的标记数）。希望这会有所帮助!!!

public class ShowMapActivity extends MapActivity{
    private MapController mapControll;
    private GeoPoint geoPoint=null;
    private MapView mapview;
    private MyItemizedOverlay userPicOverlay;
    private MyItemizedOverlay nearPicOverlay;
    private Drawable userPic,atmPic;
    private OverlayItem nearatms[] = new OverlayItem[50];
    public static Context context;

    @Override
    protected void onCreate(Bundle icicle) {
        // TODO Auto-generated method stub
        super.onCreate(icicle);
        context = getApplicationContext();
        setContentView(R.layout.your layout xml);
        showMap();
    }

    public void showMap() {
        // TODO Auto-generated method stub

        try {
            geoPoint = new GeoPoint((int)(latitude * 1E6),(int)(longitude * 1E6));          
            mapview = (MapView)findViewById(R.id.mapview);
            mapControll= mapview.getController();
            mapview.setBuiltInZoomControls(true);
            mapview.setStreetView(true);
            mapControll.setZoom(16);
            mapControll.animateTo(geoPoint);

            userPic = this.getResources().getDrawable(R.drawable.your pic);
            userPicOverlay = new MyItemizedOverlay(userPic);
            OverlayItem overlayItem = new OverlayItem(geoPoint, "I'm Here!!!", null);
            userPicOverlay.addOverlay(overlayItem);
            mapview.getOverlays().add(userPicOverlay);


            atmPic = this.getResources().getDrawable(R.drawable.your pic);
            nearPicOverlay = new MyItemizedOverlay(atmPic);
            for (int i = 0; i < define your length here; i++) {
                nearatms[i] = new OverlayItem(new GeoPoint((int)((latitude) * 1E6)),(int)(longitude) * 1E6)),"Name", null);//just check the brackets i just made change here so....
                nearPicOverlay.addOverlay(nearatms[i]);
            }
            mapview.getOverlays().add(nearPicOverlay);
            //Added symbols will be displayed when map is redrawn so force redraw now
            mapview.postInvalidate();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    protected boolean isRouteDisplayed() {
        // TODO Auto-generated method stub
        return false;
    }

}

用于放置标记的分项类

public class MyItemizedOverlay extends ItemizedOverlay<OverlayItem> {

    private ArrayList<OverlayItem> myOverlays ;

    public MyItemizedOverlay(Drawable defaultMarker) {
        super(boundCenterBottom(defaultMarker));
        myOverlays = new ArrayList<OverlayItem>();
        populate();
    }

    public void addOverlay(OverlayItem overlay){
        myOverlays.add(overlay);
        populate();
    }

    @Override
    protected OverlayItem createItem(int i) {
        return myOverlays.get(i);
    }

    // Removes overlay item i
    public void removeItem(int i){
        myOverlays.remove(i);
        populate();
    }

    // Returns present number of items in list
    @Override
    public int size() {
        return myOverlays.size();
    }


    public void addOverlayItem(OverlayItem overlayItem) {
        myOverlays.add(overlayItem);
        populate();
    }


    public void addOverlayItem(int lat, int lon, String title) {
        try {
            GeoPoint point = new GeoPoint(lat, lon);
            OverlayItem overlayItem = new OverlayItem(point, title, null);
            addOverlayItem(overlayItem);    
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

    @Override
    protected boolean onTap(int index) {
        // TODO Auto-generated method stub
        String title = myOverlays.get(index).getTitle();
        Toast.makeText(ShowMapActivity.context, title, Toast.LENGTH_LONG).show();
        return super.onTap(index);
    }
}

Answer 2

要防止多次绘图，您需要一个缓存。这是MapOverlay
要添加多个标记，您必须使用ItemizedOverlay。 This may help you.

Answer 3

您应该按照开发者网站上的Android Map View教程进行操作。

第2部分有构建叠加的部分。

http://developer.android.com/resources/tutorials/views/hello-mapview.html

应该在Draw方法中完成最少的工作;它被称为很多，包括每次地图移动/缩放/“无效”

Answer 4

你想要开始使用ItemizedOverlay，这是一个点数组。您可以在此处找到文档http://code.google.com/android/add-ons/google-apis/reference/index.html。然后你想要调用ItemizedOverlay.draw（）方法，该方法将根据它们的位置绘制其中的所有点。希望这可以帮助。

在Android中的谷歌地图上添加多个标记

4 个答案: