图形页面上添加触摸图钉 [英] MapView adding pushpins on touch

问题描述

我设法在屏幕上显示的地图。现在，用户将围绕它的地图和preSS移动。经过上的一个点pressing我需要添加一个图钉在屏幕上的pressed位置。如果用户决定去另外一点，当所选择的点pressing，第一个图钉会disapear和新将在新的位置绘制

I managed to get the map shown on the screen. Now the user will move around the map and press on it. After pressing on a point I need to add a push pin on screen on the pressed location. If the user decides to go for another point, when pressing on the chosen point, the first pushpin would disapear and a new one will be drawn on the new location

我不喜欢这样的：

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;
        }        

    } 

此画最初的图钉（该map_flag资源）。当我得到的吐司与coordonates在地图上点击......一切都剩下要做的就是在一个新的点击，擦除旧针，并添加一个新的。

This draws the initial pushpin (the map_flag resource). When clicking on the map I get the Toast with the coordonates... all is left to do is on a new click, erase the old pin and add a new one.

但怎么办呢？

推荐答案

我会使用 ItemizedOverlay ，而不是一个常规重叠。然后，所有你需要做的就是更新您的 OverlayItem 的对象集合，并调用填充（）在 ItemizedOverlay 。

I would use an ItemizedOverlay, rather than a regular Overlay. Then, all you need to do is update your collection of OverlayItem objects and call populate() on the ItemizedOverlay.

下面是 呈现出示例项目拖使用针 ItemizedOverlay 的-drop。

Here is a sample project showing drag-and-drop of a pin using ItemizedOverlay.

这篇关于图形页面上添加触摸图钉的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！