Android谷歌地图中的高效地图叠加

Question

我想做以下事情,并且有几天坚持这些:

1. 当我移动地图时,我试图绘制多段线(我已编码折线,但设法解码那些). 我发现的唯一解决方案是将Geopoints转换为屏幕坐标...如果我移动地图则不会移动.
   

2. 我曾经HelloItemizedOverlay添加了大约150个标记,它变得非常慢.
   知道该怎么办？我在考虑线程(处理程序).

3. 我正在寻找某种定时器功能,它定期执行一个给定的功能,比如每1分钟左右.

4. 我也在寻找从所有标记/线等清除谷歌地图的方法.

Answer 1

答案如下:

1)这是我使用的解决方案:

/** Called when the activity is first created. */
private List<Overlay> mapOverlays;

private Projection projection;  

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

    linearLayout = (LinearLayout) findViewById(R.id.zoomview);
    mapView = (MapView) findViewById(R.id.mapview);
    mapView.setBuiltInZoomControls(true);

    mapOverlays = mapView.getOverlays();        
    projection = mapView.getProjection();
    mapOverlays.add(new MyOverlay());        

}

@Override
protected boolean isRouteDisplayed() {
    return false;
}

class MyOverlay extends Overlay{

    public MyOverlay(){

    }   

    public void draw(Canvas canvas, MapView mapv, boolean shadow){
        super.draw(canvas, mapv, shadow);

    Paint   mPaint = new Paint();
        mPaint.setDither(true);
        mPaint.setColor(Color.RED);
        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(2);

        GeoPoint gP1 = new GeoPoint(19240000,-99120000);
        GeoPoint gP2 = new GeoPoint(37423157, -122085008);

        Point p1 = new Point();
        Point p2 = new Point();

    Path    path = new Path();

    Projection  projection.toPixels(gP1, p1);
        projection.toPixels(gP2, p2);

        path.moveTo(p2.x, p2.y);
        path.lineTo(p1.x,p1.y);

        canvas.drawPath(path, mPaint);
    }

礼貌:在Google地图上绘制线条/路径

2)这对我有用:

createMarkers()
{ 
    for(elem:bigList)
    { 
        GeoPoint geoPoint = new GeoPoint((int)(elem.getLat()*1000000), (int) (elem.getLon()*1000000)); 
        OverlayItem overlayItem = new OverlayItem(geoPoint, elem.getName(), elem.getData()); 
        itemizedOverlay.addOverlay(overlayItem); 
    } 

    itemizedOverlay.populateNow(); 
    mapOverlays.add(itemizedOverlay); //outside of for loop 
} 

在MyOverlay中:

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

public void populateNow()
{
    populate(); 
}

礼貌:stackoverflow.com未知链接

3)最好的方法是使用计时器类.在此链接中给出了计时器类的详细描述以及如何使用它:

http://life.csu.edu.au/java-tut/essential/threads/timer.html

4)我使用了这段代码:

if(!mapOverlays.isEmpty()) 
{ 
    mapOverlays.clear(); 
    mapView.invalidate(); 
} 

希望这些答案能帮助至少另一个人.谢谢.