我有一个程序,我想在两点之间划一条线。然后我想要另一条线在另外两个点之间绘制。当我绘制一条线时,它会删除上一行。我试图让两条线不同叠加,但它仍然删除旧线并放入新线。我是否防止这种情况发生,以及如何使所有叠加层保持不变?任何帮助将不胜感激。如何在屏幕上绘制多个地图叠加层?
Activity类中的Overlay类。
这是onkeydown事件()
case KeyEvent.KEYCODE_8:
twoPoints.add(a);
twoPoints.add(b);
MapOverlay newOverlay = new MapOverlay();
listOfOverlays = mapView.getOverlays();
listOfOverlays.add(newOverlay);
mapView.postInvalidate();
System.out.println("Test overlays 1 Point");
break;
case KeyEvent.KEYCODE_9:
twoPoints.remove(1);
twoPoints.add(c);
MapOverlay newOverlay1 = new MapOverlay();
listOfOverlays.add(newOverlay1);
mapView.postInvalidate();
System.out.println("Test Overlays 2 Point");
break;
这是覆盖类:
public class MapOverlay extends com.google.android.maps.Overlay
{
@Override
public void draw(Canvas canvas, MapView mapView, boolean shadow)
{
super.draw(canvas,mapView,shadow);
//-- Create new paint object --
Paint mPaint = new Paint();
mPaint.setDither(true);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(2);
//System.out.println("Point 1");
//System.out.println("Point 2");
for(int i =0; i < twoPoints.size()-1;i++)
{
Point screenPt1 = new Point();
mapView.getProjection().toPixels(twoPoints.get(i), screenPt1);
Point screenPt2 = new Point();
mapView.getProjection().toPixels(twoPoints.get(i+1), screenPt2);
canvas.drawLine(screenPt1.x, screenPt1.y, screenPt2.x, screenPt2.y, mPaint);
System.out.println("Point 3");
}
//mapView.invalidate();
}
}
已真正困惑我有一段时间了。
从你的问题我得到的是,你想显示2点之间的方向?我对吗? – Prem 2012-03-27 06:06:12
如果你想方向,那么我建议你应该使用谷歌地图Web服务.... – Prem 2012-03-27 06:06:58