使用Android 2.3在2个地理位置之间绘制一条线

Question

i am trying to draw a line between 2 geopoints. i am able to show to geopoints on the map. Its working fine. but i am not able to draw a line between 2 points. program has no error but line is not getting displayed. can anyone tell me what i have to change.

public class HelloMapView extends MapActivity {
/** Called when the activity is first created. */
 LinearLayout linearLayout;
MapView mapView; 
MapController mc;
GeoPoint p,p1;

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.a);             
        canvas.drawBitmap(bmp, screenPts.x, screenPts.y-50, null);  

        //Coordinates 2 

      //---translate the GeoPoint to screen pixels---
        Point screenPts1 = new Point();
        mapView.getProjection().toPixels(p1, screenPts1);

        //---add the marker---
        Bitmap bmp1 = BitmapFactory.decodeResource(
            getResources(), R.drawable.b);             
        canvas.drawBitmap(bmp1, screenPts1.x, screenPts1.y-50, null); 

        //----------- Start--------------//

        Projection projection = mapView.getProjection();
        Path path = new Path();

        Point from = new Point();
        Point to = new Point();
        projection.toPixels(p, from);
        projection.toPixels(p1, to);
        path.moveTo(from.x, from.y);
        path.lineTo(to.x, to.y);

        Paint mPaint = new Paint();
        mPaint.setStyle(Style.FILL);
        mPaint.setColor(0xFFFF0000);
        mPaint.setAntiAlias(true);
        canvas.drawPath(path,mPaint);
        super.draw(canvas, mapView, shadow);         


        return true;
    }
} 


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

    mapView = (MapView) findViewById(R.id.mapview);

    mapView.setBuiltInZoomControls(true);

    mapView = (MapView) findViewById(R.id.mapview);



    mapView.displayZoomControls(true);
    mc = mapView.getController();
    String coordinates[] = {"12.958998", "77.658998"};
    double lat = Double.parseDouble(coordinates[0]);
    double lng = Double.parseDouble(coordinates[1]);

    p = new GeoPoint(
        (int) (lat * 1E6), 
        (int) (lng * 1E6));


    String coordinates1[] = {"12.95967","77.64918"};
    double lat1 = Double.parseDouble(coordinates1[0]);
    double lng1 = Double.parseDouble(coordinates1[1]);

    p1 = new GeoPoint(
        (int) (lat1 * 1E6), 
        (int) (lng1 * 1E6));


    mc.animateTo(p);
    mc.animateTo(p1);
    mc.setZoom(16); 

  //---Add a location marker---
    MapOverlay mapOverlay = new MapOverlay();
    List<Overlay> listOfOverlays = mapView.getOverlays();
    listOfOverlays.clear();
    listOfOverlays.add(mapOverlay);        

    mapView.invalidate();


}

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

}

Answer 1

忘记所有的Path东西，只需使用以下行（对我有用）：

canvas.drawLine(screenPts.x, screenPts.y, screenPts1.x, screenPts1.y, mPaint);

Answer 2

I suspect you need to change this line:

mPaint.setStyle(Style.FILL);

to:

mPaint.setStyle(Style.STROKE);

Also, while it's probably not related to your problem, it looks like you are calling super.draw twice, once at the beginning and once at the end. You probably just want to call it at the beginning.