android - 在 map View 中绘制透明的圆圈

Question

我有 mapview 和 Overlay 的问题。

每次更改 GPS 位置时，我都必须在 map 上画一个圆圈。我在扩展覆盖的覆盖类中使用了绘制方法。问题是我必须以透明方式绘制这些圆圈，但是当圆圈在交点处相互重叠时，颜色会有所不同，因为存在 alpha 总和。

我该如何解决？

这是我的覆盖类:

public class ImpactOverlay extends Overlay {

private static int CIRCLERADIUS = 0;
private GeoPoint geopoint;
private int myCircleRadius;
Point point = new Point();
Paint circle = new Paint(Paint.ANTI_ALIAS_FLAG);
private long systemTime= -1 ;



public ImpactOverlay(GeoPoint point, int myRadius) {

    geopoint = point;
    CIRCLERADIUS = myRadius; // assegna raggio del cerchio
}

@Override
public void draw(Canvas canvas, MapView mapView, boolean shadow) {

     // Transfrom geoposition to Point on canvas
     Projection projection = mapView.getProjection();
     projection.toPixels(geopoint, point);

     // the circle to mark the spot
     circle.setColor(Color.parseColor("#88ff0000"));
     circle.setAlpha(122); // trasparenza

     myCircleRadius = metersToRadius(CIRCLERADIUS, mapView,
     (double) geopoint.getLatitudeE6() / 1000000);

     canvas.drawCircle(point.x, point.y, myCircleRadius, circle);       

}



public static int metersToRadius(float meters, MapView map, double latitude) {
    return (int) (map.getProjection().metersToEquatorPixels(meters) * (1 / Math
            .cos(Math.toRadians(latitude))));
}

@Override
/* Implementa il doppio tap per eseguire zoom sulla mappa */
public boolean onTouchEvent(MotionEvent event, MapView mapView) {
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        if ((System.currentTimeMillis() - systemTime) < 250) {
            mapView.getController().zoomIn();
        }
        systemTime = System.currentTimeMillis();
        break;
    }

    return false;
}
}

Answer 1

        CircleOptions circle = new CircleOptions();
        circle.center(new LatLng(latitude, longitude))
        .radius(1500)//in meters
        .strokeColor(Color.BLUE)//border color
        .strokeWidth(3.0f)//border width
        .fillColor(0x200000ff);//inside circle
        googleMap.addCircle(circle);//GoogleMap googleMap(initialize accordingly)