圈画在图形页面透明度 [英] draw circle with transparency in mapview

问题描述

我有一个图形页面和覆盖的问题。

我一定要画在地图上的每次改变GPS位置的圆。
我使用的方法战平扩展覆盖我的叠加类。
问题是，我必须提请这些圆圈的透明度，但是当圈的交汇点相互重叠点是不同的颜色，因为有阿尔法的总和。

我怎样才能解决这个问题？

这是我的叠加类：

公共类ImpactOverlay扩展覆盖{私有静态诠释CIRCLERADIUS = 0;
私人的GeoPoint的GeoPoint;
私人诠释myCircleRadius;
逐点=新点（）;
油漆圈=新的油漆（Paint.ANTI_ALIAS_FLAG）;
私人长期SYSTEMTIME = -1;公共ImpactOverlay（GeoPoint的角度，诠释myRadius）{    的GeoPoint =点;
    CIRCLERADIUS = myRadius; // assegna raggio德尔cerchio
}@覆盖
公共无效画（油画画布，MapView类MapView类，布尔阴影）{     // Transfrom geoposition到点在画布上
     投影投影= MapView.getProjection（）在;
     projection.toPixels（GeoPoint对象，点）;     //圆圈标记现货
     circle.setColor（Color.parseColor（＃88ff0000））;
     circle.setAlpha（122）; // trasparenza     myCircleRadius = metersToRadius（CIRCLERADIUS，MapView类，
     （双）geopoint.getLatitudeE6（）/ 1000000）;     canvas.drawCircle（point.x，point.y，myCircleRadius，圆圈）;}公共静态INT metersToRadius（浮点米，MapView的地图，双纬度）{
    回报（INT）（map.getProjection（）。metersToEquatorPixels（米）*（1 /数学
            名为.cos（Math.toRadians（纬度））））;
}@覆盖
每eseguire变焦苏拉mappa / * Implementa IL Doppio的自来水* /
公共布尔onTouchEvent（MotionEvent事件，MapView类MapView类）{
    开关（event.getAction（））{
    案例MotionEvent.ACTION_DOWN：
        如果（（System.currentTimeMillis的（） - SYSTEMTIME）所述; 250）{
            。mapView.getController（）zoomIn（）;
        }
        SYSTEMTIME = System.currentTimeMillis的（）;
        打破;
    }    返回false;
}
}


解决方案

  CircleOptions圈=新CircleOptions（）;
        circle.center（新经纬度（纬度，经度））
        .radius（1500）//在米
        .strokeColor（Color.BLUE）//边框颜色
        .strokeWidth（3.0F）//边框宽度
        .fillColor（0x200000ff）; //内圆
        googleMap.addCircle（圈）; // GoogleMap的GoogleMap的（相应的初始化）
 

I have a problem with mapview and Overlay.

I must to draw a circle on the map everytime that change GPS position. I used the method draw in my overlay class that extend overlay. The problem is that I must draw these circles with transparency, but when the circles overlap each other in the intersection point the color it's different because there is a sum of alpha.

How I can fix it?

This is my overlay class:

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;
}
}

解决方案

        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)

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