android地图圆形覆盖，动态改变半径？

我在我的应用程序中有一个地图视图，我正在这张地图上画一些圆形覆盖图。一切正常，但当我缩放地图时，覆盖半径不会改变。我曾尝试在论坛和谷歌上搜索解决方案，但找不到一个适合我的。有人有什么想法吗

这是我的密码：

HelloLogleMaps.java（主要活动）

提前感谢您的帮助

class myLocationOverlay extends com.google.android.maps.Overlay {

    private static final double defaultLatitude = Double.parseDouble("your_default_latitude");
    private static final double defaultLongitude = Double.parseDouble("your_default_longitude");
    private static final float defaultAccuracy = 250f; // or whatever you wish it to be


    Location currentLocation; // this should be already known

    private Paint accuracyPaint;
    private Point center;
    private Point left;
    private Drawable drawable;
    private int width;
    private int height;

    @Override
    public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) {
        super.draw(canvas, mapView, shadow);

        accuracyPaint = new Paint();
        accuracyPaint.setAntiAlias(true);
        accuracyPaint.setStrokeWidth(2.0f);

        drawable = mapView.getContext().getResources().getDrawable(R.drawable.my_location_dot);
        width = drawable.getIntrinsicWidth();
        height = drawable.getIntrinsicHeight();
        center = new Point();
        left = new Point();
        double latitude;
        double longitude;
        float accuracy;
        Projection projection = mapView.getProjection();

        if(currentLocation == null) {
            latitude = defaultLatitude;
            longitude = defaultLongitude;
            accuracy = defaultAccuracy;
        } else {
            latitude = currentLocation.getLatitude();
            longitude = currentLocation.getLongitude();
            accuracy = currentLocation.getAccuracy();
        }            

        float[] result = new float[1];

        Location.distanceBetween(latitude, longitude, latitude, longitude + 1, result);
        float longitudeLineDistance = result[0];

        GeoPoint leftGeo = new GeoPoint((int)(latitude * 1E6), (int)((longitude - accuracy / longitudeLineDistance) * 1E6));
        projection.toPixels(leftGeo, left);
        projection.toPixels(myLocationPoint, center);
        int radius = center.x - left.x;

        accuracyPaint.setColor(0xff6666ff);
        accuracyPaint.setStyle(Style.STROKE);
        canvas.drawCircle(center.x, center.y, radius, accuracyPaint);

        accuracyPaint.setColor(0x186666ff);
        accuracyPaint.setStyle(Style.FILL);
        canvas.drawCircle(center.x, center.y, radius, accuracyPaint);

        drawable.setBounds(center.x - width / 2, center.y - height / 2, center.x + width / 2, center.y + height / 2);
        drawable.draw(canvas);

        return true;
    }
}

---

将R.drawable.my_location\u dot更改为您使用的任何位置标记，并查看当前位置是已知的

我知道此线程已存在几个月，但总是有更简单的方法来实现非常类似的结果。 我知道，所提供的方法可以更精确地计算圆的大小，但是，如果您只需要计算某个区域周围的任何圆，则此代码需要更少的处理，从而使UI更流畅：

public class MapCircleOverlay extends Overlay {

private GeoPoint point;
private Paint paint1, paint2;

public MapCircleOverlay(GeoPoint point) {
    this.point = point;

    paint1 = new Paint();
    paint1.setARGB(128, 0, 0, 255);
    paint1.setStrokeWidth(2);
    paint1.setStrokeCap(Paint.Cap.ROUND);
    paint1.setAntiAlias(true);
    paint1.setDither(false);
    paint1.setStyle(Paint.Style.STROKE);

    paint2 = new Paint();
    paint2.setARGB(64, 0, 0, 255);  

}

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

    Point pt = mapView.getProjection().toPixels(point, null);
    float radius = (float) Math.pow(2, mapView.getZoomLevel() - 10);

    if(radius < canvas.getHeight()/25){
        radius = canvas.getHeight()/25;
    }

    canvas.drawCircle(pt.x, pt.y, radius, paint2);
    canvas.drawCircle(pt.x, pt.y, radius, paint1);

}

}

公共类MapCircleOverlay扩展了覆盖{
专用地质点；
私人油漆1、油漆2；
公共地图圆形覆盖图（地质点）{
这个点=点；
油漆1=新油漆（）；
paint1.setARGB（128,0,025）；
油漆1.设置行程宽度（2）；
油漆1.固定行程盖（油漆.盖.圆形）；
paint1.setAntiAlias（真）；
1.设置抖动（假）；
paint1.setStyle（Paint.Style.STROKE）；
油漆2=新油漆（）；
paint2.setARGB（64,0,025）；
}
@凌驾
公共空白绘制（画布、地图视图、地图视图、布尔阴影）{
Point pt=mapView.getProjection（）.toPixels（点，null）；
浮点半径=（float）Math.pow（2，mapView.getZoomLevel（）-10）；
if（半径

说明： 文档说明，对于每个zoomLevel，地图的大小都会加倍（或减半），因此只要半径加倍或减半，其大小在整个图形中都会保持一致

可以更改“-10”以改变圆的大小（如果需要，可以在构造函数中完成）

此外，可以根据需要调整min_r（最小半径）计算，这只是为了防止用户缩小时圆完全消失

希望它能帮助别人；）

---

我修改了Bundius的答案，因此它可以与仪表一起工作，您可以将其作为构造函数的一部分输入。

对不起，我知道被接受的答案很旧，但存在一个本机更好的解决方案

 // Add a circle in Sydney
 Circle circle = map.addCircle(new CircleOptions()
     .center(new LatLng(-33.87365, 151.20689))
     .radius(10000)
     .strokeColor(Color.RED)
     .fillColor(Color.BLUE));

我希望这对某人有帮助（）

---

参考资料：

将半径添加到屏幕后，您将如何更改半径？

public class MapCircleOverlay extends Overlay {

private GeoPoint point;
private Paint paint1, paint2;

public MapCircleOverlay(GeoPoint point) {
    this.point = point;

    paint1 = new Paint();
    paint1.setARGB(128, 0, 0, 255);
    paint1.setStrokeWidth(2);
    paint1.setStrokeCap(Paint.Cap.ROUND);
    paint1.setAntiAlias(true);
    paint1.setDither(false);
    paint1.setStyle(Paint.Style.STROKE);

    paint2 = new Paint();
    paint2.setARGB(64, 0, 0, 255);  

}

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

    Point pt = mapView.getProjection().toPixels(point, null);
    float radius = (float) Math.pow(2, mapView.getZoomLevel() - 10);

    if(radius < canvas.getHeight()/25){
        radius = canvas.getHeight()/25;
    }

    canvas.drawCircle(pt.x, pt.y, radius, paint2);
    canvas.drawCircle(pt.x, pt.y, radius, paint1);

}

}

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;

public class MapCircleOverlay extends Overlay {

private GeoPoint point;
private Paint paint1, paint2;
private float radius; //in meters

public MapCircleOverlay(GeoPoint point, float radius) {
    this.point = point;

    paint1 = new Paint();
    paint1.setARGB(128, 0, 0, 255);
    paint1.setStrokeWidth(2);
    paint1.setStrokeCap(Paint.Cap.ROUND);
    paint1.setAntiAlias(true);
    paint1.setDither(false);
    paint1.setStyle(Paint.Style.STROKE);

    paint2 = new Paint();
    paint2.setARGB(64, 0, 0, 255);

    this.radius = radius;
}

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

    Point pt = mapView.getProjection().toPixels(point, null);
    float projectedRadius = mapView.getProjection().metersToEquatorPixels(radius);

    canvas.drawCircle(pt.x, pt.y, projectedRadius, paint2);
    canvas.drawCircle(pt.x, pt.y, projectedRadius, paint1);

}

}

 // Add a circle in Sydney
 Circle circle = map.addCircle(new CircleOptions()
     .center(new LatLng(-33.87365, 151.20689))
     .radius(10000)
     .strokeColor(Color.RED)
     .fillColor(Color.BLUE));

private CircleOptions circle;
double radiusInMeters = 50.0;
int strokeColor = 0xffff0000; //red outline
int shadeColor = 0x44ff0000;

 @Override
 public void onLocationChanged(Location location) {

 ...
    LatLng mylatlng= new LatLng(currentLat, currentLon);
    circle = new CircleOptions().center(mylatlng).radius(radiusInMeters).fillColor(shadeColor).strokeColor(strokeColor).strokeWidth(3);
    mMap.addCircle(circle);

 ...

}