在Android的地图视图上绘制一定半径的圆 [英] Draw circle of certain radius on map view in Android

问题描述

我想在地图视图上画一个圆圈.我希望用户输入半径，对于该半径，我必须在地图上显示圆圈.之后，我必须在该圆圈的某些位置显示标记.

I want to draw a circle on map view. I want the user to input the radius and for that radius I have to show circle on map. After that I have to display markers on some locations on that circle.

我知道如何在地图视图上显示标记.

I know how to display markers on on map view.

如何在地图视图上绘制圆圈并在该圆圈边界上显示标记.

How can I draw circle on map view and to show markers on that circle boundary.

推荐答案

在ItemizedOverlay的实现中，做类似onDraw中的drawCircle方法方法

In the implementation of the ItemizedOverlay, do something like the method drawCircle from the onDraw method

protected void drawCircle(Canvas canvas, Point curScreenCoords) {
    curScreenCoords = toScreenPoint(curScreenCoords);
    int CIRCLE_RADIUS = 50;
    // Draw inner info window
    canvas.drawCircle((float) curScreenCoords.x, (float) curScreenCoords.y, CIRCLE_RADIUS, getInnerPaint());
    // if needed, draw a border for info window
    canvas.drawCircle(curScreenCoords.x, curScreenCoordsy, CIRCLE_RADIUS, getBorderPaint());
}

private Paint innerPaint, borderPaint;

public Paint getInnerPaint() {
    if (innerPaint == null) {
        innerPaint = new Paint();
        innerPaint.setARGB(225, 68, 89, 82); // gray
        innerPaint.setAntiAlias(true);
    }
    return innerPaint;
}

public Paint getBorderPaint() {
    if (borderPaint == null) {
        borderPaint = new Paint();
        borderPaint.setARGB(255, 68, 89, 82);
        borderPaint.setAntiAlias(true);
        borderPaint.setStyle(Style.STROKE);
        borderPaint.setStrokeWidth(2);
    }
    return borderPaint;
}

@Override
protected void onDraw(Canvas canvas) {
    Point p = new Point();
    for(OverlayItem item : items) {
        drawCircle(canvas, getProjection().toPixels(item.getPoint(), p));
    }
}

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