arcgis for android 定位圆

最新推荐文章于 2021-06-03 04:43:11 发布

原创最新推荐文章于 2021-06-03 04:43:11 发布 · 671 阅读

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CC 4.0 BY-SA版权

本文介绍两种在地图上绘制圆形的方法。方法一通过计算圆周上的点来构建多边形并填充颜色；方法二利用GeometryEngine.buffer函数直接生成缓冲区多边形。这两种方法均可应用于地图视图中显示圆形区域。

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方法一： /**
* 绘制圆,配合 cleargraphicLayer()清除
*
* @param center 圆心
* @param radius 半径
* @param alpha 填充的透明度 0-100
* @param fillColor 填充的颜色
*/
public void DrawCircle(Point center, double radius, int alpha, int fillColor) {
if (graphicLayer == null) { //是否已添加绘制图层
graphicLayer = new GraphicsLayer();
mapView.addLayer(graphicLayer);
}
Polygon polygon = new Polygon();
getCircle(center, radius, polygon);
FillSymbol symbol = new SimpleFillSymbol(fillColor);
SimpleLineSymbol simplelinesymbol = new SimpleLineSymbol(Color.BLUE, (float) 0.5);
symbol.setOutline(simplelinesymbol);
symbol.setAlpha(alpha);
Graphic g = new Graphic(polygon,symbol);
graphicLayer.addGraphic(g);
}

/**
* 获取圆的图形对象
*
* @param center
* @param radius
* @return
*/
public static Polygon getCircle(Point center, double radius) {
Polygon polygon = new Polygon();
getCircle(center, radius, polygon);
return polygon;
}

private static void getCircle(Point center, double radius, Polygon circle) {
circle.setEmpty();
Point[] points = getPoints(center, radius);
circle.startPath(points[0]);
for (int i = 1; i < points.length; i++)
circle.lineTo(points[i]);
}

private static Point[] getPoints(Point center, double radius) {
Point[] points = new Point[50];
double sin;
double cos;
double x;
double y;
for (double i = 0; i < 50; i++) {
sin = Math.sin(Math.PI * 2 * i / 50);
cos = Math.cos(Math.PI * 2 * i / 50);
x = center.getX() + radius * sin;
y = center.getY() + radius * cos;
points[(int) i] = new Point(x, y);
}
return points;
}

方法二：

Polygon polygon = GeometryEngine.buffer(mapPoint,mapView.getSpatialReference(), 100, null);
FillSymbol symbol = new SimpleFillSymbol(Color.BLUE);
SimpleLineSymbol simplelinesymbol = new SimpleLineSymbol(Color.BLUE,(float) 0.5);
symbol.setOutline(simplelinesymbol);
symbol.setAlpha(30);
Graphic g = new Graphic(polygon, symbol);
graphicLayer.addGraphic(g);