leaflet 如何绘制圆

方法1（根据指定的半径和中心点去绘制圆）
var polygon1 = new L.Circle([34, 108], 120000, {
color: 'red', //颜色
fillColor: '#f03',
fillOpacity: 0.4, //透明度
});

方法2（根据半径和中心点去构造polygon类型的圆）
var radius = 2;
//点集
var parts = [];
//计算圆的边缘所有点
for (var i = 0; i < 360; i++) {
var radians = (i + 1) * Math.PI / 180;
var circlePoint = [Math.cos(radians) * radius + 34, Math.sin(radians) * radius + 108];
parts[i] = circlePoint;
}

var polygon1 = L.polygon(parts, {
color: 'green'
});


方法3，（地图上绘制一点拖动鼠标动态绘制圆形）
function DrawCircle() {
var r = 0
var i = null
var tempCircle = new L.circle()
map.dragging.disable(); //将mousemove事件移动地图禁用
map.on('mousedown', onmouseDown);
map.on('mouseup', onmouseUp);
map.on('mousemove', onMove)

function onmouseDown(e) {
i = e.latlng
//确定圆心
}

function onMove(e) {
if (i) {
r = L.latLng(e.latlng).distanceTo(i)
tempCircle.setLatLng(i)
tempCircle.setRadius(r)
tempCircle.setStyle({
color: '#ff0000',
fillColor: '#ff0000',
fillOpacity: 1
})
map.addLayer(tempCircle)

}
}

function onmouseUp(e) {
r = L.latLng(e.latlng).distanceTo(i) //计算半径
L.circle(i, {
radius: r,
color: '#ff0000',
fillColor: '#ff0000',
fillOpacity: 1
}).addTo(map)
alert('圆心坐标为：' + i + ';半径为：' + r);
i = null
r = 0
map.dragging.enable();

}
}

方法4，（使用draw插件绘制圆）
var editableLayers = new L.FeatureGroup();
map.addLayer(editableLayers);

var drawControl = new L.Control.Draw({
position: 'topleft',
draw: {
polyline: false,
polygon: false,
circle: {},
rectangle: false,
marker: false,
remove: true
},
edit: {
featureGroup: editableLayers,
remove: true
}
});
map.addControl(drawControl);

handleMapEvent(drawControl._container, map);

map.on(L.Draw.Event.CREATED, function (e) {
var type = e.layerType,
layer = e.layer;
if (type === 'marker') {
layer.bindPopup('A popup!');
}
editableLayers.addLayer(layer);

});