Leaflet中原生方式实现测量面积

╰+攻爆jí腚メ 2023-10-01 05:28 20阅读 0赞

## 场景 ##

Leaflet中原生方式实现测距：

[Leaflet中原生方式实现测距\_BADAO\_LIUMANG\_QIZHI的博客-CSDN博客][Leaflet_BADAO_LIUMANG_QIZHI_-CSDN]

在上面实现测量距离的基础上，实现测量面积效果如下

![191c742509ab439996a2b8b5631789cb.gif][]

注：

博客：  
[BADAO\_LIUMANG\_QIZHI的博客\_霸道流氓气质\_CSDN博客-C\#,SpringBoot,架构之路领域博主][BADAO_LIUMANG_QIZHI_CSDN_-C_SpringBoot]  
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## 实现 ##

完整代码：

<!doctype html>
    <html lang="en">
    
    <head>
        <meta charset="UTF-8">
        <title>leaflet实现测量面积</title>
        <link rel="stylesheet" href="https://unpkg.com/leaflet@1.7.1/dist/leaflet.css" />
        <style>
            #mapButton {
                position: absolute;
                z-index: 10000;
            }
    
            html,
            body,
            #map {
                padding: 0;
                margin: 0;
                width: 100%;
                height: 100%;
                overflow: hidden;
                position: absolute;
            }
        </style>
    </head>
    
    <body>
        <div id="mapButton">
            <br><br><br><br>
            <button type="button" id="areaMeasure">测面积</button>
            <button type="button" id="clearMeasure">清除</button>
        </div>
        <div id="map">
        </div>
        <script src="http://cdn.bootcss.com/jquery/1.11.0/jquery.min.js"></script>
        <script type="text/javascript" src="https://unpkg.com/leaflet@1.7.1/dist/leaflet.js"></script>
        <script type="text/javascript">
            var map = L.map('map').setView([36.09, 120.35], 13);
            L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
                attribution: ''
            }).addTo(map);
    
            var DRAWING = false; //是否正在绘制
            var BarDRAWLAYERS = [];
            var MEASUREAREATOOLTIP; //量面提示
            var DRAWPOLYGON; //绘制的面
            var DRAWMOVEPOLYGON; //绘制过程中的面
            var DRAWPOLYGONPOINTS = []; //绘制的面的节点集
    
            var MEASURERESULT = 0; //测量结果
    
            //测量面积按钮点击事件
            $('#areaMeasure').click(function () {
                //开始绘制多边形
                startDrawPolygon();
            });
    
            /*多边形*/
            function startDrawPolygon(func) {
                MEASURERESULT = 0;
                map.getContainer().style.cursor = 'crosshair';
                //地图添加鼠标按下事件
                map.on('mousedown', function (e) {
                    DRAWING = true;
                    DRAWPOLYGONPOINTS.push(e.latlng);
                    DRAWPOLYGON.addLatLng(e.latlng);
                });
                //地图添加鼠标移动事件
                map.on('mousemove', function (e) {
                    if (DRAWING) {
                        //清除上次数据
                        if (DRAWMOVEPOLYGON != undefined && DRAWMOVEPOLYGON != null) {
                            map.removeLayer(DRAWMOVEPOLYGON);
                        }
                        var prevPoint = DRAWPOLYGONPOINTS[DRAWPOLYGONPOINTS.length - 1];
                        var firstPoint = DRAWPOLYGONPOINTS[0];
                        DRAWMOVEPOLYGON = new L.Polygon([firstPoint, prevPoint, e.latlng], shapeOptions);
                        map.addLayer(DRAWMOVEPOLYGON);
                    }
                });
                
                //地图添加鼠标双击事件
                map.on('dblclick', function (e) {
                    map.getContainer().style.cursor = '';
                    var tempPoints = [];
                    for (var i = 0; i < DRAWPOLYGONPOINTS.length; i++) {
                        tempPoints.push(DRAWPOLYGONPOINTS[i]);
                    }
                    tempPoints.push(e.latlng);
                    //计算面积
                    var distance = CalArea(tempPoints);
                    //声明标记
                    marker = new L.Marker(e.latlng, {
                        draggable: false
                    });
                    //地图上添加标记
                    map.addLayer(marker);
                    //标记弹窗显示面积
                    marker.bindPopup("总面积：" + (distance / 1000000).toFixed(3) + '平方公里').openPopup();
                    if (DRAWING) {
                        if (DRAWMOVEPOLYGON != undefined && DRAWMOVEPOLYGON != null) {
                            map.removeLayer(DRAWMOVEPOLYGON);
                            DRAWMOVEPOLYGON = null;
                        }
                        BarDRAWLAYERS.push(DRAWPOLYGON);
                        if (func) {
                            func(DRAWPOLYGONPOINTS);
                        }
                        DRAWPOLYGONPOINTS = [];
                        DRAWING = false;
                        //地图移除事件
                        map.off('mousedown');
                        map.off('mousemove');
                        map.off('dblclick');
                    }
                });
    
                var shapeOptions = {
                        color: '#F54124',
                        weight: 3,
                        opacity: 0.8,
                        fill: true,
                        fillColor: null,
                        fillOpacity: 0.2,
                        clickable: true
                    },
    
                DRAWPOLYGON = new L.Polygon([], shapeOptions);
                map.addLayer(DRAWPOLYGON);
    
                //计算面积
                function CalArea(latLngs) {
                    var pointsCount = latLngs.length,
                        area = 0.0,
                        d2r = Math.PI / 180,
                        p1, p2;
                    if (pointsCount > 2) {
                        for (var i = 0; i < pointsCount; i++) {
                            p1 = latLngs[i];
                            p2 = latLngs[(i + 1) % pointsCount];
                            area += ((p2.lng - p1.lng) * d2r) *
                                (2 + Math.sin(p1.lat * d2r) + Math.sin(p2.lat * d2r));
                        }
                        area = area * 6378137.0 * 6378137.0 / 2.0;
                    }
                    return Math.abs(area);
                }
            }
    
            //清除按钮点击事件
            $('#clearMeasure').click(function () {
                qingchu()
            })
    
            //执行清除方法
            function qingchu(func) {
                for (var i = 0; i < BarDRAWLAYERS.length; i++) {
                    //移除图层
                    map.removeLayer(BarDRAWLAYERS[i]);
                }
                //清空数组
                BarDRAWLAYERS = [];
                if (marker) {
                    map.removeLayer(marker)
                }
            }
        </script>
    </body>
    
    </html>

[Leaflet_BADAO_LIUMANG_QIZHI_-CSDN]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/122358379
[191c742509ab439996a2b8b5631789cb.gif]: https://img-blog.csdnimg.cn/191c742509ab439996a2b8b5631789cb.gif
[BADAO_LIUMANG_QIZHI_CSDN_-C_SpringBoot]: https://blog.csdn.net/badao_liumang_qizhi