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使用Leaflet创建地图拓扑图

之前我们采用过 Openlayers+Qunee的方案,实现地图拓扑图,鉴于Openlayers是一种古老项目,略显臃肿,面向更新的前端地图方案,在客户的介绍下,我们找到了leaflet - 基于HTML5的轻量地图客户端方案,结合Qunee使用,以及第三方插件,实现更加轻快的地图拓扑图应用 Leaflet介绍 leaflet是一个开源软件,作者在乌克兰,在移动设备上的有良好的体验,比较新和现代的地图客户端,类库压缩后只有33k,非常小巧,这一点让qunee都相形见绌,先看一个leaflet的入门示例

官方示例

// create a map in the "map" div, set the view to a given place and zoom
var map = L.map(‘map‘).setView([51.505, -0.09], 13);

// add an OpenStreetMap tile layer
L.tileLayer(‘http://{s}.tile.osm.org/{z}/{x}/{y}.png‘).addTo(map);

// add a marker in the given location, attach some popup content to it and open the popup
L.marker([51.5, -0.09]).addTo(map)
    .bindPopup(‘A pretty CSS3 popup. 
 Easily customizable.‘)
    .openPopup();

运行效果如下: 

hello leaflet

结合Qunee拓扑图

Leaflet地图上可以添加点线面基本图形,如果需要展示更复杂的图形或者链接关系,显得力不足,可以结合Qunee组件使用,下面我们让地图和拓扑图叠加起来,在地图上显示拓扑元素,并整合两者的交互

图层叠加

在地图的DIV容器中添加一个孩子div,作为拓扑图的画布,并设置相应的css,然后调用超类的构造函数,取消默认的双击和滚轮操作,已被后面地图与拓扑图的交互同步
var MapGraph = function (map) {
    var container = map._container;
    var canvas = document.createElement("div");
    canvas.style.width = "100%";
    canvas.style.height = "100%";

    container.appendChild(canvas);

    Q.doSuperConstructor(this, MapGraph, [canvas]);
    this.enableWheelZoom = false;
    this.enableDoubleClickToOverview = false;
    this.originAtCenter = false;
    this.setMap(map);
    ...
}

关联地图

下面实现拓扑图与地图的绑定,在#setMap(map)函数中,监听了地图的zoomstart和zoomend事件,根据经纬度动态的调整图元的屏幕位置,同样在节点被拖动后,也需要设置新的经纬度
MapGraph.prototype = {
    map: null,
    mapShowing: true,
    enableInertia: false,
    createNodeByLonLat: function (name, lon, lat) {
        var l = this.toLonLat(lon, lat);
        var p = this.getPixelFromLonLat(l);
        var node = graph.createNode(name, p.x, p.y);
        node.lonLat = l;
        return node;
    },
    toLonLat: function (lon, lat) {
        return new L.latLng(lat, lon);
    },
    getPixelFromLonLat: function (lonLat) {
        return this.map.latLngToContainerPoint(lonLat, this.map._zoom);
    },
    getLonLatFromPixel: function (x, y) {
        return this.map.containerPointToLatLng([x, y]);
    },
    setMap: function (map) {
        this.map = map;

        this.map.on("zoomstart", this.hideGraph, this);
        this.map.on("zoomend", this.updateNodes, this);

        this.html.ondblclick = createEventFunction(this, function (evt) {
            if (this.getElementByMouseEvent(evt)) {
                Q.stopEvent(evt);
            }
        });
        this.interactionDispatcher.addListener(function (evt) {
            if (evt.kind == Q.InteractionEvent.ELEMENT_MOVE_END) {
                var datas = evt.datas;
                Q.forEach(datas, function (data) {
                    var pixel = this.toCanvas(data.location.x, data.location.y);
                    data.lonLat = this.getLonLatFromPixel(pixel.x, pixel.y);
                }, this);
            }
        }, this)
    },
    hideGraph: function(){
        this.html.style.visibility = "hidden";
    },
    showGraph: function(){
        this.html.style.visibility = "";
    },
    translate: function (tx, ty) {
        Q.doSuper(this, MapGraph, "translate", arguments);
        this.map.panBy([-tx, -ty], {animate: false});
    },
    resetVisibility: function () {
        this.forEach(function (e) {
            if (e.invalidateVisibility) {
                e.invalidateVisibility(true);
            }
        });
    },
    updateNodes: function () {
        this.translateTo(0, 0, 1, true);
        this.resetVisibility();
        this.forEach(function (d) {
            if (d instanceof Q.Node) {
                var l = d.lonLat;
                var p = this.getPixelFromLonLat(l);
                d.location = p;
            }
        }, this);
        this.showGraph();
    }
}

Q.extend(MapGraph, Q.Graph);
此外还可以通过可见过滤器实现,不同比例尺显示不同的节点

运行效果

在线示例: http://demo.qunee.com/map/mapByLeafLet.html 

leaflet + qunee