135 lines
3.9 KiB
JavaScript
135 lines
3.9 KiB
JavaScript
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/**
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* @requires SuperMap/Util.js
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* @requires SuperMap/Layer/CanvasLayer.js
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*/
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/**
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* Class: SuperMap.Layer.OSM
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* 此图层可以访问OpenStreetMap的地图服务。
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*
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* Inherits from:
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* - <SuperMap.Layer.CanvasLayer>
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*/
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SuperMap.Layer.OSM = SuperMap.Class(SuperMap.CanvasLayer, {
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/**
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* APIProperty: name
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* {String}图层名称，默认为“OpenStreetMap”，防止初始化时未设置图层名
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*
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*/
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name: "OpenStreetMap",
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/**
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* Property: url
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* {String}默认的OpenStreetMap的三个服务器地址，不需要要用户设置
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*/
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url: [
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'http://a.tile.openstreetmap.org/${z}/${x}/${y}.png',
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'http://b.tile.openstreetmap.org/${z}/${x}/${y}.png',
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'http://c.tile.openstreetmap.org/${z}/${x}/${y}.png'
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],
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/**
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* Property: attribution
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* {String} The layer attribution.
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*/
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attribution: "Data CC-By-SA by <a style='white-space: nowrap' target='_blank' href='http://openstreetmap.org/'>OpenStreetMap</a>",
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/**
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* Constructor: SuperMap.Layer.OSM
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* 创建OSM图层，可以浏览OpenStreetMap地图
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* Example:
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* (code)
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*
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* var osm = new SuperMap.Layer.OSM("MyName");
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*
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* (end)
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*
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* 默认为墨卡托投影，所以当需要地图定位以及添加元素在地图上时都需要坐标转换
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* Example:
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* (code)
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*
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* var markers = new SuperMap.Layer.Markers( "Markers" );
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* map.addLayer(markers);
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* var size = new SuperMap.Size(21,25);
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* var offset = new SuperMap.Pixel(-(size.w/2), -size.h);
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* var icon = new SuperMap.Icon('图片地址', size, offset);
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* markers.addMarker(new SuperMap.Marker(new SuperMap.LonLat(118,40 ).transform(
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* new SuperMap.Projection("EPSG:4326"),
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* map.getProjectionObject()),icon));
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*
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* (end)
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* Parameters:
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* name - {String} 图层名称
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*/
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initialize: function(name, options) {
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options = SuperMap.Util.extend({
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projection: "EPSG:3857",
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numZoomLevels: 20
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}, options);
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SuperMap.CanvasLayer.prototype.initialize.apply(this,[name,this.url,{},options] );
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},
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/**
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* Method: clone
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*/
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clone: function(obj) {
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if (obj == null) {
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obj = new SuperMap.Layer.OSM(
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this.name, this.url, this.getOptions());
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}
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obj = SuperMap.CanvasLayer.prototype.clone.apply(this, [obj]);
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return obj;
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},
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/**
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* APIMethod: destroy
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* 解构OSM类，释放资源。
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*/
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destroy: function () {
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var me = this;
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SuperMap.CanvasLayer.prototype.destroy.apply(me, arguments);
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},
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/**
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* Method: getTileUrl
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* 获取瓦片的URL。
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*
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* Parameters:
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* xyz - {Object} 一组键值对，表示瓦片X, Y, Z方向上的索引。
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*
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* Returns
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* {String} 瓦片的 URL 。
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*/
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getTileUrl: function (xyz) {
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var me = this, url;
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if (SuperMap.Util.isArray(this.url)) {
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url = me.selectUrl(xyz, this.url);
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}
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url= SuperMap.String.format(url, {
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x: xyz.x,
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y: xyz.y,
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z: xyz.z
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});
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return url;
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},
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/**
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* Method: selectUrl
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* 通过某种方式实现在一组url数组中选出合理的url
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* Parameters:
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* xyz - {Object} 一组键值对，表示瓦片X, Y, Z方向上的索引。
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* urls - {Array(String)} url数组
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*
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* Returns:
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* {String} 一个合理的url，主要用于出图访问多个服务器，提高效率
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*/
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selectUrl: function(xyz, urls) {
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var id=Math.abs(xyz.x+xyz.y)%urls.length;
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var url=urls[id];
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return url;
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},
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CLASS_NAME: "SuperMap.Layer.OSM"
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});
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