• OL记载Arcgis Server切片


    概述:

    本文讲述如何在OpenLayers中调用Arcgis Server切片并显示。


    思路:

    在OpenLayers中加载Arcgis Server切片用XYZ图层,Arcgis Server的切片调用地址我们可以看到如下:


    可以看到,切片的请求地址为http://localhost:6080/arcgis/rest/services/china/MapServer/z/y/x,其中,z为缩放级别,x,y分别为改切片距离tileOrigin的行列号,其计算方式为:

            var res = this.getResolution();
            var originTileX = (this.tileOrigin.lon + (res * this.tileSize.w/2));
            var originTileY = (this.tileOrigin.lat - (res * this.tileSize.h/2));
            var center = bounds.getCenterLonLat();
            var point = { x: center.lon, y: center.lat };
            var x = (Math.round(Math.abs((center.lon - originTileX) / (res * this.tileSize.w)))); 
            var y = (Math.round(Math.abs((originTileY - center.lat) / (res * this.tileSize.h)))); 
            var z = this.map.getZoom();

    将之封装为一个OpenLayers扩展类OpenLayers.Layer.AgsTileLayer,该类的代码方式为:

    OpenLayers.Layer.AgsTileLayer = OpenLayers.Class(OpenLayers.Layer.XYZ, {
        url: null,
        tileOrigin: null,
        tileSize: new OpenLayers.Size(256, 256),
        type: 'png',
        useScales: false,
        overrideDPI: false,
        initialize: function(name, url, options) { 
            OpenLayers.Layer.XYZ.prototype.initialize.apply(this, arguments);
        },
        getURL: function (bounds) {
            var res = this.getResolution();
            var originTileX = (this.tileOrigin.lon + (res * this.tileSize.w/2));
            var originTileY = (this.tileOrigin.lat - (res * this.tileSize.h/2));
            var center = bounds.getCenterLonLat();
            var point = { x: center.lon, y: center.lat };
            var x = (Math.round(Math.abs((center.lon - originTileX) / (res * this.tileSize.w)))); 
            var y = (Math.round(Math.abs((originTileY - center.lat) / (res * this.tileSize.h)))); 
            var z = this.map.getZoom();
            var url = this.url;
            var s = '' + x + y + z;
            if (OpenLayers.Util.isArray(url)) {
                url = this.selectUrl(s, url);
            }
            url = url + '/tile/${z}/${y}/${x}';
            url = OpenLayers.String.format(url, {'x': x, 'y': y, 'z': z});
            return OpenLayers.Util.urlAppend(
                url, OpenLayers.Util.getParameterString(this.params)
            );
        },
    
        CLASS_NAME: 'OpenLayers.Layer.AgsTileLayer'
    }); 

    调用方式为:

    <script src="AgsTileLayer.js"></script>

                var tiled = new OpenLayers.Layer.AgsTileLayer( "AGSCache",
                        "http://localhost:6080/arcgis/rest/services/china/MapServer", {
                            isBaseLayer: true,
                            tileSize: new OpenLayers.Size(256, 256),
                            resolutions: [
                                0.07614275218656896,
                                0.03807137609328448,
                                0.01903568804664224,
                                0.00951784402332112,
                                0.00475892201166056
                            ],
                            tileOrigin: new OpenLayers.LonLat(-400 , 400),
                            maxExtent: bounds,
                            projection: 'EPSG:4326'
                        });
                map.addLayers([tiled]);

    代码中涉及到的参数可以从http://localhost:6080/arcgis/rest/services/china/MapServer?f=pjson返回的JSON数据中获取,如下:

    {
       "capabilities" : "Map,Query,Data",
       "copyrightText" : "",
       "currentVersion" : 10.110,
       "description" : "",
       "documentInfo" : {
          "AntialiasingMode" : "None",
          "Author" : "",
          "Category" : "",
          "Comments" : "",
          "Keywords" : "",
          "Subject" : "",
          "TextAntialiasingMode" : "Force",
          "Title" : ""
       },
       "fullExtent" : {
          "spatialReference" : {
             "latestWkid" : 4326,
             "wkid" : 4326
          },
          "xmax" : 134.9767976465060,
          "xmin" : 73.45100463562233,
          "ymax" : 53.53194315222358,
          "ymin" : 18.16324718764174
       },
       "initialExtent" : {
          "spatialReference" : {
             "latestWkid" : 4326,
             "wkid" : 4326
          },
          "xmax" : 138.0530872970502,
          "xmin" : 70.37471498507816,
          "ymax" : 55.85657468506156,
          "ymin" : 35.30335092712114
       },
       "layers" : [
          {
             "defaultVisibility" : true,
             "id" : 0,
             "maxScale" : 0,
             "minScale" : 0,
             "name" : "province",
             "parentLayerId" : -1,
             "subLayerIds" : null
          },
          {
             "defaultVisibility" : true,
             "id" : 1,
             "maxScale" : 0,
             "minScale" : 0,
             "name" : "bcity",
             "parentLayerId" : -1,
             "subLayerIds" : null
          },
          {
             "defaultVisibility" : true,
             "id" : 2,
             "maxScale" : 0,
             "minScale" : 0,
             "name" : "bcounty",
             "parentLayerId" : -1,
             "subLayerIds" : null
          }
       ],
       "mapName" : "Layers",
       "maxImageHeight" : 2048,
       "maxImageWidth" : 2048,
       "maxRecordCount" : 1000,
       "maxScale" : 1000000,
       "minScale" : 32000000,
       "serviceDescription" : "",
       "singleFusedMapCache" : true,
       "spatialReference" : {
          "latestWkid" : 4326,
          "wkid" : 4326
       },
       "supportedImageFormatTypes" : "PNG32,PNG24,PNG,JPG,DIB,TIFF,EMF,PS,PDF,GIF,SVG,SVGZ,BMP",
       "supportedQueryFormats" : "JSON, AMF",
       "supportsDynamicLayers" : false,
       "tables" : [],
       "tileInfo" : {
          "cols" : 256,
          "compressionQuality" : 0,
          "dpi" : 96,
          "format" : "PNG",
          "lods" : [
             {
                "level" : 0,
                "resolution" : 0.07614275218656896,
                "scale" : 32000000
             },
             {
                "level" : 1,
                "resolution" : 0.03807137609328448,
                "scale" : 16000000
             },
             {
                "level" : 2,
                "resolution" : 0.01903568804664224,
                "scale" : 8000000
             },
             {
                "level" : 3,
                "resolution" : 0.009517844023321120,
                "scale" : 4000000
             },
             {
                "level" : 4,
                "resolution" : 0.004758922011660560,
                "scale" : 2000000
             },
             {
                "level" : 5,
                "resolution" : 0.002379461005830280,
                "scale" : 1000000
             }
          ],
          "origin" : {
             "x" : -400,
             "y" : 400
          },
          "rows" : 256,
          "spatialReference" : {
             "latestWkid" : 4326,
             "wkid" : 4326
          }
       },
       "units" : "esriDecimalDegrees"
    }




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  • 原文地址:https://www.cnblogs.com/lzugis/p/6539811.html
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