我會承認,我從來沒有使用Mapnik的,所以我不什麼都可以做,但假設你發佈的代碼錯別字 - 例如,應該是「秤: '而不是'縮放[' - 不在你的工作代碼中,你不能在你的地圖選項中設置任何其他的比例依賴選項(例如,numZoomLevels,minZoomlevel),因爲它們將覆蓋你的比例設置。
但更重要的是,圖層設置將覆蓋地圖設置,在這種情況下,我認爲OpenLayers.Layer.OSM作爲第三方提供商並不會讓您設置自己的比例尺。如果使用OSM的相對較小的區域,爲什麼不下載maxExtents的邊界框並自己提供地圖數據以獲得更大的靈活性?
一些有用的鏈接:
http://trac.osgeo.org/openlayers/wiki/SettingZoomLevels
https://gis.stackexchange.com/questions/1825/openlayers-use-scales-instead-of-resolutions
補充說:
這裏是你的地圖,這是正確的縮放(非Mapnik的)發揮小提琴到最大程度而不是全世界,按要求:
http://jsfiddle.net/Cybele42/UfWp9/3/
的Javascript:
var projMercator = new OpenLayers.Projection("GOOGLE");
var projBritNatGrid = new OpenLayers.Projection("EPSG:27700");
var navigation_control = new OpenLayers.Control.Navigation({});
var controls_array = [
navigation_control,
new OpenLayers.Control.PanZoomBar({}),
new OpenLayers.Control.LayerSwitcher({}),
new OpenLayers.Control.MousePosition({})
];
var layerOSM = new OpenLayers.Layer.OSM("OpenStreetMap");
var scales = [200000,150000,100000,50000,20000,10000,5000,2500];
var map = new OpenLayers.Map({
div: "map",
units: 'm',
scales: scales,
Projection: projMercator,
DisplayProj: projBritNatGrid,
controls: controls_array
});
map.addLayer(layerOSM);
var myMaxExtent = new OpenLayers.Bounds("350000,380000, 380000,400000");
myMaxExtent.transform(projBritNatGrid, projMercator);
var lonlat = new OpenLayers.LonLat("362431.71","389042.78");
lonlat.transform(projBritNatGrid, projMercator);
map.setCenter(lonlat, 13);
map.events.register("zoomend", map, function(){
document.getElementById("getCenter").innerHTML=map.getCenter();
document.getElementById("getScale").innerHTML=map.getScale();
});
HTML:
<script type="text/javascript" src="http://openlayers.org/dev/OpenLayers.js"></script>
<script type="text/javascript" src="http://cdnjs.cloudflare.com/ajax/libs/proj4js/1.1.0/proj4js-compressed.min.js"></script>
<script type="text/javascript" src="http://spatialreference.org/ref/epsg/27700/proj4js/"></script>
<div id="map"></div>
<table class="gridtable">
<tr><th>object</th><th>value</th></tr>
<tr><td>Center</td><td><div id="getCenter"></div></td></tr>
<tr><td>Scale</td><td><div id="getScale"></div></td></tr>
</table>
CSS:
#map
{
width: 600px;
height: 600px;
border: 1px solid black;
}
table.gridtable {
font-family: verdana,arial,sans-serif;
font-size:11px;
color:#333333;
border: 1px solid black;
}
table.gridtable th {
border: 1px solid black;
padding: 8px;
background-color: khaki;
}
table.gridtable td {
padding: 8px;
border: 1px solid black;
background-color: #ffffff;
}