关于openlayers

今天刚接触到openlayers这个东西，感觉挺好的，我从google的地图上抓了四张256*256的图片，放在自己的工程中，用OpenLayers.Layer.Image只能用一张图片作为地图，现在想把四张都用上弄成一张地图，该怎么弄呢？？望大侠们给个帮助。

解决方案 »

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<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页</title>
    <link rel="stylesheet" href="res/default/style.css" type="text/css" />
    <link rel="stylesheet" href="res/style.css" type="text/css" />    <script type="text/javascript" src="res/OpenLayers.js"></script>    <script type="text/javascript">var MinX = 22;
var MinY = 10;
var MaxX = 28;
var MaxY = 14;var lat,lon;if (location.search == "")
{
//全国
//   lon=120.363808;
//   lat=36.088506;

   lat=36.738403;
   lon=119.161835;


   zoom=6;
   }
   else
   {
   //http://ditu.google.cn/?ie=UTF8&ll=31.230344,121.472569&spn=0.015633,0.026436&z=15
  //http://ditu.google.cn/maps?f=q&hl=zh-CN&geocode=&q=%E9%9D%92%E5%B2%9B&ie=UTF8&ll=36.088506,120.363808&spn=0.118745,0.211487&z=12&iwloc=addr
var PI = 3.14159265358979323846;
lon = lon * 20037508.34 / 180;
lat = Math.log (Math.tan ((90 + lat) * PI / 360)) / (PI / 180);
lat = lat * 20037508.34 / 180;
}
var map;
function get_imap_url (bounds)
{
//         var res = this.map.getResolution();
//         var x = Math.round ((bounds.left - this.maxExtent.left) / (res * this.tileSize.w)); //this 是指图层
//         var y = Math.round ((this.maxExtent.top - bounds.top) / (res * this.tileSize.h));
//         var z = 17 - this.map.getZoom();
//
//         //----------------------------------
//         //shanghai 109760 53556 qingdao 109344 51424 from coords.txt
//         //naming rule://map/1x/000/1x000000.png
//         var myBounds={left:109344,top:51424};//109344 51424
//         var myDir0=Math.pow(2,z);
//         x = Math.round (x - myBounds.left/myDir0 );
//         var  myTileNum="000";
//         if(x>=0)
//         {
//            myTileNum=x.toString();
//            if(myTileNum.length==1)myTileNum="00"+myTileNum;
//            if(myTileNum.length==2)myTileNum="0"+myTileNum;
//
//         }
//         y =Math.round (y - myBounds.top/myDir0 );
//         var myTileDir="000";
//
//         if(y>=0)
//         {
//            myTileDir=y.toString();
//            if(myTileDir.length==1)myTileDir="00"+myTileDir;
//            if(myTileDir.length==2)myTileDir="0"+myTileDir;
//
//            }
//
//         var path = myDir0+"x/"
//          + myTileDir + "/"
//          + myDir0+"x" + myTileDir + myTileNum + "." + this.type;
//         if(x<0 || y<0)path="blank.png";
//         var url = this.url;
//         if (url instanceof Array)
//         {
//             url = this.selectUrl(path, url);
//         }
//         //alert(url + path);
//         return url + path;
        var res = this.map.getResolution();
        var bbox  = this.map.getMaxExtent();
        var size  = this.tileSize;        var x = Math.round ((bounds.left - bbox.left) / (res * size.w));
        var y = Math.round ((bbox.top - bounds.top) / (res * size.h));
        var z = this.map.getZoom()+3;        var path ="gm_" + x + "_" + y + "_" + z + "." + this.type;
        var url = this.url;
        if (url instanceof Array) {
            url = this.selectUrl(path, url);
        }
        return url + path;
         }        function init()
        {
            map = new OpenLayers.Map ("map",
                {
                    controls:
                    [
                    new OpenLayers.Control.Permalink(),
                    new OpenLayers.Control.MouseDefaults(),
                    new OpenLayers.Control.LayerSwitcher(),
                    new OpenLayers.Control.MousePosition(),
                    new OpenLayers.Control.PanZoomBar()
                    ],
                    maxExtent: new OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34),
                    //Resolution=20037508*2/256*2^(zoom+1),zoom取值0~15
//                    numZoomLevels:19,
//                    maxResolution:156543.0339,

                    numZoomLevels:16,
                    maxResolution:156543.0339/8,

                    units:'m',//,
                    //projection: "EPSG:41001"
                    projection: "EPSG:900913",
                    displayProjection: new OpenLayers.Projection("EPSG:4326")

                }
            );            myHome = new OpenLayers.Layer.TMS(
            "测试",
            "map/",
            {type:'png', getURL: get_imap_url} );
            map.addLayers([myHome]);
            var lonLat = new OpenLayers.LonLat(lon,lat);
//map.setCenter (lonLat, 12);
//map.zoomToExtent(new OpenLayers.Bounds(119.194965, 36.746243, 119.130549, 36.729873 ));            map.setCenter (lonLat, zoom);

        };
    </script></head>
<body onload="init()">
    <form id="form1" runat="server">
    <h1 id="title">
        Zoomify Layer Example</h1>
    <div id="tags">
    </div>
    <p id="shortdesc">
        Demo of a layer with Zoomify tiles.
    </p>
    <div id="map" class="smallmap">
    </div>
    </form>
</body>
</html>
可以直接用缓存里的图片，不过要改一下文件名本例：是gm_x_y_z.png
这个例子坐标映射可能还有点问题
谢谢naitboy的回答，我现在已经用您的代码实现了本地tiles显示！您说坐标映射有问题，其实没有问题，只是您的代码写错了而已，只需要将您的代码中if语句下的“｛ else .......}”删除掉就没事了。
（把错误找出，让更多人不走弯路！）