openlayers 3 加载地图瓦片数据

openlayers 是一套开源的js地图渲染框架，数据源可以使用天地图的数据源。

map对象相当如一个容器，它上面可以铺放多个layer，layer可以加载数据源或其它作用。

有关openlayers 的详细介绍，请参考http://openlayers.org/

下面创建一个layer

urlTemplate中包含x,y,z(z:地图级数，x:x方向序数， y:y方向序数)

function newTilesUrlLayer(urlTemplate, tileSize, zeroLevelSize) {
var resolutions = new Array(22);
for (var i = 0, ii = resolutions.length; i < ii; ++i) {
resolutions[i] = zeroLevelSize / Math.pow(2, i) / 512;
}
var layer = new ol.layer.Tile({
source: new ol.source.XYZ({
tileSize: tileSize,
tileUrlFunction: tileUrlFunctionCallBack,
projection: 'EPSG:4326',
//tilePixelRatio: tileSize / 256,
tileGrid: new ol.tilegrid.TileGrid({
resolutions: resolutions,
tileSize: tileSize,
origin:[-180,-90]
})
}),
name: ''
});

function tileUrlFunctionCallBack(tileCoord, pixelRatio, projection) {
var z = tileCoord[0];
var x = tileCoord[1];
var y = tileCoord[2];

var xStr4 = "0000" + x.toString();
xStr4 = xStr4.substr(xStr4.length - 4, 4);
var yStr4 = "0000" + y.toString();
yStr4 = yStr4.substr(yStr4.length - 4, 4);

var url = urlTemplate.replace('{z}', z.toString());
url=url.replace('{y}', yStr4);
url=url.replace('{y}', yStr4);
url = url.replace('{x}', xStr4);
url = url.replace('{x}', xStr4);
return url
}

return layer;
}

这里的tileUrlFunctionCallBack淡淡的
就是解析数据源地址的回调函数。

以下给出一个应用的例子的完整代码：

1. Itelluro.ol.js

/**
* those are for pulling tiles from Itelluro tiles source address, which would return a new layer or map that is access to openlayer3.
* refer to http://openlayers.org */

//
// map

/**
* @param {string} id The container for the map.
* @param {number} numLevels The maximum zoom level used to determine the resolution constraint.
* @param {number} dsEast  MaxX extent coordinates.
* @param {number} dsWest MinX extent coordinates
* @param {number} dsSouth MinY extent coordinates
* @param {numbere} dsNorth MaxY extent coordinates
* @param {string} sourcePackageKey Source Package Key of tiles' provider.
* @param {string} url URL address of tiles' provider.
* @param {number} tileSize The pixel of tile.
* @param {number} zeroLevelSize  The size of zero level tile.
* @return {ol.layer.Tile} return map
*/
function NewWebTilesMap(id, numLevels, dsEast, dsWest, dsSouth, dsNorth,
sourcePackageKey, url, tileSize, zeroLevelSize) {

layer1 = newItelluroLayer(sourcePackageKey, url, tileSize, zeroLevelSize);

var view = new ol.View({
center: [(dsEast + dsWest) / 2, (dsNorth + dsSouth) / 2], zoom: 0, minZoom: 0, maxZoom: numLevels,
projection: 'EPSG:4326',
maxResolution: zeroLevelSize / tileSize,
});

var map = new ol.Map({
layers: [layer1],
target: id,
view: view,
renderer: "dom"
});

return map;
}

/**
* @param {string} id The container for the map.
* @param {number} numLevels The maximum zoom level used to determine the resolution constraint.
* @param {number} dsEast  MaxX extent coordinates.
* @param {number} dsWest MinX extent coordinates
* @param {number} dsSouth MinY extent coordinates
* @param {number} dsNorth MaxY extent coordinates
* @param {string} root Local root directory of tiles' files.
* @param {number} tileSize The pixel of tile.
* @param {number} zeroLevelSize  The size of zero level tile.
* @return {ol.layer.Tile} return map
*/
function NewLocalTilesMap(id, numLevels, dsEast, dsWest, dsSouth, dsNorth,
root, tileSize, zeroLevelSize){

layer1 = newLocalTilesLayer(root, tileSize, zeroLevelSize);

var view = new ol.View({
center: [(dsEast + dsWest) / 2, (dsNorth + dsSouth) / 2], zoom: 0, minZoom: 0, maxZoom: numLevels,
projection: 'EPSG:4326',
maxResolution: zeroLevelSize / tileSize,
});

var map = new ol.Map({
layers: [layer1],
target: id,
view: view,
renderer: "dom"
});

return map;
}

//
// layer

/**
* @param {string} sourcePackageKey The package key address of tiles' provider.
* @param {string} url URL address of tiles' provider.
* @param {number} tileSize The pixel of tile.
* @param {number} zeroLevelSize  The size of zero level tile.
* @return {ol.layer.Tile} return layer
*/
function newItelluroLayer(sourcePackageKey, url, tileSize, zeroLevelSize) {
if (url.indexOf("?") > 0)
url += "&T={t}";
else
url += "?T={t}";
url = url.replace('{t}', sourcePackageKey);
return newWebTilesLayer(url, tileSize, zeroLevelSize);
}

/**
* @param {string} root Local root directory of tiles' files.
* @param {number} tileSize The pixel of tile.
* @param {number} zeroLevelSize  The size of zero level tile.
* @return {ol.layer.Tile} return layer
*/
function newLocalTilesLayer(root, tileSize, zeroLevelSize) {
var imageType = "png";
root += "\\{z}\\{y}\\{y}_{x}." + imageType;
return newTilesUrlLayer(root, tileSize, zeroLevelSize);
}

/**
* @param {string} url URL address of tiles' provider.
* @param {number} tileSize The pixel of tile.
* @param {number} zeroLevelSize  The size of zero level tile.
* @return {ol.layer.Tile} return layer
*/
function newWebTilesLayer(url, tileSize, zeroLevelSize) {
url = encodeURI(url);
if (url.indexOf("?") > 0)
url += "&L={z}&X={x}&Y={y}";
else
url += "?L={z}&X={x}&Y={y}";
return newTilesUrlLayer(url, tileSize, zeroLevelSize);
}

/**
* @param {string} urlTemplate URL template. Must include {x}, {y} or {-y}.
* @param {number} tileSize The pixel of tile.
* @param {number} zeroLevelSize  The size of zero level tile.
* @return {ol.layer.Tile} return layer
*/
function newTilesUrlLayer(urlTemplate, tileSize, zeroLevelSize) {
var resolutions = new Array(22);
for (var i = 0, ii = resolutions.length; i < ii; ++i) {
resolutions[i] = zeroLevelSize / Math.pow(2, i) / 512;
}
var layer = new ol.layer.Tile({
source: new ol.source.XYZ({
tileSize: tileSize,
tileUrlFunction: tileUrlFunctionCallBack,
projection: 'EPSG:4326',
//tilePixelRatio: tileSize / 256,
tileGrid: new ol.tilegrid.TileGrid({
resolutions: resolutions,
tileSize: tileSize,
origin:[-180,-90]
})
}),
name: ''
});

function tileUrlFunctionCallBack(tileCoord, pixelRatio, projection) {
var z = tileCoord[0];
var x = tileCoord[1];
var y = tileCoord[2];

var xStr4 = "0000" + x.toString();
xStr4 = xStr4.substr(xStr4.length - 4, 4);
var yStr4 = "0000" + y.toString();
yStr4 = yStr4.substr(yStr4.length - 4, 4);

var url = urlTemplate.replace('{z}', z.toString());
url=url.replace('{y}', yStr4);
url=url.replace('{y}', yStr4);
url = url.replace('{x}', xStr4);
url = url.replace('{x}', xStr4);
return url
}

return layer;
}

2. demo.html

<html>
<head>
<title></title>
<link rel="stylesheet" href="http://openlayers.org/en/v3.15.1/css/ol.css" type="text/css">
<script src="../mapScript/ol.js" resource="http://openlayers.org/en/v3.15.1/build/ol.js"></script>
<script src="../mapScript/Itelluro.ol.js"></script&
a8a4
gt;
<style type="text/css">
.demo {
width: 40%;
height: 400px;
margin-right: 10%;
margin-bottom:5%;
float: left;
}

.demo .olMap {
width: 100%;
height: 400px;
}
</style>
</head>
<body>
<h2>Openlayer3 使用示例</h2>
<ol>
<li><a href="#LOCAL">Demo "LOCAL"</a></li>
<li><a href="#DOM">Demo "DOM"</a></li>
<li><a href="#GIS">Demo "GIS"</a></li>
<li><a href="#DEM">Demo "DEM"</a></li>
</ol>
<br />
<hr />
<div style=" margin:auto 50px">
<div class="demo">
<a name="LOCAL">Demo "LOCAL":</a>
<div id="mapDiv1" class="olMap"></div>
</div>
<div class="demo">
<a name="DOM">
Demo "DOM":
</a>
<div id="mapDiv2" class="olMap"></div>
</div>
<div class="demo">
<a name="GIS">
Demo "GIS":
</a>
<div id="mapDiv3" class="olMap"></div>
</div>
<div class="demo">
<a name="DEM">
Demo "DEM":
</a>
<div id="mapDiv4" class="olMap"></div>
</div>
</div>
<div style="clear:both;"></div>
<hr />
<script type="text/javascript">
// Demo "LOCAL":
var map1 = NewLocalTilesMap("mapDiv1", 6, 105.75140725069299, 105.68615672963949, 30.3320666017035, 30.376267769680222, 'tilesSource/out', 512, 2.25);

// Demo "DOM":
var url2 = "http://121.199.72.208/iTelluro.Server.yaan/Service/DOM/dom.ashx"
var map2 = NewWebTilesMap("mapDiv2", 6, 180, -180, -90, 90,
"bmng", url2, 512, 36);

// Demo "GIS":
var url3 = "http://121.199.72.208/iTelluro.Server.yaan/Service/GIS/gis.ashx";
var map3 = NewWebTilesMap("mapDiv3", 6, 180, -180, -90, 90,
"全球地质图", url3, 512, 36);

// Demo "DEM":
var url4 = "http://192.168.100.18/iTelluro.Server/Service/DEM/dem.ashx?img=png";
NewWebTilesMap("mapDiv4", 6, 180, -180, -90, 90,
"30mDEMS", url4, 150, 20);
</script>
</body>
</html>