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<meta name="apple-mobile-web-app-capable" content="yes">
<title>OpenLayers Paging Strategy Example</title>
<link rel="stylesheet" href="../theme/default/style.css" type="text/css">
<link rel="stylesheet" href="style.css" type="text/css">
<script src="../lib/OpenLayers.js"></script>
<script type="text/javascript">
var map, photos, paging;
/**
* A specific format for parsing Flickr API JSON responses.
*/
OpenLayers.Format.Flickr = OpenLayers.Class(OpenLayers.Format, {
read: function(obj) {
if(obj.stat === 'fail') {
throw new Error(
['Flickr failure response (',
obj.code,
'): ',
obj.message].join(''));
}
if(!obj || !obj.photos ||
!OpenLayers.Util.isArray(obj.photos.photo)) {
throw new Error(
'Unexpected Flickr response');
}
var photos = obj.photos.photo, photo,
x, y, point,
feature, features = [];
for(var i=0,l=photos.length; i<l; i++) {
photo = photos[i];
x = photo.longitude;
y = photo.latitude;
point = new OpenLayers.Geometry.Point(x, y);
feature = new OpenLayers.Feature.Vector(point, {
title: photo.title,
img_url: photo.url_s
});
features.push(feature);
}
return features;
}
});
function init() {
map = new OpenLayers.Map('map');
var base = new OpenLayers.Layer.OSM();
var style = new OpenLayers.Style({
externalGraphic: "${img_url}",
pointRadius: 30
});
paging = new OpenLayers.Strategy.Paging();
photos = new OpenLayers.Layer.Vector("Photos", {
projection: "EPSG:4326",
strategies: [new OpenLayers.Strategy.Fixed(), paging],
protocol: new OpenLayers.Protocol.Script({
url: "http://api.flickr.com/services/rest",
params: {
api_key: 'b5e8c0e287e678671c3d8b2c0f3ced85',
format: 'json',
method: 'flickr.photos.search',
extras: 'geo,url_s',
per_page: 100,
page: 1,
bbox: [-180, -90, 180, 90]
},
callbackKey: 'jsoncallback',
format: new OpenLayers.Format.Flickr()
}),
styleMap: new OpenLayers.StyleMap(style)
});
map.addLayers([base, photos]);
photos.events.on({"featuresadded": updateButtons});
map.setCenter(new OpenLayers.LonLat(0, 0), 1);
}
function updateButtons() {
document.getElementById("prev").disabled = (paging.pageNum() < 1);
document.getElementById("next").disabled = (paging.pageNum() >= paging.pageCount() - 1);
document.getElementById("num").innerHTML = paging.pageNum() + 1;
document.getElementById("count").innerHTML = paging.pageCount();
}
</script>
</head>
<body onload="init()">
<h1 id="title">Paging Strategy Example</h1>
<div id="tags">
vector, feature, stylemap, paging, strategy, flickr, script
</div>
<p id="shortdesc">
Uses a paging strategy to cache large batches of features and render a page at a time.
</p>
<div id="map" class="smallmap"></div>
Displaying page <span id="num">0</span> of <span id="count">...</span>
<button id="prev" disabled="disabled" onclick="paging.pagePrevious();">previous</button>
<button id="next" disabled="disabled" onclick="paging.pageNext();">next</button>
<br><br>
<div id="docs">
<p>The Paging strategy lets you apply client side paging for protocols
that do not support paging on the server. In this case, the protocol requests a
batch of 100 features, the strategy caches those and supplies a single
page at a time to the layer.</p>
<p>This particular example uses the <a
href="http://www.flickr.com/services/api/">Flickr API.</a></p>
</div>
</body>
</html>
