OpenLayers示例代码：平铺加载事件
OpenLayers示例代码：平铺加载事件
<!DOCTYPE html>
<html>
<head>
<title>Tile Load Events</title>
<link rel="stylesheet" href="https://openlayers.org/en/v4.0.1/css/ol.css" type="text/css">
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
<script src="https://openlayers.org/en/v4.0.1/build/ol.js"></script>
<style>
.map {
background: #E0ECED;
}
.wrapper {
position: relative;
}
#progress {
position: absolute;
bottom: 0;
left: 0;
height: 2px;
background: rgba(0, 60, 136, 0.4);
width: 0;
transition: width 250ms;
} </style>
</head>
<body>
<div class="wrapper">
<div id="map" class="map"></div>
<div id="progress"></div>
</div>
<script>
/**
* Renders a progress bar.
* @param {Element} el The target element.
* @constructor
*/
function Progress(el) {
this.el = el;
this.loading = 0;
this.loaded = 0;
}
/**
* Increment the count of loading tiles.
*/
Progress.prototype.addLoading = function() {
if (this.loading === 0) {
this.show();
}
++this.loading;
this.update();
};
/**
* Increment the count of loaded tiles.
*/
Progress.prototype.addLoaded = function() {
var this_ = this;
setTimeout(function() {
++this_.loaded;
this_.update();
}, 100);
};
/**
* Update the progress bar.
*/
Progress.prototype.update = function() {
var width = (this.loaded / this.loading * 100).toFixed(1) + '%';
this.el.style.width = width;
if (this.loading === this.loaded) {
this.loading = 0;
this.loaded = 0;
var this_ = this;
setTimeout(function() {
this_.hide();
}, 500);
}
};
/**
* Show the progress bar.
*/
Progress.prototype.show = function() {
this.el.style.visibility = 'visible';
};
/**
* Hide the progress bar.
*/
Progress.prototype.hide = function() {
if (this.loading === this.loaded) {
this.el.style.visibility = 'hidden';
this.el.style.width = 0;
}
};
var progress = new Progress(document.getElementById('progress'));
var source = new ol.source.TileJSON({
url: 'https://api.tiles.mapbox.com/v3/mapbox.world-bright.json?secure',
crossOrigin: 'anonymous'
});
source.on('tileloadstart', function() {
progress.addLoading();
});
source.on('tileloadend', function() {
progress.addLoaded();
});
source.on('tileloaderror', function() {
progress.addLoaded();
});
var map = new ol.Map({
logo: false,
layers: [
new ol.layer.Tile({source: source})
],
target: 'map',
view: new ol.View({
center: [0, 0],
zoom: 2
})
});
</script>
</body>
</html>
说明：
OpenLayers示例代码：平铺加载事件
