OpenLayers示例代码：地震与自定义符号
OpenLayers示例代码：地震与自定义符号
<!DOCTYPE html>
<html>
<head>
<title>Earthquakes with custom symbols</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>
</head>
<body>
<div id="map" class="map"></div>
<script>
var symbol = [[0, 0], [4, 2], [6, 0], [10, 5], [6, 3], [4, 5], [0, 0]];
var scale;
var scaleFunction = function(coordinate) {
return [coordinate[0] * scale, coordinate[1] * scale];
};
var styleCache = {};
var styleFunction = function(feature) {
// 2012_Earthquakes_Mag5.kml stores the magnitude of each earthquake in a
// standards-violating <magnitude> tag in each Placemark. We extract it from
// the Placemark's name instead.
var name = feature.get('name');
var magnitude = parseFloat(name.substr(2));
var size = parseInt(10 + 40 * (magnitude - 5), 10);
scale = size / 10;
var style = styleCache[size];
if (!style) {
var canvas =
/** @type {HTMLCanvasElement} */ (document.createElement('canvas'));
var vectorContext = ol.render.toContext(
/** @type {CanvasRenderingContext2D} */ (canvas.getContext('2d')),
{size: [size, size], pixelRatio: 1});
vectorContext.setStyle(new ol.style.Style({
fill: new ol.style.Fill({color: 'rgba(255, 153, 0, 0.4)'}),
stroke: new ol.style.Stroke({color: 'rgba(255, 204, 0, 0.2)', width: 2})
}));
vectorContext.drawGeometry(new ol.geom.Polygon([symbol.map(scaleFunction)]));
style = new ol.style.Style({
image: new ol.style.Icon({
img: canvas,
imgSize: [size, size],
rotation: 1.2
})
});
styleCache[size] = style;
}
return style;
};
var vector = new ol.layer.Vector({
source: new ol.source.Vector({
url: 'https://openlayers.org/en/v4.0.1/examples/data/kml/2012_Earthquakes_Mag5.kml',
format: new ol.format.KML({
extractStyles: false
})
}),
style: styleFunction
});
var raster = new ol.layer.Tile({
source: new ol.source.Stamen({
layer: 'toner'
})
});
var map = new ol.Map({
layers: [raster, vector],
target: 'map',
view: new ol.View({
center: [0, 0],
zoom: 2
})
});
</script>
</body>
</html>
说明：
OpenLayers示例代码：地震与自定义符号
