openlayer熱力圖權重與顏色關係研究
阿新 • • 發佈:2018-12-29
熱力圖的權重與顏色的關係的例子,選中feature獲取其權重值,還需進一步研究。
<!DOCTYPE html>
<html>
<head>
<title>Earthquakes Heatmap</title>
<link rel="stylesheet" href="http://openlayers.org/en/v3.18.2/css/ol.css" type="text/css">
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
<script src="http://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
<script src="http://openlayers.org/en/v3.18.2/build/ol.js"></script>
</head>
<body>
<div id="map" class="map"></div>
<form >
<label>radius size</label>
<input id="radius" type="range" min="1" max="50" step="1" value="5"/>
<label>blur size</label>
<input id="blur" type="range" min="1" max="50" step="1" value="15"/>
<label>Action type </label >
<select id="type" class="form-control">
<option value="click" selected>Click</option>
<option value="singleclick">Single-click</option>
<option value="pointermove">Hover</option>
<option value="altclick">Alt+Click</option>
<option value="none">None</option>
</select>
<span id="status"></span>
</form>
<script>
var blur = document.getElementById('blur');
var radius = document.getElementById('radius');
var vector = new ol.layer.Heatmap({
source: new ol.source.Vector({
url: 'http://openlayers.org/en/v3.18.2/examples/data/kml/2012_Earthquakes_Mag5.kml',
format: new ol.format.KML({
extractStyles: false
})
}),
blur: parseInt(blur.value, 10),
radius: parseInt(radius.value, 10)
});
vector.getSource().on('addfeature', function(event) {
// 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 = event.feature.get('name');
var magnitude = parseFloat(name.substr(2));
event.feature.set('weight', magnitude - 5);
});
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
})
});
var select = null; // ref to currently selected interaction
// select interaction working on "singleclick"
var selectSingleClick = new ol.interaction.Select();
// select interaction working on "click"
var selectClick = new ol.interaction.Select({
condition: ol.events.condition.click
});
// select interaction working on "pointermove"
var selectPointerMove = new ol.interaction.Select({
condition: ol.events.condition.pointerMove
});
var selectAltClick = new ol.interaction.Select({
condition: function(mapBrowserEvent) {
return ol.events.condition.click(mapBrowserEvent) &&
ol.events.condition.altKeyOnly(mapBrowserEvent);
}
});
var selectElement = document.getElementById('type');
var changeInteraction = function() {
if (select !== null) {
map.removeInteraction(select);
}
var value = selectElement.value;
if (value == 'singleclick') {
select = selectSingleClick;
} else if (value == 'click') {
select = selectClick;
} else if (value == 'pointermove') {
select = selectPointerMove;
} else if (value == 'altclick') {
select = selectAltClick;
} else {
select = null;
}
if (select !== null) {
map.addInteraction(select);
select.on('select', function(e) {
var feature = e.target.getFeatures();
document.getElementById('status').innerHTML = 'weight:' +feature.getArray()[0].get("weight");
});
}
};
/**
* onchange callback on the select element.
*/
selectElement.onchange = changeInteraction;
changeInteraction();
blur.addEventListener('input', function() {
vector.setBlur(parseInt(blur.value, 10));
});
radius.addEventListener('input', function() {
vector.setRadius(parseInt(radius.value, 10));
});
</script>
</body>
</html>