1. 程式人生 > >openlayer熱力圖權重與顏色關係研究

openlayer熱力圖權重與顏色關係研究

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 &nbsp;</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>