OpenLayers示例代码：图标像素操作
OpenLayers示例代码：图标像素操作
<!DOCTYPE html>
<html>
<head>
<title>Icon Pixel Operations</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>
function createStyle(src, img) {
return new ol.style.Style({
image: new ol.style.Icon(/** @type {olx.style.IconOptions} */ ({
anchor: [0.5, 0.96],
src: src,
img: img,
imgSize: img ? [img.width, img.height] : undefined
}))
});
}
var iconFeature = new ol.Feature(new ol.geom.Point([0, 0]));
iconFeature.set('style', createStyle('https://openlayers.org/en/v4.0.1/examples/data/icon.png', undefined));
var map = new ol.Map({
layers: [
new ol.layer.Tile({
source: new ol.source.Stamen({layer: 'watercolor'})
}),
new ol.layer.Vector({
style: function(feature) {
return feature.get('style');
},
source: new ol.source.Vector({features: [iconFeature]})
})
],
target: document.getElementById('map'),
view: new ol.View({
center: [0, 0],
zoom: 3
})
});
var selectStyle = {};
var select = new ol.interaction.Select({
style: function(feature) {
var image = feature.get('style').getImage().getImage();
if (!selectStyle[image.src]) {
var canvas = document.createElement('canvas');
var context = canvas.getContext('2d');
canvas.width = image.width;
canvas.height = image.height;
context.drawImage(image, 0, 0, image.width, image.height);
var imageData = context.getImageData(0, 0, canvas.width, canvas.height);
var data = imageData.data;
for (var i = 0, ii = data.length; i < ii; i = i + (i % 4 == 2 ? 2 : 1)) {
data[i] = 255 - data[i];
}
context.putImageData(imageData, 0, 0);
selectStyle[image.src] = createStyle(undefined, canvas);
}
return selectStyle[image.src];
}
});
map.addInteraction(select);
map.on('pointermove', function(evt) {
map.getTargetElement().style.cursor =
map.hasFeatureAtPixel(evt.pixel) ? 'pointer' : '';
});
</script>
</body>
</html>
说明：
OpenLayers示例代码：图标像素操作
