OpenLayers示例代码：绘制形状
OpenLayers示例代码：绘制形状
<!DOCTYPE html>
<html>
<head>
<title>Draw Shapes</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>
<form class="form-inline">
<label>Shape type </label>
<select id="type">
<option value="Square">Square</option>
<option value="Box">Box</option>
<option value="Star">Star</option>
<option value="None">None</option>
</select>
</form>
<script>
var raster = new ol.layer.Tile({
source: new ol.source.OSM()
});
var source = new ol.source.Vector({wrapX: false});
var vector = new ol.layer.Vector({
source: source
});
var map = new ol.Map({
layers: [raster, vector],
target: 'map',
view: new ol.View({
center: [-11000000, 4600000],
zoom: 4
})
});
var typeSelect = document.getElementById('type');
var draw; // global so we can remove it later
function addInteraction() {
var value = typeSelect.value;
if (value !== 'None') {
var geometryFunction;
if (value === 'Square') {
value = 'Circle';
geometryFunction = ol.interaction.Draw.createRegularPolygon(4);
} else if (value === 'Box') {
value = 'Circle';
geometryFunction = ol.interaction.Draw.createBox();
} else if (value === 'Star') {
value = 'Circle';
geometryFunction = function(coordinates, geometry) {
if (!geometry) {
geometry = new ol.geom.Polygon(null);
}
var center = coordinates[0];
var last = coordinates[1];
var dx = center[0] - last[0];
var dy = center[1] - last[1];
var radius = Math.sqrt(dx * dx + dy * dy);
var rotation = Math.atan2(dy, dx);
var newCoordinates = [];
var numPoints = 12;
for (var i = 0; i < numPoints; ++i) {
var angle = rotation + i * 2 * Math.PI / numPoints;
var fraction = i % 2 === 0 ? 1 : 0.5;
var offsetX = radius * fraction * Math.cos(angle);
var offsetY = radius * fraction * Math.sin(angle);
newCoordinates.push([center[0] + offsetX, center[1] + offsetY]);
}
newCoordinates.push(newCoordinates[0].slice());
geometry.setCoordinates([newCoordinates]);
return geometry;
};
}
draw = new ol.interaction.Draw({
source: source,
type: /** @type {ol.geom.GeometryType} */ (value),
geometryFunction: geometryFunction
});
map.addInteraction(draw);
}
}
/**
* Handle change event.
*/
typeSelect.onchange = function() {
map.removeInteraction(draw);
addInteraction();
};
addInteraction();
</script>
</body>
</html>
说明：
OpenLayers示例代码：绘制形状
