Openlayers示例17 | Freehand Drawing(手绘)
这个例子演示了ol/interaction/Draw徒手模式。在徒手绘图期间，在拖动时添加点。设置freehand: true为启用手绘模式。请注意，可以使用该freehandCondition选项有条件地启用手绘模式。例如，要Shift使用键切换手绘模式，请使用freehandCondition: shiftKeyOnly。
<!DOCTYPE html>
<html lang="zn">
<head>
<meta charset="UTF-8">
<!-- 引入OpenLayers CSS样式 -->
<link rel="stylesheet"
href="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.13.0/css/ol.css">
<!-- 引入OpenLayers JS库 -->
<script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.13.0/build/ol.js"></script>
<!-- css代码 -->
<style>
.map {
width: 100%;
height: 500px;
}
</style>
<title>Freehand Drawing</title>
</head>
<body>
<div id="map" class="map"></div>
<form class="form-inline">
<label for="type">Geometry type </label>
<select id="type">
<option value="LineString">LineString</option>
<option value="Polygon">Polygon</option>
<option value="Circle">Circle</option>
<option value="None">None</option>
</select>
</form>
</body>
<script>
const raster = new ol.layer.Tile({
source: new ol.source.OSM(),
});
const source = new ol.source.Vector({wrapX: false});
const vector = new ol.layer.Vector({
source: source,
});
const map = new ol.Map({
layers: [raster, vector],
target: 'map',
view: new ol.View({
center: [-11000000, 4600000],
zoom: 4,
}),
});
const typeSelect = document.getElementById('type');
let draw; // global so we can remove it later
function addInteraction() {
const value = typeSelect.value;
if (value !== 'None') {
draw = new ol.interaction.Draw({
source: source,
type: typeSelect.value,
freehand: true,
});
map.addInteraction(draw);
}
}
/**
* Handle change event.
*/
typeSelect.onchange = function () {
map.removeInteraction(draw);
addInteraction();
};
addInteraction();
</script>
</html>
