Openlayers示例17 | Freehand Drawing(手绘)

Freehand Drawing

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 &nbsp;</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>