Layer Clipping

This example uses OpenLayers v4.0.1. The latest is v.

#### Layer Clipping

Layer clipping example

Layer clipping example

Related API documentation:

- ol.Map
,
- ol.View
,
- ol.control
,
- ol.layer.Tile
,
- ol.source.OSM

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Layer Clipping Layer clipping example var osm = new ol.layer.Tile({ source: new ol.source.OSM() }); var map = new ol.Map({ layers: [osm], target: 'map', controls: ol.control.defaults({ attributionOptions: /** @type {olx.control.AttributionOptions} */ ({ collapsible: false }) }), view: new ol.View({ center: [0, 0], zoom: 2 }) }); osm.on('precompose', function(event) { var ctx = event.context; ctx.save(); var pixelRatio = event.frameState.pixelRatio; var size = map.getSize(); ctx.translate(size[0] / 2 * pixelRatio, size[1] / 2 * pixelRatio); ctx.scale(3 * pixelRatio, 3 * pixelRatio); ctx.translate(-75, -80); ctx.beginPath(); ctx.moveTo(75, 40); ctx.bezierCurveTo(75, 37, 70, 25, 50, 25); ctx.bezierCurveTo(20, 25, 20, 62.5, 20, 62.5); ctx.bezierCurveTo(20, 80, 40, 102, 75, 120); ctx.bezierCurveTo(110, 102, 130, 80, 130, 62.5); ctx.bezierCurveTo(130, 62.5, 130, 25, 100, 25); ctx.bezierCurveTo(85, 25, 75, 37, 75, 40); ctx.clip(); ctx.translate(75, 80); ctx.scale(1 / 3 / pixelRatio, 1 / 3 / pixelRatio); ctx.translate(-size[0] / 2 * pixelRatio, -size[1] / 2 * pixelRatio); }); osm.on('postcompose', function(event) { var ctx = event.context; ctx.restore(); }); #map { background: transparent; } <div id="map" class="map"></div>

    <!DOCTYPE html>
    <html>
      <head>
        <title>Layer Clipping</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>
        <style>
          #map {
            background: transparent;
          }
        </style>
      </head>
      <body>
        <div id="map" class="map"></div>
        <script>
          var osm = new ol.layer.Tile({
            source: new ol.source.OSM()
          });

          var map = new ol.Map({
            layers: [osm],
            target: 'map',
            controls: ol.control.defaults({
              attributionOptions: /** @type {olx.control.AttributionOptions} */ ({
                collapsible: false
              })
            }),
            view: new ol.View({
              center: [0, 0],
              zoom: 2
            })
          });

          osm.on('precompose', function(event) {
            var ctx = event.context;
            ctx.save();
            var pixelRatio = event.frameState.pixelRatio;
            var size = map.getSize();
            ctx.translate(size[0] / 2 * pixelRatio, size[1] / 2 * pixelRatio);
            ctx.scale(3 * pixelRatio, 3 * pixelRatio);
            ctx.translate(-75, -80);
            ctx.beginPath();
            ctx.moveTo(75, 40);
            ctx.bezierCurveTo(75, 37, 70, 25, 50, 25);
            ctx.bezierCurveTo(20, 25, 20, 62.5, 20, 62.5);
            ctx.bezierCurveTo(20, 80, 40, 102, 75, 120);
            ctx.bezierCurveTo(110, 102, 130, 80, 130, 62.5);
            ctx.bezierCurveTo(130, 62.5, 130, 25, 100, 25);
            ctx.bezierCurveTo(85, 25, 75, 37, 75, 40);
            ctx.clip();
            ctx.translate(75, 80);
            ctx.scale(1 / 3 / pixelRatio, 1 / 3 / pixelRatio);
            ctx.translate(-size[0] / 2 * pixelRatio, -size[1] / 2 * pixelRatio);
          });

          osm.on('postcompose', function(event) {
            var ctx = event.context;
            ctx.restore();
          });
        </script>
      </body>
    </html>