Advanced View Positioning

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Advanced View Positioning

(best fit).
(with min resolution),

This example demonstrates how a map's view can be adjusted so a geometry or coordinate is positioned at a specific pixel location.

This example demonstrates how a map's view can be adjusted so a geometry or coordinate is positioned at a specific pixel location. The map above has top, right, bottom, and left padding applied inside the viewport. The view's fit method is used to fit a geometry in the view with the same padding. The view's centerOn method is used to position a coordinate (Lausanne) at a specific pixel location (the center of the black box).

Use Alt+Shift+Drag to rotate the map.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Advanced View Positioning</title>
    <!-- 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>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
      .mapcontainer {
        position: relative;
        margin-bottom: 20px;
      }
      .map {
        width: 1000px;
        height: 600px;
      }
      div.ol-zoom {
        top: 178px;
        left: 158px;
      }
      div.ol-rotate {
        top: 178px;
        right: 58px;
      }
      .map div.ol-attribution {
        bottom: 30px;
        right: 50px;
      }
      .padding-top {
        position: absolute;
        top: 0;
        left: 0px;
        width: 1000px;
        height: 170px;
        background: rgba(255, 255, 255, 0.5);
      }
      .padding-left {
        position: absolute;
        top: 170px;
        left: 0;
        width: 150px;
        height: 400px;
        background: rgba(255, 255, 255, 0.5);
      }
      .padding-right {
        position: absolute;
        top: 170px;
        left: 950px;
        width: 50px;
        height: 400px;
        background: rgba(255, 255, 255, 0.5);
      }
      .padding-bottom {
        position: absolute;
        top: 570px;
        left: 0px;
        width: 1000px;
        height: 30px;
        background: rgba(255, 255, 255, 0.5);
      }
      .center {
        position: absolute;
        border: solid 1px black;
        top: 490px;
        left: 560px;
        width: 20px;
        height: 20px;
      }
    </style>
  </head>
  <body>
    <div class="mapcontainer">
      <div id="map" class="map"></div>
      <div class="padding-top"></div>
      <div class="padding-left"></div>
      <div class="padding-right"></div>
      <div class="padding-bottom"></div>
      <div class="center"></div>
    </div>
    <button id="zoomtoswitzerland">Zoom to Switzerland</button> (best fit).<br/>
    <button id="zoomtolausanne">Zoom to Lausanne</button> (with min resolution),<br/>
    <button id="centerlausanne">Center on Lausanne</button>
    <script src="index.js"></script>
  </body>
</html>

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index.jsimport 'ol/ol.css';
import Map from 'ol/Map';
import View from 'ol/View';
import GeoJSON from 'ol/format/GeoJSON';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import {OSM, Vector as VectorSource} from 'ol/source';
import {Circle as CircleStyle, Fill, Stroke, Style} from 'ol/style';

/** @type {VectorSource<import("../src/ol/geom/SimpleGeometry.js").default>} */
var source = new VectorSource({
  url: 'data/geojson/switzerland.geojson',
  format: new GeoJSON()
});
var style = new Style({
  fill: new Fill({
    color: 'rgba(255, 255, 255, 0.6)'
  }),
  stroke: new Stroke({
    color: '#319FD3',
    width: 1
  }),
  image: new CircleStyle({
    radius: 5,
    fill: new Fill({
      color: 'rgba(255, 255, 255, 0.6)'
    }),
    stroke: new Stroke({
      color: '#319FD3',
      width: 1
    })
  })
});
var vectorLayer = new VectorLayer({
  source: source,
  style: style
});
var view = new View({
  center: [0, 0],
  zoom: 1
});
var map = new Map({
  layers: [
    new TileLayer({
      source: new OSM()
    }),
    vectorLayer
  ],
  target: 'map',
  view: view
});

var zoomtoswitzerland =
    document.getElementById('zoomtoswitzerland');
zoomtoswitzerland.addEventListener('click', function() {
  var feature = source.getFeatures()[0];
  var polygon = feature.getGeometry();
  view.fit(polygon, {padding: [170, 50, 30, 150]});
}, false);

var zoomtolausanne = document.getElementById('zoomtolausanne');
zoomtolausanne.addEventListener('click', function() {
  var feature = source.getFeatures()[1];
  var point = feature.getGeometry();
  view.fit(point, {padding: [170, 50, 30, 150], minResolution: 50});
}, false);

var centerlausanne = document.getElementById('centerlausanne');
centerlausanne.addEventListener('click', function() {
  var feature = source.getFeatures()[1];
  var point = feature.getGeometry();
  var size = map.getSize();
  view.centerOn(point.getCoordinates(), size, [570, 500]);
}, false);

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package.json{
  "name": "center",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}