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如何使用OpenLayers div创建PDF文件

javascriptjqueryhtmlpdfopenlayers
3
我正在尝试找到一种使用OpenLayers创建PDF文件的解决方案。我有一个包含WMTS瓦片的div，使用它我想为我的用户创建PDF文件。我已经在互联网上搜索过，但没有找到解决方案。
在“mapContainer”中，所有我的OpenLayers WMTS瓦片都将被创建，并使用这些瓦片来创建PDF文件，直接下载到用户PC。
我之前使用了“window.print()”，但它截断了对用户可见的某些地图数据。请提供任何可能的解决方案。
1个回答
1

我记得Openlayers3提供了一个打印PDF的例子(导出PDF示例)。

<!DOCTYPE html>
<html>
  <head>
    <title>Export PDF example</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v3.20.1/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/v3.20.1/build/ol.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.2.61/jspdf.min.js"></script>
    <style>
      .map {
        max-width: 566px;
      }
    </style>
  </head>
  <body>
    <div class="row-fluid">
      <div class="span12">
        <div id="map" class="map"></div>
      </div>
    </div>
    <form class="form">
      <label>Page size </label>
      <select id="format">
        <option value="a0">A0 (slow)</option>
        <option value="a1">A1</option>
        <option value="a2">A2</option>
        <option value="a3">A3</option>
        <option value="a4" selected>A4</option>
        <option value="a5">A5 (fast)</option>
      </select>
      <label>Resolution </label>
      <select id="resolution">
        <option value="72">72 dpi (fast)</option>
        <option value="150">150 dpi</option>
        <option value="300">300 dpi (slow)</option>
      </select>
    </form>
    <button id="export-pdf">Export PDF</button>
    <script>
      var raster = new ol.layer.Tile({
        source: new ol.source.OSM()
      });

      var format = new ol.format.WKT();
      var feature = format.readFeature(
          'POLYGON((10.689697265625 -25.0927734375, 34.595947265625 ' +
              '-20.1708984375, 38.814697265625 -35.6396484375, 13.502197265625 ' +
              '-39.1552734375, 10.689697265625 -25.0927734375))');
      feature.getGeometry().transform('EPSG:4326', 'EPSG:3857');

      var vector = new ol.layer.Vector({
        source: new ol.source.Vector({
          features: [feature]
        })
      });


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


      var dims = {
        a0: [1189, 841],
        a1: [841, 594],
        a2: [594, 420],
        a3: [420, 297],
        a4: [297, 210],
        a5: [210, 148]
      };

      var loading = 0;
      var loaded = 0;

      var exportButton = document.getElementById('export-pdf');

      exportButton.addEventListener('click', function() {

        exportButton.disabled = true;
        document.body.style.cursor = 'progress';

        var format = document.getElementById('format').value;
        var resolution = document.getElementById('resolution').value;
        var dim = dims[format];
        var width = Math.round(dim[0] * resolution / 25.4);
        var height = Math.round(dim[1] * resolution / 25.4);
        var size = /** @type {ol.Size} */ (map.getSize());
        var extent = map.getView().calculateExtent(size);

        var source = raster.getSource();

        var tileLoadStart = function() {
          ++loading;
        };

        var tileLoadEnd = function() {
          ++loaded;
          if (loading === loaded) {
            var canvas = this;
            window.setTimeout(function() {
              loading = 0;
              loaded = 0;
              var data = canvas.toDataURL('image/png');
              var pdf = new jsPDF('landscape', undefined, format);
              pdf.addImage(data, 'JPEG', 0, 0, dim[0], dim[1]);
              pdf.save('map.pdf');
              source.un('tileloadstart', tileLoadStart);
              source.un('tileloadend', tileLoadEnd, canvas);
              source.un('tileloaderror', tileLoadEnd, canvas);
              map.setSize(size);
              map.getView().fit(extent, size);
              map.renderSync();
              exportButton.disabled = false;
              document.body.style.cursor = 'auto';
            }, 100);
          }
        };

        map.once('postcompose', function(event) {
          source.on('tileloadstart', tileLoadStart);
          source.on('tileloadend', tileLoadEnd, event.context.canvas);
          source.on('tileloaderror', tileLoadEnd, event.context.canvas);
        });

        map.setSize([width, height]);
        map.getView().fit(extent, /** @type {ol.Size} */ (map.getSize()));
        map.renderSync();

      }, false);
    </script>
  </body>
</html>

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