Question

我想在openlayer2中绘制一个bufffer。它可以是多边形或圆形，如圆圈所示。我检查了所有绘制功能的官方示例，但我没有找到任何有用的材料。我附上了一个例子

＆＃13;

<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <title>Modify Feature</title>
    <link rel="stylesheet" href="style.css" type="text/css">
    <link rel="stylesheet" href="style1.css" type="text/css">
    <style type="text/css">
        #controls {
            width: 512px;
        }
        #controlToggle {
            padding-left: 1em;
        }
        #controlToggle li {
            list-style: none;
        }
    </style>
    <script src="OpenLayers.js"></script>
    <script type="text/javascript">
        var map, vectors, controls;
        function init(){
            map = new OpenLayers.Map('map');
            var wms = new OpenLayers.Layer.WMS( "OpenLayers WMS", 
                "http://vmap0.tiles.osgeo.org/wms/vmap0?", {layers: 'basic'}); 
            OpenLayers.Feature.Vector.style['default']['strokeWidth'] = '2';

            // allow testing of specific renderers via "?renderer=Canvas", etc
          

            vectors = new OpenLayers.Layer.Vector("Vector Layer", {
               
            });

            map.addLayers([wms, vectors]);
            map.addControl(new OpenLayers.Control.LayerSwitcher());
            map.addControl(new OpenLayers.Control.MousePosition());
            
            if (console && console.log) {
                function report(event) {
                    console.log(event.type, event.feature ? event.feature.id : event.components);
                }
                vectors.events.on({
                    "beforefeaturemodified": report,
                    "featuremodified": report,
                    "afterfeaturemodified": report,
                    "vertexmodified": report,
                    "sketchmodified": report,
                    "sketchstarted": report,
                    "sketchcomplete": report
                });
            }
            controls = {
                
              
                
                regular: new OpenLayers.Control.DrawFeature(vectors,
                            OpenLayers.Handler.RegularPolygon,
                            {handlerOptions: {sides: 5}}),
                modify: new OpenLayers.Control.ModifyFeature(vectors)
            };
            
            for(var key in controls) {
                map.addControl(controls[key]);
            }
            
            map.setCenter(new OpenLayers.LonLat(0, 0), 3);
            document.getElementById('noneToggle').checked = true;
        }
        
        function update() {
            // reset modification mode
            controls.modify.mode = OpenLayers.Control.ModifyFeature.RESHAPE;
          
            var resize = document.getElementById("resize").checked;
            if(resize) {
                controls.modify.mode |= OpenLayers.Control.ModifyFeature.RESIZE;
                var keepAspectRatio = document.getElementById("keepAspectRatio").checked;
                if (keepAspectRatio) {
                    controls.modify.mode &= ~OpenLayers.Control.ModifyFeature.RESHAPE;
                }
            }
         
            controls.modify.createVertices = document.getElementById("createVertices").checked;
      
          
        }

        function toggleControl(element) {
            for(key in controls) {
                var control = controls[key];
                if(element.value == key && element.checked) {
                    control.activate();
                } else {
                    control.deactivate();
                }
            }
        }
        
    </script>
  </head>
  <body onload="init()">
    <h1 id="title">OpenLayers 2 Modify Feature Example</h1>
    <div id="tags">
        vertices, digitizing, draw, drawing
    </div>
    <div id="shortdesc">A demonstration of the ModifyFeature control for editing vector features.</div>
    <div id="map" class="smallmap"></div>
    <div id="controls">
        <ul id="controlToggle">
            <li>
                <input type="radio" name="type" value="none" id="noneToggle"
                       onclick="toggleControl(this);" checked="checked" />
                <label for="noneToggle">navigate</label>
            </li>
           
          
          
            <li>
                <input type="radio" name="type" value="regular" id="regularToggle" onclick="toggleControl(this);" />
                <label for="regularToggle">draw regular polygon</label>
                <label for="sides"> - sides</label>
                <input id="sides" type="text" size="2" maxlength="2"
                       name="sides" value="5" onchange="update()" />
                <ul>
                    

                </ul>
            </li>
            <li>
                <input type="radio" name="type" value="modify" id="modifyToggle"
                       onclick="toggleControl(this);" />
                <label for="modifyToggle">modify feature</label>
                <ul>
                   
                   
                    <li>
                        <input id="resize" type="checkbox"
                               name="resize" onchange="update()" />
                        <label for="resize">allow resizing</label>
                        (<input id="keepAspectRatio" type="checkbox"
                               name="keepAspectRatio" onchange="update()" checked="checked" />
                        <label for="keepAspectRatio">keep aspect ratio</label>)
                    </li>
                 
                </ul>
            </li>
        </ul>
    </div>
  </body>
</html>

＆＃13;

Answer 1

如果要在点周围创建一个圆，可以使用openlayers内置函数

OpenLayers.Geometry.Polygon.createRegularPolygon = function(origin, radius, sides, rotation)

，传递用户指定的无线电。

否则，如果要缓冲任意多边形，可以使用JSTS库提供的缓冲区功能。

您可以在此处找到openlayers的示例 http://bjornharrtell.github.io/jsts/examples/buffer.html

Openlayers2：我想根据用户输入长度在openlayer2上绘制一个缓冲区

1 个答案: