本文实例为大家分享了openlayers4.6.5实现距离量测和面积量测的具体代码，供大家参考，具体内容如下
版本： openlayers4.6.5
效果图：
小插曲：
原本使用ol官方提供的 量测例子，就挺不错的。但是由于放在项目中后。量测样式不知道为啥出不来，找了半天原因 也没有找到，单独在一个html中完全没问题。所以推测可能和项目中哪些地方有冲突，但是问题暂时没找出来，项目也比较急，所以只能自己实现文字标注部门的样式，实现效果如上图gif所示。
实现原理：
量测功能还是使用了ol例子提供的源码，修改部分主要是在标注这一块，另外就是时刻去添加这个标注 然后时刻删除这个标注 就可以了。
完整的js代码如下（鼠标样式图标 我没放上来，有需要的我给你发邮箱）：
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var draw;var click=false;var output=0;var vector;var source;var lastPolygonLabelFeature;//记录上一个面标注要素 var lastLengthLabelFeature;//记录上一个点标注要素$( function(){ $("#measureDistance").click(function(){ if(draw){ map.removeInteraction(draw); } addInteraction("length"); setMeasureCur(); }) $("#measureArea").click(function(){ if(draw){ map.removeInteraction(draw); } addInteraction("area"); setMeasureCur(); }) $("#measureClear").click(function(){ map.removeInteraction(draw); vector.setSource(null); source=new ol.source.Vector(); vector.setSource(source); lastPolygonLabelFeature=null; lastLengthLabelFeature=null; click=false; sketch = null; output="0"; reSetCur(); }) function setMeasureCur(){ $('#map').css({ cursor:"url(../../static/images/measureIcon/measure.cur), auto" }); } function reSetCur(){ $('#map').css('cursor','default'); } source = new ol.source.Vector(); vector = new ol.layer.Vector({ source: source, style: new ol.style.Style({ fill: new ol.style.Fill({//面的填充颜色 color: 'rgba(255, 0, 0, 0.1)' }), stroke: new ol.style.Stroke({ color: 'rgb(255,116,3)', width: 2 }), image: new ol.style.Circle({ radius: 3, stroke: new ol.style.Stroke({ color: 'rgba(255, 0, 0,1)', width: 2 }), fill: new ol.style.Fill({ color: 'rgba(255,255,255)' }) }) }) }); map.addLayer(vector); var sketch; var pointerMoveHandler = function(evt) { if (evt.dragging) { return; } var Coord; if(sketch){ var geom = sketch.getGeometry(); if (geom instanceof ol.geom.Polygon) { if(lastPolygonLabelFeature){ //鼠标移动 不停的添加和删除 source.removeFeature(lastPolygonLabelFeature); } Coord = geom.getInteriorPoint().getCoordinates(); //新建一个要素ol.Feature var newFeature = new ol.Feature({ geometry: new ol.geom.Point(Coord), //几何信息 name: output }); lastPolygonLabelFeature=newFeature; newFeature.setStyle(createLabelStyle(newFeature,0,0)); } else if (geom instanceof ol.geom.LineString) { if(lastLengthLabelFeature){ source.removeFeature(lastLengthLabelFeature); } Coord = geom.getLastCoordinate(); //新建一个要素ol.Feature var newFeature = new ol.Feature({ geometry: new ol.geom.Point(Coord), //几何信息 name: output }); lastLengthLabelFeature=newFeature; newFeature.setStyle(createLabelStyle(newFeature,35,-10)); } //设置要素样式 source.addFeature(newFeature); } }; map.on('pointermove', pointerMoveHandler); map.on('click', function(evt){ var coordinate = evt.coordinate; //鼠标单击点的坐标 console.log(coordinate); if(output=="0"){ lastPolygonLabelFeature=null; if(lastLengthLabelFeature){ source.removeFeature(lastLengthLabelFeature); lastLengthLabelFeature=null; } return; } var Coord; if(sketch){ var geom = sketch.getGeometry(); if (geom instanceof ol.geom.Polygon) { if(lastPolygonLabelFeature){ source.removeFeature(lastPolygonLabelFeature); } Coord = geom.getInteriorPoint().getCoordinates(); //新建一个要素ol.Feature var newFeature = new ol.Feature({ geometry: new ol.geom.Point(Coord), //几何信息 name: output }); lastPolygonLabelFeature=newFeature; newFeature.setStyle(createLabelStyle(newFeature,0,0)); //设置要素样式 source.addFeature(newFeature); } else if (geom instanceof ol.geom.LineString) { Coord = geom.getLastCoordinate(); //新建一个要素ol.Feature var newFeature = new ol.Feature({ geometry: new ol.geom.Point(Coord), //几何信息 name: output }); newFeature.setStyle(createLabelStyle(newFeature,35,-10)); //设置要素样式 source.addFeature(newFeature); } var pointFeature = new ol.Feature({ geometry: new ol.geom.Point(coordinate), //几何信息 name: output }); source.addFeature(pointFeature); } }); //矢量标注样式设置函数，设置image为图标ol.style.Icon function createLabelStyle(feature,offsetX,offsetY){ return new ol.style.Style({// image: new ol.style.Icon({// anchor: [0.5, 60], //锚点// anchorOrigin:'top-right', //锚点源// anchorXUnits: 'fraction', //锚点X值单位// anchorYUnits: 'pixels', //锚点Y值单位// offsetOrigin: 'top-right', //偏移原点// opacity: 0.75,// src: 'OL3Demo/images/label/blueIcon.png' //图标的URL// }), text: new ol.style.Text({ textAlign: 'center', //位置 textBaseline: 'middle', //基准线 font: 'normal 10px sans-serif', //文字样式 text: feature.get('name'), //文本内容 fill: new ol.style.Fill({ //文本填充样式（即文字颜色) color: 'white' }), stroke: new ol.style.Stroke({ color: 'black', width: 5 }), offsetX:offsetX, offsetY:offsetY }) }); } function addInteraction(drawType) { var type = (drawType== 'area' ? 'Polygon' : 'LineString'); draw = new ol.interaction.Draw({ source: source, type: type, style: new ol.style.Style({ fill: new ol.style.Fill({ color: 'rgba(255, 0, 0, 0.2)' }), stroke: new ol.style.Stroke({ color: 'rgb(255,116,3)',// lineDash: [10, 10],//虚线 width: 2 }), image: new ol.style.Circle({ radius: 5, stroke: new ol.style.Stroke({ color: 'rgba(255, 0, 0, 0.1)' }), fill: new ol.style.Fill({ color: 'rgba(255,116,3, 0.3)' }) }) }) }); map.addInteraction(draw); var listener; draw.on('drawstart', function(evt) { // set sketch sketch = evt.feature; listener = sketch.getGeometry().on('change', function(evt) { var geom = evt.target; if (geom instanceof ol.geom.Polygon) { output = formatArea(geom); } else if (geom instanceof ol.geom.LineString) { output = formatLength(geom); } }); }, this); draw.on('drawend', function() { // unset sketch sketch = null; ol.Observable.unByKey(listener); output="0"; }, this); } var formatLength = function(line) { var length = ol.Sphere.getLength(line); var output; if (length > 100) { output = (Math.round(length / 1000 * 100) / 100) + ' ' + '千米'; } else { output = (Math.round(length * 100) / 100) + ' ' + '米'; } return output; }; var formatArea = function(polygon) { var area = ol.Sphere.getArea(polygon); var output; if (area > 10000) { output = (Math.round(area / 1000000 * 100) / 100) + ' ' + '平方千米'; } else { output = (Math.round(area * 100) / 100) + ' ' + '平方米'; } return output; };}) |
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/yangniceyangyang/article/details/103769133
