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本文實(shí)例為大家分享了Openlayers測(cè)量距離與面積的具體代碼,供大家參考,具體內(nèi)容如下
1、地圖測(cè)量功能
一般的地圖的測(cè)量功能主要表現(xiàn)在兩個(gè)方面,一是測(cè)量距離,一是測(cè)量面積;面積的測(cè)量是根據(jù)鼠標(biāo)繪制的范圍,通過地理坐標(biāo)系的轉(zhuǎn)換而計(jì)算出實(shí)際面積大小,距離的測(cè)量是根據(jù)鼠標(biāo)在地圖上繪制的點(diǎn),實(shí)時(shí)計(jì)算出兩點(diǎn)之間的實(shí)際距離,下面我們就在Openlayers3中來實(shí)現(xiàn)這一功能;
2、代碼實(shí)現(xiàn)
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title></title> <script src="../lib/ol/ol.js"></script> <link href="../css/ol.css" rel="stylesheet" /> <script src="../lib/jquery/jquery-1.8.2.js"></script> <link href="../css/bootstrap.min.css" rel="stylesheet" /> <script src="../lib/bootstrap/bootstrap.min.js"></script> <style type="text/css"> #map { width: 100%; height: 100%; position: absolute; } #menu { float: left; position: absolute; bottom: 10px; left: 10px; z-index: 2000; } .checkbox { left: 20px; } /** * 提示框的樣式信息 */ .tooltip { position: relative; background: rgba(0, 0, 0, 0.5); border-radius: 4px; color: white; padding: 4px 8px; opacity: 0.7; white-space: nowrap; } .tooltip-measure { opacity: 1; font-weight: bold; } .tooltip-static { background-color: #ffffff; color: black; border: 1px solid white; } .tooltip-measure:before, .tooltip-static:before { border-top: 6px solid rgba(0, 0, 0, 0.5); border-right: 6px solid transparent; border-left: 6px solid transparent; content: ""; position: absolute; bottom: -6px; margin-left: -7px; left: 50%; } .tooltip-static:before { border-top-color: #ffffff; } #scalebar { float: left; margin-bottom: 10px; } </style> <script type="text/javascript"> $(function () { //初始化地圖 var map = new ol.Map({ target: 'map', layers: [ new ol.layer.Tile({ source:new ol.source.OSM() }) ], view: new ol.View({ center: new ol.proj.fromLonLat([114.4250, 23.0890]), zoom: 18, maxZoom: 20 }) }); //定義矢量數(shù)據(jù)源 var source = new ol.source.Vector(); //定義矢量圖層 var vector = new ol.layer.Vector({ source: source, style: new ol.style.Style({ fill: new ol.style.Fill({ color:'rgba(255,255,255,0.2)' }), stroke: new ol.style.Stroke({ color: '#e21e0a', width:2 }), image: new ol.style.Circle({ radius: 5, fill: new ol.style.Fill({ color:'#ffcc33' }) }) }) }); //將矢量圖層添加到地圖中 map.addLayer(vector); //添加比例尺控件 var scaleLineControl = new ol.control.ScaleLine({ units: 'metric', target: 'scalebar', className: 'ol-scale-line' }); map.addControl(scaleLineControl); //創(chuàng)建一個(gè)WGS84球體對(duì)象 var wgs84Sphere = new ol.Sphere(6378137); //創(chuàng)建一個(gè)當(dāng)前要繪制的對(duì)象 var sketch = new ol.Feature(); //創(chuàng)建一個(gè)幫助提示框?qū)ο? var helpTooltipElement; //創(chuàng)建一個(gè)幫助提示信息對(duì)象 var helpTooltip; //創(chuàng)建一個(gè)測(cè)量提示框?qū)ο? var measureTooltipElement; //創(chuàng)建一個(gè)測(cè)量提示信息對(duì)象 var measureTooltip; //繼續(xù)繪制多邊形的提示信息 var continuePolygonMsg = 'Click to continue drawing the polygon'; //繼續(xù)繪制線段的提示信息 var continueLineMsg = 'Click to continue drawing the line'; //鼠標(biāo)移動(dòng)觸發(fā)的函數(shù) var pointerMoveHandler = function (evt) { //Indicates if the map is currently being dragged. //Only set for POINTERDRAG and POINTERMOVE events. Default is false. //如果是平移地圖則直接結(jié)束 if (evt.dragging) { return; } //幫助提示信息 var helpMsg = 'Click to start drawing'; if (sketch) { //Get the feature's default geometry. //A feature may have any number of named geometries. //獲取繪圖對(duì)象的幾何要素 var geom = sketch.getGeometry(); //如果當(dāng)前繪制的幾何要素是多邊形,則將繪制提示信息設(shè)置為多邊形繪制提示信息 //如果當(dāng)前繪制的幾何要素是多線段,則將繪制提示信息設(shè)置為多線段繪制提示信息 if (geom instanceof ol.geom.Polygon) { helpMsg = continuePolygonMsg; } else if (geom instanceof ol.geom.LineString) { helpMsg = continueLineMsg; } } //設(shè)置幫助提示要素的內(nèi)標(biāo)簽為幫助提示信息 helpTooltipElement.innerHTML = helpMsg; //設(shè)置幫助提示信息的位置 //The coordinate in view projection corresponding to the original browser event. helpTooltip.setPosition(evt.coordinate); //移除幫助提示要素的隱藏樣式 $(helpTooltipElement).removeClass('hidden'); }; //觸發(fā)pointermove事件 map.on('pointermove', pointerMoveHandler); //當(dāng)鼠標(biāo)移除地圖視圖的時(shí)為幫助提示要素添加隱藏樣式 $(map.getViewport()).on('mouseout', function () { $(helpTooltipElement).addClass('hidden'); }); //獲取大地測(cè)量復(fù)選框 var geodesicCheckbox = document.getElementById('geodesic'); //獲取類型 var typeSelect = document.getElementById('type'); //定義一個(gè)交互式繪圖對(duì)象 var draw; //添加交互式繪圖對(duì)象的函數(shù) function addInteraction() { // 獲取當(dāng)前選擇的繪制類型 var type = typeSelect.value == 'area' ? 'Polygon' : 'LineString'; //創(chuàng)建一個(gè)交互式繪圖對(duì)象 draw = new ol.interaction.Draw({ //繪制的數(shù)據(jù)源 source: source, //繪制類型 type: type, //樣式 style: new ol.style.Style({ fill: new ol.style.Fill({ color:'rgba(255,255,255,0.2)' }), stroke: new ol.style.Stroke({ color: 'rgba(0,0,0,0.5)', lineDash: [10, 10], width:2 }), image: new ol.style.Circle({ radius: 5, stroke: new ol.style.Stroke({ color:'rgba(0,0,0,0.7)' }), fill: new ol.style.Fill({ color: 'rgba(255,255,255,0.2)' }) }) }) }); //將交互繪圖對(duì)象添加到地圖中 map.addInteraction(draw); //創(chuàng)建測(cè)量提示框 createMeasureTooltip(); //創(chuàng)建幫助提示框 createHelpTooltip(); //定義一個(gè)事件監(jiān)聽 var listener; //定義一個(gè)控制鼠標(biāo)點(diǎn)擊次數(shù)的變量 var count = 0; //繪制開始事件 draw.on('drawstart', function (evt) { //The feature being drawn. sketch = evt.feature; //提示框的坐標(biāo) var tooltipCoord = evt.coordinate; //監(jiān)聽?zhēng)缀我氐腸hange事件 //Increases the revision counter and dispatches a 'change' event. listener = sketch.getGeometry().on('change', function (evt) { //The event target. //獲取繪制的幾何對(duì)象 var geom = evt.target; //定義一個(gè)輸出對(duì)象,用于記錄面積和長(zhǎng)度 var output; if (geom instanceof ol.geom.Polygon) { map.removeEventListener('singleclick'); map.removeEventListener('dblclick'); //輸出多邊形的面積 output = formatArea(geom); //Return an interior point of the polygon. //獲取多變形內(nèi)部點(diǎn)的坐標(biāo) tooltipCoord = geom.getInteriorPoint().getCoordinates(); } else if (geom instanceof ol.geom.LineString) { //輸出多線段的長(zhǎng)度 output = formatLength(geom); //Return the last coordinate of the geometry. //獲取多線段的最后一個(gè)點(diǎn)的坐標(biāo) tooltipCoord = geom.getLastCoordinate(); } //設(shè)置測(cè)量提示框的內(nèi)標(biāo)簽為最終輸出結(jié)果 measureTooltipElement.innerHTML = output; //設(shè)置測(cè)量提示信息的位置坐標(biāo) measureTooltip.setPosition(tooltipCoord); }); //地圖單擊事件 map.on('singleclick', function (evt) { //設(shè)置測(cè)量提示信息的位置坐標(biāo),用來確定鼠標(biāo)點(diǎn)擊后測(cè)量提示框的位置 measureTooltip.setPosition(evt.coordinate); //如果是第一次點(diǎn)擊,則設(shè)置測(cè)量提示框的文本內(nèi)容為起點(diǎn) if (count == 0) { measureTooltipElement.innerHTML = "起點(diǎn)"; } //根據(jù)鼠標(biāo)點(diǎn)擊位置生成一個(gè)點(diǎn) var point = new ol.geom.Point(evt.coordinate); //將該點(diǎn)要素添加到矢量數(shù)據(jù)源中 source.addFeature(new ol.Feature(point)); //更改測(cè)量提示框的樣式,使測(cè)量提示框可見 measureTooltipElement.className = 'tooltip tooltip-static'; //創(chuàng)建測(cè)量提示框 createMeasureTooltip(); //點(diǎn)擊次數(shù)增加 count++; }); //地圖雙擊事件 map.on('dblclick', function (evt) { //根據(jù) var point = new ol.geom.Point(evt.coordinate); source.addFeature(new ol.Feature(point)); }); }, this); //繪制結(jié)束事件 draw.on('drawend', function (evt) { count = 0; //設(shè)置測(cè)量提示框的樣式 measureTooltipElement.className = 'tooltip tooltip-static'; //Set the offset for this overlay. //設(shè)置偏移量 measureTooltip.setOffset([0, -7]); //清空繪制要素 sketch = null; //清空測(cè)量提示要素 measureTooltipElement = null; //創(chuàng)建測(cè)量提示框 createMeasureTooltip(); //Removes an event listener using the key returned by on() or once(). //移除事件監(jiān)聽 ol.Observable.unByKey(listener); //移除地圖單擊事件 map.removeEventListener('singleclick'); }, this); } //創(chuàng)建幫助提示框 function createHelpTooltip() { //如果已經(jīng)存在幫助提示框則移除 if (helpTooltipElement) { helpTooltipElement.parentNode.removeChild(helpTooltipElement); } //創(chuàng)建幫助提示要素的div helpTooltipElement = document.createElement('div'); //設(shè)置幫助提示要素的樣式 helpTooltipElement.className = 'tooltip hidden'; //創(chuàng)建一個(gè)幫助提示的覆蓋標(biāo)注 helpTooltip = new ol.Overlay({ element: helpTooltipElement, offset: [15, 0], positioning:'center-left' }); //將幫助提示的覆蓋標(biāo)注添加到地圖中 map.addOverlay(helpTooltip); } //創(chuàng)建測(cè)量提示框 function createMeasureTooltip() { //創(chuàng)建測(cè)量提示框的div measureTooltipElement = document.createElement('div'); measureTooltipElement.setAttribute('id','lengthLabel'); //設(shè)置測(cè)量提示要素的樣式 measureTooltipElement.className = 'tooltip tooltip-measure'; //創(chuàng)建一個(gè)測(cè)量提示的覆蓋標(biāo)注 measureTooltip = new ol.Overlay({ element: measureTooltipElement, offset: [0, -15], positioning:'bottom-center' }); //將測(cè)量提示的覆蓋標(biāo)注添加到地圖中 map.addOverlay(measureTooltip); } //測(cè)量類型發(fā)生改變時(shí)觸發(fā)事件 typeSelect.onchange = function () { //移除之前的繪制對(duì)象 map.removeInteraction(draw); //重新進(jìn)行繪制 addInteraction(); }; //格式化測(cè)量長(zhǎng)度 var formatLength = function (line) { //定義長(zhǎng)度變量 var length; //如果大地測(cè)量復(fù)選框被勾選,則計(jì)算球面距離 if (geodesicCheckbox.checked) { //Return the coordinates of the linestring. //獲取坐標(biāo)串 var coordinates = line.getCoordinates(); //初始長(zhǎng)度為0 length = 0; //獲取源數(shù)據(jù)的坐標(biāo)系 var sourceProj = map.getView().getProjection(); //進(jìn)行點(diǎn)的坐標(biāo)轉(zhuǎn)換 for (var i = 0; i < coordinates.length - 1; i++) { //第一個(gè)點(diǎn) var c1 = ol.proj.transform(coordinates[i], sourceProj, 'EPSG:4326'); //第二個(gè)點(diǎn) var c2 = ol.proj.transform(coordinates[i + 1], sourceProj, 'EPSG:4326'); //獲取轉(zhuǎn)換后的球面距離 //Returns the distance from c1 to c2 using the haversine formula. length += wgs84Sphere.haversineDistance(c1,c2); } } else { //Return the length of the linestring on projected plane. //計(jì)算平面距離 length = Math.round(line.getLength() * 100) / 100; } //定義輸出變量 var output; //如果長(zhǎng)度大于1000,則使用km單位,否則使用m單位 if (length > 1000) { output = (Math.round(length / 1000 * 100) / 100) + ' ' + 'km'; //換算成KM單位 } else { output = (Math.round(length * 100) / 100) + ' ' + 'm'; //m為單位 } return output; }; //格式化測(cè)量面積 var formatArea = function (polygon) { //定義面積變量 var area; //如果大地測(cè)量復(fù)選框被勾選,則計(jì)算球面面積 if (geodesicCheckbox.checked) { //獲取初始坐標(biāo)系 var sourceProj = map.getView().getProjection(); //Make a complete copy of the geometry. //Transform each coordinate of the geometry from one coordinate reference system to another. //The geometry is modified in place. For example, a line will be transformed to a line and a circle to a circle. //If you do not want the geometry modified in place, first clone() it and then use this function on the clone. //克隆該幾何對(duì)象然后轉(zhuǎn)換坐標(biāo)系 var geom = polygon.clone().transform(sourceProj, 'EPSG:4326'); //Return the Nth linear ring of the polygon geometry. //Return null if the given index is out of range. //The exterior linear ring is available at index 0 and the interior rings at index 1 and beyond. //獲取多邊形的坐標(biāo)系 var coordinates = geom.getLinearRing(0).getCoordinates(); //Returns the geodesic area for a list of coordinates. //獲取球面面積 area = Math.abs(wgs84Sphere.geodesicArea(coordinates)); } else { //獲取平面面積 area = polygon.getArea(); } //定義輸出變量 var output; //當(dāng)面積大于10000時(shí),轉(zhuǎn)換為平方千米,否則為平方米 if (area > 10000) { output = (Math.round(area/1000000*100)/100) + ' ' + 'km<sup>2</sup>'; } else { output = (Math.round(area*100)/100) + ' ' + 'm<sup>2</sup>'; } return output; }; //添加交互繪圖對(duì)象 addInteraction(); }); </script> </head> <body> <div id="map"> <div id="menu"> <label>測(cè)量類型選擇</label> <select id="type"> <option value="length">長(zhǎng)度</option> <option value="area">面積</option> </select> <label class="checkbox"><input type="checkbox" id="geodesic" />使用大地測(cè)量</label> </div> </div> <div id="scalebar"></div> </body> </html>
3、結(jié)果展示
測(cè)量距離
測(cè)量面積
此外,還能勾選使用大地測(cè)量的復(fù)選框,進(jìn)行球面距離和面積的測(cè)量
以上就是本文的全部?jī)?nèi)容,希望對(duì)大家的學(xué)習(xí)有所幫助,也希望大家多多支持億速云。
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