当标记移动时，打开图层删除通过的行

编程问答 2022-06-15

问题描述

我正在使用开放层，我偶然发现了一个问题。

这是我要实现的目标，就是在标记移动时删除通过的行。

要进一步说明，请查看下面的示例：

https://openlayers.org/en/latest/examples/feature-move-animation.html

点击开始动画时，标记会移动，但是会保留标记经过的黄线，我想在标记移动时删除标记后面的那条线。

如何使用OpenLayers？

解决方法

从the example referenced开始，一种选择是添加新行Feature，然后更新其坐标以删除已经遍历的坐标

  • 添加新的Polyline：

    // new line feature (polyline) 
var lineCoords = route.getCoordinates();
var lineFeature = new ol.Feature({
  type: 'line',geometry: route.clone()
});

  • 将新功能添加到矢量层：

    var vectorLayer = new ol.layer.Vector({ // VectorLayer({
  source: new ol.source.Vector({ // VectorSource({
    features: [geoMarker,startMarker,endMarker,lineFeature],

  • 在moveFeature函数中，更新线的坐标以删除已经遍历的坐标：

    var moveFeature = function (event) {
    // ...
    var currentPoint = new ol.geom.Point(routeCoords[index]);
    coords=routeCoords.slice(index);
    lineFeature.getGeometry().setCoordinates(coords);

working example

screenshot of resulting map in the middle of animating

代码段： 

// This long string is placed here due to jsFiddle limitations.
// It is usually loaded with AJAX.
var polyline = [
  'hldhx@lnau`BCG_EaC??cFjAwDjF??uBlKMd@}@z@??aC^yk@z_@se@b[wFdE??wFfE}N','fIoGxB_I\\gG}@eHoCyTmPqGaBaHOoD\\??yVrGotA|N??o[N_STiwAtEmHGeHcAkiA}^','aMyBiHOkFNoI`CcVvM??gG^gF_@iJwC??eCcA]OoL}DwFyCaCgCcCwDcGwHsSoX??wI_E','kUFmq@hBiOqBgTwS??iYse@gYq\\cp@ce@{vA}s@csJqaE}{@iRaqE{lBeRoIwd@_T{]_','Ngn@{PmhEwaA{SeF_u@kQuyAw]wQeEgtAsZ}LiCarAkVwI}D??_}RcjEinPspDwSqCgs@','sPua@_OkXaMeT_Nwk@ob@gV}TiYs[uTwXoNmT{Uyb@wNg]{Nqa@oDgNeJu_@_G}YsFw]k','DuZyDmm@i_@uyIJe~@jCg|@nGiv@zUi_BfNqaAvIow@dEed@dCcf@r@qz@Egs@{Acu@mC','um@yIey@gGig@cK_m@aSku@qRil@we@{mAeTej@}Tkz@cLgr@aHko@qOmcEaJw~C{w@ka','i@qBchBq@kmBS{kDnBscBnFu_Dbc@_~QHeU`IuyDrC_}@bByp@fCyoA?qMbD}{AIkeAgB','k_A_A{UsDke@gFej@qH{o@qGgb@qH{`@mMgm@uQus@kL{_@yOmd@ymBgwE}x@ouBwtA__','DuhEgaKuWct@gp@cnBii@mlBa_@}|Asj@qrCg^eaC}L{dAaJ_aAiOyjByH{nAuYu`GsAw','Xyn@ywMyOyqD{_@cfIcDe}@y@aeBJmwA`CkiAbFkhBlTgdDdPyiB`W}xDnSa}DbJyhCrX','itAhT}x@bE}Z_@qW_Kwv@qKaaAiBgXvIm}A~JovAxCqW~WanB`XewBbK{_A`K}fBvAmi@','xBycBeCauBoF}}@qJioAww@gjHaPopA_NurAyJku@uGmi@cDs[eRaiBkQstAsQkcByNma','CsK_uBcJgbEw@gkB_@ypEqDoqSm@eZcDwjBoGw`BoMegBaU_`Ce_@_uBqb@ytBwkFqiT_','fAqfEwe@mfCka@_eC_UmlB}MmaBeWkkDeHwqAoX}~DcBsZmLcxBqOwqE_DkyAuJmrJ\\o','~CfIewG|YibQxBssB?es@qGciA}RorAoVajA_nAodD{[y`AgPqp@mKwr@ms@umEaW{dAm','b@umAw|@ojBwzDaaJsmBwbEgdCsrFqhAihDquAi`Fux@}_Dui@_eB_u@guCuyAuiHukA_','lKszAu|OmaA{wKm}@clHs_A_rEahCssKo\\sgBsSglAqk@yvDcS_wAyTwpBmPc|BwZknF','oFscB_GsaDiZmyMyLgtHgQonHqT{hKaPg}Dqq@m~Hym@c`EuiBudIabB{hF{pWifx@snA','w`GkFyVqf@y~BkoAi}Lel@wtc@}`@oaXi_C}pZsi@eqGsSuqJ|Lqeb@e]kgPcaAu}SkDw','zGhn@gjYh\\qlNZovJieBqja@ed@siO{[ol\\kCmjMe\\isHorCmec@uLebB}EqiBaCg}','@m@qwHrT_vFps@kkI`uAszIrpHuzYxx@e{Crw@kpDhN{wBtQarDy@knFgP_yCu\\wyCwy','A{kHo~@omEoYmoDaEcPiuAosDagD}rO{{AsyEihCayFilLaiUqm@_bAumFo}DgqA_uByi','@swC~AkzDlhA}xEvcBa}Cxk@ql@`rAo|@~bBq{@``Bye@djDww@z_C_cAtn@ye@nfC_eC','|gGahH~s@w}@``Fi~FpnAooC|u@wlEaEedRlYkrPvKerBfYs}Arg@m}AtrCkzElw@gjBb','h@woBhR{gCwGkgCc[wtCuOapAcFoh@uBy[yBgr@c@iq@o@wvEv@sp@`FajBfCaq@fIipA','dy@ewJlUc`ExGuaBdEmbBpBssArAuqBBg}@s@g{AkB{bBif@_bYmC}r@kDgm@sPq_BuJ_','s@{X_{AsK_d@eM{d@wVgx@oWcu@??aDmOkNia@wFoSmDyMyCkPiBePwAob@XcQ|@oNdCo','SfFwXhEmOnLi\\lbAulB`X_d@|k@au@bc@oc@bqC}{BhwDgcD`l@ed@??bL{G|a@eTje@','oS~]cLr~Bgh@|b@}Jv}EieAlv@sPluD{z@nzA_]`|KchCtd@sPvb@wSb{@ko@f`RooQ~e','[upZbuIolI|gFafFzu@iq@nMmJ|OeJn^{Qjh@yQhc@uJ~j@iGdd@kAp~BkBxO{@|QsAfY','gEtYiGd]}Jpd@wRhVoNzNeK`j@ce@vgK}cJnSoSzQkVvUm^rSgc@`Uql@xIq\\vIgg@~k','Dyq[nIir@jNoq@xNwc@fYik@tk@su@neB}uBhqEesFjoGeyHtCoD|D}Ed|@ctAbIuOzqB','_}D~NgY`\\um@v[gm@v{Cw`G`w@o{AdjAwzBh{C}`Gpp@ypAxn@}mAfz@{bBbNia@??jI','ab@`CuOlC}YnAcV`@_^m@aeB}@yk@YuTuBg^uCkZiGk\\yGeY}Lu_@oOsZiTe[uWi[sl@','mo@soAauAsrBgzBqgAglAyd@ig@asAcyAklA}qAwHkGi{@s~@goAmsAyDeEirB_{B}IsJ','uEeFymAssAkdAmhAyTcVkFeEoKiH}l@kp@wg@sj@ku@ey@uh@kj@}EsFmG}Jk^_r@_f@m','~@ym@yjA??a@cFd@kBrCgDbAUnAcBhAyAdk@et@??kF}D??OL'
].join('');

var route = /** @type {import("../src/ol/geom/LineString.js").default} */ (new ol.format.Polyline({
  factor: 1e6,}).readGeometry(polyline,{
  dataProjection: 'EPSG:4326',featureProjection: 'EPSG:3857',}));

var routeCoords = route.getCoordinates();
var routeLength = routeCoords.length;

var routeFeature = new ol.Feature({
  type: 'route',geometry: route,});
var lineCoords = route.getCoordinates();
var lineFeature = new ol.Feature({
  type: 'line',geometry: route.clone()
});
var geoMarker = /** @type Feature<import("../src/ol/geom/Point").default> */ (new ol.Feature({
  type: 'geoMarker',geometry: new ol.geom.Point(routeCoords[0]),}));
var startMarker = new ol.Feature({
  type: 'icon',});
var endMarker = new ol.Feature({
  type: 'icon',geometry: new ol.geom.Point(routeCoords[routeLength - 1]),});

var styles = {
  'line': new ol.style.Style({
    stroke: new ol.style.Stroke({
      width: 6,color: "blue",}),'route': new ol.style.Style({
    stroke: new ol.style.Stroke({
      width: 6,color: [237,212,0.8],'icon': new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5,1],src: 'https://openlayers.org/en/v4.6.5/examples/data/icon.png','geoMarker': new ol.style.Style({
    image: new ol.style.Circle({ // CircleStyle({
      radius: 7,fill: new ol.style.Fill({
        color: 'black'
      }),stroke: new ol.style.Stroke({
        color: 'white',width: 2,};

var animating = false;
var speed,now;
var speedInput = document.getElementById('speed');
var startButton = document.getElementById('start-animation');

var vectorLayer = new ol.layer.Vector({ // VectorLayer({
  source: new ol.source.Vector({ // VectorSource({
    features: [ /* routeFeature,*/ geoMarker,style: function(feature) {
    // hide geoMarker if animation is active
    if (animating && feature.get('type') === 'geoMarker') {
      return null;
    }
    return styles[feature.get('type')];
  },});

var key = 'otwSpfI7kCJve6AMTcr0';
var attributions =
  '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
  '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';

var center = [-5639523.95,-3501274.52];
var map = new ol.Map({
  target: document.getElementById('map'),view: new ol.View({
    center: center,zoom: 10,minZoom: 2,maxZoom: 19,layers: [
    new ol.layer.Tile({ // TileLayer({
      source: new ol.source.XYZ({
        attributions: attributions,url: 'https://api.maptiler.com/maps/hybrid/{z}/{x}/{y}.jpg?key=' + key,tileSize: 512,vectorLayer
  ],});

var moveFeature = function(event) {
  var vectorContext = ol.render.getVectorContext(event);
  var frameState = event.frameState;

  if (animating) {
    var elapsedTime = frameState.time - now;
    // here the trick to increase speed is to jump some indexes
    // on lineString coordinates
    var index = Math.round((speed * elapsedTime) / 1000);

    if (index >= routeLength) {
      stopAnimation(true);
      return;
    }

    var currentPoint = new ol.geom.Point(routeCoords[index]);
    coords = routeCoords.slice(index);
    lineFeature.getGeometry().setCoordinates(coords);
    var feature = new ol.Feature(currentPoint);
    vectorContext.drawFeature(feature,styles.geoMarker);
  }
  // tell OpenLayers to continue the postrender animation
  map.render();
};

function startAnimation() {
  if (animating) {
    stopAnimation(false);
  } else {
    animating = true;
    now = new Date().getTime();
    speed = speedInput.value;
    startButton.textContent = 'Cancel Animation';
    // hide geoMarker
    geoMarker.setStyle(null);
    // just in case you pan somewhere else
    map.getView().setCenter(center);
    vectorLayer.on('postrender',moveFeature);
    map.render();
  }
}

/**
 * @param {boolean} ended end of animation.
 */
function stopAnimation(ended) {
  animating = false;
  startButton.textContent = 'Start Animation';

  // if animation cancelled set the marker at the beginning
  var coord = ended ? routeCoords[routeLength - 1] : routeCoords[0];
  var geometry = geoMarker.getGeometry();
  geometry.setCoordinates(coord);
  //remove listener
  vectorLayer.un('postrender',moveFeature);
}

startButton.addEventListener('click',startAnimation,false);
html,body {
  height: 100%;
  width: 100%;
  padding: 0px;
  margin: 0px;
}

.map {
  height: 90%;
  width: 100%;
}
<link rel="stylesheet" href="https://openlayers.org/en/v6.4.3/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/v6.4.3/build/ol.js" type="text/javascript"></script>
<div id="map" class="map"></div>
<label for="speed">
      speed:&nbsp;
      <input id="speed" type="range" min="10" max="999" step="10" value="60">
    </label>
<button id="start-animation">Start Animation</button>

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