如何绘制动画开放层线串路径？答案

【问题标题】：How to drawing animated openlayers linestring path?如何绘制动画开放层线串路径？
【发布时间】：2015-11-04 19:01:07
【问题描述】：

我使用 openlaers 地图 api。我想在我的路径中显示动画路线，例如http://jerusalem.com/map#!/tour/the_way_of_the_cross/location/abu_jaafar。怎么做？谢谢。

这是我的 Java Script，我从 XML 文件中获取数据。

<script type="text/javascript">                          
                var zoom=13

        var map; //complex object of type OpenLayers.Map

        function init() {
            map = new OpenLayers.Map ("map", {
                controls:[
                    new OpenLayers.Control.Navigation(),
                    new OpenLayers.Control.PanZoomBar(),
                    new OpenLayers.Control.LayerSwitcher(),
                    new OpenLayers.Control.Attribution()],
                maxExtent: new OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34),
                maxResolution: 156543.0399,
                numZoomLevels: 19,
                units: 'm',
                projection: new OpenLayers.Projection("EPSG:900913"),
                displayProjection: new OpenLayers.Projection("EPSG:4326")
            } );

            // Define the map layer
            // Here we use a predefined layer that will be kept up to date with URL changes
            layerMapnik = new OpenLayers.Layer.OSM.Mapnik("Mapnik");
            map.addLayer(layerMapnik);
            layerCycleMap = new OpenLayers.Layer.OSM.CycleMap("CycleMap");
            map.addLayer(layerCycleMap);
            layerMarkers = new OpenLayers.Layer.Markers("Markers");
            map.addLayer(layerMarkers);

        //   Add the Layer with the GPX Track
            var lgpx = new OpenLayers.Layer.Vector("Descrizione del layer", {
                strategies: [new OpenLayers.Strategy.Fixed()],
                protocol: new OpenLayers.Protocol.HTTP({
                    url: "c.php",
                    format: new OpenLayers.Format.GPX()
                }),
                style: {strokeColor: "blue", strokeWidth: 5, strokeOpacity: 0.5},

            projection: new OpenLayers.Projection("EPSG:4326")

            });



            map.addLayer(lgpx);

        }

    </script>

【问题讨论】：

标签： javascript xml openlayers gpx

【解决方案1】：

在Drawing animated openlayers linestring path 尝试答案。好像挺像的。

这是答案的重要部分：

function drawAnimatedLine(startPt, endPt, style, steps, time, fn) {
    var directionX = (endPt.x - startPt.x) / steps;
    var directionY = (endPt.y - startPt.y) / steps;
    var i = 0;
    var prevLayer;
    var ivlDraw = setInterval(function () {
        if (i > steps) {
            clearInterval(ivlDraw);
            if (fn) fn();
            return;
        }
        var newEndPt = new OpenLayers.Geometry.Point(startPt.x + i * directionX, startPt.y + i * directionY);
        var line = new OpenLayers.Geometry.LineString([startPt, newEndPt]);
        var fea = new OpenLayers.Feature.Vector(line, {}, style);
        var vec = new OpenLayers.Layer.Vector();
        vec.addFeatures([fea]);
        map.addLayer(vec);
        if(prevLayer) map.removeLayer(prevLayer);
        prevLayer = vec;
        i++;
    }, time / steps);
}

time 参数指定您希望动画持续多长时间（以毫秒为单位），steps 指定您想要多少步将动画分为。 fn 是一个将被执行的回调动画完成后。

【讨论】：