抱歉打扰你们，但我坚持了他半天的时间。
我想使用LineString对象在OpenLayers中绘制折线，因此我已从文档中复制了示例。它运行正常，但我在屏幕上看不到该行
代码看起来像这样
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title></title>
<script type="text/javascript" src="http://openlayers.org/api/OpenLayers.js"></script>
<script src="http://www.openstreetmap.org/openlayers/OpenStreetMap.js"></script>
<script src='http://maps.google.com/maps?file=api&v=2&key=ABQIAAAAjpkAC9ePGem0lIq5XcMiuhR_wWLPFku8Ix9i2SXYRVK3e45q1BQUd_beF8dtzKET_EteAjPdGDwqpQ'></script>
<script type="text/javascript">
var map;
var lineLayer ;
var points;
var style;
var polygonFeature
function test()
{
lineLayer = new OpenLayers.Layer.Vector("Line Layer");
style = { strokeColor: '#0000ff',
strokeOpacity: 1,
strokeWidth: 10
};
map.addLayer(lineLayer);
points = new Array();
points[0] =new OpenLayers.LonLat(-2.460181,27.333984 ).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());;
points[1] = new OpenLayers.LonLat(-3.864255,-22.5 ).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());;
var linear_ring = new OpenLayers.Geometry.LinearRing(points);
polygonFeature = new OpenLayers.Feature.Vector(
new OpenLayers.Geometry.Polygon([linear_ring]), null, style);
lineLayer.addFeatures([polygonFeature]);
alert("1");
}
function initialize()
{
map = new OpenLayers.Map ("map_canvas", {
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);
var lonLat = new OpenLayers.LonLat(0, 0).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());
map.zoomTo(3);
map.setCenter(lonLat, 19);
test();
}
</script>
</head>
<body onload="initialize()" >
<div id="map_canvas" style="width: 828px; height: 698px"></div>
</body>
</html>
我确定我在创建地图时缺少某些参数，但我真的不知道是哪一个。
最佳答案
您会在这一行中忘记“ s”字符：
lineLayer.addFeatures([lineFeature]);
函数'addFeature'不存在：OpenLayers.Layer.Vector.addFeatures
要查看该功能，请按住键盘上的Shift键并尝试绘制一个框
编辑：好的，现在我知道您想要什么了。
您需要为数据库中的每个点创建一个OpenLayers.Point对象。一种解决方案是使用和Ajax调用您自己的PHP函数来检索它们。 PHP文件包含获取它们的代码。我建议以JSON格式（可能是字符串）返回它们。使用JQuery框架：
$.ajax({
url: 'your_php_file.php',
dataType: JSON // for example, you can use 'string' type too
success: function(coordinates){
}
});
现在，您的数据库中有了很多坐标。现在该绘制多边形了。以下链接可能有用
OpenLayers - how do I draw a Polygon from existing lonLat points?
希望对您有帮助。祝您满意！
编辑2：
linear_ring是属于OpenLayers.Geometry.LinearRing类的对象。 constructor需要一个OpenLayers.Geometry.Points数组，而您给它的是OpenLayers.LonLat数组。
您需要在每次创建点后添加以下行来修改此内容（根据您自己的代码修改索引）：
points[0] = new OpenLayers.Geometry.Point(points[0].lon,points[0].lat);
因此，您的测试功能如下所示：
function test(){
lineLayer = new OpenLayers.Layer.Vector("Line Layer");
style = { strokeColor: '#0000ff',
strokeOpacity: 1,
strokeWidth: 10
};
points = new Array();
points[0] =new OpenLayers.LonLat(-2.460181,27.333984 ).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());;
points[0] = new OpenLayers.Geometry.Point(points[0].lon,points[0].lat);
points[1] = new OpenLayers.LonLat(-3.864255,-22.5 ).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());;
points[1] = new OpenLayers.Geometry.Point(points[1].lon,points[1].lat);
var linear_ring = new OpenLayers.Geometry.LinearRing(points);
polygonFeature = new OpenLayers.Feature.Vector(
new OpenLayers.Geometry.Polygon([linear_ring]), null, style);
lineLayer.addFeatures([polygonFeature]);
map.addLayer(lineLayer);
}
结果是这样的：Image result
关于javascript - 打开图层LineString不起作用，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/5032699/