Strati aperti La lunestro non funziona

StackOverflow https://stackoverflow.com/questions/5032699

Domanda

Scusa per disturbarti ragazzi, ma sono bloccato con il suo problema per mezza giornata.

Voglio disegnare la linea Poly in OpenLayers usando la lineeString oggetto, quindi ho copiato l'esempio dalla documentazione.Funziona bene ma non riesco a vedere la linea sullo schermo

Codice Sembra questo 

      <!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&amp;v=2&amp;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>
.

Sono sicuro che mi manca un parametro nella creazione della mappa o qualcosa del genere, ma non riesco davvero a capire quale.

È stato utile?

Soluzione

You forget 's' character in this line:

lineLayer.addFeatures([lineFeature]);

Function 'addFeature' doesn't exist: OpenLayers.Layer.Vector.addFeatures

To see the feature, hold Shift key on your keyboard and try to draw a box

EDIT: Ok, now I know how did you want.

You need to create one OpenLayers.Point object for each point you have in your DB. One solution is to use and Ajax call to your own PHP function to retrieve them. The PHP file includes code to get them. I recommend to return them in JSON format (pherhaps an string). Using JQuery framework:

$.ajax({
   url: 'your_php_file.php',
   dataType: JSON // for example, you can use 'string' type too
   success: function(coordinates){

   }
});

Now you have a lot of coordinates from your DB. It's time to draw your polygon. Following link can be useful

OpenLayers - how do I draw a Polygon from existing lonLat points?

I hope it helps you. Happy codding!

EDIT2:

linear_ring is an object belongs to OpenLayers.Geometry.LinearRing class. The constructor needs an array of OpenLayers.Geometry.Points and you was giving it OpenLayers.LonLat array.

You need to modify this adding this line after each point creation (modifying the index according to you own code):

points[0] = new OpenLayers.Geometry.Point(points[0].lon,points[0].lat);

So your test function looks like this:

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);

 }

The result is this: Image result

Altri suggerimenti

Yes, OpenLayers can programatically draw lines. Its even fast enough to draw new lines multiple times a second so you can show live data or animations. Anyway, you have a lot of stuff going on in your code. Perhaps your style is messed up and drawing invisible lines, or your data points are getting transformed incorrectly and the line is off the map. Anyway, I suggest this simple test.

Create a map, and add a vector layer. hang on to the vector layer in a global var called layerVec. Then, run this code.

var CreateLine = function()
{

  var pList = new Array();
  for(var i=0; i<200; i++)
  {
    var p = new OpenLayers.Geometry.Point();
    p.x = i;
    p.y = i;
    pList.push(p);
  }
  var g = new OpenLayers.Geometry.LineString(pList);
  var f = new OpenLayers.Feature.Vector(g,null,null);
  layerVec.addFeatures(f);
};

Dont worry about coordinates yet, this should be a line in the middle of the map. It may be tiny, or huge depending on your projection, so zoom in.

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