Radius around a point on the map

sauer · Post by **sauer** » Thu Jan 15, 2015 8:44 am

Hello,

is it possible to draw a radius around a specific point on the map,
for example with a CustomLayer or GeometryLayer?
I want to have a result like in the picture.

Bernd Welter · Post by **Bernd Welter** » Thu Jan 15, 2015 12:27 pm

Hello Sauer,

I already spoke to some experts from the core development and forwarded your request to some more developers. The answer probably depends on the interface you want to use. I assume you'd like to have a generic approach of

How to display a circle or circle area of R meters around the center (x,y)?

Let's see:

native xMap: the pure xMap api does not support a straight object or parameter setting that supports circles. From my perspective you have to compute a sufficient number of polygonpoints in Mercator coordinates. These points have to be provided within a standard Geometry layer or a Custom layer. Attention: if you use a coordinate format besides Mercator the shapes won't be "round". This is why you should compute in Mercator and - if necessary - transform the points into the coord format you want to use in the request. I added a spontaneous xsample here:

XCircle.zip

c# codesample

(175.43 KiB) Downloaded 748 times

This is the result image:

Sample output based on Mercator - circles below streets!
Code: Select all
```
List<PlainPoint> lstPlainPoints = new List<PlainPoint>();
            double arg = Math.PI * 2.0 / n;
            for (int index = 0 ; index<n ; index++)
                lstPlainPoints.Add(new PlainPoint(){
                    x = x + r * Math.Cos(arg * index),
                    y = y + r * Math.Sin(arg*index)});
```
Any other framework like Ajaxmaps, xServer.NET, ...: it is always an option to provide the same approach as with native xmap. But this is where I request the experts to give a dedicated answer.

Please be patient - I expect them to answer within the following days,

Best regards Bernd

Bernd Welter · Post by **Bernd Welter** » Thu Jan 15, 2015 12:33 pm

and a quick update: contains GeometryLayer, too...

: GeometryLayer based circle (filled area)

XCircle.zip: C# sample with geometry layerr; (181.08 KiB) Downloaded 807 times

Bernd Welter · Post by **Bernd Welter** » Thu Jan 15, 2015 1:01 pm

And here is some more info straight from the product management:

PTV recommends to use client side rendering of such objects. This is because our core efforts are spent on logistics content and expertise such as

TruckAttributes
TrafficIncidents
Historical information for dynamic routing
...

Dealing with circles, areas and so on is therefore in the scope of the client. And by the way:
Client side rendering enables you to avoid consecutive xMap requests for displaying/supress layers.

Best regards,
Bernd

AndreasJunghans · Post by **AndreasJunghans** » Thu Jan 15, 2015 3:53 pm

Here's a complete AjaxMaps tutorial example:

Code: Select all

<html>
  <head>
    <!--[if IE]><script type="text/javascript" src="webcomponent/script/excanvas.js"></script><![endif]-->
    <script type="text/javascript" src="webcomponent/script/qooxdoo/script/qx-transport.js"></script>
    <script type="text/javascript" src=".qxrpc"></script>
    <script type="text/javascript" src="webcomponent/script/map.js"></script>

    <script type="text/javascript">
      function init() {
        var container =
          document.getElementById("mapContainer");
        var map =
          new com.ptvag.webcomponent.map.Map(container);
        window.onresize = function() {
          map.updateSize();
        };

        map.setCenter({x:4303250, y:5486500});
        map.setZoom(10);

        var vectorLayer = map.getLayer("vector");

        // create circle
        var circle = new com.ptvag.webcomponent.map.vector.MeterCircle();
        circle.setX(4303250);
        circle.setY(5486500);
        circle.setColor("rgb(0,0,255)");
        circle.setMeterSize(10000);  // 10 km diameter
        
        // customize drawing (line instead of fill)
        CoordUtil = com.ptvag.webcomponent.map.CoordUtil;
        circle.draw = function(container, topLevelContainer, ctx,
                               mapLeft, mapTop, mapZoom) {
            var suPoint = {x:circle.getX(), y:circle.getY()};
            var pixCoords = CoordUtil.smartUnit2Pixel(suPoint, mapZoom);
            var realX = pixCoords.x - mapLeft + circle.getFlexX();
            var realY = mapTop - pixCoords.y + circle.getFlexY();
            var radius = circle.calculatePixelRadius(mapLeft, mapTop, mapZoom);
            ctx.strokeStyle = circle.getColor();
            ctx.lineWidth = 4;
            ctx.beginPath();
            ctx.moveTo(realX + radius, realY);
            ctx.arc(realX, realY, radius, 0, 2*Math.PI, false);
            ctx.stroke();
        };
        
        // make circle visible
        vectorLayer.addElement(circle);
      }

      qxp.dev.log.Logger.ROOT_LOGGER.setMinLevel(qxp.dev.log.Logger.LEVEL_INFO);
      qxp.dev.log.Logger.getClassLogger(qxp.core.Init).setMinLevel(qxp.dev.log.Logger.LEVEL_ERROR);
    </script>
  </head>

  <body onload="init()">
    <div id="mapContainer"
      style="width:100%;height:100%">
    </div>
  </body>
</html>

Regards,

Andreas Junghans

Bernd Welter · Post by **Bernd Welter** » Fri Jan 16, 2015 1:24 pm

Hello again,

with xServer.NET you can use a ShapeLayer and a MapPolyline object. Computation of circle points coordinates is similar to the native approach.

Best regards Bernd

Joost · Post by **Joost** » Fri Jan 16, 2015 1:32 pm

With the xServer .Net control you can take another approach and use the System.Windows.Shapes.Ellipse class instead of the MapPolyline. For a working example you can check the sample code on github: https://github.com/ptv-logistics/xservernet-bin and look at the Circles Use case.

PTV Group - Logistics Forum

Radius around a point on the map

Radius around a point on the map

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