Re: [Gwt-openlayers-devl] Measure

[Edwin C. <com...@gm...>]

Hi Michel,

At first sight this looks like formatOutput, but an important difference is
that handleMeasurements is not a function on the Measure control and you
have to do all the work for the output.

First up: In my opinion, the handleMeasurement function should not return
output (it also doesn't in the OpenLayers examples), because it's a
callback. You never know when people stop measuring and therefore when
measure will fire.

Looking at it my first impression is that you would want to make it easy to
set a handler for the onMeasure and onMeasurePartial events. The
SelectFeature control has something like this, using interfaces defined on
the class. For Measure this would be something like:

public interface MeasureListener(){
  void onMeasure(String measurements); // assuming that measurements are
passed as a String, which is a guess
}

The Measure control could have a setMeasureListener(MeasureListener
listener) method, that registers the listener. To see how that works, look
at the setFeatureControl

A user would then do:

Measure m = new Measure( args here );//instantiate control
m.setMeasureListener(new MeasureListener(){
  void onMeasure(String Measurements){
     // get place to write output the GWT way
     // do formatting and write to output place (e.g. a DOM element)
     // OR
     // call some other function to write output, that can also be called by
onMeasurePartially
  }
})

Greetings and I hope this is useful to you,
Edwin

2009/8/27 Michel vitor <mic...@gm...>

> Dear Edwin,
>
> I would like to further your explanation, my problem and I implemented the
> following function Measure of OpenLayers so that now I want to display the
> screen output in any format (ft, m etc.). And this is possible in java
> ecript.
> I'm trying to recreate in the java gwt-openlayers the following function
>
>             var control;
>             control = new
> OpenLayers.Control.Measure(OpenLayers.Handler.Path);
>             control.events.on({"measure":
> handleMeasurements,"measurepartial": handleMeasurements});
>             map.addControl(control);
>             map.setCenter(new OpenLayers.LonLat(0, 0), 3);
>         }
>
>         function handleMeasurements(x) {//this
>             var geometry = x.geometry;
>             var units = x.units;
>             var order = x.order;
>             var measure = x.measure;
>             var element = document.getElementById('output');
>             var out = "";
>             if(order == 1) {
>                 out += "measure: " + measure.toFixed(3) + " " + units;
>             } else {
>                 out += "measure: " + measure.toFixed(3) + " " + units +
> "<sup>2</" + "sup>";
>             }
>             return out;//return this value for component
>         }
>
> that looks a bit like formatOutput, but want to get the value and display
> in a component can you give me a help and my doubts as to the role that this
> prominent.
> --
> Michel Vitor A Rodrigues
> 6° Periodo de Computação
> Grupo Intec,Viçosa MG
>
>