MouseOver & Coordinates

Thu Mar 10 08:04:05 EST 2005

On Thursday 10 March 2005 13:06, Stefan Schwarzer wrote:
> Thanks Martin for that. The only thing I am not sure about is how 
the  
> javascript variable, which holds the information about the pixel 
size,  
> should be called. How does this variable get into the Javascript  
> functions?
> 
> Thanks for your help - and congratulations to your planiglobe.com 
site.  
> Looks really neat!!
> 
> Stef

If your server delivers the entire interface (page) on every map 
generation, simply set the javascript obj or variable at generation 
time.

With the last projects I send the core map elements generated (map, 
ref, scale, etc) to a hidden iframe which calls a function in the 
parent document onload to parse/copy the new content. 

Part of the document in the iframe could be a good ol' HTML-form
holding the values.

With Perl mapScript one part of the page sent back could look like:

print <<"EOFORM";
<form name="params">
  <input type="hidden" name="csz" value="$m->{cellsize}">
</form>
EOFORM

where $m is the Perl mapScript map object you are working on.

With CGI mapserver you would put a similar form into the template,
but since the cell size is not an available CGI variable - as far as I 
know - you must pass the mapextent.

<form name="params">
  <input type="hidden" name="mext" value="[MAPEXT]">
</form>

The <body> tag of the doc in the iframe could be: 

<body onload="parent.parseIframe();">

and the function in the parent doc could look like:

function parseIframe() {
  var paramsForm= parent.frames[0].document.forms["params"],
  myMap.mapext = paramsForm.elements["mext"].value;
  // or myMap.csz=paramsForm.elements["csz"].value;
}

As I said before, if you use mapextent you calc cell size yourself.

Cheers, Martin

> > On Thursday 10 March 2005 11:07, Stefan Schwarzer wrote:
> >> Hi,
> >>
> >> I would like to display the coordinates in a corner of the map, 
when a
> >> user moves the mouse over it. Is there any Javascript (or Java) 
code
> >> out there that would do this?
> >>
> >> Thanks for any suggestions.
> >>
> >> Stef
> >
> > Stefan,
> >
> > you need to know the pixel size of your map image in map units 
(DD,  
> > meters,..).
> > using MapScript you can pass this value along with every new map  
> > generated
> > as a (hidden) value and set a javascript object or variable to 
this  
> > value.
> > With mapserver CGI you must calculate this value by image size and 
map  
> > extent
> > yourself.
> >
> > Next you define an eventhandler for the mouseover event of your 
map  
> > image,
> > for instance:
> >
> > function MapElmOverHndl(e) {
> >   var imgOrig = theMap.getorig();
> >   var posx = ((e.offsetX * theMap.getcsz())+imgOrig[0]);
> >   var posy = (((400-e.offsetY) * theMap.getcsz())+imgOrig[1]));
> >   Dspl.innerHTML=posx+' '+posy;
> > }
> >
> > 'theMap.getorig()':  returns minx, miny (mapunits) of the current 
image
> > 'theMap.getcsz()': returns the cellsize (pixelsize) in mapunits
> > '400' is the image height in pixels
> > 'Dspl' is a document element like <p>, <td>, <div> or some such.
> >
> > Once you got the handler you add this event handler to your map 
image.
> > If your map image got an id of - say - 'myMap':
> >
> > for DOM-Browsers you type:
> > 
document.getElementById('myMap').addEventListener("mousemove",MapElmOve 
> > rHndl , false)
> >
> > for IE6 you type:
> > document.all['myMap''].attachEvent("onmousemover", 
MapElmOverHndl);
> >
> > A cross browser solution could look similar to:
> > var d= document;
> > if (!d.getElementById && d.all) d.getElementById = new 
Function('id',  
> > 'return d.all[id]');
> >
> > function X_addEventListener(elm, evt, lstnr, useCapture) {
> >   (! elm.addEventListener && d.all)? elm.attachEvent('on'+evt, 
lstnr)  
> > : elm.addEventListener(evt, lstnr, useCapture);
> > }
> >
> > Now you add the listener by:
> > myMapElm= d.getElementById('myMap');
> > X_addEventListener(myMapElm ,"mousemove", MapElmOverHndl, false);
> >
> > Cheers, Martin
> >
> >
> 
>         _______________________________________
> 
>         Stefan Schwarzer
>         GIS & Data Management
> 
>         UNEP/DEWA/GRID-Geneva
>         Chemin des Anemones 11
>         CH - 1219 Chatelaine
>         Switzerland
> 
>         Tel: (+41) 22.917.83.49
>         Fax: (+41) 22.917.80.29
> 
>         Internet: http://geodata.grid.unep.ch/
>         _______________________________________
> 

-- 
 --- Martin Weinelt 
 --- kk+w - digital cartography 
 --- Kiel, Germany
 --- Tel: +49.431.5791165
 --- http://www.planiglobe.com 