[OpenLayers-Users] OpenLayers.Control.ScaleLine : Add a coefficient

[Andreas Hocevar]

I think your map and/or layer configuration must be wrong. Usually this kind of problem appears when your map units don't match the projection's distance units.

I'd say there is no need to introduce a coefficient. Check your projection, and configure the map or base layer with the according units.

Regards,
Andreas.

On Mar 24, 2011, at 19:03 , Micka wrote:

> Hey,
> 
> 
> Well, I've gotten the source code of this module, so now i'm trying to add a coeficient K .
> 
> 
> The goal is to give the possibility to adjust the scaleline.
> 
> For that, I thought that we can add two function on this module :
> 
> 	• float calculateTheCoefficient(float length, int pixels );      // length in meter , pixels number of pixels that the length represent
> 	• void setTheCoefficient ( float k );
> 
> The first function will calculate the coefficient with the actual resolution and the length/pixels .
> the second function will save the coefficient for the update function() .
> 
> 
> What do you think ? 
> 
> 
> My problem, is that i don't know how to do code the first function .......
> 
> 
> 
> 
> 
> 
>    update: function() {
>         var res = this.map.getResolution();
>         res*= k;
>         if (!res) {
>             return;
>         }
> 
>         // convert maxWidth to map units
>             var maxSizeData = this.maxWidth * res; 
>     
>         // decide whether to use large or small scale units     
>             var topUnits;
>             if(maxSizeData > 0.1) {
>               topUnits = this.topOutUnits;
>             } else {
>               topUnits = this.topInUnits;
>             }
>     
>         // and to map units units
>             var curMapUnits = this.map.units;
>             var inches = OpenLayers.INCHES_PER_UNIT;
>             var topMax = maxSizeData * inches[curMapUnits] / inches[topUnits];
>     
>             // now trim this down to useful block length
>             var topRounded = this.getBarLen(topMax);
> 
>             // and back to display units
>             topMax = topRounded / inches[curMapUnits] * inches[topUnits];
> 
>             // and to pixel units
>             var topPx = topMax / res;
>            
>             // now set the pixel widths
>             this.eTop.style.width = Math.round(topPx) + "px";
>            
>             // and the values inside them
>             this.eTop.innerHTML = topRounded + " " + topUnits;    
>         },
>     
>         CLASS_NAME: "OpenLayers.Control.ScaleLine"
>     }
> 
> 
> 
> 
> 
> On Thu, Mar 24, 2011 at 3:03 PM, mickal <mickamusset at gmail.com> wrote:
> Hi,
> 
> The scale that the module displayed to me is not right, I mean :
> 
> 50 pixel => 1000km
> but in reality :
> 50 pixel => 100 m
> 
> is it possible to add a coefficient to this module ?  to adjust the scale
> that it displayed.
> 
> 
> Because otherwise I have to change my map, and this process is very long.
> 
> 
> thx,
> 
> --
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/OpenLayers-Control-ScaleLine-Add-a-coefficient-tp6204219p6204219.html
> Sent from the OpenLayers Users mailing list archive at Nabble.com.
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-- 
Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.