[mapserver-users] I have a question about the GMapPix2Geo function (listedbelow).

[Guillaume SUEUR]

Can't it be a problem with the equator ? I mean, the function needs to 
know if Y are positives or negatives so if you ask for an extent which 
includes the equator aree, how can it deals with to kinds of Y ?

Guillaume

Yewondwossen Assefa wrote:
> Do you have any values for which the function fails ?
> 
> PS : this function has been used in the GMap demo for some time now. I do not think that there is a problem with it but ...
> 
> Later
> 
> Debbie Pagurek wrote:
> 
> 
>>I have a question about the GMapPix2Geo function (listed below).
>>I have a map of the world showing in lat long.  The below function only seems to work if I am zoomed IN really far and it doesn't work if I am at the full extent of the map (minx=-180, maxx=180, miny=-90, maxy=90)
>>
>>Can anyone comment on this?  I wanted to build a mouseover function that will show the coordinates of the mouse position in the windows status bar.
>>
>>Thanks,
>>D. Pagurek
>>
>>/************************************************************************/
>>/*function GMapPix2Geo($nPixPos, $dfPixMin, $dfPixMax, $dfGeoMin,dfGeoMax, $nInversePix)                              */
>>/*      Utility function to convert a pixel position to geocoded            position.                                                       */
>>/*                                                                      */
>>/*       The parameter $nInversePix could be set to 1 for Y pixel coordinates where the UL > LR. Else set to 0.                   */
>>/************************************************************************/
>>function GMapPix2Geo($nPixPos, $dfPixMin, $dfPixMax, $dfGeoMin, $dfGeoMax, $nInversePix)
>>{
>>   // $nPixPos : pixel position (X or Y)
>>   // $dfPixMin, $dfPixMax : Pixel minimum and maximum (X or Y) of your map on the screen (should be 0 to xxx)
>>  //  $dfGeoMin, $dfGeoMax : Geographic coordinate min max (X or Y) of your map on the screen
>>
>>    $dfWidthGeo = $dfGeoMax - $dfGeoMin;
>>    $dfWidthPix = $dfPixMax - $dfPixMin;
>>
>>
>>    $dfPixToGeo = $dfWidthGeo / $dfWidthPix;
>>
>>    if (!$nInversePix)
>>        $dfDeltaPix = $nPixPos - $dfPixMin;
>>    else
>>        $dfDeltaPix = $dfPixMax - $nPixPos;
>>
>>    $dfDeltaGeo = $dfDeltaPix * $dfPixToGeo;
>>
>>    $dfPosGeo = $dfGeoMin + $dfDeltaGeo;
>>
>>    return ($dfPosGeo);
>>}
> 
> 
> --
> ----------------------------------------------------------------
> Assefa Yewondwossen
> Software Analyst
> 
> Email: assefa at dmsolutions.ca
> http://www.dmsolutions.ca/
> 
> Phone: (613) 565-5056 (ext 14)
> Fax:   (613) 565-0925
> ----------------------------------------------------------------
> 
> 
> 
> 

-- 
---------------------------
Guillaume SUEUR
Ingénieur développement SIG
GEOSIGNAL
25bis Avenue Marcel Dassault
31505 TOULOUSE CEDEX 5
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