[mapserver-users] getExtent / setExtent problems

[Daniel Morissette]

Puneet Kishor wrote:
> 
> I am trying to getExtent of a shape that I have retrieved using its index.
> 
>         $shapeExtObj = $shapeFileObj->getExtent($row_id);
>         $minx = $shapeExtObj->minx;
>         $miny = $shapeExtObj->miny;
>         $maxx = $shapeExtObj->maxx;
>         $maxy = $shapeExtObj->maxy;
> 
>         $border = 1000;
> 
>         $minx = $minx - $border;
>         $miny = $miny - $border;
>         $maxx = $maxx + $border;
>         $maxy = $maxy + $border;
> 
>         $mapObj->setExtent( $minx, $miny, $maxx, $maxy);
> 
> except, the resulting map extent of the map is slightly off-center... if my
> logic above is correct, the chosen shape should be exactly centered on the
> resulting image, with a border of 1000 feet (map coords are in feet) around
> it. Except, the chosen shape appears in the bottom left corner of the image.
> 
> What is the obviously obvious that I am doing wrong?
> 

It's so obvious that I can't see it either! :)

The PHP mapObj.setExtent() method calls msAdjustExtent() internally and
this will adjust the extents you've specified to fit the output image's
width/height ratio.  msAdjustExtent() should keep the extent you've
specified centered on the image, so I don't understand why that doesn't
work for you.

Perhaps you could try to print the values of $mapObj->extent->minx, etc.
before and after the call to SetExtent and that may give some clues on
what the problem is.

> --
> 
> Oh... nudderthing... I am unable to query the dbf files on my *nix box using
> PHP... says dbase_open() etc. are not copacetic. Could that be because the
> PHP install does not have a dbase module compiled in it? I thought that was
> automatically included. What gives here?
> 

No, dbase support is not included by default in PHP.  On Unix you have
to specify --with-dbase when you configure PHP, and on Windows I think
PHP comes with a PHP_DBASE.DLL that you can load using dl().

-- 
------------------------------------------------------------
 Daniel Morissette               morissette at dmsolutions.ca
 DM Solutions Group              http://www.dmsolutions.ca/
------------------------------------------------------------
  Don't put for tomorrow what you can do today, because if 
      you enjoy it today you can do it again tomorrow.