MapScript (centering a dynamic point layer)

[Jerod Clabaugh]

Hi:

I am just working my into the PHP/Mpascript world so bear with me.

I am working to show a list of information about a biological
specimen, displaying the locality of the specimen as a point on a
small map.

I can generate such a small map on-the fly by generating a dynamic
point layer pulling UTM coordinates from PostgreSQL/PostGIS db (with
dummy point layer in map file). No problems so far.

My problem is that some species aren't showing up on these maps b/c
they are not in the 'frame' (further south or north of the area of
the map being drawn).  I need to readjust the map to center on the
point being drawn.

I know that this likely requires adjusting the extents and using the
zoompoint method, but other than that I'm lost.

[Specs: Mapserver 4.2.2, PHP 4.3.7 CGI, Apache2, PostgreSQL 7.4.2
with PostGIS 0.81; all functional.]

I have looked online and at the mapscript wiki but all the examples I
find are trying to capture a user's click on a ma and my attempts to
modify that code have failed.  Any help you can give me is much
appreciated.

Cheers,

Jerod Clabaugh

=-=-=PHP CODE=-=-=

        //load Mapscript
        dl('php_mapscript.so');

        // generate and execute the query
        $connection = pg_connect("user=xxxx dbname=xxxx host=localhost");
        $query = "SELECT data_specimen.easting,
data_specimen.northing from data_specimen WHERE
                data_specimen.specimen_id = '$dcid'";
        $result = pg_exec($connection, $query);


        // get the number of rows in the resultset
        $rows = pg_numrows($result);

        // MapObj and ImageObj settings
        $map_path="/Library/Apache2/htdocs/demo1.map";
        $map = ms_newMapObj($map_path);
        $img = $map->draw();

        //get dummy point layer
        $layer = $map->getLayerByName("species");

        ///turn dummy point layer status to ON
        $layer->set('status', MS_ON);

                //loop through resultset, generating the points
        for ($i=0; $i<$rows; ++$i) {
        $row = pg_fetch_row($result, $i);
        $pt = ms_newPointObj();
        $pt->setXY($row[0],$row[1]);
        $pt->draw($map, $layer, $img, 0, "TEST");
        }

        //create map image
         $img_url=$img->saveWebImage(MS_PNG,1,1,0);

        // close database connection
        pg_close($connection);

=-=-=HTML CODE =-=-=

<img src="<?php echo $img_url?>" border="1">


=-=-=MAP FILE DUMMY POINT LAYER=-=-=
LAYER
  NAME species
   TYPE POINT
   STATUS OFF
   CLASS
   COLOR 255 255 0
   OUTLINECOLOR 0 0 0
   SYMBOL 'triangle'
   SIZE 8
  END
END