Zooming and Centering Question: Second Run

[Bob Bruce]

On Sun, 24 Apr 2005 23:01:06 -0400, Giridhar Manepalli <gmanepal at GMAIL.COM>
wrote:

>Hello All,
>I am using php mapscript. I cannot get the image to center when I
>click on the image and with some zooming factor.
>
>I am using image coordinates (not geographical coordinates) for zooming.
>
>1.)Can anyone think of possible reasons? I can provide with any
>necessary information.
>
>2.) Also, how do I center the image based on my click without zooming?
>
>3.) Finally, does the extent of the map automatically changed by
>mapscript, when I zoom?
>
>I hope, i can get this resolved!
>
>Thanks,
>Giridhar
>
>
>Hello All,
>I tried to center the image based on a click when I zoom using
>php/mapscript. For some reason, I am failing to do so.
>
>Is it because, the lat long I calculated using javascript is wrong?
>but it almost matches with 'ArcIMS Author'.?
>
>Can anyone write the snippet of php/mapscript code that will zoom to
>the point i click, provided I have the lat-long of the click? Also,
>can you explain what the new extent will be?
>
>Thanks,
>Giridhar

Giridhar:

here's a code snippet that I use for zooming in:

} elseif($_POST['mode'] == "ZoomInAtPT" ) {
         $new_point = ms_newPointObj();

$new_point->setXY(floatval($_POST['mapimage_x']),floatval($_POST['mapimage_y']));
         $map->zoomscale($mapscale/$mapScaleZoomFactor, $new_point,
$map->width, $map->width,

$mapRect, $maxmapRect);

the post variables are the image coordinates of the mouse click. You should
have those anyway and it shouldn't be necessary to convert them to Lat/Long.
I get $mapscale using the statement:

     $mapscale = isset($_POST['mapscale']) ? floatval($_POST['mapscale']) :
$maxscale;

and I set the post value of mapscale using the following statements:

// now set up some web page display values
     $currentscale = round($map->scale);
     $char_scale = number_format($currentscale);

and this is my code to re-center the draw:

     } elseif($_POST['mode'] == "recenter" ) {
         $new_point = ms_newPointObj();

$new_point->setXY(floatval($_POST['mapimage_x']),floatval($_POST['mapimage_y']));
         $map->zoomscale($mapscale, $new_point, $map->width, $map->width,
$mapRect, $maxmapRect);

(notice that I don't change the scale in this call)
and this is the code to set the last two values of the above call:

     if(isset($_POST['mapextent'])) {
         $extents = explode("+",$_POST['mapextent']);
         $mapRect = ms_newRectObj();

$mapRect->setextent(floatval($extents[0]),floatval($extents[1]),floatval($extents[2]),floatval($extents[3]));
         $maxmapextent = $_POST['maxmapextent']; // save this for the hidden
form variable
     } else {  // set this for the hidden form variable using the values
from the map file
         $maxmapextent = $map->extent->minx . "+" . $map->extent->miny . "+"
. $map->extent->maxx . "+" . $map->extent->maxy;
     }


     if(isset($_POST['maxmapextent'])) {
        $maxextents = explode("+",$_POST['maxmapextent']);
        $maxmapRect = ms_newRectObj();

$maxmapRect->setextent(floatval($maxextents[0]),floatval($maxextents[1]),floatval($maxextents[2]),floatval($maxextents[3]));
     }

hopefully there is enough here to get you going.

     Bob Bruce