Zooming and Centering Question: Second Run

[Giridhar Manepalli]

Thanks Bob! It really helped. Can you tell me how zoomscale and
zoompoint are different from a map point of view.

Giridhar

On 4/25/05, Bob Bruce <covariance at shaw.ca> wrote:
> 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
>