map coordinates' of a rectangle

[Sandeep Bashyal]

On Thu, 4 Nov 2004 16:20:28 +0200, temiz <temiz at DEPREM.GOV.TR> wrote:

> hello
>
> my trials yield no correct result.
> I have image coordinates of a rectangle (rubber band).
> how can I get map coordinates' of this rectangle in the form of
> minx,miny,maxx,maxy?
>
> kind regards
>
> Ahmet Temiz
>
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I'm assuming that you want the coordinates of the rubberband in geographic
coordinates...
Here's what I do:
(from the wiki)
/**
* converts pixel units into map units
*
* @param int $click_x coordinate X in pixels
* @param int $click_y coordinate Y in pixels
* @param array $current_extent holds the current extent of the map (XMin,
YMin, XMax, YMax)
* @global map object
* @return array  [0]=> X in map units; [1]=> Y in map units
*/
function click2map ($click_x, $click_y, $current_extent) {
global $map;
$x_pct = ($click_x / $map->width);
$y_pct = 1 - ($click_y / $map->height);
$x_map = $current_extent[0] + ( ($current_extent[2] - $current_extent[0])
* $x_pct);
$y_map = $current_extent[1] + ( ($current_extent[3] - $current_extent[1])
* $y_pct);
return array($x_map, $y_map);
}

//convert clicked points into geographic coordinates
$query_rect_min_xy =
click2map($_POST['mapa_x']-$_POST['w'],$_POST['mapa_y'],$current_extent);
$query_rect_max_xy =
click2map($_POST['mapa_x'],$_POST['mapa_y']-$_POST['h'],$current_extent);

where mapa_x and mapa_y are the coordinates of the clicked point; and h
and w are the height and width of the rubberband zoom box.

$query_rect = ms_newRectObj();
$query_rect->setextent($query_rect_min_xy[0],$query_rect_min_xy[1],$query_rect_max_xy[0],$query_rect_max_xy[1]);
..and so on

--
Sandeep Bashyal
--
   National GIS Officer
   Humanitarian Assistance Information System (HAIS)
   United Nations (NEP/01/008)
   UN House, Pulchowk
   G.P.O. Box 107
   Kathmandu, Nepal
   Tel: (+977) 01 5543957
        (+977) 01 5554304
   Cell:(+977) 9841270854
   Fax: (+977) 01 5528059
--------------------------------------------------
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mailto:sandeep at earthmapping.com
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