POINT TO PIXEL

[Ace Suares]

On Wednesday 08 June 2005 4:23, G Casey wrote:
> Does anyone have a good way to convert point in meters to pixel I am
> trying to compute this for the ability to zoom to a point without a
> click.
>
> the click2map (php mapscript) function (below) works  however i need
> to solve for click_x and click_y for a large extent with a known x_map
> and y_map. I have tried and seem to be getting very strange numbers.
>
> Why can I not just solve for click_x with a known x_map ????

My 'map2click' function seems to work...
you feed it a mapObject and a rectObj, the latter being the bounds of the 
shape you are looking for.

The function calculates the center of the rectangle, and return the pixel 
value.

I use it in http://www.la21.nl/resultaten2005 and it seems to do what it 
must do. It makes sure the selected shape will be centered in the small 
'zoom_map'.

// If there are any doubts: I wrote this and it's licensed under the GPL.
function map2click ( $map, $bounds ) {
	$bounds_average_x = ( $bounds->maxx + $bounds->minx ) / 2;
	$bounds_average_y = ( $bounds->miny + $bounds->maxy ) / 2;
	$x_pct = ( ( $bounds_average_x - $map->extent->minx ) / 
		( $map->extent->maxx - $map->extent->minx ) );
	$y_pct = ( ( $bounds_average_y - $map->extent->miny ) /
		( $map->extent->maxy - $map->extent->miny ) );
	$x_map = intval( $map->width * $x_pct );
	$y_map = intval( $map->height * (1 - $y_pct) );
	return array( $x_map, $y_map );
}
// take care about wrapping caused by mailer.


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