[mapguide-users] Zoom to selection

Fri Sep 21 09:09:46 EDT 2007

Thanks Kenneth.

Not sure that I understand that completely, but this is how I have dealt
with it:-

(I needed to generate a list of URLs that will zoom into the relevant
position on the map at a scale based on the size of the object)

* The centroid of the object is calculated
* The size of the object is queried at the feature source
* the hyperlinks are created server-side with a call to a JavaScript
function and the required size of the window is passed as a parameter,
plus the centroid x and y.
* The JavaScript function gets the current map size and scale, and
calculates the required scale
* It then calls the ZoomToView function

Keith

________________________________

From: mapguide-users-bounces at lists.osgeo.org
[mailto:mapguide-users-bounces at lists.osgeo.org] On Behalf Of Kenneth,
GEOGRAF A/S
Sent: 21 September 2007 10:46
To: MapGuide Users Mail List
Subject: Re: [mapguide-users] Zoom to selection

I have remarked that it is a problem that the map position (x, y, scale)
is not avalible on the server.
You must manually pass this information from the viewer to your scripts.

The width of the map should be the maximum width that can display the
bbox. To calculate this width, you must know the browser window width
and height.
Using this, you can calculate the height/width ratios and thus get the
required width. This width will be in coordinate system units.

How you go from width to scale is dependant on your coordinate system.
You might send along the current scale, and use that with the window
info to calculate a new ratio.

Regards, Kenneth, GEOGRAF A/S

Campbell, Keith A skrev: 

	Kenneth,

	I'm trying to do something similar, and I'm puzzled by your
suggestion that the new scale will be the width or height of the box.
surely there must be a conversion between the current width and scale to
get the new scale? I'm assuming that the zoom-to will be accomplished
with the Viewer API ZoomToView method which requires a scale.

	What makes this difficult is that he Web API does not seem to
have a method for getting the current view width (map units), as opposed
to display width (pixels).

	Keith

________________________________

	From: mapguide-users-bounces at lists.osgeo.org
[mailto:mapguide-users-bounces at lists.osgeo.org] On Behalf Of Kenneth,
GEOGRAF A/S
	Sent: 21 September 2007 09:09
	To: MapGuide Users Mail List
	Subject: Re: [mapguide-users] Zoom to selection

	The only way I know of, is to issue a select of the objects on
the datasource.
	While reading the objects, you can get their envelope (aka mbr,
bbox, etc..).
	If you sum up alle the objects enevlopes, you can get the
minimum rectangle in which all objects fit.
	Once you have this box, your center, will be the center of the
box, and the scale will be the width or height of the box.

	Regards, Kenneth, GEOGRAF A/S

	Ivan Milicevic skrev: 

		Hello,

		I wonder is it possible to calculate zoom extent on
selected objects? For example, I have selected various type of objects
(line, polygon, point) but I don't have any XY info in database on these
objects. How can I calclate center point and scale in this case?

		Any help-advices are wellcome.

		Greetings,

		Ivan.

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