[mapguide-users] Zoom to selection

[Kenneth, GEOGRAF A/S]

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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