[mapguide-users] MgTileService - GetTile - Cannot establish connection

[Trevor Wekel]

Hi Jason,
 
This was a deliberate exclusion.  There are a number of codependant
state variables in MgMap - like center, scale, and mapExtent.  Allowing
set access to any one variable would invalidate the others.  There are
two other objects in C++ - MgHtmlController and MgDwfController which
correctly manage the codependence.  The mapagent uses these classes.
 
There are use cases where the controllers would be useful for
manipulating MgMap state.  They could be exposed publically but the
documentation would need to be updated and the exposed methods would
have to be reviewed.  Some of the methods are no longer in use and
should be removed.  
 
I'm sure other members of the dev community and the PSC would like to
discuss this further.
 
Thanks,
Trevor
 
 

  _____  

From: Jason Birch [mailto:Jason.Birch at nanaimo.ca] 
Sent: Thursday, December 07, 2006 4:54 PM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] MgTileService - GetTile - Cannot establish
connection


I'm surprised that there are methods which are available to the MapAgent
but not the APIs.  
 
Was this a case of deliberate exclusion, or not enough time to get
everything in?  I can see there being some arguments for not exposing
these methods (only need them for rendering, etc) but there are
apparently going to be some use cases for accessing them :)
 
Jason

  _____  

From: Walt Welton-Lair 
Sent: Thursday, December 07, 2006 15:47
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] MgTileService - GetTile - Cannot establish
connection


Sorry about that - I forgot that the Set methods weren't exposed.
 
As Alain mentioned, currently the only way to update the view is via
certain HTTP requests.  GETMAP / GETMAPUPDATE / GETPLOT are used in the
context of DWFViewer, while GETMAPIMAGE and GETVISIBLEMAPEXTENT are used
in the context of AJAX Viewer.  You can include additional parameters
with any of these requests to update view related information:
 
    SETDISPLAYDPI=<dpi>
    SETDISPLAYWIDTH=<width>
    SETDISPLAYHEIGHT=<height>
    SETVIEWSCALE=<scale>
    SETVIEWCENTERX=<centerX>
    SETVIEWCENTERY=<centerY>

While you can use a viewer to make these requests for you, you can make
the HTTP requests yourself and get the same effect.  You could write an
application that:
 
1) creates a session
2) creates an MgMap for your MapDefinition that is part of your session
3) makes one of the HTTP requests above
    - GETVISIBLEMAPEXTENT is the simplest
    - include the SETVIEWSCALE parameter with the request to set the
scale you want
4) makes calls to GetTile
5) repeats steps 3 and 4 for each desired scale
 
For steps 1 and 2 there's should be sample code under the MgMap
documentation.
 
For step 3 something like .NET's HttpRequest class probably works.  Just
make the request to your MG server, e.g.
http:://localhost/mapguide/mapagent?OPERATION=GETVISIBLEMAPEXTENT&VERSIO
N=1.0.0&SESSION=<sessionId>&MAPNAME=<mapName>&SETVIEWSCALE=<scale>
 
Here, mapName is the name from the MgMap.
 
Walt
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