[mapguide-users] Polygon labels - fusion problems

[Paul Spencer]

Traian,

my understanding was that I should be using GetMapImage for drawing  
the map and GetVisibleMapExtent/GetDynamicMapOverlay for the  
selection.  And in fact, I think Trevor modified GetDynamicMapOverlay  
to allow rendering just the selection.

 From what you said below, it now appears that I should be using  
GetVisibleMapExtent/GetDynamicMapOverlay for rendering map draws.

Note that this is problematic for OpenLayers because it currently uses  
a synchronous AJAX call to GetVisibleMapExtent which is not desirable  
and will require a rework of the MapGuide support in OpenLayers to  
allow this to be done asynchronously.

Is there any reason why the two operations would be implemented  
differently?  Is one more correct than the other?

Cheers

Paul

On 15-Feb-08, at 6:20 PM, Jason Birch wrote:

> Traian, Paul,
>
> I observed considerable performance degradation between the old  
> version
> of Fusion (pre-MGOS) that used GetDynamicMapOverlay instead of GetMap.
> This was with my Cemetery map data that has the nasty buffered roads
> layer.  Sheboygan seemed to be fairly quick regardless.
>
> I'm wondering if this difference (clipping off) could be the  
> culprit?  I
> don't see the same performance decrease in the AJAX viewer for this  
> map.
>
> I discussed this with Paul earlier, and think I was supposed to  
> submit a
> bug report, but wasn't able to quickly put together a reproducible  
> error
> report and it slipped my mind (doh!).
>
> Jason
>
>
> -----Original Message-----
> From: Traian Stanev
> Subject: RE: [mapguide-users] Polygon labels - fusion problems
>
>
> I think it could be that Fusion uses a RenderMap API which uses  
> viewport
> clipping turned off (resulting in labels always being at the true
> centroid of polygons) while the MG ajax viewer uses
> RenderDynamicOverlay, which has viewport clipping turned on, resulting
> in polygons being labeled at the centroid of the clipped region.
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--
Paul Spencer
CTO, DM Solutions Group Inc
http://www.dmsolutions.ca/