That might be tough to support properly given the complexity of the stylization, especially because they can scale, be offset, etc based on attributes.
Basically, you're stuck in a chicken/egg situation where you need the data to calculate the symbol MBRs to figure out how much data to request :) Jason On 2010-02-16, Miller, Craig <[email protected]> wrote: > With the points, you could only fetch an over-post if there is a point layer > that has a large symbol. You could use the radius of the symbol to > determine how much additional area to fetch. You'd need MBRs for every > possible symbol to be rendered before setting the map window MBR and > fetching data. > > Craig > On Tue, Feb 16, 2010 at 2:37 PM, Jason Birch <[email protected]> wrote: > >> How would you handle this James? >> >> The spatial intersection that MapGuide performs with the current >> viewport's >> extents is critical to performance when you are dealing with large amounts >> of data, and many of the FDO data sources are optimized using R-Tree (or >> similar) indices to return only the data which is currently in view. >> >> I guess you could conceivably fetch an over-post of the current extents by >> some factor, but that would only work for a subset of point symbols (those >> where the maximum dimensions of the theming is < half the expanded extent >> dimension, and it would mean that everyone has to live with the decreased >> performance of the over-fetch. >> >> A few options: >> - Make the over-fetch percentage or distance configurable per server, per >> map, or per-layer >> - Only apply the over-fetch to points (there are actually cases where the >> same problem happens with lines and polygons, so I don't think this is >> valid) >> >> I personally feel that the current behaviour is generally OK, but there >> are >> definitely cases where you wouldn't want features missed just because >> their >> mid-point isn't in the current view extents. >> >> Regardless of the solution, I think this would take some work, so might >> require some funding or somehow making it important to one of the >> developers. >> >> Jason >> >> >> On 16 February 2010 12:06, JamesDudden wrote: >> >>> I understand how it happens and it does make sense but it renders the >>> theming of points useless if they are going to be anything larger than a >>> few >>> pixels. >>> >>> I think it would be good to see future versions of Mapguide become more >>> intelligent and be able to cope with theming of points. >>> >>> >> _______________________________________________ >> mapguide-users mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/mapguide-users >> >> > > > -- > Craig Miller > Geospatial Software Architect > _______________________________________________ mapguide-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapguide-users
