Thanks everyone for your help on this subject. I found a method of OGR (which mitab uses) called SetSpatialFilterRect(...), as Uffe mentioned. This filters using MapInfo's .map spatial index.
http://ogr.maptools.org/ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Uffe Kousgaard Sent: 05 June 2006 14:10 To: Mapinfo-L Subject: Re: [MI-L] How mapinfo loads map data MessageIt is possible if you use the MITAB C++ source code directly (setspatialfilter), while the C API (and the DLL) do not allow it. Regards Uffe ----- Original Message ----- From: Warren Vick, Europa Technologies Ltd. To: 'Tim Smith' ; '<MapInfo-L' Sent: Monday, June 05, 2006 12:17 PM Subject: RE: [MI-L] How mapinfo loads map data Hello Tim, The ability to dynamically load only the parts of a map layer that are in a current view is achieved through a spatial index. This avoids the need for any map renderer to go through all features to test if they are needed for the view. MapInfo uses a spatial indexing method known as R-Tree. Since I'm not too familiar with MITAB, I don't know if it has the ability to use this index to query features in a table based on a coordinate rectangle. It would not surprise me if it didn't since I believe MITAB was originally written for external (i.e. outside a MapInfo environment) read/write of TAB file sets, and maybe not with a home-brew renderer in mind. Regards, Warren Vick _______________________________________________ MapInfo-L mailing list [email protected] http://www.directionsmag.com/mailman/listinfo/mapinfo-l ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ _______________________________________________ MapInfo-L mailing list [email protected] http://www.directionsmag.com/mailman/listinfo/mapinfo-l
