[Xastir] County borders

[Craig Anderson]

When Xastir starts up it will "index" the maps it has.  This is a process where Xastir looks at all the map data files it has (the "edges folder" you have) and matches the data format of each map file with a dbfawk file (usually in /usr/share/xastir/config). The dbfawk file will determine how that map data is displayed; i.e. the process of changing colors, sizes, zoom levels, or other display attributes is controlled by the control statements listed in the dbfawk files.

Xastir also determines the coverage area of every map file to determine when it needs to dig through that file based on the area it is trying to display on screen.  Every time Xastir displays a screen it determines all the map files that are touched by that view and uses the matching dbfawk file to search through that map file and pull out only the objects that fit in that screen view.  

Unfortunately, changing how an object is displayed is not a very easy process.  And it is not very fine-grained.  if you change a dbfawk file you will change the display attribute of that style of object in *every* map Xastir displays, not just the 3 or 4 counties you want.  To do this correctly you need to know the contents of the map files and the dbfawk files.  Use the "dbfinfo" program to show you the format of the map data file so you can know which dbfawk file is digging through that map file (because the schema in the map file matches the schema listed in the dbfawk file).  Then you can figure out which map feature you want to display and how to set it's color, size, zoom level, etc.

Then comes the issue of layering your map objects so that roads and streams get displayed on top of color fills and not covered by them.  This happens in the Map->Map Chooser->Properties dialog box.

You don't need to become a mapping expert, but pretty close.  :-)

Craig
n6yxk

On Feb 14, 2010, at 7:17 PM, Keith Kaiser wrote:

> I'd like to outline each county in a color (red). I use the new Tiger maps so I'm guessing its the edges folder that I need to work with, like this one; tl_2008_20091_edges Folder.
> 
> Which file inside do I need to play with, or do you know exactly how I would go about doing this? I'd also like to fill each county with a different county. I'm doing this for a collection of counties so it can be anywhere from 5 to about 15 no more.
> 
> Thanks guys.
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