[Xastir] maps

[J. Lance Cotton]

Chris Hare, KD5WIM wrote:
> 1.  If zoom gets to far out, stop loading selected maps like city
> streets - get a little dynamic on what gets loaded based upon zoom level

A good idea. So good that it's already implemented! For shapefile maps, if 
you choose Map->Enable Map Levels, Xastir will do this, only displaying 
appropriate information on the screen. I haven't found that this speeds up 
the loading much, since Xastir still has to look through every element in 
the shape file (but only load those in view).

I have shapefiles for roads of all the counties in TX. When I zoom out to 
1/4 the state, it can take a good few minutes on a 2.2 GHz computer to load 
all the maps, even with map levels enabled. But at least the screen isn't 
cluttered with all the little tiny lines! ;-)

> 2.  How about caching the tigermap?  It doesn't change all that much(if
> at all) in a 24 hour period....  caching it would speed up the ability
> to move around rather than loading it again each time you press "PAN".

Another good idea! The roadblocks for this feature are questions like "How 
far past the Xastir window edges to we get map data from TigerMaps?" If we 
grab a huge map and only display part of it (so that we can pan without 
re-downloading), it can take even longer to get the map image. The server 
may even timeout. I don't know if there is a maximum image size that can be 
requested from the map server.

One way to manually implement this is to make up a custom URL request to the 
tigermaps server and download this large map file to the hard drive. Then 
carefully construct your own .geo file linking points on the image with 
coordinates in the Xastir world. Put it all in the maps folder and enjoy a 
static map that isn't downloaded from the Internet every time you pan/zoom.

-Lance KJ5O
-- 
J. Lance Cotton, KJ5O
joe at lightningflash.net
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat the 
cookies.