[Xastir] Shapefile Question

[Curt Mills]

On Mon, 20 Sep 2004, Gerry Creager N5JXS wrote:

> re: Wx alert counties, what I've done on one of my web-map pages is have
> the filled county outline at a lower layer, but the county outline in
> color at a higher layer.  Works pretty well.  I'd demonstrate, but we
> don't have any severe weather in Texas right now...  :-)

Doesn't fit into our current scheme for drawing though.

1) All maps are drawn to one pixmap.  That then remains static
unless they pan/zoom or change map selections.  We don't touch it
again otherwise.  Of course the auto-update radar images and the
like cause us to repeat step #1 at each interval, but if we're not
doing that, we're not drawing maps at all after the initial draw.

2) When we update weather alerts, we copy the map image we created
in step #1 and draw on top of it.  If weather alerts aren't
changing, we don't ever touch this raster image, or at least that
was the original idea.  I think it's still valid.

For step #2, we have no concept of map layers.  All map layering is
in step #1.

3) When we update symbols/tracks, we copy the image from #2 and draw
on top of it.  This happens often.  It's fast, as we're not drawing
any maps or weather alerts.

4) We take the image we created in #3 and copy it to the X11
display.

The end result is that we do #3 and #4 often.  #2 much less often
(only when weather alerts are added or expire), and  #1 only when
pans or zooms occur, when something is changed in Map Chooser, or
when an auto-update map event is triggered.

-- 
Curt, WE7U.				archer at eskimo dot com
http://www.eskimo.com/~archer
  Lotto:  A tax on people who are bad at math. - unknown
Windows:  Microsoft's tax on computer illiterates. - WE7U.
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