[debian] navit: rendering is slow

Fox Mulder Quakeman1 at gmx.net
Fri Dec 26 12:35:46 CET 2008

arne anka wrote:
> i enabled the small screen gui ("internal" it is called, i think) and  
> tried out navigation.
> so far rendering is _very_ slow and the cpu usage applet always shows  
> about 80-100% usage -- thus eating power quite fast, i presume.
> it takes a long while (and someinteraktion) to make the current map to  
> appear, even after gps obtained a fix i had to swith to some dilog and  
> back to the map view to make it rerender.
> after the map was there and navigation hints appeared i made the  
> matchbox-keyboard appear which took up the upper part of the screen. after  
> disabling the keyboard the part of the navit window remained grey (though  
> the window's top bar was redrawn immediately by xfce), after several  
> minutes the small rectangles were redrawn -- but that was about all,  
> navigation information ("turn in ... meters") seemed not related to my  
> current position anymore and the map never was redrawn while the cpu usage  
> was still exceptionally high.
> after about 15min i killed navit.
> navit is 0.1.0+svn-1791, built without speech, map is the eu.bin linked to  
> in the navit wiki.
If you installed the precompiled navit version i would suggest to
compile it from source yourself. I don't know why, but the precompiled
version runs very bad on my fr with debian. After i compiled my own
version (1778) it runs much better. I also had trouble with very high
cpu usage but with my new compiled version i got quite low cpu usage
when navit is idle.

> my questions so far:
> - is navit's navigation usable at all on a device so limited? (other  
> experiences?)
I tried routing between two nearby towns (~6km) and it worked quite good.

> - is the high cpu usage rather a bug or an unavoidable side effect because  
> of the fr's little mind?
I think this is some kind of bug with the precompiled versions in
conjunction with debian.

> - is there a tweak to make rendering more responsive (eg by rendering less  
> detailed?)
You have to enable the fast-map-drag patch by hand. Therefor you have to
add drag_bitmap="1" to the navit tag (like recent_dest) in navit.xml.


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