[maemo-developers] QT map widget

[From: Joerg Reisenweber]

[kate.alhola at nokia.com So  13. Juni 2010]:
> ----- Original message -----
> For application performance and cpu usage also time needed for tile pre-
> processing need to be counted.
> 
> Does it some scaling for tiles after loading them ?
> 
> Finally time used for scaling tiles is one key issues. Do we scale them or 
> download every size. How much cpu power is used for scaling or do we leave 
> it all for GPU ?

The main concern is about scaling has to be done *only once* and NOT for every 
refresh of the display. Depending on how ignorant the widget is coded, you 
might end with a redraw() triggered for every visible tile of the map, if the 
map content is only shifted aside by a few pixels. Then each tile object does 
all the scaling again, and that's for sure not the optimum way to implement 
that.
Displaying a minimal change of the map, quite usually this means moving the 
bitmap by a few pixels and adding a few new pixels to the canvas at one side, 
this is definitely a completely different thing than drawing a new map from 
scratch which should be avoided as much as possible, for obvious performance 
considerations.

Or simply put: if you got CPU load issues on displaying a slowly and minimally 
changing map, then you did something terribly wrong.

/j
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