Am 31.10.2011 16:18, schrieb Albrecht Dreß:
> Hi Oliver:
>
> Am 29.10.11 14:01 schrieb(en) Oliver Eichler:
>> @Albrecht & Michael can one of you both test this on OS X. I would be
>> interested if the little obnoxious transparent problem on some OS X
>> based platforms can be solved by that.
>
> Tested it on 10.5/Intel, and unfortunately it does /not/ fix the
> rendering issue. Didn't test it on 10.4/PPC yet (as building takes
> *ages*), but as this issue seems to be visible only on 10.5, my
> impression is that this is something being buried either in OS X 10.5
> itself or in the interface between Qt and OS X. Thus, changing the
> method to build the pixel representation has no influence on the
> rendering (and its errors) on the lower level.
>
> Cheers, Albrecht.


:( well it was worth a try. Thanks.

I tried to speed up Garmin maps a bit. The results are in SVN. 
Unfortunately exchanging QImage with QPixmap for line drawing did not 
help. Still vector maps are rendered slow.

I would summarize this as: Using QPixmap to draw full screen bitmaps is 
faster than QImage. However rendering polylines seems to be faster on a 
QImage.

Right now the idea is to draw into a buffer that is defined by IMap 
which is the common interface class for all map render objects. The 
buffer is drawn each time the map content changes. But not each time the 
screen updates. Additionally it is available for off screen operations.

Maybe it's an idea to have two buffers. A QPixmap one and a QImage one. 
For raster maps the QPixmap one is used all the time as it is the faster 
choice.

For the vector maps QPixmap is used while moving / zooming the map and 
QImage when rendering the map in full details. I have to think about this...


Oliver

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