Hello,
in my current project, I need a marquee.
I adapted the component from here:
http://forum.lazarus.freepascal.org/index.php?topic=24646.0
which is a descendant of a TCustomLabel using a timer to move the text
position.
I have several problems with it:
- it is very cpu intensive (I have to put it over a picture, so the
invalidate will also force the repainting of the bitmap I guess)
- the minimum timer interval is 10ms, and even that it's not guaranteed
(the resolution on windows is around 15ms and I got a very different
speed of the label using 10ms under virtualized windows xp and a real
windows 7 machine)
- with such a low value (10ms) sometimes the application gets bogged
down, specifically it cannot process the modal dialog I use to shut down
the application.
- I solved the flickering by setting DoubleBuffered to the containing
widget (a TPageControl), but, again, I think that takes its toll on cpu
usage.
I tried to use a thread (with synchronize) instead of a ttimer to obtain
a lower interval, but that only compounds the problems.
For the time being, I'm using 50ms and change the number of pixels to
change the speed, however if I scroll more than 2 pixels every 50ms the
scrolling isn't smooth enough, but the required speed should be 6 or 7
pixels, and that's very unpleasant to the eye.
Any suggestion?
--
Luca Olivetti
Wetron Automation Technology http://www.wetron.es/
Tel. +34 93 5883004 (Ext.3010) Fax +34 93 5883007
--
_______________________________________________
Lazarus mailing list
Lazarus@lists.lazarus.freepascal.org
http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
