In issue http://bugs.freepascal.org/view.php?id=12377, reporter said:
> Painting to an Bitmap and paint this on the Canvas would be much faster
This assertion is, of course, incorrect. I assume that the reporter's problem is
actually that the TChart flickers when repainted.
The flickering is caused by two sources:
1) The TChart is TGraphicControl, so Parent control erases chart's background
before every repaint.
2) TChart itself draws directly to screen, first clearing the canvas.
First source obviously needs fixing, and I attached to the issue a
patch which fixes it.
The only caveat is that TChart is now TWinControl -- can it lead to some
undesirable consequences I am not aware of?
The second source can also easily be fixed by double-buffering, but
before I do that,
I have two questions:
1) TWinControl.WMPaint already contains double-buffering code, but it
is protected
by {$ifdef BUFFERED_WMPAINT}. What is the reason of this? Is there some
ongoing work to implement double-buffering globally?
2) If double-buffering will be implemented in TAChart itself, it will
have some negative
performance impact. So, should I make it optional via DoubleBuffer property?
--
Alexander S. Klenin
Insight Experts Ltd.
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