From: "Joe C. Hecht" <joehecht@gte.net>
Subject: Re: LineTo is slow on fast machines
Date: 20 Jan 1999 00:00:00 GMT
Message-ID: <36A62D9A.970@gte.net>
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Its a driver/card issue.

I can recommend some of "Joes best bets" for
*accelerated* drawing:

1) Use a non VCL background bitmap buffer. ie: a raw
(non TBitmap) memory dc. Use win api functions to blt the
results to you paintbox.

2) If you are using *bunches* of Canvas.Moveto's and
Canvas.Linetos, the VCL overhead of TCanvas can be
significant over the same calls done using straight
windows API functions.

3) Consider using the Windows PolyLine function instead
of sperate calls to moveto and lineto.

4) Horizontal and vertical lines can often be drawn
faster using the Windows API function PatBlt().

Hope that helps.

Joe

Dimitrios I. Koutsourelis wrote:
>
> My application draws on Form.PaintBox.Canvas a lot of lines (more than
> 10000). It uses MoveTo - LineTo. On my desktop (Pentium MMX 233, 64MB,
> VideoCard Mystiq with 2MB) it runs really fast and it is 3-4 times faster
> than it used to be on DOS.
>
> However, it is really slow on many other fast computers (P-II 350, 64MB, and
> DiamondViper with 8MB). It runs 5-6 times slower compared to my computer.
>
> Is it a configuaration problem, or what else ?

--
Joe C. Hecht
http://home1.gte.net/joehecht/index.htm