nanogui: Drawing performance
Subject:
Re: Drawing performance
From:
"Greg Haerr" ####@####.####
Date:
16 Feb 2001 17:16:13 -0000
Message-Id: <02e201c09839$b164b960$15320cd0@gregh>
: drawing speed will go down obviously. Lines, Arcs,
: Curves also have the problem, but draw Horizontal_Line
: and Vertical_Line are very fast, why?
Well, first, it's faster to draw horizontal and vertical
lines ;-) Curves must either calculate sin/cos or do a table
lookup per pixel, which is much slower.
And how to
: imporve the performance?
The Microwindows screen driver interface (look at
microwin/src/include/device.h) has entry points only for
read/write pixel, draw horz/vert line, and blit. The
other routines calculate each point and test for clipping
each point as well. To improve performance, take
one of the routines you want faster out of engine/devdraw.c,
and move it into a screen driver entry point, after having
checked that the area drawn is VISIBLE (GdClipArea) and
doesn't require clipping.
Regards,
Greg
:
: Best Regards,
: Yi Yang
:
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