Subject: Drawing performance (was Re: Bidirectional support)
From: Leonard Rosenthol (leonardr@lazerware.com)
Date: Fri Dec 15 2000 - 08:37:06 CST
At 3:25 AM +0100 12/15/00, Mike Nordell wrote:
>The drawing performance is already horrible. Not to mention the quality. At
>least in Win32 the next line overwrites the bottom pixels from the previous
>line.
That sounds like you are using the wrong (or no) leading
information to determine the line spacing information.
>I think this displays a more serios problem we have, when displaying a line
>with a string (1 or more) characters of the same type (font and so on) we
>should bunch this together as a "writeText" operation, not write every char
>ourselves. That makes AW dog-slow (I know, I've been doing some performance
>tests).
BIG TIME!
Not only is doing a single "writeText" faster, BUT it also
allows glyph rendering engines to do fancy things like subpixel
positioning, ligiturization, etc.
>I think that supporting top-down-first instead of left-right-first would
>take some effort. Also, top-down vs. left-right doesn't (AFAIK) follow the
>same convetions regarding breaking of "lines". Am I wrong?
I believe that the same conventions for line breaking apply,
which in the case of CJK don't use "white space" anyway, but a more
complex set of rules.
Leonard
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