From: Kenichi Handa <handa@m17n.org>
To: Jason Rumney <jasonr@gnu.org>
Cc: eliz@gnu.org, lennart.borgman@gmail.com,
monnier@IRO.UMontreal.CA, emacs-devel@gnu.org
Subject: calculation of text extents [Re: Memory leak]
Date: Sat, 24 May 2008 11:30:40 +0900 [thread overview]
Message-ID: <E1JzjWq-0008DY-Gt@etlken.m17n.org> (raw)
In-Reply-To: <482D8332.5030908@gnu.org> (message from Jason Rumney on Fri, 16 May 2008 13:50:58 +0100)
In article <482D8332.5030908@gnu.org>, Jason Rumney <jasonr@gnu.org> writes:
> A while ago I noticed w32font_open being called multiple times for the
> same font, so I suspect that we may be overlooking the font cache in
> places and reopening fonts when we could be reusing an existing font.
With the recent fix of font-cache handling, I think the
number of calling `open' callback of a font-backend for the
same font is reduced. Can you confirm that?
> There is another similar problem when we get text extents - each redraw
> cycle can call w32font_text_extents a number of times for the same
> glyph_string (from compute_glyph_string_overhangs, left_overwriting and
> right_overwriting in quick succession in draw_glyphs, with nested
> compute_overhangs_and_x within some of the if statements that cause
> extra calls for preceding and following glyph_strings if there is
> overhang, which there often is with antialising enabled). Perhaps this
> operation is cheap with the X font backends, but on Windows it is
> expensive (even with caching of metrics), and I suspect this is a major
> cause of the slowdown reported by Windows users.
It seems that we can reduce the number of calling
`text_extents' callback by recording lbearing and rbearing
in struct glyph; which grows the size of that structure from
the current 32-byte to 36-byte. I'm not sure how much that
change impacts the memory usage of Emacs, but isn't it worth
trying?
---
Kenichi Handa
handa@ni.aist.go.jp
next prev parent reply other threads:[~2008-05-24 2:30 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-15 22:50 Memory leak Stefan Monnier
2008-05-15 23:06 ` David Kastrup
2008-05-16 0:25 ` Lennart Borgman (gmail)
2008-05-16 8:35 ` Eli Zaretskii
2008-05-16 9:03 ` Juanma Barranquero
2008-05-16 9:25 ` Eli Zaretskii
2008-05-16 9:29 ` Juanma Barranquero
2008-05-16 9:46 ` Eli Zaretskii
2008-05-16 9:49 ` Juanma Barranquero
2008-05-16 20:13 ` Stephen J. Turnbull
2008-05-16 21:15 ` [OT, silly] " Thomas Lord
2008-05-16 20:41 ` David Robinow
2008-05-16 21:36 ` Lennart Borgman (gmail)
2008-05-17 7:10 ` Eli Zaretskii
2008-05-16 9:43 ` Eli Zaretskii
2008-05-16 12:50 ` Jason Rumney
2008-05-19 8:05 ` Kenichi Handa
2008-05-19 8:45 ` YAMAMOTO Mitsuharu
2008-05-19 11:13 ` Kenichi Handa
2008-05-19 11:59 ` YAMAMOTO Mitsuharu
2008-05-23 2:24 ` Kenichi Handa
2008-05-19 13:34 ` David Hansen
2008-05-19 19:42 ` David Hansen
2008-05-24 2:30 ` Kenichi Handa [this message]
2008-05-16 2:19 ` Stefan Monnier
2008-05-16 0:38 ` YAMAMOTO Mitsuharu
2008-05-17 15:16 ` Evil Boris
2008-05-17 19:11 ` Stephen J. Turnbull
2008-05-17 19:17 ` Eric Hanchrow
2008-05-18 11:26 ` Jan Djärv
2008-05-18 11:29 ` David Kastrup
2008-05-20 6:46 ` Jan Djärv
2008-05-18 13:34 ` Werner LEMBERG
2008-05-20 6:48 ` Jan Djärv
2008-05-19 2:44 ` Stephen J. Turnbull
2008-05-20 6:50 ` Jan Djärv
2008-05-21 6:10 ` Stephen J. Turnbull
2008-05-21 17:32 ` Stefan Monnier
2008-05-23 13:54 ` Evil Boris
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