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List:       cairo
Subject:    Re: [cairo] concurrent text rendering issue
From:       Kozhevnikov Mikhail <mikhailkozhevnikov () yandex ! ru>
Date:       2010-03-30 9:48:09
Message-ID: 28501269942489 () webmail23 ! yandex ! ru
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Hi,

While my previous email is awaiting moderator approval, having 140Kb attachment, I've \
worked out the solution, more or less.

The point is, cairo_show_text and cairo_text_extents are not thread safe on Windows, \
at least when using default font backend. I'm not quite sure they're supposed to be \
thread safe, but so they appear on Linux.

Regards, 
Mikhail.

28.03.10, 22:08, "Kozhevnikov Mikhail" <mikhailkozhevnikov@yandex.ru>:

> Hi All,
> 
> I'm getting an error when renderig text concurrently on Windows.
> 
> Here's the experiment: we render repeatedly a set of letters in different font \
> sizes. Neither letters, nor font sizes change from iteration to iteration. If we do \
> it with one thread, it works fine and we get consistent results. If we use more of \
> them, the output varies - some letters are missing. Sometimes an out of memory \
> error is reported. See the sample images and code attached (only unique images are \
> stored). 
> I've found out that it only happens on Windows. Thus I suspect that this issue has \
> to do with WinAPI font selection mechanism. For example, if we confine ourselves to \
> one single font size, we wouldn't experience any problems. 
> Could anyone suggest a way to fix that? Should it be considered a bug at all?
> 
> Thanks in advance,
> Mikhail.
> 
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