GNU bug report logs - #65432
30.0.50; jerky image movements when zoomed

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Message #14 received at 65432 <at> debbugs.gnu.org (full text, mbox):

From: Manuel Giraud <manuel <at> ledu-giraud.fr>
To: Po Lu <luangruo <at> yahoo.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 65432 <at> debbugs.gnu.org
Subject: Re: bug#65432: 30.0.50; jerky image movements when zoomed
Date: Thu, 24 Aug 2023 15:48:55 +0200

Po Lu <luangruo <at> yahoo.com> writes:

[...]

>> I cannot reproduce this, on MS-Windows.  I see no difference between
>> "jerkyness" of motion commands before and after 'i -'.
>
> This is a known inefficiency with Cairo's implementation of affine
> transforms.  AFAICT, Cairo performs the transform on the CPU, which is
> aggravated by uploading the complete bitmap to the X server every time
> the image is displayed.
>
> Building without Cairo should induce Emacs to utilize XRender transforms
> instead, ameliorating this problem.

Thanks, I'm going to try without Cairo.  But would it be possible to
have Emacs using cairo for everything except for raster images?
-- 
Manuel Giraud

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