GNU bug report logs - #38394
Fwd: Use different image filtering when zooming in vs zooming out

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From: Alan Third <alan <at> idiocy.org>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 38394 <at> debbugs.gnu.org
Subject: bug#38394: Fwd: Use different image filtering when zooming in vs zooming out
Date: Sun, 2 Aug 2020 21:35:15 +0100

[Message part 1 (text/plain, inline)]

On Sun, Aug 02, 2020 at 07:52:25PM +0200, Lars Ingebrigtsen wrote:
> Alan Third <alan <at> idiocy.org> writes:
> 
> > It might be worth smoothing on scaling down, but not on scaling up.
> > That way if you zoom in you get exact pixels, but zooming out you
> > don’t get aliasing effects.
> >
> > I don’t know if that would add any other problems...
> 
> You apparently didn't apply this patch?

There didn't appear to be much enthusiasm so I just left it in case
someone requested it in the future.

> > * src/image.c (image_set_transform [HAVE_XRENDER]): Use different filter
> > when zooming in vs zooming out.
> 
> I think it makes sense...  although I'm not sure of what the effects are
> if you just increase the image size by, say, a couple percent.

I've attached an updated version of this patch and a screenshot
showing the result with a couple of levels of scaling.

Annoyingly we now use Cairo by default which is unaffected by this
change, so only plain X users will see this behaviour.
-- 
Alan Third

[scaling.png (image/png, attachment)]

[0001-Don-t-smooth-images-when-scaling-up-bug-38394.patch (text/plain, attachment)]

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