bug#43128: Acknowledgement (27.1; DPI change not detected after switching to Emacs 27.1)

[Vincent Bernat <bernat@luffy.cx>]

On 2022-10-27 18:33, Eli Zaretskii wrote:
>> Date: Tue, 25 Oct 2022 23:02:16 +0200
>> From: Vincent Bernat <bernat@luffy.cx>
>> Cc: mituharu@math.s.chiba-u.ac.jp, 43128@debbugs.gnu.org
>>
>>> I'll try to do something, but I have no experience with either Xft or
>>> Cairo, so if that's something clever to do, I am likely to fail.
>>
>> I was able to build this patch. I did replace XftDefaultSubstitute() by
>> something that looks correct. However, for XftDefaultSet(), it seems
>> there is no mechanism to override the defaults for fontconfig or cairo,
>> so it seems not needed to find a substitute.
> 
> Sorry, I don't understand.  Are you saying that the patch you posted
> solves the problem for you?  Then what do you mean in the last
> sentence above about XftDefaultSet?

The patch works for me, but I was unable to replace XftDefaultSet. From 
my understanding, while Xft has a way to override the defaults, this is 
not the case for fontconfig and Cairo. So, I suppose this is not needed 
for fontconfig and Cairo and other parts of the code should ensure the 
new settings are used without relying on defaults.

Also, the Cairo-specific part of the patch makes no difference for me. I 
have included it because Cairo documentation says to put it there.