Subject: Re: bug#35696: preview-latex does not work under any Emacs themes and bug#35571: 12.1; Changing foreground breaks previews

From: Ikumi Keita <[email-masked]>
Date: Tue, 28 May 2019 23:29:38 +0900

>>>>> David Kastrup <[email-masked]> writes:
>> Thanks for your advice, the attached patch works well.  The foreground
>> color of the generated image matches with the default face of emacs
>> without `preview-pdf-color-string', at least for gs 9.27 on my machine.

Ah, my bad, I was looking at the outcome of dvipng, not pdf2dsc.  After
I changed my setup to use pdf2dsc, the foreground color is just black.
Especially, on the theme with dark background, math formulae are hard to
read.  So this patch does not make sense.  Sorry.

> Ah, that removes the functionality completely.  Since this patch sets up
> a per-page hook, it would be my guess that this was supposed to guard
> against cases where some images set up or leave their own page-wide
> color (possibly just using \usepackage{color} is enough to cause
> trouble).  Maybe it's the best we can do for now.  No idea.

Now I'm wondering where "the last change to these code lines" mentioned
in your previous reply.  The command
"git log --grep=preview-pdf-color-string"
shows only two entries for me:
commit c5fe24eb9d59ff06be73f13d1a8c0a21885bc08c
Author: Ralf Angeli <[email-masked]>
Date:   Wed Jun 8 07:16:21 2005 +0000

commit ed3cdfa35a8fd9a3df2954ef62f93b70459d872f
Author: David Kastrup <[email-masked]>
Date:   Tue Apr 12 15:12:39 2005 +0000

The former involves only texinfo document change, so only meaningful
commit is the latter.  But the function `preview-pdf-color-string' was
first introduced in the latter commit, and it already had exactly the
same form as today at that time.  I suppose the function has never
changed since then.

Regards,
Ikumi Keita