Re: No NEWS entry for doc-view-mupdf-use-svg (Emacs 30.0.91 feedback)

[Eli Zaretskii <eliz@gnu.org>]

> From: Tassilo Horn <tsdh@gnu.org>
> Cc: emacs-devel@gnu.org,  Eli Zaretskii <eliz@gnu.org>, visuweshm@gmail.com
> Date: Mon, 23 Sep 2024 08:44:35 +0200
> 
> Morgan Willcock <morgan@ice9.digital> writes:
> 
> > When looking at the SVG files in the location browsed by
> > doc-view-dired-cache I can see that the Azure invoice has:
> >
> > - A transparent background with black and grey text on it.
> > - A dark grey border with white text on it.
> > - A white border with black text on it.
> >
> > The transparent background is shown as white or black, depending on
> > whether the light or dark theme is loaded, but the text is always
> > readable because the text colour complements the background.
> >
> > The problem is the text that is not on the transparent area of the
> > document, presumably because a coloured border cannot be identified as
> > being part of the background and so the border colours will never
> > follow the theme.
> >
> > Based on my usage, setting doc-view-mupdf-use-svg to t seems to make
> > reading PDF documents significantly more difficult.
> >
> > Perhaps there should be an option to just assume a white background
> > and render using the original colours, and turn that on by default.
> 
> That's what Visuwesh's advice of setting doc-view-svg-face's
> foreground/background to black and white would do.  We could do that by
> default instead of inheriting from the default face (which is modified
> by the theme).  That would probably give sensible results in most cases.
> 
> I've also tried un-inheriting doc-view-svg-face from the default face so
> that it is the empty face, i.e., all its attributes are nil.  In that
> case, it looks exactly as if it inherited from the default face, i.e.,
> the document is styled according to the theme with the same problems for
> certain files as you see.
> 
> I've also created a PDF with blue background and different text colors.
> In that case, doc-view-svg-face set to "black on wide" doesn't seem to
> have any effect.  The foreground/background colors of the document
> appear exactly as I've specified them in the original LaTeX document and
> as the Evince or mupdf PDF viewer show them, too.
> 
> Eli, what do you think?

Sorry, I don't understand what you are asking me about.  Please
elaborate

It sounds like PDF documents with colors have inherent problems with
doc-view-mupdf-use-svg and/or themes, so maybe we should warn about
this in NEWS and in the doc string, and suggest that people either
customize the doc-view-svg-face, or disable doc-view-mupdf-use-svg.