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

[Visuwesh <visuweshm@gmail.com>]

[திங்கள் செப்டம்பர் 23, 2024] Tassilo Horn wrote:

> 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?
>
>> Would that be what a regular PDF viewer does?
>
> It seems so.

AFAIU, the "dark-mode" PDF viewers offer has a lot that goes into it
especially wrt making images actually viewable.  Since we don't do any
such complex handling (nor do we instruct mutool to do it), we present
an unreadable document in this case.  I believe it would be best to
default the face to be black-on-white, and let the user customise the
face to match whatever colour they want at their own risk.

> Bye,
>   Tassilo