bug#56889: 13.1.3; Adjustment of foreground color not working for fraction lines and tikz in preview

[Ikumi Keita]

Hi Frank,

>>>>> Frank Selensky <frankselensky@live.com> writes:
> I am using a theme with a dark background, so I rely on auctex to
> convert the foreground color to the one set in my theme while previewing
> latex fragments. This works fine for most latex fragments. But it does
> not work for the lines of a fraction. Here the numerator and denominator
> are converted to the right color, but the fraction line itself stays
> black. Apart from that, in tikzpictures the color of the lines and text
> is not converted and still black.

> This happens for me for example when I try to preview the latex
> fragments in the following:

> ```
> \documentclass[a4paper]{article}
> \usepackage{amsmath}
> \usepackage{tikz}

> \begin{document}
> \[\frac{123}{abv}\]

> \begin{tikzpicture}
> \draw(0,0) -- (1,2);
> \node[draw] at (-1,-2) {A};
> \end{tikzpicture}
> \end{document}
> ```

> What I would expect is, that everything (where no other color was
> specified explicitly) is turned into the foreground color of my theme
> when previewing.

Foreground color adjusting is somewhat fragile feature, and I'm afraid
that preview-latex can't satisfy your request for pdflatex.

According to ghostscript developer, preview-latex sets the "default"
color, but if the pdf has explicit color specification, ghostscript
obeys it to render the image out of pdf. I guess that pdflatex specifies
black for the line of fractions explicitly while it doesn't for "texts"
of numerator and denominator. If this guess is correct, fraction lines
are always rendered as black.

I confirmed that the following workarounds work, but I admit that
they aren't satisfactory solutions, sorry:
(1) Turn off PDF mode by C-c C-t C-p and set `preview-image-type' to
    `dvipng'.
(2) Set `preview-pdf-color-adjust-method' to nil.

Regards,
Ikumi Keita
#StandWithUkraine #StopWarInUkraine