How do you tweak the colors in a theme for a particular document?

#1

For example, when using the “Dark vador” theme in document X, how would you modify the color of headings in document X only?

#2

I have investigated a bit, starting from packages/themes/vador/vador-scene.ts
I have figured out (or maybe figure out again: it is possible that i knew and I forgot) that the title block is a table, so you need to modify the background of the cell which contains the title.
You can do it by adding a cwith condition with cell-background (sorry that the formatting is cramped, I am not able to format the code in a different way and retain the possibilty of pasting it in the preamble of a TeXmacs document with the command Paste from -> TeXmacs)

<assign|vador-title-bg-color|light blue>

<assign|doc-title-block|<macro|body|<tabular*|<tformat|<twith|table-width|1par>|<cwith|1|1|1|1|cell-lsep|0spc>|<cwith|1|1|1|1|cell-rsep|0spc>|<cwith|1|1|1|1|cell-bsep|0spc>|<cwith|1|1|1|1|cell-tsep|0spc>|<cwith|1|1|1|1|cell-hyphen|t>|<cwith|1|1|1|1|cell-background|<value|vador-title-bg-color>>|<table|<row|<\cell>
  <\with|par-mode|center>
    <arg|body>
  </with>
</cell>>>>>>>

For other elements I would have to investigate one by one, sorry but I do not have an overview of page formatting :slight_smile:

Edit: after a bit more investigation, here is how to change the color of section headings:

<assign|prefixed-line|<\macro|prefix|body>
  <\with|par-first|0fn>
    <\description-table>
      <tformat|<twith|table-valign|T>|<twith|table-hmode|min>|<cwith|1|-1|1|-1|cell-lsep|0em>|<cwith|1|-1|1|-1|cell-rsep|0em>|<cwith|1|1|1|-1|cell-tsep|0em>|<cwith|-1|-1|1|-1|cell-bsep|0em>|<cwith|1|-1|1|-1|cell-vcorrect|n>|<table|<row|<cell|<with|color|red|<arg|prefix>>>|<\cell>
        <with|color|red|<arg|body>>
      </cell>>>>
    </description-table>
  </with>
</macro>>

Changing background using again the cwith condition here is not as flexible as I would like, I am not able to alter the background of the whole line.

#3

Maybe the GUI should allow you to override the color from a theme from within a document and also to change it back to the default?

#4

I believe this is possible to program by a user—did not try it myself. It could be a nice project :slight_smile:

#5

I think this should be a general feature in the GUI: the ability to override many sorts of properties (not just colors) in a style/theme from within a document and also to change them back to their defaults for that style/theme.

#6

I think it is a valid effort trying to program it in. If you have the time and enough Scheme experience it could even be something worth your attention (as a first step, you could publish it on tm-forge).
I did not think about this enough to have a clear idea of how it works, maybe one would have also to systematize the way themes modify typographical elements.