How to create a custom background in TextMeshPro?

Unity Engine
1

Hey, I want to create a custom background for part of my text.
I want to display key a player needs to press with other TextMeshPro text like so:7095208--845197--upload_2021-4-30_19-30-55.png
but I want to have a custom image background
7095208--845200--upload_2021-4-30_19-31-15.png
in the marked area.
I know I can insert an image glyph, but I would have to prerender all possible keys, which is not ideal.
How can I achieve it?

7095208--845191--upload_2021-4-30_19-23-58.png
7095208--845194--upload_2021-4-30_19-30-36.png

2

I’d probably do it with separate image components underlaid behind the text. You can use the various CharacterInfo APIs from TMPro to get the exact position/sizing etc. for the characters.

Or insert the empty image glyph in the text and use separate text components to display the letters on top.