Is there a way to enforce straight mouse movement(horizontal, vertical, diagonal) in macos?

Question

I was wondering if there is a way to enforce a straight pointer movement in macOS.

For instance when you are annotating a PDF document, you may want to make a straight stroke as an underline.

So what I'm looking for is a feature like when moving your pointers with the shift key pressed, then the pointer movement would be restricted to a straight line (either horizontal, vertical, or diagonal).

Is there such feature in macOS, or other applications which makes this possible?

Answer 1

You can, in fact, make specific dedicated underlines.

In the top bar, the pencil tool, there are options for Underline & strikethrough.
Both will track any text you select, letter, word or paragraph…

Giving this [the blue highlight is the selection, the red line is the added underline]

^{Instructions from my beer-making xmas prezzie ;)}