PR: Shift maximum character edge line to match editor characters

[rhkarls]

Description of Changes

The vertical line indicating the maximum characters per line (edge line) is shifted 3 units to the right so that it aligns with the characters of the editor.

Current behavior:

Shifting line to the right by 3 units:

This is tested also for other font sizes (7-16) and works well, as well as other standard monospace fonts shipping with Windows.

Why shift by 3?
I tested with 3 first based on this being added to the line number margin

spyder/spyder/plugins/editor/panels/linenumber.py

Line 186 in bb2ed9a

margin = 3+self.editor.fontMetrics().width('9'*digits)

And it works quite well, by chance I suppose. I also tried removing the 3 from the line number margin (without shifting edge line), but this has no effect.

An alternative solution which also appears to work quite well is to shift the line relative to the character width. Might be more robust for different (odd) fonts/resolutions. To keep this simple fix very simple I stuck with shifting 3 units as it appears to work well across sizes and fonts. Example shifting 1/3rd of a character width, an appropriate number is probably between 1/3 and 1/2.

char_width = self.editor.fontMetrics().width('9')
x = column * char_width + 0.33 * char_width

Issue(s) Resolved

Fixes #16248

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: Reinert Huseby Karlsen

[ccordoba12]

Thanks a lot for your help @rhkarls! Please make your branch to derive from our 5.x branch (instead of master), with the following commands:

git checkout 5.x
git checkout shift-editor-edge-line
git rebase --onto 5.x master shift-editor-edge-line
git push -f origin shift-editor-edge-line

Otherwise looks good to me.

[rhkarls]

Thanks a lot for your help @rhkarls! Please make your branch to derive from our 5.x branch (instead of master), with the following commands:

git checkout 5.x
git checkout shift-editor-edge-line
git rebase --onto 5.x master shift-editor-edge-line
git push -f origin shift-editor-edge-line

Otherwise looks good to me.

Cheers! Hope its good with the 5.x branch now - sorry I missed to checkout 5.x earlier

[ccordoba12]

Thanks @rhkarls!

Note: The failures in our tests are unrelated to this.