Fix get_visible_line_count in RichTextLabel

[voylin]

Fixes #75847

The _draw_line() function in RichTextLabel was adding to line_count, no matter how many lines were actually visible. This made the function get_visible_line_count() to return an incorrect amount. For visible_characters = 0 it would return 0, but setting it any higher would return a line count for all lines, even ones which weren't visible.

I hope this is enough to fix and close #75847

[bruvzg]

This looks OK, but will also change behavior on completely empty lines (which were counted before), and I'm not sure if it's desired.

[KoBeWi]

This looks OK, but will also change behavior on completely empty lines (which were counted before), and I'm not sure if it's desired.

You mean they are no longer counted?
I tested and it seems to work, at least partially

test

test

correctly returns 3 lines.

test

incorrectly (?) returns 3 lines. Looks like if the text ends with empty line, it will be ignored. All other empty lines are properly counted.

[bruvzg]

Looks like if the text ends with empty line, it will be ignored. All other empty lines are properly counted.

All other lines except last probably aren't fully empty (contain line break character).

[bruvzg]

Old code was not counting the last empty line either, so this should not be a concern (at least not in this PR context).

[voylin]

This looks OK, but will also change behavior on completely empty lines (which were counted before), and I'm not sure if it's desired.

I just tested this but empty lines are still being counted, so not really an issue.

I'm just printing the visible lines in _process for this quick test.

[akien-mga]

Thanks!