Expose selection_start

[achristmascarl]

for #80; it is useful information to have access to when the direction of the selection matters

[rhysd]

I feel the following method is a better interface because the word start is a bit confusing when the cursor is before the start position. I think that users want to obtain the range of the selected text rather than a single (row, col) position.

pub fn selection_range(&self) -> Option<((usize, usize), (usize, usize))> {
    // Return (row, col) pair of selection range
}

What do you think?

[achristmascarl]

I think that makes sense!

[achristmascarl]

actually, @rhysd selection_range() conflicts with the private fn which has a different behavior:

tui-textarea/src/textarea.rs

Lines 1433 to 1444 in 93cfabd

	fn selection_range(&self) -> Option<(Pos, Pos)> {
	let (sr, sc) = self.selection_start?;
	let (er, ec) = self.cursor;
	let (so, eo) = (self.line_offset(sr, sc), self.line_offset(er, ec));
	let s = Pos::new(sr, sc, so);
	let e = Pos::new(er, ec, eo);
	match (sr, so).cmp(&(er, eo)) {
	Ordering::Less => Some((s, e)),
	Ordering::Equal => None,
	Ordering::Greater => Some((e, s)),
	}
	}

i guess we could call the public fn something like unordered_selection_range() or selection_range_raw()? although those are a bit unwieldy

[rhysd]

Oops, please just rename the private method to selection_range_ (or selection_range_impl if clippy gets unhappy). Then I will rename it to more proper name after merging this PR.

[rhysd]

Thanks!

[rhysd]

@achristmascarl I modified the API to always make start <= end where let (start, end) = textarea.selection_range() because it is natural to put a smaller value at the left side of the range like a..b.

For your use case, please do the following trick to get the selection start.

let (start, end) = textarea.selection_range();
let selection_start = if start == textarea.cursor() { end } else { start };

[achristmascarl]

ok, that makes sense 👍

[rhysd]

v0.6.1 was released.

https://github.com/rhysd/tui-textarea/releases/tag/v0.6.1