Line width measurement different when aligned

[Imberflur]

Line width appears to be measured from the left side of the bounds rather than the start of the text (for LTR text). This is noticeable when text is aligned so that it doesn't start at the left side (e.g. Align::Center or Align::Right). (looking at the code, I believe the same applies to RTL text but in the opposite direction)

Is this intentional or a bug? For layout of UIs it would be useful to have this be the width of the actual text.

For example:

    use cosmic_text::{Align, Attrs, AttrsList, BufferLine, FontSystem, Shaping, Wrap};

    let mut font_system = FontSystem::new();
    let font_size = 14.0;
    let width = 8000.0;

    let mut line = BufferLine::new(
        "Hello, Rust!",
        AttrsList::new(Attrs::new()),
        Shaping::Advanced,
    );

    let layout = line.layout(&mut font_system, font_size, width, Wrap::None);
    let w = layout[0].w;

    line.set_align(Some(Align::Center));
    let layout = line.layout(&mut font_system, font_size, width, Wrap::None);
    let center_w = layout[0].w;

    line.set_align(Some(Align::Right));
    let layout = line.layout(&mut font_system, font_size, width, Wrap::None);
    let right_w = layout[0].w;

    dbg!(w);
    dbg!(center_w);
    dbg!(right_w);

prints:

w = 74.242
center_w = 4037.121
right_w = 8000.0

I have a tested a potential fix locally that could be made into a PR.