wisp/view/
widgets.rs

1use crate::theme::Theme;
2use crate::view::edit_buffer::EditBuffer;
3use crate::view::wrap::{as_u16, fit_prefix};
4use ratatui::buffer::Buffer;
5use ratatui::layout::{Constraint, Layout, Rect};
6use ratatui::style::{Modifier, Style};
7use ratatui::text::{Line, Span};
8use ratatui::widgets::{Scrollbar, ScrollbarOrientation, ScrollbarState, StatefulWidget, Widget};
9use std::borrow::Cow;
10use unicode_width::UnicodeWidthStr;
11
12/// A key and what it does, for [`key_hints`]. Borrowed for the fixed labels most
13/// footers use, owned for the ones that interpolate live state.
14pub type KeyHint = (&'static str, Cow<'static, str>);
15
16/// Columns a vertical scrollbar track occupies.
17pub const SCROLLBAR_WIDTH: u16 = 1;
18
19/// Splits `area` into the rows and the scrollbar track beside them, so the
20/// track never sits on top of a row. Without a scrollbar the rows get it all.
21///
22/// Every scrolling pane in the UI — list, document, and form — carves its area
23/// up this way, and builds its rows to the width this leaves.
24pub fn rows_and_track(area: Rect, scrollbar: bool) -> (Rect, Rect) {
25    let track_width = if scrollbar { SCROLLBAR_WIDTH } else { 0 };
26    let [rows, track] = Layout::horizontal([Constraint::Min(0), Constraint::Length(track_width)]).areas(area);
27    (rows, track)
28}
29
30/// The full-width, one-row `Rect` for the `index`-th visible row of `area`, or
31/// nothing once `index` falls past the bottom.
32pub fn row_area(area: Rect, index: usize) -> Option<Rect> {
33    let offset = as_u16(index);
34    (offset < area.height).then(|| Rect { y: area.y + offset, height: 1, ..area })
35}
36
37/// Draws already-built rows directly into a buffer area.
38#[derive(Clone)]
39pub struct RowsView<'a> {
40    lines: Cow<'a, [Line<'static>]>,
41}
42
43impl<'a> RowsView<'a> {
44    pub fn new(lines: &'a [Line<'static>]) -> Self {
45        Self { lines: Cow::Borrowed(lines) }
46    }
47
48    pub fn from_lines(lines: impl IntoIterator<Item = Line<'static>>) -> Self {
49        Self { lines: Cow::Owned(lines.into_iter().collect()) }
50    }
51}
52
53impl Widget for RowsView<'_> {
54    fn render(self, area: Rect, buf: &mut Buffer) {
55        for (index, line) in self.lines.iter().enumerate() {
56            let Some(row) = row_area(area, index) else {
57                return;
58            };
59            line.render(row, buf);
60        }
61    }
62}
63
64/// Draws the vertical scrollbar for `content_rows` of content scrolled to
65/// `offset`, sized against the rows `area` can actually show.
66///
67/// The track length is the number of reachable scroll positions rather than the
68/// row count, so the thumb reaches the bottom exactly when the last row is
69/// visible.
70pub fn render_vertical_scrollbar(area: Rect, buf: &mut Buffer, content_rows: usize, offset: usize) {
71    let scrollable = content_rows.saturating_sub(usize::from(area.height));
72    let mut state = ScrollbarState::new(scrollable).position(offset);
73    StatefulWidget::render(Scrollbar::new(ScrollbarOrientation::VerticalRight), area, buf, &mut state);
74}
75
76/// A footer's key hints, each key in the accent colour ahead of its muted
77/// description. Every full-screen route labels its keys the same way.
78///
79/// A single space separates the pairs: the highlighted keys already break them
80/// up, and these footers are long enough that anything wider wraps at 80
81/// columns.
82pub fn key_hints(hints: &[(impl AsRef<str>, impl AsRef<str>)], theme: &Theme) -> Line<'static> {
83    let key_style = Style::from((theme.accent, Modifier::BOLD));
84    let muted = Style::from(theme.muted);
85    let mut spans = Vec::with_capacity(hints.len() * 3);
86    for (key, description) in hints {
87        if !spans.is_empty() {
88            spans.push(Span::raw(" "));
89        }
90        spans.push(Span::styled(key.as_ref().to_string(), key_style));
91        spans.push(Span::styled(format!(" {}", description.as_ref()), muted));
92    }
93    Line::from(spans)
94}
95
96pub(crate) fn visible_window(buffer: &EditBuffer, width: usize) -> (String, usize) {
97    if width == 0 {
98        return (String::new(), 0);
99    }
100    let text = buffer.text();
101    let cursor_column = text[..buffer.cursor()].width();
102    let start_column = cursor_column.saturating_sub(width.saturating_sub(1));
103    let (start, _) = fit_prefix(text, start_column);
104    let cursor_width = text[start..buffer.cursor()].width();
105    let (visible_len, _) = fit_prefix(&text[start..], width);
106    (text[start..start + visible_len].to_string(), cursor_width.min(width.saturating_sub(1)))
107}
wisp/view/widgets.rs

wisp/view/
widgets.rs
