Inline tui as helix-tui fork.

We only rely on some of the rendering primitives and implement our
Cursive-style compositor on top.

1 files changed, 745 insertions, 0 deletions

diff --git a/helix-tui/src/buffer.rs b/helix-tui/src/buffer.rs
new file mode 100644
index 00000000..8a227ce7
--- /dev/null
+++ b/helix-tui/src/buffer.rs
@@ -0,0 +1,745 @@
+use crate::{
+    layout::Rect,
+    style::{Color, Modifier, Style},
+    text::{Span, Spans},
+};
+use std::cmp::min;
+use unicode_segmentation::UnicodeSegmentation;
+use unicode_width::UnicodeWidthStr;
+
+/// A buffer cell
+#[derive(Debug, Clone, PartialEq)]
+pub struct Cell {
+    pub symbol: String,
+    pub fg: Color,
+    pub bg: Color,
+    pub modifier: Modifier,
+}
+
+impl Cell {
+    pub fn set_symbol(&mut self, symbol: &str) -> &mut Cell {
+        self.symbol.clear();
+        self.symbol.push_str(symbol);
+        self
+    }
+
+    pub fn set_char(&mut self, ch: char) -> &mut Cell {
+        self.symbol.clear();
+        self.symbol.push(ch);
+        self
+    }
+
+    pub fn set_fg(&mut self, color: Color) -> &mut Cell {
+        self.fg = color;
+        self
+    }
+
+    pub fn set_bg(&mut self, color: Color) -> &mut Cell {
+        self.bg = color;
+        self
+    }
+
+    pub fn set_style(&mut self, style: Style) -> &mut Cell {
+        if let Some(c) = style.fg {
+            self.fg = c;
+        }
+        if let Some(c) = style.bg {
+            self.bg = c;
+        }
+        self.modifier.insert(style.add_modifier);
+        self.modifier.remove(style.sub_modifier);
+        self
+    }
+
+    pub fn style(&self) -> Style {
+        Style::default()
+            .fg(self.fg)
+            .bg(self.bg)
+            .add_modifier(self.modifier)
+    }
+
+    pub fn reset(&mut self) {
+        self.symbol.clear();
+        self.symbol.push(' ');
+        self.fg = Color::Reset;
+        self.bg = Color::Reset;
+        self.modifier = Modifier::empty();
+    }
+}
+
+impl Default for Cell {
+    fn default() -> Cell {
+        Cell {
+            symbol: " ".into(),
+            fg: Color::Reset,
+            bg: Color::Reset,
+            modifier: Modifier::empty(),
+        }
+    }
+}
+
+/// A buffer that maps to the desired content of the terminal after the draw call
+///
+/// No widget in the library interacts directly with the terminal. Instead each of them is required
+/// to draw their state to an intermediate buffer. It is basically a grid where each cell contains
+/// a grapheme, a foreground color and a background color. This grid will then be used to output
+/// the appropriate escape sequences and characters to draw the UI as the user has defined it.
+///
+/// # Examples:
+///
+/// ```
+/// use helix_tui::buffer::{Buffer, Cell};
+/// use helix_tui::layout::Rect;
+/// use helix_tui::style::{Color, Style, Modifier};
+///
+/// let mut buf = Buffer::empty(Rect{x: 0, y: 0, width: 10, height: 5});
+/// buf.get_mut(0, 2).set_symbol("x");
+/// assert_eq!(buf.get(0, 2).symbol, "x");
+/// buf.set_string(3, 0, "string", Style::default().fg(Color::Red).bg(Color::White));
+/// assert_eq!(buf.get(5, 0), &Cell{
+///     symbol: String::from("r"),
+///     fg: Color::Red,
+///     bg: Color::White,
+///     modifier: Modifier::empty()
+/// });
+/// buf.get_mut(5, 0).set_char('x');
+/// assert_eq!(buf.get(5, 0).symbol, "x");
+/// ```
+#[derive(Debug, Clone, PartialEq)]
+pub struct Buffer {
+    /// The area represented by this buffer
+    pub area: Rect,
+    /// The content of the buffer. The length of this Vec should always be equal to area.width *
+    /// area.height
+    pub content: Vec<Cell>,
+}
+
+impl Default for Buffer {
+    fn default() -> Buffer {
+        Buffer {
+            area: Default::default(),
+            content: Vec::new(),
+        }
+    }
+}
+
+impl Buffer {
+    /// Returns a Buffer with all cells set to the default one
+    pub fn empty(area: Rect) -> Buffer {
+        let cell: Cell = Default::default();
+        Buffer::filled(area, &cell)
+    }
+
+    /// Returns a Buffer with all cells initialized with the attributes of the given Cell
+    pub fn filled(area: Rect, cell: &Cell) -> Buffer {
+        let size = area.area() as usize;
+        let mut content = Vec::with_capacity(size);
+        for _ in 0..size {
+            content.push(cell.clone());
+        }
+        Buffer { area, content }
+    }
+
+    /// Returns a Buffer containing the given lines
+    pub fn with_lines<S>(lines: Vec<S>) -> Buffer
+    where
+        S: AsRef<str>,
+    {
+        let height = lines.len() as u16;
+        let width = lines
+            .iter()
+            .map(|i| i.as_ref().width() as u16)
+            .max()
+            .unwrap_or_default();
+        let mut buffer = Buffer::empty(Rect {
+            x: 0,
+            y: 0,
+            width,
+            height,
+        });
+        for (y, line) in lines.iter().enumerate() {
+            buffer.set_string(0, y as u16, line, Style::default());
+        }
+        buffer
+    }
+
+    /// Returns the content of the buffer as a slice
+    pub fn content(&self) -> &[Cell] {
+        &self.content
+    }
+
+    /// Returns the area covered by this buffer
+    pub fn area(&self) -> &Rect {
+        &self.area
+    }
+
+    /// Returns a reference to Cell at the given coordinates
+    pub fn get(&self, x: u16, y: u16) -> &Cell {
+        let i = self.index_of(x, y);
+        &self.content[i]
+    }
+
+    /// Returns a mutable reference to Cell at the given coordinates
+    pub fn get_mut(&mut self, x: u16, y: u16) -> &mut Cell {
+        let i = self.index_of(x, y);
+        &mut self.content[i]
+    }
+
+    /// Returns the index in the Vec<Cell> for the given global (x, y) coordinates.
+    ///
+    /// Global coordinates are offset by the Buffer's area offset (`x`/`y`).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use helix_tui::buffer::Buffer;
+    /// # use helix_tui::layout::Rect;
+    /// let rect = Rect::new(200, 100, 10, 10);
+    /// let buffer = Buffer::empty(rect);
+    /// // Global coordinates to the top corner of this buffer's area
+    /// assert_eq!(buffer.index_of(200, 100), 0);
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// Panics when given an coordinate that is outside of this Buffer's area.
+    ///
+    /// ```should_panic
+    /// # use helix_tui::buffer::Buffer;
+    /// # use helix_tui::layout::Rect;
+    /// let rect = Rect::new(200, 100, 10, 10);
+    /// let buffer = Buffer::empty(rect);
+    /// // Top coordinate is outside of the buffer in global coordinate space, as the Buffer's area
+    /// // starts at (200, 100).
+    /// buffer.index_of(0, 0); // Panics
+    /// ```
+    pub fn index_of(&self, x: u16, y: u16) -> usize {
+        debug_assert!(
+            x >= self.area.left()
+                && x < self.area.right()
+                && y >= self.area.top()
+                && y < self.area.bottom(),
+            "Trying to access position outside the buffer: x={}, y={}, area={:?}",
+            x,
+            y,
+            self.area
+        );
+        ((y - self.area.y) * self.area.width + (x - self.area.x)) as usize
+    }
+
+    /// Returns the (global) coordinates of a cell given its index
+    ///
+    /// Global coordinates are offset by the Buffer's area offset (`x`/`y`).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use helix_tui::buffer::Buffer;
+    /// # use helix_tui::layout::Rect;
+    /// let rect = Rect::new(200, 100, 10, 10);
+    /// let buffer = Buffer::empty(rect);
+    /// assert_eq!(buffer.pos_of(0), (200, 100));
+    /// assert_eq!(buffer.pos_of(14), (204, 101));
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// Panics when given an index that is outside the Buffer's content.
+    ///
+    /// ```should_panic
+    /// # use helix_tui::buffer::Buffer;
+    /// # use helix_tui::layout::Rect;
+    /// let rect = Rect::new(0, 0, 10, 10); // 100 cells in total
+    /// let buffer = Buffer::empty(rect);
+    /// // Index 100 is the 101th cell, which lies outside of the area of this Buffer.
+    /// buffer.pos_of(100); // Panics
+    /// ```
+    pub fn pos_of(&self, i: usize) -> (u16, u16) {
+        debug_assert!(
+            i < self.content.len(),
+            "Trying to get the coords of a cell outside the buffer: i={} len={}",
+            i,
+            self.content.len()
+        );
+        (
+            self.area.x + i as u16 % self.area.width,
+            self.area.y + i as u16 / self.area.width,
+        )
+    }
+
+    /// Print a string, starting at the position (x, y)
+    pub fn set_string<S>(&mut self, x: u16, y: u16, string: S, style: Style)
+    where
+        S: AsRef<str>,
+    {
+        self.set_stringn(x, y, string, usize::MAX, style);
+    }
+
+    /// Print at most the first n characters of a string if enough space is available
+    /// until the end of the line
+    pub fn set_stringn<S>(
+        &mut self,
+        x: u16,
+        y: u16,
+        string: S,
+        width: usize,
+        style: Style,
+    ) -> (u16, u16)
+    where
+        S: AsRef<str>,
+    {
+        let mut index = self.index_of(x, y);
+        let mut x_offset = x as usize;
+        let graphemes = UnicodeSegmentation::graphemes(string.as_ref(), true);
+        let max_offset = min(self.area.right() as usize, width.saturating_add(x as usize));
+        for s in graphemes {
+            let width = s.width();
+            if width == 0 {
+                continue;
+            }
+            // `x_offset + width > max_offset` could be integer overflow on 32-bit machines if we
+            // change dimenstions to usize or u32 and someone resizes the terminal to 1x2^32.
+            if width > max_offset.saturating_sub(x_offset) {
+                break;
+            }
+
+            self.content[index].set_symbol(s);
+            self.content[index].set_style(style);
+            // Reset following cells if multi-width (they would be hidden by the grapheme),
+            for i in index + 1..index + width {
+                self.content[i].reset();
+            }
+            index += width;
+            x_offset += width;
+        }
+        (x_offset as u16, y)
+    }
+
+    pub fn set_spans<'a>(&mut self, x: u16, y: u16, spans: &Spans<'a>, width: u16) -> (u16, u16) {
+        let mut remaining_width = width;
+        let mut x = x;
+        for span in &spans.0 {
+            if remaining_width == 0 {
+                break;
+            }
+            let pos = self.set_stringn(
+                x,
+                y,
+                span.content.as_ref(),
+                remaining_width as usize,
+                span.style,
+            );
+            let w = pos.0.saturating_sub(x);
+            x = pos.0;
+            remaining_width = remaining_width.saturating_sub(w);
+        }
+        (x, y)
+    }
+
+    pub fn set_span<'a>(&mut self, x: u16, y: u16, span: &Span<'a>, width: u16) -> (u16, u16) {
+        self.set_stringn(x, y, span.content.as_ref(), width as usize, span.style)
+    }
+
+    #[deprecated(
+        since = "0.10.0",
+        note = "You should use styling capabilities of `Buffer::set_style`"
+    )]
+    pub fn set_background(&mut self, area: Rect, color: Color) {
+        for y in area.top()..area.bottom() {
+            for x in area.left()..area.right() {
+                self.get_mut(x, y).set_bg(color);
+            }
+        }
+    }
+
+    pub fn set_style(&mut self, area: Rect, style: Style) {
+        for y in area.top()..area.bottom() {
+            for x in area.left()..area.right() {
+                self.get_mut(x, y).set_style(style);
+            }
+        }
+    }
+
+    /// Resize the buffer so that the mapped area matches the given area and that the buffer
+    /// length is equal to area.width * area.height
+    pub fn resize(&mut self, area: Rect) {
+        let length = area.area() as usize;
+        if self.content.len() > length {
+            self.content.truncate(length);
+        } else {
+            self.content.resize(length, Default::default());
+        }
+        self.area = area;
+    }
+
+    /// Reset all cells in the buffer
+    pub fn reset(&mut self) {
+        for c in &mut self.content {
+            c.reset();
+        }
+    }
+
+    /// Merge an other buffer into this one
+    pub fn merge(&mut self, other: &Buffer) {
+        let area = self.area.union(other.area);
+        let cell: Cell = Default::default();
+        self.content.resize(area.area() as usize, cell.clone());
+
+        // Move original content to the appropriate space
+        let size = self.area.area() as usize;
+        for i in (0..size).rev() {
+            let (x, y) = self.pos_of(i);
+            // New index in content
+            let k = ((y - area.y) * area.width + x - area.x) as usize;
+            if i != k {
+                self.content[k] = self.content[i].clone();
+                self.content[i] = cell.clone();
+            }
+        }
+
+        // Push content of the other buffer into this one (may erase previous
+        // data)
+        let size = other.area.area() as usize;
+        for i in 0..size {
+            let (x, y) = other.pos_of(i);
+            // New index in content
+            let k = ((y - area.y) * area.width + x - area.x) as usize;
+            self.content[k] = other.content[i].clone();
+        }
+        self.area = area;
+    }
+
+    /// Builds a minimal sequence of coordinates and Cells necessary to update the UI from
+    /// self to other.
+    ///
+    /// We're assuming that buffers are well-formed, that is no double-width cell is followed by
+    /// a non-blank cell.
+    ///
+    /// # Multi-width characters handling:
+    ///
+    /// ```text
+    /// (Index:) `01`
+    /// Prev:    `コ`
+    /// Next:    `aa`
+    /// Updates: `0: a, 1: a'
+    /// ```
+    ///
+    /// ```text
+    /// (Index:) `01`
+    /// Prev:    `a `
+    /// Next:    `コ`
+    /// Updates: `0: コ` (double width symbol at index 0 - skip index 1)
+    /// ```
+    ///
+    /// ```text
+    /// (Index:) `012`
+    /// Prev:    `aaa`
+    /// Next:    `aコ`
+    /// Updates: `0: a, 1: コ` (double width symbol at index 1 - skip index 2)
+    /// ```
+    pub fn diff<'a>(&self, other: &'a Buffer) -> Vec<(u16, u16, &'a Cell)> {
+        let previous_buffer = &self.content;
+        let next_buffer = &other.content;
+        let width = self.area.width;
+
+        let mut updates: Vec<(u16, u16, &Cell)> = vec![];
+        // Cells invalidated by drawing/replacing preceeding multi-width characters:
+        let mut invalidated: usize = 0;
+        // Cells from the current buffer to skip due to preceeding multi-width characters taking their
+        // place (the skipped cells should be blank anyway):
+        let mut to_skip: usize = 0;
+        for (i, (current, previous)) in next_buffer.iter().zip(previous_buffer.iter()).enumerate() {
+            if (current != previous || invalidated > 0) && to_skip == 0 {
+                let x = i as u16 % width;
+                let y = i as u16 / width;
+                updates.push((x, y, &next_buffer[i]));
+            }
+
+            to_skip = current.symbol.width().saturating_sub(1);
+
+            let affected_width = std::cmp::max(current.symbol.width(), previous.symbol.width());
+            invalidated = std::cmp::max(affected_width, invalidated).saturating_sub(1);
+        }
+        updates
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn cell(s: &str) -> Cell {
+        let mut cell = Cell::default();
+        cell.set_symbol(s);
+        cell
+    }
+
+    #[test]
+    fn it_translates_to_and_from_coordinates() {
+        let rect = Rect::new(200, 100, 50, 80);
+        let buf = Buffer::empty(rect);
+
+        // First cell is at the upper left corner.
+        assert_eq!(buf.pos_of(0), (200, 100));
+        assert_eq!(buf.index_of(200, 100), 0);
+
+        // Last cell is in the lower right.
+        assert_eq!(buf.pos_of(buf.content.len() - 1), (249, 179));
+        assert_eq!(buf.index_of(249, 179), buf.content.len() - 1);
+    }
+
+    #[test]
+    #[should_panic(expected = "outside the buffer")]
+    fn pos_of_panics_on_out_of_bounds() {
+        let rect = Rect::new(0, 0, 10, 10);
+        let buf = Buffer::empty(rect);
+
+        // There are a total of 100 cells; zero-indexed means that 100 would be the 101st cell.
+        buf.pos_of(100);
+    }
+
+    #[test]
+    #[should_panic(expected = "outside the buffer")]
+    fn index_of_panics_on_out_of_bounds() {
+        let rect = Rect::new(0, 0, 10, 10);
+        let buf = Buffer::empty(rect);
+
+        // width is 10; zero-indexed means that 10 would be the 11th cell.
+        buf.index_of(10, 0);
+    }
+
+    #[test]
+    fn buffer_set_string() {
+        let area = Rect::new(0, 0, 5, 1);
+        let mut buffer = Buffer::empty(area);
+
+        // Zero-width
+        buffer.set_stringn(0, 0, "aaa", 0, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["     "]));
+
+        buffer.set_string(0, 0, "aaa", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["aaa  "]));
+
+        // Width limit:
+        buffer.set_stringn(0, 0, "bbbbbbbbbbbbbb", 4, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["bbbb "]));
+
+        buffer.set_string(0, 0, "12345", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["12345"]));
+
+        // Width truncation:
+        buffer.set_string(0, 0, "123456", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["12345"]));
+    }
+
+    #[test]
+    fn buffer_set_string_zero_width() {
+        let area = Rect::new(0, 0, 1, 1);
+        let mut buffer = Buffer::empty(area);
+
+        // Leading grapheme with zero width
+        let s = "\u{1}a";
+        buffer.set_stringn(0, 0, s, 1, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["a"]));
+
+        // Trailing grapheme with zero with
+        let s = "a\u{1}";
+        buffer.set_stringn(0, 0, s, 1, Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["a"]));
+    }
+
+    #[test]
+    fn buffer_set_string_double_width() {
+        let area = Rect::new(0, 0, 5, 1);
+        let mut buffer = Buffer::empty(area);
+        buffer.set_string(0, 0, "コン", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["コン "]));
+
+        // Only 1 space left.
+        buffer.set_string(0, 0, "コンピ", Style::default());
+        assert_eq!(buffer, Buffer::with_lines(vec!["コン "]));
+    }
+
+    #[test]
+    fn buffer_with_lines() {
+        let buffer =
+            Buffer::with_lines(vec!["┌────────┐", "│コンピュ│", "│ーa 上で│", "└────────┘"]);
+        assert_eq!(buffer.area.x, 0);
+        assert_eq!(buffer.area.y, 0);
+        assert_eq!(buffer.area.width, 10);
+        assert_eq!(buffer.area.height, 4);
+    }
+
+    #[test]
+    fn buffer_diffing_empty_empty() {
+        let area = Rect::new(0, 0, 40, 40);
+        let prev = Buffer::empty(area);
+        let next = Buffer::empty(area);
+        let diff = prev.diff(&next);
+        assert_eq!(diff, vec![]);
+    }
+
+    #[test]
+    fn buffer_diffing_empty_filled() {
+        let area = Rect::new(0, 0, 40, 40);
+        let prev = Buffer::empty(area);
+        let next = Buffer::filled(area, Cell::default().set_symbol("a"));
+        let diff = prev.diff(&next);
+        assert_eq!(diff.len(), 40 * 40);
+    }
+
+    #[test]
+    fn buffer_diffing_filled_filled() {
+        let area = Rect::new(0, 0, 40, 40);
+        let prev = Buffer::filled(area, Cell::default().set_symbol("a"));
+        let next = Buffer::filled(area, Cell::default().set_symbol("a"));
+        let diff = prev.diff(&next);
+        assert_eq!(diff, vec![]);
+    }
+
+    #[test]
+    fn buffer_diffing_single_width() {
+        let prev = Buffer::with_lines(vec![
+            "          ",
+            "┌Title─┐  ",
+            "│      │  ",
+            "│      │  ",
+            "└──────┘  ",
+        ]);
+        let next = Buffer::with_lines(vec![
+            "          ",
+            "┌TITLE─┐  ",
+            "│      │  ",
+            "│      │  ",
+            "└──────┘  ",
+        ]);
+        let diff = prev.diff(&next);
+        assert_eq!(
+            diff,
+            vec![
+                (2, 1, &cell("I")),
+                (3, 1, &cell("T")),
+                (4, 1, &cell("L")),
+                (5, 1, &cell("E")),
+            ]
+        );
+    }
+
+    #[test]
+    #[rustfmt::skip]
+    fn buffer_diffing_multi_width() {
+        let prev = Buffer::with_lines(vec![
+            "┌Title─┐  ",
+            "└──────┘  ",
+        ]);
+        let next = Buffer::with_lines(vec![
+            "┌称号──┐  ",
+            "└──────┘  ",
+        ]);
+        let diff = prev.diff(&next);
+        assert_eq!(
+            diff,
+            vec![
+                (1, 0, &cell("称")),
+                // Skipped "i"
+                (3, 0, &cell("号")),
+                // Skipped "l"
+                (5, 0, &cell("─")),
+            ]
+        );
+    }
+
+    #[test]
+    fn buffer_diffing_multi_width_offset() {
+        let prev = Buffer::with_lines(vec!["┌称号──┐"]);
+        let next = Buffer::with_lines(vec!["┌─称号─┐"]);
+
+        let diff = prev.diff(&next);
+        assert_eq!(
+            diff,
+            vec![(1, 0, &cell("─")), (2, 0, &cell("称")), (4, 0, &cell("号")),]
+        );
+    }
+
+    #[test]
+    fn buffer_merge() {
+        let mut one = Buffer::filled(
+            Rect {
+                x: 0,
+                y: 0,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("1"),
+        );
+        let two = Buffer::filled(
+            Rect {
+                x: 0,
+                y: 2,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("2"),
+        );
+        one.merge(&two);
+        assert_eq!(one, Buffer::with_lines(vec!["11", "11", "22", "22"]));
+    }
+
+    #[test]
+    fn buffer_merge2() {
+        let mut one = Buffer::filled(
+            Rect {
+                x: 2,
+                y: 2,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("1"),
+        );
+        let two = Buffer::filled(
+            Rect {
+                x: 0,
+                y: 0,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("2"),
+        );
+        one.merge(&two);
+        assert_eq!(
+            one,
+            Buffer::with_lines(vec!["22  ", "22  ", "  11", "  11"])
+        );
+    }
+
+    #[test]
+    fn buffer_merge3() {
+        let mut one = Buffer::filled(
+            Rect {
+                x: 3,
+                y: 3,
+                width: 2,
+                height: 2,
+            },
+            Cell::default().set_symbol("1"),
+        );
+        let two = Buffer::filled(
+            Rect {
+                x: 1,
+                y: 1,
+                width: 3,
+                height: 4,
+            },
+            Cell::default().set_symbol("2"),
+        );
+        one.merge(&two);
+        let mut merged = Buffer::with_lines(vec!["222 ", "222 ", "2221", "2221"]);
+        merged.area = Rect {
+            x: 1,
+            y: 1,
+            width: 4,
+            height: 4,
+        };
+        assert_eq!(one, merged);
+    }
+}