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, } 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(lines: Vec) -> Buffer where S: AsRef, { 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 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. 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. 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(&mut self, x: u16, y: u16, string: S, style: Style) where S: AsRef, { 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( &mut self, x: u16, y: u16, string: S, width: usize, style: Style, ) -> (u16, u16) where S: AsRef, { self.set_string_truncated(x, y, string, width, style, false) } /// Print at most the first `width` characters of a string if enough space is available /// until the end of the line. If `markend` is true appends a `…` at the end of /// truncated lines. pub fn set_string_truncated( &mut self, x: u16, y: u16, string: S, width: usize, style: Style, ellipsis: bool, ) -> (u16, u16) where S: AsRef, { let mut index = self.index_of(x, y); let mut x_offset = x as usize; let width = if ellipsis { width - 1 } else { width }; 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; } if ellipsis && x_offset - (x as usize) < string.as_ref().chars().count() { self.content[index].set_symbol("…"); } (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(); } } /// Clear an area in the buffer pub fn clear(&mut self, area: Rect) { for x in area.left()..area.right() { for y in area.top()..area.bottom() { self.get_mut(x, y).reset(); } } } /// Clear an area in the buffer with a default style. pub fn clear_with(&mut self, area: Rect, style: Style) { for x in area.left()..area.right() { for y in area.top()..area.bottom() { let cell = self.get_mut(x, y); cell.reset(); cell.set_style(style); } } } /// 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")] #[cfg(debug_assertions)] 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")] #[cfg(debug_assertions)] 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); } }