use crate::{ buffer::Buffer, layout::{Alignment, Rect}, style::Style, text::{StyledGrapheme, Text}, widgets::{ reflow::{LineComposer, LineTruncator, WordWrapper}, Block, Widget, }, }; use std::iter; use unicode_width::UnicodeWidthStr; fn get_line_offset(line_width: u16, text_area_width: u16, alignment: Alignment) -> u16 { match alignment { Alignment::Center => (text_area_width / 2).saturating_sub(line_width / 2), Alignment::Right => text_area_width.saturating_sub(line_width), Alignment::Left => 0, } } /// A widget to display some text. /// /// # Examples /// /// ``` /// # use helix_tui::text::{Text, Spans, Span}; /// # use helix_tui::widgets::{Block, Borders, Paragraph, Wrap}; /// # use helix_tui::style::{Style, Color, Modifier}; /// # use helix_tui::layout::{Alignment}; /// let text = vec![ /// Spans::from(vec![ /// Span::raw("First"), /// Span::styled("line",Style::default().add_modifier(Modifier::ITALIC)), /// Span::raw("."), /// ]), /// Spans::from(Span::styled("Second line", Style::default().fg(Color::Red))), /// ]; /// Paragraph::new(text) /// .block(Block::default().title("Paragraph").borders(Borders::ALL)) /// .style(Style::default().fg(Color::White).bg(Color::Black)) /// .alignment(Alignment::Center) /// .wrap(Wrap { trim: true }); /// ``` #[derive(Debug, Clone)] pub struct Paragraph<'a> { /// A block to wrap the widget in block: Option>, /// Widget style style: Style, /// How to wrap the text wrap: Option, /// The text to display text: Text<'a>, /// Scroll scroll: (u16, u16), /// Alignment of the text alignment: Alignment, } /// Describes how to wrap text across lines. /// /// ## Examples /// /// ``` /// # use helix_tui::widgets::{Paragraph, Wrap}; /// # use helix_tui::text::Text; /// let bullet_points = Text::from(r#"Some indented points: /// - First thing goes here and is long so that it wraps /// - Here is another point that is long enough to wrap"#); /// /// // With leading spaces trimmed (window width of 30 chars): /// Paragraph::new(bullet_points.clone()).wrap(Wrap { trim: true }); /// // Some indented points: /// // - First thing goes here and is /// // long so that it wraps /// // - Here is another point that /// // is long enough to wrap /// /// // But without trimming, indentation is preserved: /// Paragraph::new(bullet_points).wrap(Wrap { trim: false }); /// // Some indented points: /// // - First thing goes here /// // and is long so that it wraps /// // - Here is another point /// // that is long enough to wrap /// ``` #[derive(Debug, Clone, Copy)] pub struct Wrap { /// Should leading whitespace be trimmed pub trim: bool, } impl<'a> Paragraph<'a> { pub fn new(text: T) -> Paragraph<'a> where T: Into>, { Paragraph { block: None, style: Default::default(), wrap: None, text: text.into(), scroll: (0, 0), alignment: Alignment::Left, } } pub fn block(mut self, block: Block<'a>) -> Paragraph<'a> { self.block = Some(block); self } pub fn style(mut self, style: Style) -> Paragraph<'a> { self.style = style; self } pub fn wrap(mut self, wrap: Wrap) -> Paragraph<'a> { self.wrap = Some(wrap); self } pub fn scroll(mut self, offset: (u16, u16)) -> Paragraph<'a> { self.scroll = offset; self } pub fn alignment(mut self, alignment: Alignment) -> Paragraph<'a> { self.alignment = alignment; self } } impl<'a> Widget for Paragraph<'a> { fn render(mut self, area: Rect, buf: &mut Buffer) { buf.set_style(area, self.style); let text_area = match self.block.take() { Some(b) => { let inner_area = b.inner(area); b.render(area, buf); inner_area } None => area, }; if text_area.height < 1 { return; } let style = self.style; let mut styled = self.text.lines.iter().flat_map(|spans| { spans .0 .iter() .flat_map(|span| span.styled_graphemes(style)) // Required given the way composers work but might be refactored out if we change // composers to operate on lines instead of a stream of graphemes. .chain(iter::once(StyledGrapheme { symbol: "\n", style: self.style, })) }); let mut line_composer: Box = if let Some(Wrap { trim }) = self.wrap { Box::new(WordWrapper::new(&mut styled, text_area.width, trim)) } else { let mut line_composer = Box::new(LineTruncator::new(&mut styled, text_area.width)); if let Alignment::Left = self.alignment { line_composer.set_horizontal_offset(self.scroll.1); } line_composer }; let mut y = 0; while let Some((current_line, current_line_width)) = line_composer.next_line() { if y >= self.scroll.0 { let mut x = get_line_offset(current_line_width, text_area.width, self.alignment); for StyledGrapheme { symbol, style } in current_line { buf.get_mut(text_area.left() + x, text_area.top() + y - self.scroll.0) .set_symbol(if symbol.is_empty() { // If the symbol is empty, the last char which rendered last time will // leave on the line. It's a quick fix. " " } else { symbol }) .set_style(*style); x += symbol.width() as u16; } } y += 1; if y >= text_area.height + self.scroll.0 { break; } } } }