Paragraph: word wrapping

examples/paragraph.rs

@@ -30,12 +30,13 @@ fn main() -> Result<(), failure::Error> {
 
  let events = Events::new();
 
+ let mut scroll: u16 = 0;
  loop {
  terminal.draw(|mut f| {
  let size = f.size();
 
  // Words made "loooong" to demonstrate line breaking.
- let s = "Veeeeeeeeeeeeeeeery loooooooooooooooooong striiiiiiiiiiiiiiiiiiiiiiiiiing. ";
+ let s = "Veeeeeeeeeeeeeeeery  loooooooooooooooooong  striiiiiiiiiiiiiiiiiiiiiiiiiing.  ";
  let mut long_line = s.repeat(usize::from(size.width) / s.len() + 4);
  long_line.push('\n');
 
@@ -58,16 +59,16 @@ fn main() -> Result<(), failure::Error> {
  .split(size);
 
  let text = [
- Text::raw("This a line\n"),
- Text::styled("This a line\n", Style::default().fg(Color::Red)),
- Text::styled("This a line\n", Style::default().bg(Color::Blue)),
+ Text::raw("This is a line \n"),
+ Text::styled("This is a line \n", Style::default().fg(Color::Red)),
+ Text::styled("This is a line\n", Style::default().bg(Color::Blue)),
  Text::styled(
- "This a longer line\n",
+ "This is a longer line\n",
  Style::default().modifier(Modifier::CrossedOut),
  ),
- Text::raw(&long_line),
+ Text::styled(&long_line, Style::default().bg(Color::Green)),
  Text::styled(
- "This a line\n",
+ "This is a line\n",
  Style::default().fg(Color::Green).modifier(Modifier::Italic),
  ),
  ];
@@ -88,6 +89,7 @@ fn main() -> Result<(), failure::Error> {
  .block(block.clone().title("Center, wrap"))
  .alignment(Alignment::Center)
  .wrap(true)
+ .scroll(scroll)
  .render(&mut f, chunks[2]);
  Paragraph::new(text.iter())
  .block(block.clone().title("Right, wrap"))
@@ -96,6 +98,9 @@ fn main() -> Result<(), failure::Error> {
  .render(&mut f, chunks[3]);
  })?;
 
+ scroll += 1;
+ scroll %= 10;
+
  match events.next()? {
  Event::Input(key) => {
  if key == Key::Char('q') {

src/widgets/mod.rs

@@ -7,6 +7,7 @@ mod chart;
 mod gauge;
 mod list;
 mod paragraph;
+mod reflow;
 mod sparkline;
 mod table;
 mod tabs;

src/widgets/paragraph.rs

@@ -1,13 +1,21 @@
 use either::Either;
-use itertools::{multipeek, MultiPeek};
 use unicode_segmentation::UnicodeSegmentation;
 use unicode_width::UnicodeWidthStr;
 
 use buffer::Buffer;
 use layout::{Alignment, Rect};
 use style::Style;
+use widgets::reflow::{LineComposer, LineTruncator, Styled, WordWrapper};
 use widgets::{Block, Text, Widget};
 
+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
@@ -96,7 +104,7 @@ where
  }
 }
 
-impl<'a, 't, T> Widget for Paragraph<'a, 't, T>
+impl<'a, 't, 'b, T> Widget for Paragraph<'a, 't, T>
 where
  T: Iterator<Item = &'t Text<'t>>,
 {
@@ -116,94 +124,37 @@ where
  self.background(&text_area, buf, self.style.bg);
 
  let style = self.style;
- let styled = self.text.by_ref().flat_map(|t| match *t {
+ let mut styled = self.text.by_ref().flat_map(|t| match *t {
  Text::Raw(ref d) => {
  let data: &'t str = d; // coerce to &str
- Either::Left(UnicodeSegmentation::graphemes(data, true).map(|g| (g, style)))
+ Either::Left(UnicodeSegmentation::graphemes(data, true).map(|g| Styled(g, style)))
  }
  Text::Styled(ref d, s) => {
  let data: &'t str = d; // coerce to &str
- Either::Right(UnicodeSegmentation::graphemes(data, true).map(move |g| (g, s)))
+ Either::Right(UnicodeSegmentation::graphemes(data, true).map(move |g| Styled(g, s)))
  }
  });
- let mut styled = multipeek(styled);
 
- fn get_cur_line_len<'a, I: Iterator<Item = (&'a str, Style)>>(
- styled: &mut MultiPeek<I>,
- ) -> u16 {
- let mut line_len = 0;
- while match &styled.peek() {
- Some(&(x, _)) => x != "\n",
- None => false,
- } {
- line_len += 1;
- }
- line_len
- };
-
- let mut x = match self.alignment {
- Alignment::Center => {
- (text_area.width / 2).saturating_sub(get_cur_line_len(&mut styled) / 2)
- }
- Alignment::Right => (text_area.width).saturating_sub(get_cur_line_len(&mut styled)),
- Alignment::Left => 0,
+ let mut line_composer: Box<dyn LineComposer> = if self.wrapping {
+ Box::new(WordWrapper::new(&mut styled, text_area.width))
+ } else {
+ Box::new(LineTruncator::new(&mut styled, text_area.width))
  };
  let mut y = 0;
-
- let mut remove_leading_whitespaces = false;
- while let Some((string, style)) = styled.next() {
- if string == "\n" {
- x = match self.alignment {
- Alignment::Center => {
- (text_area.width / 2).saturating_sub(get_cur_line_len(&mut styled) / 2)
- }
-
- Alignment::Right => {
- (text_area.width).saturating_sub(get_cur_line_len(&mut styled))
- }
- Alignment::Left => 0,
- };
- y += 1;
- continue;
- }
- let token_end_index = x + string.width() as u16 - 1;
- let last_column_index = text_area.width - 1;
- if token_end_index > last_column_index {
- if !self.wrapping {
- continue; // Truncate the remainder of the line.
- } else {
- x = match self.alignment {
- Alignment::Center => {
- (text_area.width / 2).saturating_sub(get_cur_line_len(&mut styled) / 2)
- }
-
- Alignment::Right => {
- (text_area.width).saturating_sub(get_cur_line_len(&mut styled) + 1)
- }
- Alignment::Left => 0,
- };
- y += 1;
- remove_leading_whitespaces = true
+ while let Some((current_line, current_line_width)) = line_composer.next_line() {
+ if y >= self.scroll {
+ let mut x = get_line_offset(current_line_width, text_area.width, self.alignment);
+ for Styled(symbol, style) in current_line {
+ buf.get_mut(text_area.left() + x, text_area.top() + y - self.scroll)
+ .set_symbol(symbol)
+ .set_style(*style);
+ x += symbol.width() as u16;
  }
  }
-
- if remove_leading_whitespaces && string == " " {
- continue;
- }
- remove_leading_whitespaces = false;
-
- if y > text_area.height + self.scroll - 1 {
+ y += 1;
+ if y >= text_area.height + self.scroll {
  break;
  }
-
- if y < self.scroll {
- continue;
- }
-
- buf.get_mut(text_area.left() + x, text_area.top() + y - self.scroll)
- .set_symbol(string)
- .set_style(style);
- x += string.width() as u16;
  }
  }
 }