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, 197 insertions, 0 deletions

diff --git a/helix-tui/src/widgets/paragraph.rs b/helix-tui/src/widgets/paragraph.rs
new file mode 100644
index 00000000..ecce8581
--- /dev/null
+++ b/helix-tui/src/widgets/paragraph.rs
@@ -0,0 +1,197 @@
+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<Block<'a>>,
+    /// Widget style
+    style: Style,
+    /// How to wrap the text
+    wrap: Option<Wrap>,
+    /// 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<T>(text: T) -> Paragraph<'a>
+    where
+        T: Into<Text<'a>>,
+    {
+        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<dyn LineComposer> = 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;
+            }
+        }
+    }
+}