feat(widgets/table): allow one row to be selected

examples/table.rs

@@ -1,28 +1,26 @@
 #[allow(dead_code)]
 mod util;
 
-use std::io;
-
-use termion::event::Key;
-use termion::input::MouseTerminal;
-use termion::raw::IntoRawMode;
-use termion::screen::AlternateScreen;
-use tui::backend::TermionBackend;
-use tui::layout::{Constraint, Layout};
-use tui::style::{Color, Modifier, Style};
-use tui::widgets::{Block, Borders, Row, Table};
-use tui::Terminal;
-
 use crate::util::event::{Event, Events};
+use std::io;
+use termion::{event::Key, input::MouseTerminal, raw::IntoRawMode, screen::AlternateScreen};
+use tui::{
+    backend::TermionBackend,
+    layout::{Constraint, Layout},
+    style::{Color, Modifier, Style},
+    widgets::{Block, Borders, Row, Table, TableState},
+    Terminal,
+};
 
-struct App<'a> {
+pub struct StatefulTable<'a> {
+    state: TableState,
     items: Vec<Vec<&'a str>>,
-    selected: usize,
 }
 
-impl<'a> App<'a> {
-    fn new() -> App<'a> {
-        App {
+impl<'a> StatefulTable<'a> {
+    fn new() -> StatefulTable<'a> {
+        StatefulTable {
+            state: TableState::default(),
             items: vec![
                 vec!["Row11", "Row12", "Row13"],
                 vec!["Row21", "Row22", "Row23"],
@@ -30,10 +28,49 @@ impl<'a> App<'a> {
                 vec!["Row41", "Row42", "Row43"],
                 vec!["Row51", "Row52", "Row53"],
                 vec!["Row61", "Row62", "Row63"],
+                vec!["Row71", "Row72", "Row73"],
+                vec!["Row81", "Row82", "Row83"],
+                vec!["Row91", "Row92", "Row93"],
+                vec!["Row101", "Row102", "Row103"],
+                vec!["Row111", "Row112", "Row113"],
+                vec!["Row121", "Row122", "Row123"],
+                vec!["Row131", "Row132", "Row133"],
+                vec!["Row141", "Row142", "Row143"],
+                vec!["Row151", "Row152", "Row153"],
+                vec!["Row161", "Row162", "Row163"],
+                vec!["Row171", "Row172", "Row173"],
+                vec!["Row181", "Row182", "Row183"],
+                vec!["Row191", "Row192", "Row193"],
             ],
-            selected: 0,
         }
     }
+    pub fn next(&mut self) {
+        let i = match self.state.selected() {
+            Some(i) => {
+                if i >= self.items.len() - 1 {
+                    0
+                } else {
+                    i + 1
+                }
+            }
+            None => 0,
+        };
+        self.state.select(Some(i));
+    }
+
+    pub fn previous(&mut self) {
+        let i = match self.state.selected() {
+            Some(i) => {
+                if i == 0 {
+                    self.items.len() - 1
+                } else {
+                    i - 1
+                }
+            }
+            None => 0,
+        };
+        self.state.select(Some(i));
+    }
 }
 
 fn main() -> Result<(), failure::Error> {
@@ -47,36 +84,33 @@ fn main() -> Result<(), failure::Error> {
 
     let events = Events::new();
 
-    // App
-    let mut app = App::new();
+    let mut table = StatefulTable::new();
 
     // Input
     loop {
         terminal.draw(|mut f| {
-            let selected_style = Style::default().fg(Color::Yellow).modifier(Modifier::BOLD);
-            let normal_style = Style::default().fg(Color::White);
-            let header = ["Header1", "Header2", "Header3"];
-            let rows = app.items.iter().enumerate().map(|(i, item)| {
-                if i == app.selected {
-                    Row::StyledData(item.into_iter(), selected_style)
-                } else {
-                    Row::StyledData(item.into_iter(), normal_style)
-                }
-            });
-
             let rects = Layout::default()
                 .constraints([Constraint::Percentage(100)].as_ref())
                 .margin(5)
                 .split(f.size());
 
-            let table = Table::new(header.iter(), rows)
+            let selected_style = Style::default().fg(Color::Yellow).modifier(Modifier::BOLD);
+            let normal_style = Style::default().fg(Color::White);
+            let header = ["Header1", "Header2", "Header3"];
+            let rows = table
+                .items
+                .iter()
+                .map(|i| Row::StyledData(i.into_iter(), normal_style));
+            let t = Table::new(header.iter(), rows)
                 .block(Block::default().borders(Borders::ALL).title("Table"))
+                .highlight_style(selected_style)
+                .highlight_symbol(">> ")
                 .widths(&[
                     Constraint::Percentage(50),
                     Constraint::Length(30),
                     Constraint::Max(10),
                 ]);
-            f.render_widget(table, rects[0]);
+            f.render_stateful_widget(t, rects[0], &mut table.state);
         })?;
 
         match events.next()? {
@@ -85,17 +119,10 @@ fn main() -> Result<(), failure::Error> {
                     break;
                 }
                 Key::Down => {
-                    app.selected += 1;
-                    if app.selected > app.items.len() - 1 {
-                        app.selected = 0;
-                    }
+                    table.next();
                 }
                 Key::Up => {
-                    if app.selected > 0 {
-                        app.selected -= 1;
-                    } else {
-                        app.selected = app.items.len() - 1;
-                    }
+                    table.previous();
                 }
                 _ => {}
             },

src/widgets/mod.rs

@@ -20,7 +20,7 @@ pub use self::gauge::Gauge;
 pub use self::list::{List, ListState};
 pub use self::paragraph::Paragraph;
 pub use self::sparkline::Sparkline;
-pub use self::table::{Row, Table};
+pub use self::table::{Row, Table, TableState};
 pub use self::tabs::Tabs;
 
 use crate::buffer::Buffer;

src/widgets/table.rs

@@ -1,15 +1,47 @@
-use std::collections::HashMap;
-use std::fmt::Display;
-use std::iter::Iterator;
+use crate::{
+    buffer::Buffer,
+    layout::{Constraint, Rect},
+    style::Style,
+    widgets::{Block, StatefulWidget, Widget},
+};
+use cassowary::{
+    strength::{MEDIUM, REQUIRED, WEAK},
+    WeightedRelation::*,
+    {Expression, Solver},
+};
+use std::{
+    collections::HashMap,
+    fmt::Display,
+    iter::{self, Iterator},
+};
+use unicode_width::UnicodeWidthStr;
 
-use cassowary::strength::{MEDIUM, REQUIRED, WEAK};
-use cassowary::WeightedRelation::*;
-use cassowary::{Expression, Solver};
+pub struct TableState {
+    offset: usize,
+    selected: Option<usize>,
+}
+
+impl Default for TableState {
+    fn default() -> TableState {
+        TableState {
+            offset: 0,
+            selected: None,
+        }
+    }
+}
 
-use crate::buffer::Buffer;
-use crate::layout::{Constraint, Rect};
-use crate::style::Style;
-use crate::widgets::{Block, Widget};
+impl TableState {
+    pub fn selected(&self) -> Option<usize> {
+        self.selected
+    }
+
+    pub fn select(&mut self, index: Option<usize>) {
+        self.selected = index;
+        if index.is_none() {
+            self.offset = 0;
+        }
+    }
+}
 
 /// Holds data to be displayed in a Table widget
 pub enum Row<D>
@@ -60,6 +92,10 @@ pub struct Table<'a, H, R> {
     column_spacing: u16,
     /// Space between the header and the rows
     header_gap: u16,
+    /// Style used to render the selected row
+    highlight_style: Style,
+    /// Symbol in front of the selected rom
+    highlight_symbol: Option<&'a str>,
     /// Data to display in each row
     rows: R,
 }
@@ -76,9 +112,11 @@ where
             header: H::default(),
             header_style: Style::default(),
             widths: &[],
-            rows: R::default(),
             column_spacing: 1,
             header_gap: 1,
+            highlight_style: Style::default(),
+            highlight_symbol: None,
+            rows: R::default(),
         }
     }
 }
@@ -96,9 +134,11 @@ where
             header: header.into_iter(),
             header_style: Style::default(),
             widths: &[],
-            rows,
             column_spacing: 1,
             header_gap: 1,
+            highlight_style: Style::default(),
+            highlight_symbol: None,
+            rows,
         }
     }
     pub fn block(mut self, block: Block<'a>) -> Table<'a, H, R> {
@@ -145,6 +185,16 @@ where
         self
     }
 
+    pub fn highlight_symbol(mut self, highlight_symbol: &'a str) -> Table<'a, H, R> {
+        self.highlight_symbol = Some(highlight_symbol);
+        self
+    }
+
+    pub fn highlight_style(mut self, highlight_style: Style) -> Table<'a, H, R> {
+        self.highlight_style = highlight_style;
+        self
+    }
+
     pub fn column_spacing(mut self, spacing: u16) -> Table<'a, H, R> {
         self.column_spacing = spacing;
         self
@@ -156,7 +206,7 @@ where
     }
 }
 
-impl<'a, H, D, R> Widget for Table<'a, H, R>
+impl<'a, H, D, R> StatefulWidget for Table<'a, H, R>
 where
     H: Iterator,
     H::Item: Display,
@@ -164,7 +214,9 @@ where
     D::Item: Display,
     R: Iterator<Item = Row<D>>,
 {
-    fn render(mut self, area: Rect, buf: &mut Buffer) {
+    type State = TableState;
+
+    fn render(mut self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
         // Render block if necessary and get the drawing area
         let table_area = match self.block {
             Some(ref mut b) => {
@@ -234,18 +286,51 @@ where
         }
         y += 1 + self.header_gap;
 
+        // Use highlight_style only if something is selected
+        let (selected, highlight_style) = match state.selected {
+            Some(i) => (Some(i), self.highlight_style),
+            None => (None, self.style),
+        };
+        let highlight_symbol = self.highlight_symbol.unwrap_or("");
+        let blank_symbol = iter::repeat(" ")
+            .take(highlight_symbol.width())
+            .collect::<String>();
+
         // Draw rows
         let default_style = Style::default();
         if y < table_area.bottom() {
             let remaining = (table_area.bottom() - y) as usize;
-            for (i, row) in self.rows.by_ref().take(remaining).enumerate() {
-                let (data, style) = match row {
-                    Row::Data(d) => (d, default_style),
-                    Row::StyledData(d, s) => (d, s),
+
+            // Make sure the table shows the selected item
+            state.offset = if let Some(selected) = selected {
+                if selected >= remaining + state.offset - 1 {
+                    selected + 1 - remaining
+                } else if selected < state.offset {
+                    selected
+                } else {
+                    state.offset
+                }
+            } else {
+                0
+            };
+            for (i, row) in self.rows.skip(state.offset).take(remaining).enumerate() {
+                let (data, style, symbol) = match row {
+                    Row::Data(d) | Row::StyledData(d, _)
+                        if Some(i) == state.selected.map(|s| s - state.offset) =>
+                    {
+                        (d, highlight_style, highlight_symbol)
+                    }
+                    Row::Data(d) => (d, default_style, blank_symbol.as_ref()),
+                    Row::StyledData(d, s) => (d, s, blank_symbol.as_ref()),
                 };
                 x = table_area.left();
-                for (w, elt) in solved_widths.iter().zip(data) {
-                    buf.set_stringn(x, y + i as u16, format!("{}", elt), *w as usize, style);
+                for (c, (w, elt)) in solved_widths.iter().zip(data).enumerate() {
+                    let s = if c == 0 {
+                        format!("{}{}", symbol, elt)
+                    } else {
+                        format!("{}", elt)
+                    };
+                    buf.set_stringn(x, y + i as u16, s, *w as usize, style);
                     x += *w + self.column_spacing;
                 }
             }
@@ -253,6 +338,20 @@ where
     }
 }
 
+impl<'a, H, D, R> Widget for Table<'a, H, R>
+where
+    H: Iterator,
+    H::Item: Display,
+    D: Iterator,
+    D::Item: Display,
+    R: Iterator<Item = Row<D>>,
+{
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        let mut state = TableState::default();
+        StatefulWidget::render(self, area, buf, &mut state);
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;