use crate::{ buffer::Buffer, layout::{Corner, Rect}, style::Style, text::Text, widgets::{Block, StatefulWidget, Widget}, }; use std::iter::{self, Iterator}; use unicode_width::UnicodeWidthStr; #[derive(Debug, Clone)] pub struct ListState { offset: usize, selected: Option, } impl Default for ListState { fn default() -> ListState { ListState { offset: 0, selected: None, } } } impl ListState { pub fn selected(&self) -> Option { self.selected } pub fn select(&mut self, index: Option) { self.selected = index; if index.is_none() { self.offset = 0; } } } #[derive(Debug, Clone, PartialEq)] pub struct ListItem<'a> { content: Text<'a>, style: Style, } impl<'a> ListItem<'a> { pub fn new(content: T) -> ListItem<'a> where T: Into>, { ListItem { content: content.into(), style: Style::default(), } } pub fn style(mut self, style: Style) -> ListItem<'a> { self.style = style; self } pub fn height(&self) -> usize { self.content.height() } } /// A widget to display several items among which one can be selected (optional) /// /// # Examples /// /// ``` /// # use helix_tui::widgets::{Block, Borders, List, ListItem}; /// # use helix_tui::style::{Style, Color, Modifier}; /// let items = [ListItem::new("Item 1"), ListItem::new("Item 2"), ListItem::new("Item 3")]; /// List::new(items) /// .block(Block::default().title("List").borders(Borders::ALL)) /// .style(Style::default().fg(Color::White)) /// .highlight_style(Style::default().add_modifier(Modifier::ITALIC)) /// .highlight_symbol(">>"); /// ``` #[derive(Debug, Clone)] pub struct List<'a> { block: Option>, items: Vec>, /// Style used as a base style for the widget style: Style, start_corner: Corner, /// Style used to render selected item highlight_style: Style, /// Symbol in front of the selected item (Shift all items to the right) highlight_symbol: Option<&'a str>, } impl<'a> List<'a> { pub fn new(items: T) -> List<'a> where T: Into>>, { List { block: None, style: Style::default(), items: items.into(), start_corner: Corner::TopLeft, highlight_style: Style::default(), highlight_symbol: None, } } pub fn block(mut self, block: Block<'a>) -> List<'a> { self.block = Some(block); self } pub fn style(mut self, style: Style) -> List<'a> { self.style = style; self } pub fn highlight_symbol(mut self, highlight_symbol: &'a str) -> List<'a> { self.highlight_symbol = Some(highlight_symbol); self } pub fn highlight_style(mut self, style: Style) -> List<'a> { self.highlight_style = style; self } pub fn start_corner(mut self, corner: Corner) -> List<'a> { self.start_corner = corner; self } } impl<'a> StatefulWidget for List<'a> { type State = ListState; fn render(mut self, area: Rect, buf: &mut Buffer, state: &mut Self::State) { buf.set_style(area, self.style); let list_area = match self.block.take() { Some(b) => { let inner_area = b.inner(area); b.render(area, buf); inner_area } None => area, }; if list_area.width < 1 || list_area.height < 1 { return; } if self.items.is_empty() { return; } let list_height = list_area.height as usize; let mut start = state.offset; let mut end = state.offset; let mut height = 0; for item in self.items.iter().skip(state.offset) { if height + item.height() > list_height { break; } height += item.height(); end += 1; } let selected = state.selected.unwrap_or(0).min(self.items.len() - 1); while selected >= end { height = height.saturating_add(self.items[end].height()); end += 1; while height > list_height { height = height.saturating_sub(self.items[start].height()); start += 1; } } while selected < start { start -= 1; height = height.saturating_add(self.items[start].height()); while height > list_height { end -= 1; height = height.saturating_sub(self.items[end].height()); } } state.offset = start; let highlight_symbol = self.highlight_symbol.unwrap_or(""); let blank_symbol = iter::repeat(" ") .take(highlight_symbol.width()) .collect::(); let mut current_height = 0; let has_selection = state.selected.is_some(); for (i, item) in self .items .iter_mut() .enumerate() .skip(state.offset) .take(end - start) { let (x, y) = match self.start_corner { Corner::BottomLeft => { current_height += item.height() as u16; (list_area.left(), list_area.bottom() - current_height) } _ => { let pos = (list_area.left(), list_area.top() + current_height); current_height += item.height() as u16; pos } }; let area = Rect { x, y, width: list_area.width, height: item.height() as u16, }; let item_style = self.style.patch(item.style); buf.set_style(area, item_style); let is_selected = state.selected.map(|s| s == i).unwrap_or(false); let elem_x = if has_selection { let symbol = if is_selected { highlight_symbol } else { &blank_symbol }; let (x, _) = buf.set_stringn(x, y, symbol, list_area.width as usize, item_style); x } else { x }; let max_element_width = (list_area.width - (elem_x - x)) as usize; for (j, line) in item.content.lines.iter().enumerate() { buf.set_spans(elem_x, y + j as u16, line, max_element_width as u16); } if is_selected { buf.set_style(area, self.highlight_style); } } } } impl<'a> Widget for List<'a> { fn render(self, area: Rect, buf: &mut Buffer) { let mut state = ListState::default(); StatefulWidget::render(self, area, buf, &mut state); } }