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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<usize>,
}
impl Default for ListState {
fn default() -> ListState {
ListState {
offset: 0,
selected: None,
}
}
}
impl ListState {
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;
}
}
}
#[derive(Debug, Clone, PartialEq)]
pub struct ListItem<'a> {
content: Text<'a>,
style: Style,
}
impl<'a> ListItem<'a> {
pub fn new<T>(content: T) -> ListItem<'a>
where
T: Into<Text<'a>>,
{
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<Block<'a>>,
items: Vec<ListItem<'a>>,
/// 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<T>(items: T) -> List<'a>
where
T: Into<Vec<ListItem<'a>>>,
{
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::<String>();
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);
}
}
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