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|
use easy_cast::Cast;
use ratatui::{
buffer::Buffer,
layout::{Alignment, Rect},
style::Style,
text::{StyledGrapheme, Text},
widgets::{Block, StatefulWidget, Widget, Wrap},
};
use std::iter;
use unicode_width::UnicodeWidthStr;
use super::reflow::{LineComposer, LineTruncator, WordWrapper};
const 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,
}
}
#[derive(Debug, Clone)]
pub struct StatefulParagraph<'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>,
/// Alignment of the text
alignment: Alignment,
}
#[derive(Debug, Default, Clone, Copy)]
pub struct ScrollPos {
pub x: u16,
pub y: u16,
}
#[derive(Debug, Copy, Clone, Default)]
pub struct ParagraphState {
/// Scroll
scroll: ScrollPos,
/// after all wrapping this is the amount of lines
lines: u16,
/// last visible height
height: u16,
}
impl ParagraphState {
pub const fn lines(self) -> u16 {
self.lines
}
pub const fn height(self) -> u16 {
self.height
}
pub const fn scroll(self) -> ScrollPos {
self.scroll
}
pub fn set_scroll(&mut self, scroll: ScrollPos) {
self.scroll = scroll;
}
}
impl<'a> StatefulParagraph<'a> {
pub fn new<T>(text: T) -> Self
where
T: Into<Text<'a>>,
{
Self {
block: None,
style: Style::default(),
wrap: None,
text: text.into(),
alignment: Alignment::Left,
}
}
#[allow(clippy::missing_const_for_fn)]
pub fn block(mut self, block: Block<'a>) -> Self {
self.block = Some(block);
self
}
pub const fn wrap(mut self, wrap: Wrap) -> Self {
self.wrap = Some(wrap);
self
}
// pub const fn style(mut self, style: Style) -> Self {
// self.style = style;
// self
// }
// pub const fn alignment(mut self, alignment: Alignment) -> Self {
// self.alignment = alignment;
// self
// }
}
impl<'a> StatefulWidget for StatefulParagraph<'a> {
type State = ParagraphState;
fn render(
mut self,
area: Rect,
buf: &mut Buffer,
state: &mut Self::State,
) {
buf.set_style(area, self.style);
let text_area = self.block.take().map_or(area, |b| {
let inner_area = b.inner(area);
b.render(area, buf);
inner_area
});
if text_area.height < 1 {
return;
}
let style = self.style;
let mut styled = self.text.lines.iter().flat_map(|line| {
line.spans
.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 self.alignment == Alignment::Left {
line_composer
.set_horizontal_offset(state.scroll.x);
}
line_composer
};
let mut y = 0;
let mut end_reached = false;
while let Some((current_line, current_line_width)) =
line_composer.next_line()
{
if !end_reached && y >= state.scroll.y {
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 - state.scroll.y,
)
.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 += Cast::<u16>::cast(symbol.width());
}
}
y += 1;
if y >= text_area.height + state.scroll.y {
end_reached = true;
}
}
state.lines = y;
state.height = area.height;
}
}
|
