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use crossterm::terminal;
const DEFAULT_TERMINAL_WIDTH: u16 = 50;
const DEFAULT_TERMINAL_HEIGHT: u16 = 20;
pub trait AreaContent {
fn height() -> u16;
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Area {
pub left: u16,
pub top: u16,
pub width: u16,
pub height: u16,
}
fn div_ceil(a: i32, b: i32) -> i32 {
a / b + if a % b != 0 { 1 } else { 0 }
}
impl Area {
pub fn uninitialized() -> Area {
Area {
left: 0,
top: 0,
height: 1,
width: 5,
}
}
pub fn new(left: u16, top: u16, width: u16, height: u16) -> Area {
assert!(width > 4);
Area {
left,
top,
width,
height,
}
}
pub fn full_screen() -> Area {
let (width, height) = terminal_size();
Area {
left: 0,
top: 0,
width,
height,
}
}
pub fn pad(&mut self, dx: u16, dy: u16) {
self.left += dx;
self.top += dy;
self.width -= 2 * dx;
self.height -= 2 * dy;
}
pub fn pad_for_max_width(&mut self, max_width: u16) {
if max_width >= self.width {
return;
}
let pw = self.width - max_width;
self.left += pw / 2;
self.width -= pw;
}
pub fn scrollbar(
&self,
scroll: i32,
content_height: i32,
) -> Option<(u16, u16)> {
compute_scrollbar(scroll, content_height, i32::from(self.height))
}
}
pub fn compute_scrollbar(
scroll: i32,
content_height: i32,
available_height: i32,
) -> Option<(u16, u16)> {
let h = available_height;
if content_height <= h {
return None;
}
let sc = div_ceil(scroll * h, content_height);
let hidden_tail = content_height - scroll - h;
let se = div_ceil(hidden_tail * h, content_height);
Some((
sc as u16,
if h > sc + se {
(h - se) as u16
} else {
sc as u16 + 1
},
))
}
pub fn terminal_size() -> (u16, u16) {
let size = terminal::size();
size.unwrap_or((DEFAULT_TERMINAL_WIDTH, DEFAULT_TERMINAL_HEIGHT))
}