gravel_frontend_fltk/
scroll.rsuse std::cmp;
pub struct Scroll {
length: i32,
max_view_size: i32,
cursor: i32,
scroll: i32,
}
impl Scroll {
pub fn new(length: i32, max_view_size: i32) -> Self {
Self {
length,
max_view_size,
cursor: 0,
scroll: 0,
}
}
pub fn cursor_up(&mut self) {
if self.cursor <= 0 {
self.bottom();
} else {
self.cursor -= 1;
self.scroll = cmp::min(self.scroll, self.cursor);
}
}
pub fn cursor_down(&mut self) {
if self.cursor >= self.length - 1 {
self.top();
} else {
self.cursor += 1;
self.scroll = cmp::max(self.scroll, self.cursor - self.view_size() + 1);
}
}
pub fn page_up(&mut self) {
if self.scroll - self.view_size() <= 0 {
self.top();
} else {
self.scroll = self.scroll() - self.view_size();
self.cursor = self.scroll;
}
}
pub fn page_down(&mut self) {
if self.scroll + self.view_size() * 2 >= self.length {
self.bottom();
} else {
self.scroll = self.scroll() + self.view_size();
self.cursor = self.scroll + self.view_size() - 1;
}
}
pub fn top(&mut self) {
self.cursor = 0;
self.scroll = 0;
}
pub fn bottom(&mut self) {
self.cursor = self.length - 1;
self.scroll = self.length - self.view_size();
}
pub fn set_length(&mut self, length: i32) {
self.length = length;
self.top();
}
pub fn view_size(&self) -> i32 {
cmp::min(self.length, self.max_view_size)
}
pub fn cursor(&self) -> i32 {
self.cursor
}
pub fn scroll(&self) -> i32 {
self.scroll
}
pub fn length(&self) -> i32 {
self.length
}
}