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use tui::{layout::Rect, widgets::TableState};
#[derive(Debug, Copy, Clone, PartialEq, Eq, Default)]
pub enum ScrollDirection {
// UP means scrolling up --- this usually DECREMENTS
Up,
// DOWN means scrolling down --- this usually INCREMENTS
#[default]
Down,
}
/// Internal state representation of a [`DataTable`](super::DataTable).
pub struct DataTableState {
/// The index from where to start displaying the rows.
pub display_start_index: usize,
/// The current scroll position.
pub current_index: usize,
/// The direction of the last attempted scroll.
pub scroll_direction: ScrollDirection,
/// tui-rs' internal table state.
pub table_state: TableState,
/// The calculated widths.
pub calculated_widths: Vec<u16>,
/// The current inner [`Rect`].
pub inner_rect: Rect,
}
impl Default for DataTableState {
fn default() -> Self {
Self {
display_start_index: 0,
current_index: 0,
scroll_direction: ScrollDirection::Down,
calculated_widths: vec![],
table_state: TableState::default(),
inner_rect: Rect::default(),
}
}
}
impl DataTableState {
/// Gets the starting position of a table.
pub fn get_start_position(&mut self, num_rows: usize, is_force_redraw: bool) {
let start_index = if is_force_redraw {
0
} else {
self.display_start_index
};
let current_scroll_position = self.current_index;
let scroll_direction = self.scroll_direction;
self.display_start_index = match scroll_direction {
ScrollDirection::Down => {
if current_scroll_position < start_index + num_rows {
// If, using the current scroll position, we can see the element
// (so within that and + num_rows) just reuse the current previously
// scrolled position.
start_index
} else if current_scroll_position >= num_rows {
// If the current position past the last element visible in the list,
// then skip until we can see that element.
current_scroll_position - num_rows + 1
} else {
// Else, if it is not past the last element visible, do not omit anything.
0
}
}
ScrollDirection::Up => {
if current_scroll_position <= start_index {
// If it's past the first element, then show from that element downwards
current_scroll_position
} else if current_scroll_position >= start_index + num_rows {
current_scroll_position - num_rows + 1
} else {
start_index
}
}
};
}
}
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