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use std::borrow::Cow;
use crate::sys;
use crate::Ui;
/// Builder for a list box widget
#[derive(Copy, Clone, Debug)]
#[must_use]
pub struct ListBox<T> {
label: T,
size: [f32; 2],
}
impl<T: AsRef<str>> ListBox<T> {
/// Constructs a new list box builder.
#[doc(alias = "ListBoxHeaderVec2", alias = "ListBoxHeaderInt")]
pub fn new(label: T) -> ListBox<T> {
ListBox {
label,
size: [0.0, 0.0],
}
}
/// Sets the list box size based on the given width and height
/// If width or height are 0 or smaller, a default value is calculated
/// Helper to calculate the size of a listbox and display a label on the right.
/// Tip: To have a list filling the entire window width, PushItemWidth(-1) and pass an non-visible label e.g. "##empty"
///
/// Default: [0.0, 0.0], in which case the combobox calculates a sensible width and height
#[inline]
pub fn size(mut self, size: impl Into<crate::math::MintVec2>) -> Self {
self.size = size.into().into();
self
}
/// Creates a list box and starts appending to it.
///
/// Returns `Some(ListBoxToken)` if the list box is open. After content has been
/// rendered, the token must be ended by calling `.end()`.
///
/// Returns `None` if the list box is not open and no content should be rendered.
#[must_use]
pub fn begin(self, ui: &Ui) -> Option<ListBoxToken<'_>> {
let should_render =
unsafe { sys::igBeginListBox(ui.scratch_txt(self.label), self.size.into()) };
if should_render {
Some(ListBoxToken::new(ui))
} else {
None
}
}
/// Creates a list box and runs a closure to construct the list contents.
/// Returns the result of the closure, if it is called.
///
/// Note: the closure is not called if the list box is not open.
pub fn build<R, F: FnOnce() -> R>(self, ui: &Ui, f: F) -> Option<R> {
self.begin(ui).map(|_list| f())
}
}
create_token!(
/// Tracks a list box that can be ended by calling `.end()`
/// or by dropping
pub struct ListBoxToken<'ui>;
/// Ends a list box
drop { sys::igEndListBox() }
);
/// # Convenience functions
impl<T: AsRef<str>> ListBox<T> {
/// Builds a simple list box for choosing from a slice of values
pub fn build_simple<V, L>(
self,
ui: &Ui,
current_item: &mut usize,
items: &[V],
label_fn: &L,
) -> bool
where
for<'b> L: Fn(&'b V) -> Cow<'b, str>,
{
let mut result = false;
let lb = self;
if let Some(_cb) = lb.begin(ui) {
for (idx, item) in items.iter().enumerate() {
let text = label_fn(item);
let selected = idx == *current_item;
if ui.selectable_config(&text).selected(selected).build() {
*current_item = idx;
result = true;
}
}
}
result
}
}