dear_imgui/widget/
list_box.rs

1use std::borrow::Cow;
2
3use crate::Ui;
4use crate::sys;
5
6/// Builder for a list box widget
7#[derive(Clone, Debug)]
8#[must_use]
9pub struct ListBox<T> {
10    label: T,
11    size: [f32; 2],
12}
13
14impl<T: AsRef<str>> ListBox<T> {
15    /// Constructs a new list box builder.
16    #[doc(alias = "ListBoxHeaderVec2", alias = "ListBoxHeaderInt")]
17    pub fn new(label: T) -> ListBox<T> {
18        ListBox {
19            label,
20            size: [0.0, 0.0],
21        }
22    }
23
24    /// Sets the list box size based on the given width and height
25    /// If width or height are 0 or smaller, a default value is calculated
26    /// Helper to calculate the size of a listbox and display a label on the right.
27    /// Tip: To have a list filling the entire window width, PushItemWidth(-1) and pass an non-visible label e.g. "##empty"
28    ///
29    /// Default: [0.0, 0.0], in which case the combobox calculates a sensible width and height
30    #[inline]
31    pub fn size(mut self, size: impl Into<[f32; 2]>) -> Self {
32        self.size = size.into();
33        self
34    }
35    /// Creates a list box and starts appending to it.
36    ///
37    /// Returns `Some(ListBoxToken)` if the list box is open. After content has been
38    /// rendered, the token must be ended by calling `.end()`.
39    ///
40    /// Returns `None` if the list box is not open and no content should be rendered.
41    #[must_use]
42    pub fn begin(self, ui: &Ui) -> Option<ListBoxToken<'_>> {
43        let size_vec = sys::ImVec2 {
44            x: self.size[0],
45            y: self.size[1],
46        };
47        let should_render = unsafe { sys::igBeginListBox(ui.scratch_txt(self.label), size_vec) };
48        if should_render {
49            Some(ListBoxToken::new(ui))
50        } else {
51            None
52        }
53    }
54    /// Creates a list box and runs a closure to construct the list contents.
55    /// Returns the result of the closure, if it is called.
56    ///
57    /// Note: the closure is not called if the list box is not open.
58    pub fn build<R, F: FnOnce() -> R>(self, ui: &Ui, f: F) -> Option<R> {
59        self.begin(ui).map(|_list| f())
60    }
61}
62
63/// Tracks a list box that can be ended by calling `.end()`
64/// or by dropping
65pub struct ListBoxToken<'ui> {
66    ui: &'ui Ui,
67}
68
69impl<'ui> ListBoxToken<'ui> {
70    /// Creates a new list box token
71    pub fn new(ui: &'ui Ui) -> Self {
72        Self { ui }
73    }
74
75    /// Ends the list box
76    pub fn end(self) {
77        // The drop implementation will handle the actual ending
78    }
79}
80
81impl<'ui> Drop for ListBoxToken<'ui> {
82    fn drop(&mut self) {
83        unsafe {
84            sys::igEndListBox();
85        }
86    }
87}
88
89/// # Convenience functions
90impl<T: AsRef<str>> ListBox<T> {
91    /// Builds a simple list box for choosing from a slice of values
92    pub fn build_simple<V, L>(
93        self,
94        ui: &Ui,
95        current_item: &mut usize,
96        items: &[V],
97        label_fn: &L,
98    ) -> bool
99    where
100        for<'b> L: Fn(&'b V) -> Cow<'b, str>,
101    {
102        let mut result = false;
103        let lb = self;
104        if let Some(_cb) = lb.begin(ui) {
105            for (idx, item) in items.iter().enumerate() {
106                let text = label_fn(item);
107                let selected = idx == *current_item;
108                if ui.selectable_config(&text).selected(selected).build() {
109                    *current_item = idx;
110                    result = true;
111                }
112            }
113        }
114        result
115    }
116}
dear_imgui/widget/list_box.rs

dear_imgui/widget/
list_box.rs
