cranpose_ui/
focus_order.rs

1use std::cell::RefCell;
2
3use cranpose_core::NodeId;
4use cranpose_foundation::SemanticsWidgetRole;
5use cranpose_ui_graphics::Rect;
6
7use crate::layout::{LayoutBox, LayoutTree};
8
9/// One focus target, with the bounds layout gave it.
10#[derive(Clone, Copy, Debug, PartialEq)]
11pub struct FocusEntry {
12    pub node_id: NodeId,
13    pub rect: Rect,
14}
15
16impl FocusEntry {
17    pub fn center(&self) -> (f32, f32) {
18        (
19            self.rect.x + self.rect.width * 0.5,
20            self.rect.y + self.rect.height * 0.5,
21        )
22    }
23}
24
25thread_local! {
26    static FOCUS_ORDER: RefCell<Vec<FocusEntry>> = const { RefCell::new(Vec::new()) };
27}
28
29/// Replaces the focus order a later [`crate::FocusManager`] move reads. The
30/// app shell publishes it after a layout pass.
31pub fn set_focus_order(entries: Vec<FocusEntry>) {
32    FOCUS_ORDER.with(|cell| *cell.borrow_mut() = entries);
33}
34
35/// Reads the published focus order.
36pub fn with_focus_order<T>(reader: impl FnOnce(&[FocusEntry]) -> T) -> T {
37    FOCUS_ORDER.with(|cell| reader(&cell.borrow()))
38}
39
40/// How many focus targets the last published order holds.
41pub fn focus_order_len() -> usize {
42    FOCUS_ORDER.with(|cell| cell.borrow().len())
43}
44
45/// Walks `tree` in the order the layout pass placed it and keeps the nodes
46/// that registered a focus target and take space on screen.
47pub fn collect_focus_order(tree: &LayoutTree) -> Vec<FocusEntry> {
48    let mut entries = Vec::new();
49    collect_from_box(tree.root(), &mut entries);
50    entries
51}
52
53fn collect_from_box(layout_box: &LayoutBox, entries: &mut Vec<FocusEntry>) {
54    if crate::focus_dispatch::has_focus_target(layout_box.node_id) && takes_space(layout_box.rect) {
55        entries.push(FocusEntry {
56            node_id: layout_box.node_id,
57            rect: layout_box.rect,
58        });
59    }
60    for child in &layout_box.children {
61        collect_from_box(child, entries);
62    }
63}
64
65fn takes_space(rect: Rect) -> bool {
66    rect.width > 0.0
67        && rect.height > 0.0
68        && rect.x.is_finite()
69        && rect.y.is_finite()
70        && rect.width.is_finite()
71        && rect.height.is_finite()
72}
73
74/// The focus targets under one node, in the order layout gave them. An arrow
75/// key inside a selectable group moves among these and no others.
76pub fn collect_focus_order_under(tree: &LayoutTree, node_id: NodeId) -> Vec<FocusEntry> {
77    let mut entries = Vec::new();
78    if let Some(layout_box) = find_box(tree.root(), node_id) {
79        collect_from_box(layout_box, &mut entries);
80    }
81    entries
82}
83
84/// The nearest node above the given one that declares
85/// [`selectable_group`](crate::Modifier::selectable_group), when there is one.
86pub fn selectable_group_of(tree: &LayoutTree, node_id: NodeId) -> Option<NodeId> {
87    group_above(tree.root(), node_id, None)
88}
89
90fn group_above(layout_box: &LayoutBox, node_id: NodeId, group: Option<NodeId>) -> Option<NodeId> {
91    let group = if declares_selectable_group(layout_box) {
92        Some(layout_box.node_id)
93    } else {
94        group
95    };
96    if layout_box.node_id == node_id {
97        return group;
98    }
99    layout_box
100        .children
101        .iter()
102        .find_map(|child| group_above(child, node_id, group))
103}
104
105fn declares_selectable_group(layout_box: &LayoutBox) -> bool {
106    crate::modifier::collect_semantics_from_modifier(&layout_box.node_data.modifier).is_some_and(
107        |config| config.selectable_group || config.role == Some(SemanticsWidgetRole::Menu),
108    )
109}
110
111fn find_box(layout_box: &LayoutBox, node_id: NodeId) -> Option<&LayoutBox> {
112    if layout_box.node_id == node_id {
113        return Some(layout_box);
114    }
115    layout_box
116        .children
117        .iter()
118        .find_map(|child| find_box(child, node_id))
119}
cranpose_ui/focus_order.rs

cranpose_ui/
focus_order.rs
