yog_ui/
layout.rs

1use crate::text;
2use crate::widget::{Widget, WidgetKind};
3
4#[derive(Debug, Clone, Copy, PartialEq)]
5pub enum FlexDir { Row, Column }
6#[derive(Debug, Clone, Copy, PartialEq)]
7pub enum Align { Start, Center, End }
8
9#[derive(Debug, Clone, Copy, Default)]
10pub struct Rect { pub x: f32, pub y: f32, pub w: f32, pub h: f32 }
11
12#[derive(Debug, Clone)]
13pub struct LayoutNode {
14    pub rect: Rect,
15    pub id: Option<String>,
16    pub on_click: Option<String>,
17    pub children: Vec<LayoutNode>,
18    pub enabled: bool,
19    pub focused: bool,
20}
21
22impl Default for LayoutNode {
23    fn default() -> Self {
24        Self { rect: Rect::default(), id: None, on_click: None,
25               children: Vec::new(), enabled: true, focused: false }
26    }
27}
28
29/// Compute layout starting at (0,0) with given available size.
30/// Returns the root LayoutNode with absolute coordinates.
31pub fn compute(widget: &Widget, avail_w: f32, avail_h: f32) -> LayoutNode {
32    let mut node = LayoutNode {
33        id: widget.id.clone(), on_click: widget.on_click.clone(),
34        enabled: widget.enabled, focused: widget.focused,
35        ..Default::default()
36    };
37    layout_widget(widget, &mut node, 0.0, 0.0, avail_w, avail_h);
38    node
39}
40
41fn layout_widget(w: &Widget, node: &mut LayoutNode, x: f32, y: f32, max_w: f32, max_h: f32) {
42    let s = &w.style;
43    let has_children = !w.children.is_empty();
44
45    // Determine own size
46    let mut ww = if s.w > 0.0 { s.w.min(max_w) } else { max_w };
47    let mut hh = if s.h > 0.0 { s.h.min(max_h) } else { max_h };
48
49    if !has_children {
50        // Leaf: size to content (text, item slot, spacer)
51        match &w.kind {
52            WidgetKind::Label(t) | WidgetKind::Button(t) => {
53                let avail_w = (max_w - s.pad[1] - s.pad[3]).max(0.0);
54                // Wrap only when max_w is a real constraint (not "unlimited").
55                if avail_w < 4096.0 {
56                    ww = (avail_w + s.pad[1] + s.pad[3]).max(s.min_w).min(max_w);
57                    hh = (text::text_height(t, avail_w, s.font_scale) + s.pad[0] + s.pad[2])
58                        .max(s.min_h).min(max_h);
59                } else {
60                    let tw = t.len() as f32 * text::CHAR_W * s.font_scale;
61                    ww = (tw + s.pad[1] + s.pad[3]).max(s.min_w).min(max_w);
62                    hh = (text::LINE_H * s.font_scale + s.pad[0] + s.pad[2]).max(s.min_h).min(max_h);
63                }
64            }
65            WidgetKind::ItemSlot(_) => {
66                ww = (18.0 + s.pad[1] + s.pad[3]).max(s.min_w).min(max_w);
67                hh = (18.0 + s.pad[0] + s.pad[2]).max(s.min_h).min(max_h);
68            }
69            WidgetKind::Spacer => {
70                ww = s.min_w.max(1.0).min(max_w);
71                hh = s.min_h.max(1.0).min(max_h);
72            }
73            WidgetKind::Panel(_) => {} // panel with no children → size to min or available
74            WidgetKind::McImage { img_w, img_h, .. } => {
75                ww = (*img_w + s.pad[1] + s.pad[3]).max(s.min_w).min(max_w);
76                hh = (*img_h + s.pad[0] + s.pad[2]).max(s.min_h).min(max_h);
77            }
78        }
79    }
80
81    node.rect = Rect { x, y, w: ww, h: hh };
82
83    if !has_children { return; }
84
85    // Flex layout for children
86    let dir = if matches!(w.kind, WidgetKind::Panel(_)) && w.flex_dir == FlexDir::Row { FlexDir::Row } else { FlexDir::Column };
87    let content_w = ww - s.pad[1] - s.pad[3];
88    let content_h = hh - s.pad[0] - s.pad[2];
89
90    // Measure children
91    let mut child_nodes: Vec<LayoutNode> = Vec::new();
92    let mut total_flex: f32 = 0.0;
93    let mut used_main: f32 = 0.0;
94
95    for child in &w.children {
96        let mut cn = LayoutNode {
97            id: child.id.clone(), on_click: child.on_click.clone(),
98            enabled: child.enabled, focused: child.focused,
99            ..Default::default()
100        };
101        let cmw = if dir == FlexDir::Row { f32::MAX } else { content_w };
102        let cmh = if dir == FlexDir::Column { f32::MAX } else { content_h };
103        layout_widget(child, &mut cn, 0.0, 0.0, cmw, cmh);
104        if dir == FlexDir::Row { used_main += cn.rect.w; }
105        else { used_main += cn.rect.h; }
106        total_flex += child.style.flex;
107        child_nodes.push(cn);
108    }
109    let gaps = s.gap * (w.children.len().saturating_sub(1) as f32);
110    used_main += gaps;
111
112    let available = (if dir == FlexDir::Row { content_w } else { content_h }) - used_main;
113    let mut pos = if dir == FlexDir::Row { s.pad[3] } else { s.pad[0] };
114
115    // Position children
116    for (i, child) in w.children.iter().enumerate() {
117        let cn = &mut child_nodes[i];
118        if dir == FlexDir::Row {
119            if child.style.flex > 0.0 && total_flex > 0.0 && available > 0.0 {
120                cn.rect.w += available * child.style.flex / total_flex;
121            }
122            cn.rect.x = x + pos;
123            cn.rect.y = y + s.pad[0] + match s.align {
124                Align::Center => (content_h - cn.rect.h) / 2.0,
125                Align::End => content_h - cn.rect.h,
126                _ => 0.0,
127            };
128            pos += cn.rect.w + s.gap;
129        } else {
130            if child.style.flex > 0.0 && total_flex > 0.0 && available > 0.0 {
131                cn.rect.h += available * child.style.flex / total_flex;
132            }
133            cn.rect.x = x + s.pad[3] + match s.align {
134                Align::Center => (content_w - cn.rect.w) / 2.0,
135                Align::End => content_w - cn.rect.w,
136                _ => 0.0,
137            };
138            cn.rect.y = y + pos;
139            pos += cn.rect.h + s.gap;
140        }
141        // Recursively layout children of children
142        if !child.children.is_empty() {
143            layout_widget(child, cn, cn.rect.x, cn.rect.y, cn.rect.w, cn.rect.h);
144        }
145    }
146
147    // Auto-size: shrink to content
148    if s.w <= 0.0 {
149        let cw: f32 = child_nodes.iter().map(|c| c.rect.x - x + c.rect.w).fold(0.0f32, f32::max);
150        node.rect.w = (cw + s.pad[1] + s.pad[3]).max(s.min_w).min(max_w);
151    }
152    if s.h <= 0.0 {
153        let ch: f32 = child_nodes.iter().map(|c| c.rect.y - y + c.rect.h).fold(0.0f32, f32::max);
154        node.rect.h = (ch + s.pad[0] + s.pad[2]).max(s.min_h).min(max_h);
155    }
156
157    node.children = child_nodes;
158}
159
160/// Hit-test: find deepest clickable, enabled node at (mx, my).
161pub fn hit_test(node: &LayoutNode, mx: f32, my: f32) -> Option<&LayoutNode> {
162    let r = &node.rect;
163    if mx < r.x || my < r.y || mx > r.x + r.w || my > r.y + r.h { return None; }
164    for child in node.children.iter().rev() {
165        if let Some(hit) = hit_test(child, mx, my) { return Some(hit); }
166    }
167    if node.on_click.is_some() && node.enabled { Some(node) } else { None }
168}
169
170/// Walk tree and set `focused = true` on the node whose id matches, false on all others.
171pub fn set_focus(node: &mut LayoutNode, focused_id: Option<&str>) {
172    node.focused = focused_id.is_some() && node.id.as_deref() == focused_id;
173    for child in &mut node.children { set_focus(child, focused_id); }
174}
yog_ui/layout.rs

yog_ui/
layout.rs
