yog_ui/
layout.rs

1use crate::text;
2use crate::widget::{Dock, 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 = text::str_width(t, 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        // Explicit width/height always wins over content sizing.
80        if s.w > 0.0 { ww = s.w.min(max_w); }
81        if s.h > 0.0 { hh = s.h.min(max_h); }
82    }
83
84    node.rect = Rect { x, y, w: ww, h: hh };
85
86    if !has_children { return; }
87
88    // Flex layout for children
89    let dir = if matches!(w.kind, WidgetKind::Panel(_)) && w.flex_dir == FlexDir::Row { FlexDir::Row } else { FlexDir::Column };
90    let content_w = ww - s.pad[1] - s.pad[3];
91    let content_h = hh - s.pad[0] - s.pad[2];
92
93    // Helpers for Dock
94    // Returns effective flex factor (Dock::Fill implies at least 1.0).
95    let effective_flex = |child: &Widget| -> f32 {
96        if child.style.dock == Dock::Fill { child.style.flex.max(1.0) } else { child.style.flex }
97    };
98    // Returns true if this child consumes main-axis space in the normal forward pass.
99    let in_flow = |child: &Widget| -> bool {
100        match (dir, child.style.dock) {
101            (FlexDir::Row,    Dock::Right)  => false,
102            (FlexDir::Column, Dock::Bottom) => false,
103            _ => true,
104        }
105    };
106
107    // Measure children
108    let mut child_nodes: Vec<LayoutNode> = Vec::new();
109    let mut total_flex: f32 = 0.0;
110    let mut used_main: f32  = 0.0;
111
112    for child in &w.children {
113        let dock = child.style.dock;
114        let mut cn = LayoutNode {
115            id: child.id.clone(), on_click: child.on_click.clone(),
116            enabled: child.enabled, focused: child.focused,
117            ..Default::default()
118        };
119        // Determine measurement constraints based on Dock + direction.
120        let (cmw, cmh) = match (dir, dock) {
121            // Fill: constrain both axes so text can wrap to container dimensions.
122            (FlexDir::Row,    Dock::Fill) => (content_w, content_h),
123            (FlexDir::Column, Dock::Fill) => (content_w, content_h),
124            // Cross-axis fill: constrain cross axis, unlimited main axis.
125            (FlexDir::Row,    Dock::Left | Dock::Right) => (f32::MAX, content_h),
126            (FlexDir::Column, Dock::Top  | Dock::Bottom) => (content_w, f32::MAX),
127            // Default flex behaviour.
128            (FlexDir::Row,    _) => (f32::MAX, content_h),
129            (FlexDir::Column, _) => (content_w, f32::MAX),
130        };
131        layout_widget(child, &mut cn, 0.0, 0.0, cmw, cmh);
132        if in_flow(child) {
133            if dir == FlexDir::Row { used_main += cn.rect.w; }
134            else                   { used_main += cn.rect.h; }
135        }
136        total_flex += effective_flex(child);
137        child_nodes.push(cn);
138    }
139    let flow_count = w.children.iter().filter(|c| in_flow(c)).count();
140    let gaps = s.gap * (flow_count.saturating_sub(1) as f32);
141    used_main += gaps;
142
143    let available = (if dir == FlexDir::Row { content_w } else { content_h }) - used_main;
144    let mut pos = if dir == FlexDir::Row { s.pad[3] } else { s.pad[0] };
145
146    // --- Forward pass: position in-flow children (not Dock::Right / Dock::Bottom) ---
147    for (i, child) in w.children.iter().enumerate() {
148        if !in_flow(child) { continue; }
149        let dock = child.style.dock;
150        let cn = &mut child_nodes[i];
151        if dir == FlexDir::Row {
152            let ef = effective_flex(child);
153            if ef > 0.0 && total_flex > 0.0 && available > 0.0 {
154                cn.rect.w += available * ef / total_flex;
155            }
156            if dock == Dock::Fill || dock == Dock::Left || dock == Dock::Right {
157                cn.rect.h = content_h; // stretch cross axis
158            }
159            cn.rect.x = x + pos;
160            cn.rect.y = y + s.pad[0] + match s.align {
161                Align::Center => (content_h - cn.rect.h) / 2.0,
162                Align::End    => content_h - cn.rect.h,
163                _             => 0.0,
164            };
165            pos += cn.rect.w + s.gap;
166        } else {
167            let ef = effective_flex(child);
168            if ef > 0.0 && total_flex > 0.0 && available > 0.0 {
169                cn.rect.h += available * ef / total_flex;
170            }
171            if dock == Dock::Fill || dock == Dock::Top || dock == Dock::Bottom {
172                cn.rect.w = content_w; // stretch cross axis
173            }
174            cn.rect.x = x + s.pad[3] + match s.align {
175                Align::Center => (content_w - cn.rect.w) / 2.0,
176                Align::End    => content_w - cn.rect.w,
177                _             => 0.0,
178            };
179            cn.rect.y = y + pos;
180            pos += cn.rect.h + s.gap;
181        }
182        if !child.children.is_empty() {
183            layout_widget(child, cn, cn.rect.x, cn.rect.y, cn.rect.w, cn.rect.h);
184        }
185    }
186
187    // --- Reverse pass: position Dock::Right / Dock::Bottom children from the far edge ---
188    let mut rpos = if dir == FlexDir::Row {
189        x + s.pad[3] + content_w
190    } else {
191        y + s.pad[0] + content_h
192    };
193    for (i, child) in w.children.iter().enumerate() {
194        if in_flow(child) { continue; }
195        let dock = child.style.dock;
196        let cn = &mut child_nodes[i];
197        if dir == FlexDir::Row {
198            if dock == Dock::Fill || dock == Dock::Left || dock == Dock::Right {
199                cn.rect.h = content_h;
200            }
201            rpos -= cn.rect.w;
202            cn.rect.x = rpos;
203            cn.rect.y = y + s.pad[0] + match s.align {
204                Align::Center => (content_h - cn.rect.h) / 2.0,
205                Align::End    => content_h - cn.rect.h,
206                _             => 0.0,
207            };
208            rpos -= s.gap;
209        } else {
210            if dock == Dock::Fill || dock == Dock::Top || dock == Dock::Bottom {
211                cn.rect.w = content_w;
212            }
213            rpos -= cn.rect.h;
214            cn.rect.y = rpos;
215            cn.rect.x = x + s.pad[3] + match s.align {
216                Align::Center => (content_w - cn.rect.w) / 2.0,
217                Align::End    => content_w - cn.rect.w,
218                _             => 0.0,
219            };
220            rpos -= s.gap;
221        }
222        if !child.children.is_empty() {
223            layout_widget(child, cn, cn.rect.x, cn.rect.y, cn.rect.w, cn.rect.h);
224        }
225    }
226
227    // Auto-size: shrink to content
228    if s.w <= 0.0 {
229        let cw: f32 = child_nodes.iter().map(|c| c.rect.x - x + c.rect.w).fold(0.0f32, f32::max);
230        node.rect.w = (cw + s.pad[1] + s.pad[3]).max(s.min_w).min(max_w);
231    }
232    if s.h <= 0.0 {
233        let ch: f32 = child_nodes.iter().map(|c| c.rect.y - y + c.rect.h).fold(0.0f32, f32::max);
234        node.rect.h = (ch + s.pad[0] + s.pad[2]).max(s.min_h).min(max_h);
235    }
236
237    node.children = child_nodes;
238}
239
240/// Hit-test: find deepest clickable, enabled node at (mx, my).
241pub fn hit_test(node: &LayoutNode, mx: f32, my: f32) -> Option<&LayoutNode> {
242    let r = &node.rect;
243    if mx < r.x || my < r.y || mx > r.x + r.w || my > r.y + r.h { return None; }
244    for child in node.children.iter().rev() {
245        if let Some(hit) = hit_test(child, mx, my) { return Some(hit); }
246    }
247    if node.on_click.is_some() && node.enabled { Some(node) } else { None }
248}
249
250/// Walk tree and set `focused = true` on the node whose id matches, false on all others.
251pub fn set_focus(node: &mut LayoutNode, focused_id: Option<&str>) {
252    node.focused = focused_id.is_some() && node.id.as_deref() == focused_id;
253    for child in &mut node.children { set_focus(child, focused_id); }
254}
yog_ui/layout.rs

yog_ui/
layout.rs
