tawasuyu/taffy

1mod common {
2    pub mod image;
3    pub mod text;
4}
5use common::image::{image_measure_function, ImageContext};
6use common::text::{text_measure_function, FontMetrics, TextContext, WritingMode, LOREM_IPSUM};
7use taffy::util::print_tree;
8use taffy::{
9    compute_cached_layout, compute_flexbox_layout, compute_grid_layout, compute_leaf_layout, compute_root_layout,
10    prelude::*, round_layout, Cache, CacheTree,
11};
12
13#[derive(Debug, Copy, Clone)]
14#[allow(dead_code)]
15enum NodeKind {
16    Flexbox,
17    Grid,
18    Text,
19    Image,
20}
21
22struct Node {
23    kind: NodeKind,
24    style: Style,
25    text_data: Option<TextContext>,
26    image_data: Option<ImageContext>,
27    cache: Cache,
28    unrounded_layout: Layout,
29    final_layout: Layout,
30    children: Vec<usize>,
31}
32
33impl Default for Node {
34    fn default() -> Self {
35        Node {
36            kind: NodeKind::Flexbox,
37            style: Style::default(),
38            text_data: None,
39            image_data: None,
40            cache: Cache::new(),
41            unrounded_layout: Layout::with_order(0),
42            final_layout: Layout::with_order(0),
43            children: Vec::new(),
44        }
45    }
46}
47
48#[allow(dead_code)]
49impl Node {
50    pub fn new_row(style: Style) -> Node {
51        Node {
52            kind: NodeKind::Flexbox,
53            style: Style { display: Display::Flex, flex_direction: FlexDirection::Row, ..style },
54            ..Node::default()
55        }
56    }
57    pub fn new_column(style: Style) -> Node {
58        Node {
59            kind: NodeKind::Flexbox,
60            style: Style { display: Display::Flex, flex_direction: FlexDirection::Column, ..style },
61            ..Node::default()
62        }
63    }
64    pub fn new_grid(style: Style) -> Node {
65        Node { kind: NodeKind::Grid, style: Style { display: Display::Grid, ..style }, ..Node::default() }
66    }
67    pub fn new_text(style: Style, text_data: TextContext) -> Node {
68        Node { kind: NodeKind::Text, style, text_data: Some(text_data), ..Node::default() }
69    }
70    pub fn new_image(style: Style, image_data: ImageContext) -> Node {
71        Node { kind: NodeKind::Image, style, image_data: Some(image_data), ..Node::default() }
72    }
73}
74
75struct Tree {
76    nodes: Vec<Node>,
77}
78
79impl Tree {
80    pub fn new() -> Tree {
81        Tree { nodes: Vec::new() }
82    }
83
84    pub fn add_node(&mut self, node: Node) -> usize {
85        self.nodes.push(node);
86        self.nodes.len() - 1
87    }
88
89    pub fn append_child(&mut self, parent: usize, child: usize) {
90        self.nodes[parent].children.push(child);
91    }
92
93    #[inline(always)]
94    fn node_from_id(&self, node_id: NodeId) -> &Node {
95        &self.nodes[usize::from(node_id)]
96    }
97
98    #[inline(always)]
99    fn node_from_id_mut(&mut self, node_id: NodeId) -> &mut Node {
100        &mut self.nodes[usize::from(node_id)]
101    }
102
103    pub fn compute_layout(&mut self, root: usize, available_space: Size<AvailableSpace>, use_rounding: bool) {
104        compute_root_layout(self, NodeId::from(root), available_space);
105        if use_rounding {
106            round_layout(self, NodeId::from(root))
107        }
108    }
109
110    pub fn print_tree(&mut self, root: usize) {
111        print_tree(self, NodeId::from(root));
112    }
113}
114
115struct ChildIter<'a>(std::slice::Iter<'a, usize>);
116impl Iterator for ChildIter<'_> {
117    type Item = NodeId;
118    fn next(&mut self) -> Option<Self::Item> {
119        self.0.next().copied().map(NodeId::from)
120    }
121}
122
123impl taffy::TraversePartialTree for Tree {
124    type ChildIter<'a> = ChildIter<'a>;
125
126    fn child_ids(&self, node_id: NodeId) -> Self::ChildIter<'_> {
127        ChildIter(self.node_from_id(node_id).children.iter())
128    }
129
130    fn child_count(&self, node_id: NodeId) -> usize {
131        self.node_from_id(node_id).children.len()
132    }
133
134    fn get_child_id(&self, node_id: NodeId, index: usize) -> NodeId {
135        NodeId::from(self.node_from_id(node_id).children[index])
136    }
137}
138
139impl taffy::TraverseTree for Tree {}
140
141impl taffy::LayoutPartialTree for Tree {
142    type CoreContainerStyle<'a>
143        = &'a Style
144    where
145        Self: 'a;
146
147    fn get_core_container_style(&self, node_id: NodeId) -> Self::CoreContainerStyle<'_> {
148        &self.node_from_id(node_id).style
149    }
150
151    fn set_unrounded_layout(&mut self, node_id: NodeId, layout: &Layout) {
152        self.node_from_id_mut(node_id).unrounded_layout = *layout;
153    }
154
155    fn resolve_calc_value(&self, _val: *const (), _basis: f32) -> f32 {
156        0.0
157    }
158
159    fn compute_child_layout(&mut self, node_id: NodeId, inputs: taffy::tree::LayoutInput) -> taffy::tree::LayoutOutput {
160        compute_cached_layout(self, node_id, inputs, |tree, node_id, inputs| {
161            let node = &mut tree.nodes[usize::from(node_id)];
162            let font_metrics = FontMetrics { char_width: 10.0, char_height: 10.0 };
163
164            match node.kind {
165                NodeKind::Flexbox => compute_flexbox_layout(tree, node_id, inputs),
166                NodeKind::Grid => compute_grid_layout(tree, node_id, inputs),
167                NodeKind::Text => compute_leaf_layout(
168                    inputs,
169                    &node.style,
170                    |_val, _basis| 0.0,
171                    |known_dimensions, available_space| {
172                        text_measure_function(
173                            known_dimensions,
174                            available_space,
175                            node.text_data.as_ref().unwrap(),
176                            &font_metrics,
177                        )
178                    },
179                ),
180                NodeKind::Image => compute_leaf_layout(
181                    inputs,
182                    &node.style,
183                    |_val, _basis| 0.0,
184                    |known_dimensions, _available_space| {
185                        image_measure_function(known_dimensions, node.image_data.as_ref().unwrap())
186                    },
187                ),
188            }
189        })
190    }
191}
192
193impl CacheTree for Tree {
194    fn cache_get(
195        &self,
196        node_id: NodeId,
197        known_dimensions: Size<Option<f32>>,
198        available_space: Size<AvailableSpace>,
199        run_mode: taffy::RunMode,
200    ) -> Option<taffy::LayoutOutput> {
201        self.node_from_id(node_id).cache.get(known_dimensions, available_space, run_mode)
202    }
203
204    fn cache_store(
205        &mut self,
206        node_id: NodeId,
207        known_dimensions: Size<Option<f32>>,
208        available_space: Size<AvailableSpace>,
209        run_mode: taffy::RunMode,
210        layout_output: taffy::LayoutOutput,
211    ) {
212        self.node_from_id_mut(node_id).cache.store(known_dimensions, available_space, run_mode, layout_output)
213    }
214
215    fn cache_clear(&mut self, node_id: NodeId) {
216        self.node_from_id_mut(node_id).cache.clear();
217    }
218}
219
220impl taffy::LayoutFlexboxContainer for Tree {
221    type FlexboxContainerStyle<'a>
222        = &'a Style
223    where
224        Self: 'a;
225
226    type FlexboxItemStyle<'a>
227        = &'a Style
228    where
229        Self: 'a;
230
231    fn get_flexbox_container_style(&self, node_id: NodeId) -> Self::FlexboxContainerStyle<'_> {
232        &self.node_from_id(node_id).style
233    }
234
235    fn get_flexbox_child_style(&self, child_node_id: NodeId) -> Self::FlexboxItemStyle<'_> {
236        &self.node_from_id(child_node_id).style
237    }
238}
239
240impl taffy::LayoutGridContainer for Tree {
241    type GridContainerStyle<'a>
242        = &'a Style
243    where
244        Self: 'a;
245
246    type GridItemStyle<'a>
247        = &'a Style
248    where
249        Self: 'a;
250
251    fn get_grid_container_style(&self, node_id: NodeId) -> Self::GridContainerStyle<'_> {
252        &self.node_from_id(node_id).style
253    }
254
255    fn get_grid_child_style(&self, child_node_id: NodeId) -> Self::GridItemStyle<'_> {
256        &self.node_from_id(child_node_id).style
257    }
258}
259
260impl taffy::RoundTree for Tree {
261    fn get_unrounded_layout(&self, node_id: NodeId) -> &Layout {
262        &self.node_from_id(node_id).unrounded_layout
263    }
264
265    fn set_final_layout(&mut self, node_id: NodeId, layout: &Layout) {
266        self.node_from_id_mut(node_id).final_layout = *layout;
267    }
268}
269
270impl taffy::PrintTree for Tree {
271    fn get_debug_label(&self, node_id: NodeId) -> &'static str {
272        match self.node_from_id(node_id).kind {
273            NodeKind::Flexbox => "FLEX",
274            NodeKind::Grid => "GRID",
275            NodeKind::Text => "TEXT",
276            NodeKind::Image => "IMAGE",
277        }
278    }
279
280    fn get_final_layout(&self, node_id: NodeId) -> &Layout {
281        &self.node_from_id(node_id).final_layout
282    }
283}
284
285fn main() -> Result<(), taffy::TaffyError> {
286    let mut tree = Tree::new();
287
288    let root = Node::new_column(Style::DEFAULT);
289    let root_id = tree.add_node(root);
290
291    let text_node = Node::new_text(
292        Style::default(),
293        TextContext { text_content: LOREM_IPSUM.into(), writing_mode: WritingMode::Horizontal },
294    );
295    let text_node_id = tree.add_node(text_node);
296    tree.append_child(root_id, text_node_id);
297
298    let image_node = Node::new_image(Style::default(), ImageContext { width: 400.0, height: 300.0 });
299    let image_node_id = tree.add_node(image_node);
300    tree.append_child(root_id, image_node_id);
301
302    // Compute layout and print result
303    tree.compute_layout(root_id, Size::MAX_CONTENT, true);
304    tree.print_tree(root_id);
305
306    Ok(())
307}