Call measure function on leaf nodes even if the node does not have context (#598)
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::tree::Cache;
8use taffy::util::print_tree;
9use taffy::{
10 compute_cached_layout, compute_flexbox_layout, compute_grid_layout, compute_leaf_layout, compute_root_layout,
11 prelude::*, round_layout,
12};
13
14#[derive(Debug, Copy, Clone)]
15#[allow(dead_code)]
16enum NodeKind {
17 Flexbox,
18 Grid,
19 Text,
20 Image,
21}
22
23struct Node {
24 kind: NodeKind,
25 style: Style,
26 text_data: Option<TextContext>,
27 image_data: Option<ImageContext>,
28 cache: Cache,
29 unrounded_layout: Layout,
30 final_layout: Layout,
31 children: Vec<Node>,
32}
33
34impl Default for Node {
35 fn default() -> Self {
36 Node {
37 kind: NodeKind::Flexbox,
38 style: Style::default(),
39 text_data: None,
40 image_data: None,
41 cache: Cache::new(),
42 unrounded_layout: Layout::with_order(0),
43 final_layout: Layout::with_order(0),
44 children: Vec::new(),
45 }
46 }
47}
48
49#[allow(dead_code)]
50impl Node {
51 pub fn new_row(style: Style) -> Node {
52 Node {
53 kind: NodeKind::Flexbox,
54 style: Style { display: Display::Flex, flex_direction: FlexDirection::Row, ..style },
55 ..Node::default()
56 }
57 }
58 pub fn new_column(style: Style) -> Node {
59 Node {
60 kind: NodeKind::Flexbox,
61 style: Style { display: Display::Flex, flex_direction: FlexDirection::Column, ..style },
62 ..Node::default()
63 }
64 }
65 pub fn new_grid(style: Style) -> Node {
66 Node { kind: NodeKind::Grid, style: Style { display: Display::Grid, ..style }, ..Node::default() }
67 }
68 pub fn new_text(style: Style, text_data: TextContext) -> Node {
69 Node { kind: NodeKind::Text, style, text_data: Some(text_data), ..Node::default() }
70 }
71 pub fn new_image(style: Style, image_data: ImageContext) -> Node {
72 Node { kind: NodeKind::Image, style, image_data: Some(image_data), ..Node::default() }
73 }
74 pub fn append_child(&mut self, node: Node) {
75 self.children.push(node);
76 }
77
78 unsafe fn as_id(&self) -> NodeId {
79 NodeId::from(self as *const Node as usize)
80 }
81
82 pub fn compute_layout(&mut self, available_space: Size<AvailableSpace>, use_rounding: bool) {
83 let root_node_id = unsafe { self.as_id() };
84 compute_root_layout(&mut StatelessLayoutTree, root_node_id, available_space);
85 if use_rounding {
86 round_layout(&mut StatelessLayoutTree, root_node_id)
87 }
88 }
89
90 pub fn print_tree(&mut self) {
91 print_tree(&mut StatelessLayoutTree, unsafe { self.as_id() });
92 }
93}
94
95struct ChildIter<'a>(std::slice::Iter<'a, Node>);
96impl<'a> Iterator for ChildIter<'a> {
97 type Item = NodeId;
98 fn next(&mut self) -> Option<Self::Item> {
99 self.0.next().map(|c| NodeId::from(c as *const Node as usize))
100 }
101}
102
103#[inline(always)]
104unsafe fn node_from_id<'a>(node_id: NodeId) -> &'a Node {
105 &*(usize::from(node_id) as *const Node)
106}
107
108#[inline(always)]
109unsafe fn node_from_id_mut<'a>(node_id: NodeId) -> &'a mut Node {
110 &mut *(usize::from(node_id) as *mut Node)
111}
112
113struct StatelessLayoutTree;
114impl TraversePartialTree for StatelessLayoutTree {
115 type ChildIter<'a> = ChildIter<'a>;
116
117 fn child_ids(&self, node_id: NodeId) -> Self::ChildIter<'_> {
118 unsafe { ChildIter(node_from_id(node_id).children.iter()) }
119 }
120
121 fn child_count(&self, node_id: NodeId) -> usize {
122 unsafe { node_from_id(node_id).children.len() }
123 }
124
125 fn get_child_id(&self, node_id: NodeId, index: usize) -> NodeId {
126 unsafe { node_from_id(node_id).children[index].as_id() }
127 }
128}
129
130impl TraverseTree for StatelessLayoutTree {}
131
132impl LayoutPartialTree for StatelessLayoutTree {
133 fn get_style(&self, node_id: NodeId) -> &Style {
134 unsafe { &node_from_id(node_id).style }
135 }
136
137 fn set_unrounded_layout(&mut self, node_id: NodeId, layout: &Layout) {
138 unsafe { node_from_id_mut(node_id).unrounded_layout = *layout };
139 }
140
141 fn get_cache_mut(&mut self, node_id: NodeId) -> &mut Cache {
142 unsafe { &mut node_from_id_mut(node_id).cache }
143 }
144
145 fn compute_child_layout(&mut self, node_id: NodeId, inputs: taffy::tree::LayoutInput) -> taffy::tree::LayoutOutput {
146 compute_cached_layout(self, node_id, inputs, |tree, node_id, inputs| {
147 let node = unsafe { node_from_id_mut(node_id) };
148 let font_metrics = FontMetrics { char_width: 10.0, char_height: 10.0 };
149
150 match node.kind {
151 NodeKind::Flexbox => compute_flexbox_layout(tree, node_id, inputs),
152 NodeKind::Grid => compute_grid_layout(tree, node_id, inputs),
153 NodeKind::Text => compute_leaf_layout(inputs, &node.style, |known_dimensions, available_space| {
154 text_measure_function(
155 known_dimensions,
156 available_space,
157 node.text_data.as_ref().unwrap(),
158 &font_metrics,
159 )
160 }),
161 NodeKind::Image => compute_leaf_layout(inputs, &node.style, |known_dimensions, _available_space| {
162 image_measure_function(known_dimensions, node.image_data.as_ref().unwrap())
163 }),
164 }
165 })
166 }
167}
168
169impl RoundTree for StatelessLayoutTree {
170 fn get_unrounded_layout(&self, node_id: NodeId) -> &Layout {
171 unsafe { &node_from_id_mut(node_id).unrounded_layout }
172 }
173
174 fn set_final_layout(&mut self, node_id: NodeId, layout: &Layout) {
175 unsafe { node_from_id_mut(node_id).final_layout = *layout }
176 }
177}
178
179impl PrintTree for StatelessLayoutTree {
180 fn get_debug_label(&self, node_id: NodeId) -> &'static str {
181 match unsafe { node_from_id(node_id).kind } {
182 NodeKind::Flexbox => "FLEX",
183 NodeKind::Grid => "GRID",
184 NodeKind::Text => "TEXT",
185 NodeKind::Image => "IMAGE",
186 }
187 }
188
189 fn get_final_layout(&self, node_id: NodeId) -> &Layout {
190 unsafe { &node_from_id(node_id).final_layout }
191 }
192}
193
194fn main() -> Result<(), taffy::TaffyError> {
195 let mut root = Node::new_column(Style::DEFAULT);
196
197 let text_node = Node::new_text(
198 Style::default(),
199 TextContext { text_content: LOREM_IPSUM.into(), writing_mode: WritingMode::Horizontal },
200 );
201 root.append_child(text_node);
202
203 let image_node = Node::new_image(Style::default(), ImageContext { width: 400.0, height: 300.0 });
204 root.append_child(image_node);
205
206 // Compute layout and print result
207 root.compute_layout(Size::MAX_CONTENT, true);
208 root.print_tree();
209
210 Ok(())
211}