Fixup for passing style to measure functions
1//! Contains [TaffyTree](crate::tree::TaffyTree): the default implementation of [LayoutTree](crate::tree::LayoutTree), and the error type for Taffy.
2#[cfg(not(feature = "std"))]
3use slotmap::SecondaryMap;
4#[cfg(feature = "std")]
5use slotmap::SparseSecondaryMap as SecondaryMap;
6use slotmap::{DefaultKey, SlotMap};
7
8use crate::geometry::Size;
9use crate::style::{AvailableSpace, Display, Style};
10use crate::tree::{
11 Cache, Layout, LayoutInput, LayoutOutput, LayoutPartialTree, NodeId, PrintTree, RoundTree, RunMode,
12 TraversePartialTree, TraverseTree,
13};
14use crate::util::debug::{debug_log, debug_log_node};
15use crate::util::sys::{new_vec_with_capacity, ChildrenVec, Vec};
16
17#[cfg(feature = "block_layout")]
18use crate::compute::compute_block_layout;
19#[cfg(feature = "flexbox")]
20use crate::compute::compute_flexbox_layout;
21#[cfg(feature = "grid")]
22use crate::compute::compute_grid_layout;
23use crate::compute::{
24 compute_cached_layout, compute_hidden_layout, compute_leaf_layout, compute_root_layout, round_layout,
25};
26use crate::{LayoutBlockContainer, LayoutFlexboxContainer, LayoutGridContainer};
27
28/// The error Taffy generates on invalid operations
29pub type TaffyResult<T> = Result<T, TaffyError>;
30
31/// An error that occurs while trying to access or modify a node's children by index.
32#[derive(Debug)]
33pub enum TaffyError {
34 /// The parent node does not have a child at `child_index`. It only has `child_count` children
35 ChildIndexOutOfBounds {
36 /// The parent node whose child was being looked up
37 parent: NodeId,
38 /// The index that was looked up
39 child_index: usize,
40 /// The total number of children the parent has
41 child_count: usize,
42 },
43 /// The parent node was not found in the [`TaffyTree`](crate::TaffyTree) instance.
44 InvalidParentNode(NodeId),
45 /// The child node was not found in the [`TaffyTree`](crate::TaffyTree) instance.
46 InvalidChildNode(NodeId),
47 /// The supplied node was not found in the [`TaffyTree`](crate::TaffyTree) instance.
48 InvalidInputNode(NodeId),
49}
50
51impl core::fmt::Display for TaffyError {
52 fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
53 match self {
54 TaffyError::ChildIndexOutOfBounds { parent, child_index, child_count } => {
55 write!(f, "Index (is {child_index}) should be < child_count ({child_count}) for parent node {parent:?}")
56 }
57 TaffyError::InvalidParentNode(parent) => {
58 write!(f, "Parent Node {parent:?} is not in the TaffyTree instance")
59 }
60 TaffyError::InvalidChildNode(child) => write!(f, "Child Node {child:?} is not in the TaffyTree instance"),
61 TaffyError::InvalidInputNode(node) => write!(f, "Supplied Node {node:?} is not in the TaffyTree instance"),
62 }
63 }
64}
65
66#[cfg(feature = "std")]
67impl std::error::Error for TaffyError {}
68
69/// Global configuration values for a TaffyTree instance
70pub(crate) struct TaffyConfig {
71 /// Whether to round layout values
72 pub(crate) use_rounding: bool,
73}
74
75impl Default for TaffyConfig {
76 fn default() -> Self {
77 Self { use_rounding: true }
78 }
79}
80
81/// Layout information for a given [`Node`](crate::node::Node)
82///
83/// Stored in a [`TaffyTree`].
84struct NodeData {
85 /// The layout strategy used by this node
86 pub(crate) style: Style,
87
88 /// The always unrounded results of the layout computation. We must store this separately from the rounded
89 /// layout to avoid errors from rounding already-rounded values. See <https://github.com/DioxusLabs/taffy/issues/501>.
90 pub(crate) unrounded_layout: Layout,
91
92 /// The final results of the layout computation.
93 /// These may be rounded or unrounded depending on what the `use_rounding` config setting is set to.
94 pub(crate) final_layout: Layout,
95
96 /// Whether the node has context data associated with it or not
97 pub(crate) has_context: bool,
98
99 /// The cached results of the layout computation
100 pub(crate) cache: Cache,
101}
102
103impl NodeData {
104 /// Create the data for a new node
105 #[must_use]
106 pub const fn new(style: Style) -> Self {
107 Self {
108 style,
109 cache: Cache::new(),
110 unrounded_layout: Layout::new(),
111 final_layout: Layout::new(),
112 has_context: false,
113 }
114 }
115
116 /// Marks a node and all of its parents (recursively) as dirty
117 ///
118 /// This clears any cached data and signals that the data must be recomputed.
119 #[inline]
120 pub fn mark_dirty(&mut self) {
121 self.cache.clear()
122 }
123}
124
125/// An entire tree of UI nodes. The entry point to Taffy's high-level API.
126///
127/// Allows you to build a tree of UI nodes, run Taffy's layout algorithms over that tree, and then access the resultant layout.
128pub struct TaffyTree<NodeContext = ()> {
129 /// The [`NodeData`] for each node stored in this tree
130 nodes: SlotMap<DefaultKey, NodeData>,
131
132 /// Functions/closures that compute the intrinsic size of leaf nodes
133 node_context_data: SecondaryMap<DefaultKey, NodeContext>,
134
135 /// The children of each node
136 ///
137 /// The indexes in the outer vector correspond to the position of the parent [`NodeData`]
138 children: SlotMap<DefaultKey, ChildrenVec<NodeId>>,
139
140 /// The parents of each node
141 ///
142 /// The indexes in the outer vector correspond to the position of the child [`NodeData`]
143 parents: SlotMap<DefaultKey, Option<NodeId>>,
144
145 /// Layout mode configuration
146 config: TaffyConfig,
147}
148
149impl Default for TaffyTree {
150 fn default() -> TaffyTree<()> {
151 TaffyTree::new()
152 }
153}
154
155/// Iterator that wraps a slice of nodes, lazily converting them to u64
156pub struct TaffyTreeChildIter<'a>(core::slice::Iter<'a, NodeId>);
157impl<'a> Iterator for TaffyTreeChildIter<'a> {
158 type Item = NodeId;
159
160 fn next(&mut self) -> Option<Self::Item> {
161 self.0.next().copied()
162 }
163}
164
165// TraversePartialTree impl for TaffyTree
166impl<NodeContext> TraversePartialTree for TaffyTree<NodeContext> {
167 type ChildIter<'a> = TaffyTreeChildIter<'a> where Self: 'a;
168
169 #[inline(always)]
170 fn child_ids(&self, parent_node_id: NodeId) -> Self::ChildIter<'_> {
171 TaffyTreeChildIter(self.children[parent_node_id.into()].iter())
172 }
173
174 #[inline(always)]
175 fn child_count(&self, parent_node_id: NodeId) -> usize {
176 self.children[parent_node_id.into()].len()
177 }
178
179 #[inline(always)]
180 fn get_child_id(&self, parent_node_id: NodeId, id: usize) -> NodeId {
181 self.children[parent_node_id.into()][id]
182 }
183}
184
185// TraverseTree impl for TaffyTree
186impl<NodeContext> TraverseTree for TaffyTree<NodeContext> {}
187
188// PrintTree impl for TaffyTree
189impl<NodeContext> PrintTree for TaffyTree<NodeContext> {
190 #[inline(always)]
191 fn get_debug_label(&self, node_id: NodeId) -> &'static str {
192 let node = &self.nodes[node_id.into()];
193 let display = node.style.display;
194 let num_children = self.child_count(node_id);
195
196 match (num_children, display) {
197 (_, Display::None) => "NONE",
198 (0, _) => "LEAF",
199 #[cfg(feature = "block_layout")]
200 (_, Display::Block) => "BLOCK",
201 #[cfg(feature = "flexbox")]
202 (_, Display::Flex) => {
203 use crate::FlexDirection;
204 match node.style.flex_direction {
205 FlexDirection::Row | FlexDirection::RowReverse => "FLEX ROW",
206 FlexDirection::Column | FlexDirection::ColumnReverse => "FLEX COL",
207 }
208 }
209 #[cfg(feature = "grid")]
210 (_, Display::Grid) => "GRID",
211 }
212 }
213
214 #[inline(always)]
215 fn get_final_layout(&self, node_id: NodeId) -> &Layout {
216 &self.nodes[node_id.into()].final_layout
217 }
218}
219
220/// View over the Taffy tree that holds the tree itself along with a reference to the context
221/// and implements LayoutTree. This allows the context to be stored outside of the TaffyTree struct
222/// which makes the lifetimes of the context much more flexible.
223pub(crate) struct TaffyView<'t, NodeContext, MeasureFunction>
224where
225 MeasureFunction:
226 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
227{
228 /// A reference to the TaffyTree
229 pub(crate) taffy: &'t mut TaffyTree<NodeContext>,
230 /// The context provided for passing to measure functions if layout is run over this struct
231 pub(crate) measure_function: MeasureFunction,
232}
233
234// TraversePartialTree impl for TaffyView
235impl<'t, NodeContext, MeasureFunction> TraversePartialTree for TaffyView<'t, NodeContext, MeasureFunction>
236where
237 MeasureFunction:
238 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
239{
240 type ChildIter<'a> = TaffyTreeChildIter<'a> where Self: 'a;
241
242 #[inline(always)]
243 fn child_ids(&self, parent_node_id: NodeId) -> Self::ChildIter<'_> {
244 self.taffy.child_ids(parent_node_id)
245 }
246
247 #[inline(always)]
248 fn child_count(&self, parent_node_id: NodeId) -> usize {
249 self.taffy.child_count(parent_node_id)
250 }
251
252 #[inline(always)]
253 fn get_child_id(&self, parent_node_id: NodeId, child_index: usize) -> NodeId {
254 self.taffy.get_child_id(parent_node_id, child_index)
255 }
256}
257
258// TraverseTree impl for TaffyView
259impl<'t, NodeContext, MeasureFunction> TraverseTree for TaffyView<'t, NodeContext, MeasureFunction> where
260 MeasureFunction:
261 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>
262{
263}
264
265// LayoutPartialTree impl for TaffyView
266impl<'t, NodeContext, MeasureFunction> LayoutPartialTree for TaffyView<'t, NodeContext, MeasureFunction>
267where
268 MeasureFunction:
269 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
270{
271 type CoreContainerStyle<'a> = &'a Style where Self : 'a;
272
273 #[inline(always)]
274 fn get_core_container_style(&self, node_id: NodeId) -> Self::CoreContainerStyle<'_> {
275 &self.taffy.nodes[node_id.into()].style
276 }
277
278 #[inline(always)]
279 fn get_cache_mut(&mut self, node: NodeId) -> &mut Cache {
280 &mut self.taffy.nodes[node.into()].cache
281 }
282
283 #[inline(always)]
284 fn set_unrounded_layout(&mut self, node_id: NodeId, layout: &Layout) {
285 self.taffy.nodes[node_id.into()].unrounded_layout = *layout;
286 }
287
288 #[inline(always)]
289 fn compute_child_layout(&mut self, node: NodeId, inputs: LayoutInput) -> LayoutOutput {
290 // If RunMode is PerformHiddenLayout then this indicates that an ancestor node is `Display::None`
291 // and thus that we should lay out this node using hidden layout regardless of it's own display style.
292 if inputs.run_mode == RunMode::PerformHiddenLayout {
293 debug_log!("HIDDEN");
294 return compute_hidden_layout(self, node);
295 }
296
297 // We run the following wrapped in "compute_cached_layout", which will check the cache for an entry matching the node and inputs and:
298 // - Return that entry if exists
299 // - Else call the passed closure (below) to compute the result
300 //
301 // If there was no cache match and a new result needs to be computed then that result will be added to the cache
302 compute_cached_layout(self, node, inputs, |tree, node, inputs| {
303 let display_mode = tree.taffy.nodes[node.into()].style.display;
304 let has_children = tree.child_count(node) > 0;
305
306 debug_log!(display_mode);
307 debug_log_node!(
308 inputs.known_dimensions,
309 inputs.parent_size,
310 inputs.available_space,
311 inputs.run_mode,
312 inputs.sizing_mode
313 );
314
315 // Dispatch to a layout algorithm based on the node's display style and whether the node has children or not.
316 match (display_mode, has_children) {
317 (Display::None, _) => compute_hidden_layout(tree, node),
318 #[cfg(feature = "block_layout")]
319 (Display::Block, true) => compute_block_layout(tree, node, inputs),
320 #[cfg(feature = "flexbox")]
321 (Display::Flex, true) => compute_flexbox_layout(tree, node, inputs),
322 #[cfg(feature = "grid")]
323 (Display::Grid, true) => compute_grid_layout(tree, node, inputs),
324 (_, false) => {
325 let node_key = node.into();
326 let style = &tree.taffy.nodes[node_key].style;
327 let has_context = tree.taffy.nodes[node_key].has_context;
328 let node_context = has_context.then(|| tree.taffy.node_context_data.get_mut(node_key)).flatten();
329 let measure_function = |known_dimensions, available_space| {
330 (tree.measure_function)(known_dimensions, available_space, node, node_context, style)
331 };
332 compute_leaf_layout(inputs, style, measure_function)
333 }
334 }
335 })
336 }
337}
338
339impl<'t, NodeContext, MeasureFunction> LayoutBlockContainer for TaffyView<'t, NodeContext, MeasureFunction>
340where
341 MeasureFunction:
342 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
343{
344 type ContainerStyle<'a> = &'a Style where Self: 'a;
345 type ItemStyle<'a> = &'a Style where Self: 'a;
346
347 #[inline(always)]
348 fn get_block_container_style(&self, node_id: NodeId) -> Self::ContainerStyle<'_> {
349 self.get_core_container_style(node_id)
350 }
351
352 #[inline(always)]
353 fn get_block_child_style(&self, child_node_id: NodeId) -> Self::ItemStyle<'_> {
354 self.get_core_container_style(child_node_id)
355 }
356}
357
358impl<'t, NodeContext, MeasureFunction> LayoutFlexboxContainer for TaffyView<'t, NodeContext, MeasureFunction>
359where
360 MeasureFunction:
361 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
362{
363 type ContainerStyle<'a> = &'a Style where Self: 'a;
364 type ItemStyle<'a> = &'a Style where Self: 'a;
365
366 #[inline(always)]
367 fn get_flexbox_container_style(&self, node_id: NodeId) -> Self::ContainerStyle<'_> {
368 &self.taffy.nodes[node_id.into()].style
369 }
370
371 #[inline(always)]
372 fn get_flexbox_child_style(&self, child_node_id: NodeId) -> Self::ItemStyle<'_> {
373 &self.taffy.nodes[child_node_id.into()].style
374 }
375}
376
377impl<'t, NodeContext, MeasureFunction> LayoutGridContainer for TaffyView<'t, NodeContext, MeasureFunction>
378where
379 MeasureFunction:
380 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
381{
382 type ContainerStyle<'a> = &'a Style where Self: 'a;
383 type ItemStyle<'a> = &'a Style where Self: 'a;
384
385 #[inline(always)]
386 fn get_grid_container_style(&self, node_id: NodeId) -> Self::ContainerStyle<'_> {
387 &self.taffy.nodes[node_id.into()].style
388 }
389
390 #[inline(always)]
391 fn get_grid_child_style(&self, child_node_id: NodeId) -> Self::ItemStyle<'_> {
392 &self.taffy.nodes[child_node_id.into()].style
393 }
394}
395
396// RoundTree impl for TaffyView
397impl<'t, NodeContext, MeasureFunction> RoundTree for TaffyView<'t, NodeContext, MeasureFunction>
398where
399 MeasureFunction:
400 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
401{
402 #[inline(always)]
403 fn get_unrounded_layout(&self, node: NodeId) -> &Layout {
404 &self.taffy.nodes[node.into()].unrounded_layout
405 }
406
407 #[inline(always)]
408 fn set_final_layout(&mut self, node_id: NodeId, layout: &Layout) {
409 self.taffy.nodes[node_id.into()].final_layout = *layout;
410 }
411}
412
413#[allow(clippy::iter_cloned_collect)] // due to no-std support, we need to use `iter_cloned` instead of `collect`
414impl<NodeContext> TaffyTree<NodeContext> {
415 /// Creates a new [`TaffyTree`]
416 ///
417 /// The default capacity of a [`TaffyTree`] is 16 nodes.
418 #[must_use]
419 pub fn new() -> Self {
420 Self::with_capacity(16)
421 }
422
423 /// Creates a new [`TaffyTree`] that can store `capacity` nodes before reallocation
424 #[must_use]
425 pub fn with_capacity(capacity: usize) -> Self {
426 TaffyTree {
427 // TODO: make this method const upstream,
428 // so constructors here can be const
429 nodes: SlotMap::with_capacity(capacity),
430 children: SlotMap::with_capacity(capacity),
431 parents: SlotMap::with_capacity(capacity),
432 node_context_data: SecondaryMap::with_capacity(capacity),
433 config: TaffyConfig::default(),
434 }
435 }
436
437 /// Enable rounding of layout values. Rounding is enabled by default.
438 pub fn enable_rounding(&mut self) {
439 self.config.use_rounding = true;
440 }
441
442 /// Disable rounding of layout values. Rounding is enabled by default.
443 pub fn disable_rounding(&mut self) {
444 self.config.use_rounding = false;
445 }
446
447 /// Creates and adds a new unattached leaf node to the tree, and returns the node of the new node
448 pub fn new_leaf(&mut self, layout: Style) -> TaffyResult<NodeId> {
449 let id = self.nodes.insert(NodeData::new(layout));
450 let _ = self.children.insert(new_vec_with_capacity(0));
451 let _ = self.parents.insert(None);
452
453 Ok(id.into())
454 }
455
456 /// Creates and adds a new unattached leaf node to the tree, and returns the [`NodeId`] of the new node
457 ///
458 /// Creates and adds a new leaf node with a supplied context
459 pub fn new_leaf_with_context(&mut self, layout: Style, context: NodeContext) -> TaffyResult<NodeId> {
460 let mut data = NodeData::new(layout);
461 data.has_context = true;
462
463 let id = self.nodes.insert(data);
464 self.node_context_data.insert(id, context);
465
466 let _ = self.children.insert(new_vec_with_capacity(0));
467 let _ = self.parents.insert(None);
468
469 Ok(id.into())
470 }
471
472 /// Creates and adds a new node, which may have any number of `children`
473 pub fn new_with_children(&mut self, layout: Style, children: &[NodeId]) -> TaffyResult<NodeId> {
474 let id = NodeId::from(self.nodes.insert(NodeData::new(layout)));
475
476 for child in children {
477 self.parents[(*child).into()] = Some(id);
478 }
479
480 let _ = self.children.insert(children.iter().copied().collect::<_>());
481 let _ = self.parents.insert(None);
482
483 Ok(id)
484 }
485
486 /// Drops all nodes in the tree
487 pub fn clear(&mut self) {
488 self.nodes.clear();
489 self.children.clear();
490 self.parents.clear();
491 }
492
493 /// Remove a specific node from the tree and drop it
494 ///
495 /// Returns the id of the node removed.
496 pub fn remove(&mut self, node: NodeId) -> TaffyResult<NodeId> {
497 let key = node.into();
498 if let Some(parent) = self.parents[key] {
499 if let Some(children) = self.children.get_mut(parent.into()) {
500 children.retain(|f| *f != node);
501 }
502 }
503
504 // Remove "parent" references to a node when removing that node
505 if let Some(children) = self.children.get(key) {
506 for child in children.iter().copied() {
507 self.parents[child.into()] = None;
508 }
509 }
510
511 let _ = self.children.remove(key);
512 let _ = self.parents.remove(key);
513 let _ = self.nodes.remove(key);
514
515 Ok(node)
516 }
517
518 /// Sets the context data associated with the node
519 pub fn set_node_context(&mut self, node: NodeId, measure: Option<NodeContext>) -> TaffyResult<()> {
520 let key = node.into();
521 if let Some(measure) = measure {
522 self.nodes[key].has_context = true;
523 self.node_context_data.insert(key, measure);
524 } else {
525 self.nodes[key].has_context = false;
526 self.node_context_data.remove(key);
527 }
528
529 self.mark_dirty(node)?;
530
531 Ok(())
532 }
533
534 /// Gets a reference to the the context data associated with the node
535 pub fn get_node_context(&self, node: NodeId) -> Option<&NodeContext> {
536 self.node_context_data.get(node.into())
537 }
538
539 /// Gets a mutable reference to the the context data associated with the node
540 pub fn get_node_context_mut(&mut self, node: NodeId) -> Option<&mut NodeContext> {
541 self.node_context_data.get_mut(node.into())
542 }
543
544 /// Gets mutable references to the the context data associated with the nodes. All keys must be valid and disjoint, otherwise None is returned.
545 pub fn get_disjoint_node_context_mut<const N: usize>(
546 &mut self,
547 keys: [NodeId; N],
548 ) -> Option<[&mut NodeContext; N]> {
549 self.node_context_data.get_disjoint_mut(keys.map(|k| k.into()))
550 }
551
552 /// Adds a `child` node under the supplied `parent`
553 pub fn add_child(&mut self, parent: NodeId, child: NodeId) -> TaffyResult<()> {
554 let parent_key = parent.into();
555 let child_key = child.into();
556 self.parents[child_key] = Some(parent);
557 self.children[parent_key].push(child);
558 self.mark_dirty(parent)?;
559
560 Ok(())
561 }
562
563 /// Inserts a `child` node at the given `child_index` under the supplied `parent`, shifting all children after it to the right.
564 pub fn insert_child_at_index(&mut self, parent: NodeId, child_index: usize, child: NodeId) -> TaffyResult<()> {
565 let parent_key = parent.into();
566
567 let child_count = self.children[parent_key].len();
568 if child_index > child_count {
569 return Err(TaffyError::ChildIndexOutOfBounds { parent, child_index, child_count });
570 }
571
572 self.parents[child.into()] = Some(parent);
573 self.children[parent_key].insert(child_index, child);
574 self.mark_dirty(parent)?;
575
576 Ok(())
577 }
578
579 /// Directly sets the `children` of the supplied `parent`
580 pub fn set_children(&mut self, parent: NodeId, children: &[NodeId]) -> TaffyResult<()> {
581 let parent_key = parent.into();
582
583 // Remove node as parent from all its current children.
584 for child in &self.children[parent_key] {
585 self.parents[(*child).into()] = None;
586 }
587
588 // Build up relation node <-> child
589 for child in children {
590 self.parents[(*child).into()] = Some(parent);
591 }
592
593 let parent_children = &mut self.children[parent_key];
594 parent_children.clear();
595 children.iter().for_each(|child| parent_children.push(*child));
596
597 self.mark_dirty(parent)?;
598
599 Ok(())
600 }
601
602 /// Removes the `child` of the parent `node`
603 ///
604 /// The child is not removed from the tree entirely, it is simply no longer attached to its previous parent.
605 pub fn remove_child(&mut self, parent: NodeId, child: NodeId) -> TaffyResult<NodeId> {
606 let index = self.children[parent.into()].iter().position(|n| *n == child).unwrap();
607 self.remove_child_at_index(parent, index)
608 }
609
610 /// Removes the child at the given `index` from the `parent`
611 ///
612 /// The child is not removed from the tree entirely, it is simply no longer attached to its previous parent.
613 pub fn remove_child_at_index(&mut self, parent: NodeId, child_index: usize) -> TaffyResult<NodeId> {
614 let parent_key = parent.into();
615 let child_count = self.children[parent_key].len();
616 if child_index >= child_count {
617 return Err(TaffyError::ChildIndexOutOfBounds { parent, child_index, child_count });
618 }
619
620 let child = self.children[parent_key].remove(child_index);
621 self.parents[child.into()] = None;
622
623 self.mark_dirty(parent)?;
624
625 Ok(child)
626 }
627
628 /// Replaces the child at the given `child_index` from the `parent` node with the new `child` node
629 ///
630 /// The child is not removed from the tree entirely, it is simply no longer attached to its previous parent.
631 pub fn replace_child_at_index(
632 &mut self,
633 parent: NodeId,
634 child_index: usize,
635 new_child: NodeId,
636 ) -> TaffyResult<NodeId> {
637 let parent_key = parent.into();
638
639 let child_count = self.children[parent_key].len();
640 if child_index >= child_count {
641 return Err(TaffyError::ChildIndexOutOfBounds { parent, child_index, child_count });
642 }
643
644 self.parents[new_child.into()] = Some(parent);
645 let old_child = core::mem::replace(&mut self.children[parent_key][child_index], new_child);
646 self.parents[old_child.into()] = None;
647
648 self.mark_dirty(parent)?;
649
650 Ok(old_child)
651 }
652
653 /// Returns the child node of the parent `node` at the provided `child_index`
654 pub fn child_at_index(&self, parent: NodeId, child_index: usize) -> TaffyResult<NodeId> {
655 let parent_key = parent.into();
656 let child_count = self.children[parent_key].len();
657 if child_index >= child_count {
658 return Err(TaffyError::ChildIndexOutOfBounds { parent, child_index, child_count });
659 }
660
661 Ok(self.children[parent_key][child_index])
662 }
663
664 /// Returns the total number of nodes in the tree
665 pub fn total_node_count(&self) -> usize {
666 self.nodes.len()
667 }
668
669 /// Returns the `NodeId` of the parent node of the specified node (if it exists)
670 ///
671 /// - Return None if the specified node has no parent
672 /// - Panics if the specified node does not exist
673 pub fn parent(&self, child_id: NodeId) -> Option<NodeId> {
674 self.parents[child_id.into()]
675 }
676
677 /// Returns a list of children that belong to the parent node
678 pub fn children(&self, parent: NodeId) -> TaffyResult<Vec<NodeId>> {
679 Ok(self.children[parent.into()].iter().copied().collect::<_>())
680 }
681
682 /// Sets the [`Style`] of the provided `node`
683 pub fn set_style(&mut self, node: NodeId, style: Style) -> TaffyResult<()> {
684 self.nodes[node.into()].style = style;
685 self.mark_dirty(node)?;
686 Ok(())
687 }
688
689 /// Gets the [`Style`] of the provided `node`
690 pub fn style(&self, node: NodeId) -> TaffyResult<&Style> {
691 Ok(&self.nodes[node.into()].style)
692 }
693
694 /// Return this node layout relative to its parent
695 pub fn layout(&self, node: NodeId) -> TaffyResult<&Layout> {
696 if self.config.use_rounding {
697 Ok(&self.nodes[node.into()].final_layout)
698 } else {
699 Ok(&self.nodes[node.into()].unrounded_layout)
700 }
701 }
702
703 /// Marks the layout computation of this node and its children as outdated
704 ///
705 /// Performs a recursive depth-first search up the tree until the root node is reached
706 ///
707 /// WARNING: this will stack-overflow if the tree contains a cycle
708 pub fn mark_dirty(&mut self, node: NodeId) -> TaffyResult<()> {
709 /// WARNING: this will stack-overflow if the tree contains a cycle
710 fn mark_dirty_recursive(
711 nodes: &mut SlotMap<DefaultKey, NodeData>,
712 parents: &SlotMap<DefaultKey, Option<NodeId>>,
713 node_key: DefaultKey,
714 ) {
715 nodes[node_key].mark_dirty();
716
717 if let Some(Some(node)) = parents.get(node_key) {
718 mark_dirty_recursive(nodes, parents, (*node).into());
719 }
720 }
721
722 mark_dirty_recursive(&mut self.nodes, &self.parents, node.into());
723
724 Ok(())
725 }
726
727 /// Indicates whether the layout of this node (and its children) need to be recomputed
728 pub fn dirty(&self, node: NodeId) -> TaffyResult<bool> {
729 Ok(self.nodes[node.into()].cache.is_empty())
730 }
731
732 /// Updates the stored layout of the provided `node` and its children
733 pub fn compute_layout_with_measure<MeasureFunction>(
734 &mut self,
735 node_id: NodeId,
736 available_space: Size<AvailableSpace>,
737 measure_function: MeasureFunction,
738 ) -> Result<(), TaffyError>
739 where
740 MeasureFunction:
741 FnMut(Size<Option<f32>>, Size<AvailableSpace>, NodeId, Option<&mut NodeContext>, &Style) -> Size<f32>,
742 {
743 let use_rounding = self.config.use_rounding;
744 let mut taffy_view = TaffyView { taffy: self, measure_function };
745 compute_root_layout(&mut taffy_view, node_id, available_space);
746 if use_rounding {
747 round_layout(&mut taffy_view, node_id);
748 }
749 Ok(())
750 }
751
752 /// Updates the stored layout of the provided `node` and its children
753 pub fn compute_layout(&mut self, node: NodeId, available_space: Size<AvailableSpace>) -> Result<(), TaffyError> {
754 self.compute_layout_with_measure(node, available_space, |_, _, _, _, _| Size::ZERO)
755 }
756
757 /// Prints a debug representation of the tree's layout
758 #[cfg(feature = "std")]
759 pub fn print_tree(&mut self, root: NodeId) {
760 crate::util::print_tree(self, root)
761 }
762
763 /// Returns an instance of LayoutTree representing the TaffyTree
764 #[cfg(test)]
765 pub(crate) fn as_layout_tree(&mut self) -> impl LayoutPartialTree + '_ {
766 TaffyView { taffy: self, measure_function: |_, _, _, _, _| Size::ZERO }
767 }
768}
769
770#[cfg(test)]
771mod tests {
772
773 use super::*;
774 use crate::style::{Dimension, Display, FlexDirection};
775 use crate::style_helpers::*;
776 use crate::util::sys;
777
778 fn size_measure_function(
779 known_dimensions: Size<Option<f32>>,
780 _available_space: Size<AvailableSpace>,
781 _node_id: NodeId,
782 node_context: Option<&mut Size<f32>>,
783 _style: &Style,
784 ) -> Size<f32> {
785 known_dimensions.unwrap_or(node_context.cloned().unwrap_or(Size::ZERO))
786 }
787
788 #[test]
789 fn new_should_allocate_default_capacity() {
790 const DEFAULT_CAPACITY: usize = 16; // This is the capacity defined in the `impl Default`
791 let taffy: TaffyTree<()> = TaffyTree::new();
792
793 assert!(taffy.children.capacity() >= DEFAULT_CAPACITY);
794 assert!(taffy.parents.capacity() >= DEFAULT_CAPACITY);
795 assert!(taffy.nodes.capacity() >= DEFAULT_CAPACITY);
796 }
797
798 #[test]
799 fn test_with_capacity() {
800 const CAPACITY: usize = 8;
801 let taffy: TaffyTree<()> = TaffyTree::with_capacity(CAPACITY);
802
803 assert!(taffy.children.capacity() >= CAPACITY);
804 assert!(taffy.parents.capacity() >= CAPACITY);
805 assert!(taffy.nodes.capacity() >= CAPACITY);
806 }
807
808 #[test]
809 fn test_new_leaf() {
810 let mut taffy: TaffyTree<()> = TaffyTree::new();
811
812 let res = taffy.new_leaf(Style::default());
813 assert!(res.is_ok());
814 let node = res.unwrap();
815
816 // node should be in the taffy tree and have no children
817 assert!(taffy.child_count(node) == 0);
818 }
819
820 #[test]
821 fn new_leaf_with_context() {
822 let mut taffy: TaffyTree<Size<f32>> = TaffyTree::new();
823
824 let res = taffy.new_leaf_with_context(Style::default(), Size::ZERO);
825 assert!(res.is_ok());
826 let node = res.unwrap();
827
828 // node should be in the taffy tree and have no children
829 assert!(taffy.child_count(node) == 0);
830 }
831
832 /// Test that new_with_children works as expected
833 #[test]
834 fn test_new_with_children() {
835 let mut taffy: TaffyTree<()> = TaffyTree::new();
836 let child0 = taffy.new_leaf(Style::default()).unwrap();
837 let child1 = taffy.new_leaf(Style::default()).unwrap();
838 let node = taffy.new_with_children(Style::default(), &[child0, child1]).unwrap();
839
840 // node should have two children
841 assert_eq!(taffy.child_count(node), 2);
842 assert_eq!(taffy.children(node).unwrap()[0], child0);
843 assert_eq!(taffy.children(node).unwrap()[1], child1);
844 }
845
846 #[test]
847 fn remove_node_should_remove() {
848 let mut taffy: TaffyTree<()> = TaffyTree::new();
849
850 let node = taffy.new_leaf(Style::default()).unwrap();
851
852 let _ = taffy.remove(node).unwrap();
853 }
854
855 #[test]
856 fn remove_node_should_detach_hierarchy() {
857 let mut taffy: TaffyTree<()> = TaffyTree::new();
858
859 // Build a linear tree layout: <0> <- <1> <- <2>
860 let node2 = taffy.new_leaf(Style::default()).unwrap();
861 let node1 = taffy.new_with_children(Style::default(), &[node2]).unwrap();
862 let node0 = taffy.new_with_children(Style::default(), &[node1]).unwrap();
863
864 // Both node0 and node1 should have 1 child nodes
865 assert_eq!(taffy.children(node0).unwrap().as_slice(), &[node1]);
866 assert_eq!(taffy.children(node1).unwrap().as_slice(), &[node2]);
867
868 // Disconnect the tree: <0> <2>
869 let _ = taffy.remove(node1).unwrap();
870
871 // Both remaining nodes should have no child nodes
872 assert!(taffy.children(node0).unwrap().is_empty());
873 assert!(taffy.children(node2).unwrap().is_empty());
874 }
875
876 #[test]
877 fn remove_last_node() {
878 let mut taffy: TaffyTree<()> = TaffyTree::new();
879
880 let parent = taffy.new_leaf(Style::default()).unwrap();
881 let child = taffy.new_leaf(Style::default()).unwrap();
882 taffy.add_child(parent, child).unwrap();
883
884 taffy.remove(child).unwrap();
885 taffy.remove(parent).unwrap();
886 }
887
888 #[test]
889 fn set_measure() {
890 let mut taffy: TaffyTree<Size<f32>> = TaffyTree::new();
891 let node = taffy.new_leaf_with_context(Style::default(), Size { width: 200.0, height: 200.0 }).unwrap();
892 taffy.compute_layout_with_measure(node, Size::MAX_CONTENT, size_measure_function).unwrap();
893 assert_eq!(taffy.layout(node).unwrap().size.width, 200.0);
894
895 taffy.set_node_context(node, Some(Size { width: 100.0, height: 100.0 })).unwrap();
896 taffy.compute_layout_with_measure(node, Size::MAX_CONTENT, size_measure_function).unwrap();
897 assert_eq!(taffy.layout(node).unwrap().size.width, 100.0);
898 }
899
900 #[test]
901 fn set_measure_of_previously_unmeasured_node() {
902 let mut taffy: TaffyTree<Size<f32>> = TaffyTree::new();
903 let node = taffy.new_leaf(Style::default()).unwrap();
904 taffy.compute_layout_with_measure(node, Size::MAX_CONTENT, size_measure_function).unwrap();
905 assert_eq!(taffy.layout(node).unwrap().size.width, 0.0);
906
907 taffy.set_node_context(node, Some(Size { width: 100.0, height: 100.0 })).unwrap();
908 taffy.compute_layout_with_measure(node, Size::MAX_CONTENT, size_measure_function).unwrap();
909 assert_eq!(taffy.layout(node).unwrap().size.width, 100.0);
910 }
911
912 /// Test that adding `add_child()` works
913 #[test]
914 fn add_child() {
915 let mut taffy: TaffyTree<()> = TaffyTree::new();
916 let node = taffy.new_leaf(Style::default()).unwrap();
917 assert_eq!(taffy.child_count(node), 0);
918
919 let child0 = taffy.new_leaf(Style::default()).unwrap();
920 taffy.add_child(node, child0).unwrap();
921 assert_eq!(taffy.child_count(node), 1);
922
923 let child1 = taffy.new_leaf(Style::default()).unwrap();
924 taffy.add_child(node, child1).unwrap();
925 assert_eq!(taffy.child_count(node), 2);
926 }
927
928 #[test]
929 fn insert_child_at_index() {
930 let mut taffy: TaffyTree<()> = TaffyTree::new();
931
932 let child0 = taffy.new_leaf(Style::default()).unwrap();
933 let child1 = taffy.new_leaf(Style::default()).unwrap();
934 let child2 = taffy.new_leaf(Style::default()).unwrap();
935
936 let node = taffy.new_leaf(Style::default()).unwrap();
937 assert_eq!(taffy.child_count(node), 0);
938
939 taffy.insert_child_at_index(node, 0, child0).unwrap();
940 assert_eq!(taffy.child_count(node), 1);
941 assert_eq!(taffy.children(node).unwrap()[0], child0);
942
943 taffy.insert_child_at_index(node, 0, child1).unwrap();
944 assert_eq!(taffy.child_count(node), 2);
945 assert_eq!(taffy.children(node).unwrap()[0], child1);
946 assert_eq!(taffy.children(node).unwrap()[1], child0);
947
948 taffy.insert_child_at_index(node, 1, child2).unwrap();
949 assert_eq!(taffy.child_count(node), 3);
950 assert_eq!(taffy.children(node).unwrap()[0], child1);
951 assert_eq!(taffy.children(node).unwrap()[1], child2);
952 assert_eq!(taffy.children(node).unwrap()[2], child0);
953 }
954
955 #[test]
956 fn set_children() {
957 let mut taffy: TaffyTree<()> = TaffyTree::new();
958
959 let child0 = taffy.new_leaf(Style::default()).unwrap();
960 let child1 = taffy.new_leaf(Style::default()).unwrap();
961 let node = taffy.new_with_children(Style::default(), &[child0, child1]).unwrap();
962
963 assert_eq!(taffy.child_count(node), 2);
964 assert_eq!(taffy.children(node).unwrap()[0], child0);
965 assert_eq!(taffy.children(node).unwrap()[1], child1);
966
967 let child2 = taffy.new_leaf(Style::default()).unwrap();
968 let child3 = taffy.new_leaf(Style::default()).unwrap();
969 taffy.set_children(node, &[child2, child3]).unwrap();
970
971 assert_eq!(taffy.child_count(node), 2);
972 assert_eq!(taffy.children(node).unwrap()[0], child2);
973 assert_eq!(taffy.children(node).unwrap()[1], child3);
974 }
975
976 /// Test that removing a child works
977 #[test]
978 fn remove_child() {
979 let mut taffy: TaffyTree<()> = TaffyTree::new();
980 let child0 = taffy.new_leaf(Style::default()).unwrap();
981 let child1 = taffy.new_leaf(Style::default()).unwrap();
982 let node = taffy.new_with_children(Style::default(), &[child0, child1]).unwrap();
983
984 assert_eq!(taffy.child_count(node), 2);
985
986 taffy.remove_child(node, child0).unwrap();
987 assert_eq!(taffy.child_count(node), 1);
988 assert_eq!(taffy.children(node).unwrap()[0], child1);
989
990 taffy.remove_child(node, child1).unwrap();
991 assert_eq!(taffy.child_count(node), 0);
992 }
993
994 #[test]
995 fn remove_child_at_index() {
996 let mut taffy: TaffyTree<()> = TaffyTree::new();
997 let child0 = taffy.new_leaf(Style::default()).unwrap();
998 let child1 = taffy.new_leaf(Style::default()).unwrap();
999 let node = taffy.new_with_children(Style::default(), &[child0, child1]).unwrap();
1000
1001 assert_eq!(taffy.child_count(node), 2);
1002
1003 taffy.remove_child_at_index(node, 0).unwrap();
1004 assert_eq!(taffy.child_count(node), 1);
1005 assert_eq!(taffy.children(node).unwrap()[0], child1);
1006
1007 taffy.remove_child_at_index(node, 0).unwrap();
1008 assert_eq!(taffy.child_count(node), 0);
1009 }
1010
1011 // Related to: https://github.com/DioxusLabs/taffy/issues/510
1012 #[test]
1013 fn remove_child_updates_parents() {
1014 let mut taffy: TaffyTree<()> = TaffyTree::new();
1015
1016 let parent = taffy.new_leaf(Style::default()).unwrap();
1017 let child = taffy.new_leaf(Style::default()).unwrap();
1018
1019 taffy.add_child(parent, child).unwrap();
1020
1021 taffy.remove(parent).unwrap();
1022
1023 // Once the parent is removed this shouldn't panic.
1024 assert!(taffy.set_children(child, &[]).is_ok());
1025 }
1026
1027 #[test]
1028 fn replace_child_at_index() {
1029 let mut taffy: TaffyTree<()> = TaffyTree::new();
1030
1031 let child0 = taffy.new_leaf(Style::default()).unwrap();
1032 let child1 = taffy.new_leaf(Style::default()).unwrap();
1033
1034 let node = taffy.new_with_children(Style::default(), &[child0]).unwrap();
1035 assert_eq!(taffy.child_count(node), 1);
1036 assert_eq!(taffy.children(node).unwrap()[0], child0);
1037
1038 taffy.replace_child_at_index(node, 0, child1).unwrap();
1039 assert_eq!(taffy.child_count(node), 1);
1040 assert_eq!(taffy.children(node).unwrap()[0], child1);
1041 }
1042 #[test]
1043 fn test_child_at_index() {
1044 let mut taffy: TaffyTree<()> = TaffyTree::new();
1045 let child0 = taffy.new_leaf(Style::default()).unwrap();
1046 let child1 = taffy.new_leaf(Style::default()).unwrap();
1047 let child2 = taffy.new_leaf(Style::default()).unwrap();
1048 let node = taffy.new_with_children(Style::default(), &[child0, child1, child2]).unwrap();
1049
1050 assert!(if let Ok(result) = taffy.child_at_index(node, 0) { result == child0 } else { false });
1051 assert!(if let Ok(result) = taffy.child_at_index(node, 1) { result == child1 } else { false });
1052 assert!(if let Ok(result) = taffy.child_at_index(node, 2) { result == child2 } else { false });
1053 }
1054 #[test]
1055 fn test_child_count() {
1056 let mut taffy: TaffyTree<()> = TaffyTree::new();
1057 let child0 = taffy.new_leaf(Style::default()).unwrap();
1058 let child1 = taffy.new_leaf(Style::default()).unwrap();
1059 let node = taffy.new_with_children(Style::default(), &[child0, child1]).unwrap();
1060
1061 assert!(taffy.child_count(node) == 2);
1062 assert!(taffy.child_count(child0) == 0);
1063 assert!(taffy.child_count(child1) == 0);
1064 }
1065
1066 #[allow(clippy::vec_init_then_push)]
1067 #[test]
1068 fn test_children() {
1069 let mut taffy: TaffyTree<()> = TaffyTree::new();
1070 let child0 = taffy.new_leaf(Style::default()).unwrap();
1071 let child1 = taffy.new_leaf(Style::default()).unwrap();
1072 let node = taffy.new_with_children(Style::default(), &[child0, child1]).unwrap();
1073
1074 let mut children = sys::Vec::new();
1075 children.push(child0);
1076 children.push(child1);
1077
1078 let children_result = taffy.children(node).unwrap();
1079 assert_eq!(children_result, children);
1080
1081 assert!(taffy.children(child0).unwrap().is_empty());
1082 }
1083 #[test]
1084 fn test_set_style() {
1085 let mut taffy: TaffyTree<()> = TaffyTree::new();
1086
1087 let node = taffy.new_leaf(Style::default()).unwrap();
1088 assert_eq!(taffy.style(node).unwrap().display, Display::Flex);
1089
1090 taffy.set_style(node, Style { display: Display::None, ..Style::default() }).unwrap();
1091 assert_eq!(taffy.style(node).unwrap().display, Display::None);
1092 }
1093 #[test]
1094 fn test_style() {
1095 let mut taffy: TaffyTree<()> = TaffyTree::new();
1096
1097 let style = Style { display: Display::None, flex_direction: FlexDirection::RowReverse, ..Default::default() };
1098
1099 let node = taffy.new_leaf(style.clone()).unwrap();
1100
1101 let res = taffy.style(node);
1102 assert!(res.is_ok());
1103 assert!(res.unwrap() == &style);
1104 }
1105 #[test]
1106 fn test_layout() {
1107 let mut taffy: TaffyTree<()> = TaffyTree::new();
1108 let node = taffy.new_leaf(Style::default()).unwrap();
1109
1110 // TODO: Improve this test?
1111 let res = taffy.layout(node);
1112 assert!(res.is_ok());
1113 }
1114
1115 #[test]
1116 fn test_mark_dirty() {
1117 let mut taffy: TaffyTree<()> = TaffyTree::new();
1118 let child0 = taffy.new_leaf(Style::default()).unwrap();
1119 let child1 = taffy.new_leaf(Style::default()).unwrap();
1120 let node = taffy.new_with_children(Style::default(), &[child0, child1]).unwrap();
1121
1122 taffy.compute_layout(node, Size::MAX_CONTENT).unwrap();
1123
1124 assert_eq!(taffy.dirty(child0).unwrap(), false);
1125 assert_eq!(taffy.dirty(child1).unwrap(), false);
1126 assert_eq!(taffy.dirty(node).unwrap(), false);
1127
1128 taffy.mark_dirty(node).unwrap();
1129 assert_eq!(taffy.dirty(child0).unwrap(), false);
1130 assert_eq!(taffy.dirty(child1).unwrap(), false);
1131 assert_eq!(taffy.dirty(node).unwrap(), true);
1132
1133 taffy.compute_layout(node, Size::MAX_CONTENT).unwrap();
1134 taffy.mark_dirty(child0).unwrap();
1135 assert_eq!(taffy.dirty(child0).unwrap(), true);
1136 assert_eq!(taffy.dirty(child1).unwrap(), false);
1137 assert_eq!(taffy.dirty(node).unwrap(), true);
1138 }
1139
1140 #[test]
1141 fn compute_layout_should_produce_valid_result() {
1142 let mut taffy: TaffyTree<()> = TaffyTree::new();
1143 let node_result = taffy.new_leaf(Style {
1144 size: Size { width: Dimension::Length(10f32), height: Dimension::Length(10f32) },
1145 ..Default::default()
1146 });
1147 assert!(node_result.is_ok());
1148 let node = node_result.unwrap();
1149 let layout_result = taffy.compute_layout(
1150 node,
1151 Size { width: AvailableSpace::Definite(100.), height: AvailableSpace::Definite(100.) },
1152 );
1153 assert!(layout_result.is_ok());
1154 }
1155
1156 #[test]
1157 fn make_sure_layout_location_is_top_left() {
1158 use crate::prelude::Rect;
1159
1160 let mut taffy: TaffyTree<()> = TaffyTree::new();
1161
1162 let node = taffy
1163 .new_leaf(Style {
1164 size: Size { width: Dimension::Percent(1f32), height: Dimension::Percent(1f32) },
1165 ..Default::default()
1166 })
1167 .unwrap();
1168
1169 let root = taffy
1170 .new_with_children(
1171 Style {
1172 size: Size { width: Dimension::Length(100f32), height: Dimension::Length(100f32) },
1173 padding: Rect {
1174 left: length(10f32),
1175 right: length(20f32),
1176 top: length(30f32),
1177 bottom: length(40f32),
1178 },
1179 ..Default::default()
1180 },
1181 &[node],
1182 )
1183 .unwrap();
1184
1185 taffy.compute_layout(root, Size::MAX_CONTENT).unwrap();
1186
1187 // If Layout::location represents top-left coord, 'node' location
1188 // must be (due applied 'root' padding): {x: 10, y: 30}.
1189 //
1190 // It's important, since result will be different for each other
1191 // coordinate space:
1192 // - bottom-left: {x: 10, y: 40}
1193 // - top-right: {x: 20, y: 30}
1194 // - bottom-right: {x: 20, y: 40}
1195 let layout = taffy.layout(node).unwrap();
1196 assert_eq!(layout.location.x, 10f32);
1197 assert_eq!(layout.location.y, 30f32);
1198 }
1199}