Upgrade rand and rand_chacha (bench deps) to 0.9 (#798)
1//! The abstractions that make up the core of Taffy's low-level API
2//!
3//! ## Examples
4//!
5//! The following examples demonstrate end-to-end implementation of Taffy's traits and usage of the low-level compute APIs:
6//!
7//! - [custom_tree_vec](https://github.com/DioxusLabs/taffy/blob/main/examples/custom_tree_vec.rs) which implements a custom Taffy tree using a `Vec` as an arena with NodeId's being index's into the Vec.
8//! - [custom_tree_owned_partial](https://github.com/DioxusLabs/taffy/blob/main/examples/custom_tree_owned_partial.rs) which implements a custom Taffy tree using directly owned children with NodeId's being index's into vec on parent node.
9//! - [custom_tree_owned_unsafe](https://github.com/DioxusLabs/taffy/blob/main/examples/custom_tree_owned_unsafe.rs) which implements a custom Taffy tree using directly owned children with NodeId's being pointers.
10//!
11//! ## Overview
12//!
13//! ### Trait dependency tree
14//!
15//! The tree below illustrates which traits depend on which other traits.
16//!
17//! ```text
18//! TraversePartialTree - Access a node's children
19//! ├── LayoutPartialTree - Run layout algorithms on a node and it's direct children
20//! └── TraverseTree - Recursively access a node's descendants
21//! ├── RoundTree - Round a float-valued` layout to integer pixels
22//! └── PrintTree - Print a debug representation of a node tree
23//! ```
24//!
25//! ### A table of traits
26//!
27//! | Trait | Requires | Enables |
28//! | --- | --- | --- |
29//! | [`LayoutPartialTree`] | [`TraversePartialTree`] | [`compute_flexbox_layout`](crate::compute_flexbox_layout)<br />[`compute_grid_layout`](crate::compute_grid_layout)<br />[`compute_block_layout`](crate::compute_block_layout)<br />[`compute_root_layout`](crate::compute_root_layout)<br />[`compute_leaf_layout`](crate::compute_leaf_layout)<br />[`compute_hidden_layout`](crate::compute_hidden_layout)<br />[`compute_cached_layout`](crate::compute_cached_layout) |
30//! | [`RoundTree`] | [`TraverseTree`] | [`round_layout`](crate::round_layout) |
31//! | [`PrintTree`] | [`TraverseTree`] | [`print_tree`](crate::print_tree) |
32//!
33//! ## All of the traits on one page
34//!
35//! ### TraversePartialTree and TraverseTree
36//! These traits are Taffy's abstraction for downward tree traversal:
37//! - [`TraversePartialTree`] allows access to a single container node, and it's immediate children. This is the only "traverse" trait that is required
38//! for use of Taffy's core layout algorithms (flexbox, grid, etc).
39//! - [`TraverseTree`] is a marker trait which uses the same API signature as `TraversePartialTree`, but extends it with a guarantee that the child/children methods can be used to recurse
40//! infinitely down the tree. It is required by the `RoundTree` and
41//! the `PrintTree` traits.
42//! ```rust
43//! # use taffy::*;
44//! pub trait TraversePartialTree {
45//! /// Type representing an iterator of the children of a node
46//! type ChildIter<'a>: Iterator<Item = NodeId>
47//! where
48//! Self: 'a;
49//!
50//! /// Get the list of children IDs for the given node
51//! fn child_ids(&self, parent_node_id: NodeId) -> Self::ChildIter<'_>;
52//!
53//! /// Get the number of children for the given node
54//! fn child_count(&self, parent_node_id: NodeId) -> usize;
55//!
56//! /// Get a specific child of a node, where the index represents the nth child
57//! fn get_child_id(&self, parent_node_id: NodeId, child_index: usize) -> NodeId;
58//! }
59//!
60//! pub trait TraverseTree: TraversePartialTree {}
61//! ```
62//!
63//! You must implement [`TraversePartialTree`] to access any of Taffy's low-level API. If your tree implementation allows you to implement [`TraverseTree`] with
64//! the correct semantics (full recursive traversal is available) then you should.
65//!
66//! ### LayoutPartialTree
67//!
68//! **Requires:** `TraversePartialTree`<br />
69//! **Enables:** Flexbox, Grid, Block and Leaf layout algorithms from the [`crate::compute`] module
70//!
71//! Any type that implements [`LayoutPartialTree`] can be laid out using [Taffy's algorithms](crate::compute)
72//!
73//! Note that this trait extends [`TraversePartialTree`] (not [`TraverseTree`]). Taffy's algorithm implementations have been designed such that they can be used for a laying out a single
74//! node that only has access to it's immediate children.
75//!
76//! ```rust
77//! # use taffy::*;
78//! pub trait LayoutPartialTree: TraversePartialTree {
79//! /// Get a reference to the [`Style`] for this node.
80//! fn get_style(&self, node_id: NodeId) -> &Style;
81//!
82//! /// Set the node's unrounded layout
83//! fn set_unrounded_layout(&mut self, node_id: NodeId, layout: &Layout);
84//!
85//! /// Get a mutable reference to the [`Cache`] for this node.
86//! fn get_cache_mut(&mut self, node_id: NodeId) -> &mut Cache;
87//!
88//! /// Compute the specified node's size or full layout given the specified constraints
89//! fn compute_child_layout(&mut self, node_id: NodeId, inputs: LayoutInput) -> LayoutOutput;
90//! }
91//! ```
92//!
93//! ### RoundTree
94//!
95//! **Requires:** `TraverseTree`
96//!
97//! Trait used by the `round_layout` method which takes a tree of unrounded float-valued layouts and performs
98//! rounding to snap the values to the pixel grid.
99//!
100//! As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
101//!
102//! ```rust
103//! # use taffy::*;
104//! pub trait RoundTree: TraverseTree {
105//! /// Get the node's unrounded layout
106//! fn get_unrounded_layout(&self, node_id: NodeId) -> &Layout;
107//! /// Get a reference to the node's final layout
108//! fn set_final_layout(&mut self, node_id: NodeId, layout: &Layout);
109//! }
110//! ```
111//!
112//! ### PrintTree
113//!
114//! **Requires:** `TraverseTree`
115//!
116//! ```rust
117//! /// Trait used by the `print_tree` method which prints a debug representation
118//! ///
119//! /// As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
120//! # use taffy::*;
121//! pub trait PrintTree: TraverseTree {
122//! /// Get a debug label for the node (typically the type of node: flexbox, grid, text, image, etc)
123//! fn get_debug_label(&self, node_id: NodeId) -> &'static str;
124//! /// Get a reference to the node's final layout
125//! fn get_final_layout(&self, node_id: NodeId) -> &Layout;
126//! }
127//! ```
128//!
129use super::{Layout, LayoutInput, LayoutOutput, NodeId, RequestedAxis, RunMode, SizingMode};
130#[cfg(feature = "detailed_layout_info")]
131use crate::debug::debug_log;
132use crate::geometry::{AbsoluteAxis, Line, Size};
133use crate::style::{AvailableSpace, CoreStyle};
134#[cfg(feature = "flexbox")]
135use crate::style::{FlexboxContainerStyle, FlexboxItemStyle};
136#[cfg(feature = "grid")]
137use crate::style::{GridContainerStyle, GridItemStyle};
138#[cfg(feature = "block_layout")]
139use crate::{BlockContainerStyle, BlockItemStyle};
140
141#[cfg(all(feature = "grid", feature = "detailed_layout_info"))]
142use crate::compute::grid::DetailedGridInfo;
143
144/// Taffy's abstraction for downward tree traversal.
145///
146/// However, this trait does *not* require access to any node's other than a single container node's immediate children unless you also intend to implement `TraverseTree`.
147pub trait TraversePartialTree {
148 /// Type representing an iterator of the children of a node
149 type ChildIter<'a>: Iterator<Item = NodeId>
150 where
151 Self: 'a;
152
153 /// Get the list of children IDs for the given node
154 fn child_ids(&self, parent_node_id: NodeId) -> Self::ChildIter<'_>;
155
156 /// Get the number of children for the given node
157 fn child_count(&self, parent_node_id: NodeId) -> usize;
158
159 /// Get a specific child of a node, where the index represents the nth child
160 fn get_child_id(&self, parent_node_id: NodeId, child_index: usize) -> NodeId;
161}
162
163/// A marker trait which extends `TraversePartialTree`
164///
165/// Implementing this trait implies the additional guarantee that the child/children methods can be used to recurse
166/// infinitely down the tree. Is required by the `RoundTree` and the `PrintTree` traits.
167pub trait TraverseTree: TraversePartialTree {}
168
169/// Any type that implements [`LayoutPartialTree`] can be laid out using [Taffy's algorithms](crate::compute)
170///
171/// Note that this trait extends [`TraversePartialTree`] (not [`TraverseTree`]). Taffy's algorithm implementations have been designed such that they can be used for a laying out a single
172/// node that only has access to it's immediate children.
173pub trait LayoutPartialTree: TraversePartialTree {
174 /// The style type representing the core container styles that all containers should have
175 /// Used when laying out the root node of a tree
176 type CoreContainerStyle<'a>: CoreStyle
177 where
178 Self: 'a;
179
180 /// Get core style
181 fn get_core_container_style(&self, node_id: NodeId) -> Self::CoreContainerStyle<'_>;
182
183 /// Resolve calc value
184 fn resolve_calc_value(&self, val: u64, basis: f32) -> f32;
185
186 /// Set the node's unrounded layout
187 fn set_unrounded_layout(&mut self, node_id: NodeId, layout: &Layout);
188
189 /// Compute the specified node's size or full layout given the specified constraints
190 fn compute_child_layout(&mut self, node_id: NodeId, inputs: LayoutInput) -> LayoutOutput;
191}
192
193/// Trait used by the `compute_cached_layout` method which allows cached layout results to be stored and retrieved.
194///
195/// The `Cache` struct implements a per-node cache that is compatible with this trait.
196pub trait CacheTree {
197 /// Try to retrieve a cached result from the cache
198 fn cache_get(
199 &self,
200 node_id: NodeId,
201 known_dimensions: Size<Option<f32>>,
202 available_space: Size<AvailableSpace>,
203 run_mode: RunMode,
204 ) -> Option<LayoutOutput>;
205
206 /// Store a computed size in the cache
207 fn cache_store(
208 &mut self,
209 node_id: NodeId,
210 known_dimensions: Size<Option<f32>>,
211 available_space: Size<AvailableSpace>,
212 run_mode: RunMode,
213 layout_output: LayoutOutput,
214 );
215
216 /// Clear all cache entries for the node
217 fn cache_clear(&mut self, node_id: NodeId);
218}
219
220/// Trait used by the `round_layout` method which takes a tree of unrounded float-valued layouts and performs
221/// rounding to snap the values to the pixel grid.
222///
223/// As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
224pub trait RoundTree: TraverseTree {
225 /// Get the node's unrounded layout
226 fn get_unrounded_layout(&self, node_id: NodeId) -> &Layout;
227 /// Get a reference to the node's final layout
228 fn set_final_layout(&mut self, node_id: NodeId, layout: &Layout);
229}
230
231/// Trait used by the `print_tree` method which prints a debug representation
232///
233/// As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
234pub trait PrintTree: TraverseTree {
235 /// Get a debug label for the node (typically the type of node: flexbox, grid, text, image, etc)
236 fn get_debug_label(&self, node_id: NodeId) -> &'static str;
237 /// Get a reference to the node's final layout
238 fn get_final_layout(&self, node_id: NodeId) -> &Layout;
239}
240
241#[cfg(feature = "flexbox")]
242/// Extends [`LayoutPartialTree`] with getters for the styles required for Flexbox layout
243pub trait LayoutFlexboxContainer: LayoutPartialTree {
244 /// The style type representing the Flexbox container's styles
245 type FlexboxContainerStyle<'a>: FlexboxContainerStyle
246 where
247 Self: 'a;
248 /// The style type representing each Flexbox item's styles
249 type FlexboxItemStyle<'a>: FlexboxItemStyle
250 where
251 Self: 'a;
252
253 /// Get the container's styles
254 fn get_flexbox_container_style(&self, node_id: NodeId) -> Self::FlexboxContainerStyle<'_>;
255
256 /// Get the child's styles
257 fn get_flexbox_child_style(&self, child_node_id: NodeId) -> Self::FlexboxItemStyle<'_>;
258}
259
260#[cfg(feature = "grid")]
261/// Extends [`LayoutPartialTree`] with getters for the styles required for CSS Grid layout
262pub trait LayoutGridContainer: LayoutPartialTree {
263 /// The style type representing the CSS Grid container's styles
264 type GridContainerStyle<'a>: GridContainerStyle
265 where
266 Self: 'a;
267
268 /// The style type representing each CSS Grid item's styles
269 type GridItemStyle<'a>: GridItemStyle
270 where
271 Self: 'a;
272
273 /// Get the container's styles
274 fn get_grid_container_style(&self, node_id: NodeId) -> Self::GridContainerStyle<'_>;
275
276 /// Get the child's styles
277 fn get_grid_child_style(&self, child_node_id: NodeId) -> Self::GridItemStyle<'_>;
278
279 /// Set the node's detailed grid information
280 ///
281 /// Implementing this method is optional. Doing so allows you to access details about the the grid such as
282 /// the computed size of each grid track and the computed placement of each grid item.
283 #[cfg(feature = "detailed_layout_info")]
284 fn set_detailed_grid_info(&mut self, _node_id: NodeId, _detailed_grid_info: DetailedGridInfo) {
285 debug_log!("LayoutGridContainer::set_detailed_grid_info called");
286 }
287}
288
289#[cfg(feature = "block_layout")]
290/// Extends [`LayoutPartialTree`] with getters for the styles required for CSS Block layout
291pub trait LayoutBlockContainer: LayoutPartialTree {
292 /// The style type representing the CSS Block container's styles
293 type BlockContainerStyle<'a>: BlockContainerStyle
294 where
295 Self: 'a;
296 /// The style type representing each CSS Block item's styles
297 type BlockItemStyle<'a>: BlockItemStyle
298 where
299 Self: 'a;
300
301 /// Get the container's styles
302 fn get_block_container_style(&self, node_id: NodeId) -> Self::BlockContainerStyle<'_>;
303
304 /// Get the child's styles
305 fn get_block_child_style(&self, child_node_id: NodeId) -> Self::BlockItemStyle<'_>;
306}
307
308// --- PRIVATE TRAITS
309
310/// A private trait which allows us to add extra convenience methods to types which implement
311/// LayoutTree without making those methods public.
312pub(crate) trait LayoutPartialTreeExt: LayoutPartialTree {
313 /// Compute the size of the node given the specified constraints
314 #[inline(always)]
315 #[allow(clippy::too_many_arguments)]
316 fn measure_child_size(
317 &mut self,
318 node_id: NodeId,
319 known_dimensions: Size<Option<f32>>,
320 parent_size: Size<Option<f32>>,
321 available_space: Size<AvailableSpace>,
322 sizing_mode: SizingMode,
323 axis: AbsoluteAxis,
324 vertical_margins_are_collapsible: Line<bool>,
325 ) -> f32 {
326 self.compute_child_layout(
327 node_id,
328 LayoutInput {
329 known_dimensions,
330 parent_size,
331 available_space,
332 sizing_mode,
333 axis: axis.into(),
334 run_mode: RunMode::ComputeSize,
335 vertical_margins_are_collapsible,
336 },
337 )
338 .size
339 .get_abs(axis)
340 }
341
342 /// Perform a full layout on the node given the specified constraints
343 #[inline(always)]
344 fn perform_child_layout(
345 &mut self,
346 node_id: NodeId,
347 known_dimensions: Size<Option<f32>>,
348 parent_size: Size<Option<f32>>,
349 available_space: Size<AvailableSpace>,
350 sizing_mode: SizingMode,
351 vertical_margins_are_collapsible: Line<bool>,
352 ) -> LayoutOutput {
353 self.compute_child_layout(
354 node_id,
355 LayoutInput {
356 known_dimensions,
357 parent_size,
358 available_space,
359 sizing_mode,
360 axis: RequestedAxis::Both,
361 run_mode: RunMode::PerformLayout,
362 vertical_margins_are_collapsible,
363 },
364 )
365 }
366
367 /// Alias to `resolve_calc_value` with a shorter function name
368 #[inline(always)]
369 fn calc(&self, val: u64, basis: f32) -> f32 {
370 self.resolve_calc_value(val, basis)
371 }
372}
373
374impl<T: LayoutPartialTree> LayoutPartialTreeExt for T {}