Feature flag calc values (#806)
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 #[inline(always)]
185 fn resolve_calc_value(&self, val: *const (), basis: f32) -> f32 {
186 let _ = val;
187 let _ = basis;
188 0.0
189 }
190
191 /// Set the node's unrounded layout
192 fn set_unrounded_layout(&mut self, node_id: NodeId, layout: &Layout);
193
194 /// Compute the specified node's size or full layout given the specified constraints
195 fn compute_child_layout(&mut self, node_id: NodeId, inputs: LayoutInput) -> LayoutOutput;
196}
197
198/// Trait used by the `compute_cached_layout` method which allows cached layout results to be stored and retrieved.
199///
200/// The `Cache` struct implements a per-node cache that is compatible with this trait.
201pub trait CacheTree {
202 /// Try to retrieve a cached result from the cache
203 fn cache_get(
204 &self,
205 node_id: NodeId,
206 known_dimensions: Size<Option<f32>>,
207 available_space: Size<AvailableSpace>,
208 run_mode: RunMode,
209 ) -> Option<LayoutOutput>;
210
211 /// Store a computed size in the cache
212 fn cache_store(
213 &mut self,
214 node_id: NodeId,
215 known_dimensions: Size<Option<f32>>,
216 available_space: Size<AvailableSpace>,
217 run_mode: RunMode,
218 layout_output: LayoutOutput,
219 );
220
221 /// Clear all cache entries for the node
222 fn cache_clear(&mut self, node_id: NodeId);
223}
224
225/// Trait used by the `round_layout` method which takes a tree of unrounded float-valued layouts and performs
226/// rounding to snap the values to the pixel grid.
227///
228/// As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
229pub trait RoundTree: TraverseTree {
230 /// Get the node's unrounded layout
231 fn get_unrounded_layout(&self, node_id: NodeId) -> &Layout;
232 /// Get a reference to the node's final layout
233 fn set_final_layout(&mut self, node_id: NodeId, layout: &Layout);
234}
235
236/// Trait used by the `print_tree` method which prints a debug representation
237///
238/// As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
239pub trait PrintTree: TraverseTree {
240 /// Get a debug label for the node (typically the type of node: flexbox, grid, text, image, etc)
241 fn get_debug_label(&self, node_id: NodeId) -> &'static str;
242 /// Get a reference to the node's final layout
243 fn get_final_layout(&self, node_id: NodeId) -> &Layout;
244}
245
246#[cfg(feature = "flexbox")]
247/// Extends [`LayoutPartialTree`] with getters for the styles required for Flexbox layout
248pub trait LayoutFlexboxContainer: LayoutPartialTree {
249 /// The style type representing the Flexbox container's styles
250 type FlexboxContainerStyle<'a>: FlexboxContainerStyle
251 where
252 Self: 'a;
253 /// The style type representing each Flexbox item's styles
254 type FlexboxItemStyle<'a>: FlexboxItemStyle
255 where
256 Self: 'a;
257
258 /// Get the container's styles
259 fn get_flexbox_container_style(&self, node_id: NodeId) -> Self::FlexboxContainerStyle<'_>;
260
261 /// Get the child's styles
262 fn get_flexbox_child_style(&self, child_node_id: NodeId) -> Self::FlexboxItemStyle<'_>;
263}
264
265#[cfg(feature = "grid")]
266/// Extends [`LayoutPartialTree`] with getters for the styles required for CSS Grid layout
267pub trait LayoutGridContainer: LayoutPartialTree {
268 /// The style type representing the CSS Grid container's styles
269 type GridContainerStyle<'a>: GridContainerStyle
270 where
271 Self: 'a;
272
273 /// The style type representing each CSS Grid item's styles
274 type GridItemStyle<'a>: GridItemStyle
275 where
276 Self: 'a;
277
278 /// Get the container's styles
279 fn get_grid_container_style(&self, node_id: NodeId) -> Self::GridContainerStyle<'_>;
280
281 /// Get the child's styles
282 fn get_grid_child_style(&self, child_node_id: NodeId) -> Self::GridItemStyle<'_>;
283
284 /// Set the node's detailed grid information
285 ///
286 /// Implementing this method is optional. Doing so allows you to access details about the the grid such as
287 /// the computed size of each grid track and the computed placement of each grid item.
288 #[cfg(feature = "detailed_layout_info")]
289 fn set_detailed_grid_info(&mut self, _node_id: NodeId, _detailed_grid_info: DetailedGridInfo) {
290 debug_log!("LayoutGridContainer::set_detailed_grid_info called");
291 }
292}
293
294#[cfg(feature = "block_layout")]
295/// Extends [`LayoutPartialTree`] with getters for the styles required for CSS Block layout
296pub trait LayoutBlockContainer: LayoutPartialTree {
297 /// The style type representing the CSS Block container's styles
298 type BlockContainerStyle<'a>: BlockContainerStyle
299 where
300 Self: 'a;
301 /// The style type representing each CSS Block item's styles
302 type BlockItemStyle<'a>: BlockItemStyle
303 where
304 Self: 'a;
305
306 /// Get the container's styles
307 fn get_block_container_style(&self, node_id: NodeId) -> Self::BlockContainerStyle<'_>;
308
309 /// Get the child's styles
310 fn get_block_child_style(&self, child_node_id: NodeId) -> Self::BlockItemStyle<'_>;
311}
312
313// --- PRIVATE TRAITS
314
315/// A private trait which allows us to add extra convenience methods to types which implement
316/// LayoutTree without making those methods public.
317pub(crate) trait LayoutPartialTreeExt: LayoutPartialTree {
318 /// Compute the size of the node given the specified constraints
319 #[inline(always)]
320 #[allow(clippy::too_many_arguments)]
321 fn measure_child_size(
322 &mut self,
323 node_id: NodeId,
324 known_dimensions: Size<Option<f32>>,
325 parent_size: Size<Option<f32>>,
326 available_space: Size<AvailableSpace>,
327 sizing_mode: SizingMode,
328 axis: AbsoluteAxis,
329 vertical_margins_are_collapsible: Line<bool>,
330 ) -> f32 {
331 self.compute_child_layout(
332 node_id,
333 LayoutInput {
334 known_dimensions,
335 parent_size,
336 available_space,
337 sizing_mode,
338 axis: axis.into(),
339 run_mode: RunMode::ComputeSize,
340 vertical_margins_are_collapsible,
341 },
342 )
343 .size
344 .get_abs(axis)
345 }
346
347 /// Perform a full layout on the node given the specified constraints
348 #[inline(always)]
349 fn perform_child_layout(
350 &mut self,
351 node_id: NodeId,
352 known_dimensions: Size<Option<f32>>,
353 parent_size: Size<Option<f32>>,
354 available_space: Size<AvailableSpace>,
355 sizing_mode: SizingMode,
356 vertical_margins_are_collapsible: Line<bool>,
357 ) -> LayoutOutput {
358 self.compute_child_layout(
359 node_id,
360 LayoutInput {
361 known_dimensions,
362 parent_size,
363 available_space,
364 sizing_mode,
365 axis: RequestedAxis::Both,
366 run_mode: RunMode::PerformLayout,
367 vertical_margins_are_collapsible,
368 },
369 )
370 }
371
372 /// Alias to `resolve_calc_value` with a shorter function name
373 #[inline(always)]
374 #[cfg(feature = "calc")]
375 fn calc(&self, val: *const (), basis: f32) -> f32 {
376 self.resolve_calc_value(val, basis)
377 }
378
379 /// Alias to `resolve_calc_value` with a shorter function name
380 #[inline(always)]
381 #[cfg(not(feature = "calc"))]
382 fn calc(&self, _val: *const (), _basis: f32) -> f32 {
383 0.0
384 }
385}
386
387impl<T: LayoutPartialTree> LayoutPartialTreeExt for T {}