Add is_table for block items (#701)
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 pointers.
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::{Cache, Layout, LayoutInput, LayoutOutput, NodeId, RequestedAxis, RunMode, SizingMode};
130use crate::geometry::{AbsoluteAxis, Line, Size};
131use crate::style::{AvailableSpace, CoreStyle};
132#[cfg(feature = "flexbox")]
133use crate::style::{FlexboxContainerStyle, FlexboxItemStyle};
134#[cfg(feature = "grid")]
135use crate::style::{GridContainerStyle, GridItemStyle};
136#[cfg(feature = "block_layout")]
137use crate::{BlockContainerStyle, BlockItemStyle};
138use core::ops::{Deref, DerefMut};
139
140/// This trait is Taffy's abstraction for downward tree traversal.
141/// 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`.
142pub trait TraversePartialTree {
143 /// Type representing an iterator of the children of a node
144 type ChildIter<'a>: Iterator<Item = NodeId>
145 where
146 Self: 'a;
147
148 /// Get the list of children IDs for the given node
149 fn child_ids(&self, parent_node_id: NodeId) -> Self::ChildIter<'_>;
150
151 /// Get the number of children for the given node
152 fn child_count(&self, parent_node_id: NodeId) -> usize;
153
154 /// Get a specific child of a node, where the index represents the nth child
155 fn get_child_id(&self, parent_node_id: NodeId, child_index: usize) -> NodeId;
156}
157
158/// A marker trait which extends `TraversePartialTree` with the additional guarantee that the child/children methods can be used to recurse
159/// infinitely down the tree. Is required by the `RoundTree` and the `PrintTree` traits.
160pub trait TraverseTree: TraversePartialTree {}
161
162/// Any type that implements [`LayoutPartialTree`] can be laid out using [Taffy's algorithms](crate::compute)
163///
164/// 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
165/// node that only has access to it's immediate children.
166pub trait LayoutPartialTree: TraversePartialTree {
167 /// The style type representing the core container styles that all containers should have
168 /// Used when laying out the root node of a tree
169 type CoreContainerStyle<'a>: CoreStyle
170 where
171 Self: 'a;
172
173 /// A mutable reference to the cache. This is an associated type to allow for different
174 /// types of mutable reference such as mutex or refcell guards
175 type CacheMut<'b>: Deref<Target = Cache> + DerefMut
176 where
177 Self: 'b;
178
179 /// Get core style
180 fn get_core_container_style(&self, node_id: NodeId) -> Self::CoreContainerStyle<'_>;
181
182 /// Set the node's unrounded layout
183 fn set_unrounded_layout(&mut self, node_id: NodeId, layout: &Layout);
184
185 /// Get a mutable reference to the [`Cache`] for this node.
186 fn get_cache_mut(&mut self, node_id: NodeId) -> Self::CacheMut<'_>;
187
188 /// Compute the specified node's size or full layout given the specified constraints
189 fn compute_child_layout(&mut self, node_id: NodeId, inputs: LayoutInput) -> LayoutOutput;
190}
191
192/// Trait used by the `round_layout` method which takes a tree of unrounded float-valued layouts and performs
193/// rounding to snap the values to the pixel grid.
194///
195/// As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
196pub trait RoundTree: TraverseTree {
197 /// Get the node's unrounded layout
198 fn get_unrounded_layout(&self, node_id: NodeId) -> &Layout;
199 /// Get a reference to the node's final layout
200 fn set_final_layout(&mut self, node_id: NodeId, layout: &Layout);
201}
202
203/// Trait used by the `print_tree` method which prints a debug representation
204///
205/// As indicated by it's dependence on `TraverseTree`, it required full recursive access to the tree.
206pub trait PrintTree: TraverseTree {
207 /// Get a debug label for the node (typically the type of node: flexbox, grid, text, image, etc)
208 fn get_debug_label(&self, node_id: NodeId) -> &'static str;
209 /// Get a reference to the node's final layout
210 fn get_final_layout(&self, node_id: NodeId) -> &Layout;
211}
212
213#[cfg(feature = "flexbox")]
214/// Extends [`LayoutPartialTree`] with getters for the styles required for Flexbox layout
215pub trait LayoutFlexboxContainer: LayoutPartialTree {
216 /// The style type representing the Flexbox container's styles
217 type FlexboxContainerStyle<'a>: FlexboxContainerStyle
218 where
219 Self: 'a;
220 /// The style type representing each Flexbox item's styles
221 type FlexboxItemStyle<'a>: FlexboxItemStyle
222 where
223 Self: 'a;
224
225 /// Get the container's styles
226 fn get_flexbox_container_style(&self, node_id: NodeId) -> Self::FlexboxContainerStyle<'_>;
227
228 /// Get the child's styles
229 fn get_flexbox_child_style(&self, child_node_id: NodeId) -> Self::FlexboxItemStyle<'_>;
230}
231
232#[cfg(feature = "grid")]
233/// Extends [`LayoutPartialTree`] with getters for the styles required for CSS Grid layout
234pub trait LayoutGridContainer: LayoutPartialTree {
235 /// The style type representing the CSS Grid container's styles
236 type GridContainerStyle<'a>: GridContainerStyle
237 where
238 Self: 'a;
239
240 /// The style type representing each CSS Grid item's styles
241 type GridItemStyle<'a>: GridItemStyle
242 where
243 Self: 'a;
244
245 /// Get the container's styles
246 fn get_grid_container_style(&self, node_id: NodeId) -> Self::GridContainerStyle<'_>;
247
248 /// Get the child's styles
249 fn get_grid_child_style(&self, child_node_id: NodeId) -> Self::GridItemStyle<'_>;
250}
251
252#[cfg(feature = "block_layout")]
253/// Extends [`LayoutPartialTree`] with getters for the styles required for CSS Block layout
254pub trait LayoutBlockContainer: LayoutPartialTree {
255 /// The style type representing the CSS Block container's styles
256 type BlockContainerStyle<'a>: BlockContainerStyle
257 where
258 Self: 'a;
259 /// The style type representing each CSS Block item's styles
260 type BlockItemStyle<'a>: BlockItemStyle
261 where
262 Self: 'a;
263
264 /// Get the container's styles
265 fn get_block_container_style(&self, node_id: NodeId) -> Self::BlockContainerStyle<'_>;
266
267 /// Get the child's styles
268 fn get_block_child_style(&self, child_node_id: NodeId) -> Self::BlockItemStyle<'_>;
269}
270
271// --- PRIVATE TRAITS
272
273/// A private trait which allows us to add extra convenience methods to types which implement
274/// LayoutTree without making those methods public.
275pub(crate) trait LayoutPartialTreeExt: LayoutPartialTree {
276 /// Compute the size of the node given the specified constraints
277 #[inline(always)]
278 #[allow(clippy::too_many_arguments)]
279 fn measure_child_size(
280 &mut self,
281 node_id: NodeId,
282 known_dimensions: Size<Option<f32>>,
283 parent_size: Size<Option<f32>>,
284 available_space: Size<AvailableSpace>,
285 sizing_mode: SizingMode,
286 axis: AbsoluteAxis,
287 vertical_margins_are_collapsible: Line<bool>,
288 ) -> f32 {
289 self.compute_child_layout(
290 node_id,
291 LayoutInput {
292 known_dimensions,
293 parent_size,
294 available_space,
295 sizing_mode,
296 axis: axis.into(),
297 run_mode: RunMode::ComputeSize,
298 vertical_margins_are_collapsible,
299 },
300 )
301 .size
302 .get_abs(axis)
303 }
304
305 /// Perform a full layout on the node given the specified constraints
306 #[inline(always)]
307 fn perform_child_layout(
308 &mut self,
309 node_id: NodeId,
310 known_dimensions: Size<Option<f32>>,
311 parent_size: Size<Option<f32>>,
312 available_space: Size<AvailableSpace>,
313 sizing_mode: SizingMode,
314 vertical_margins_are_collapsible: Line<bool>,
315 ) -> LayoutOutput {
316 self.compute_child_layout(
317 node_id,
318 LayoutInput {
319 known_dimensions,
320 parent_size,
321 available_space,
322 sizing_mode,
323 axis: RequestedAxis::Both,
324 run_mode: RunMode::PerformLayout,
325 vertical_margins_are_collapsible,
326 },
327 )
328 }
329}
330
331impl<T: LayoutPartialTree> LayoutPartialTreeExt for T {}