1# Changelog
2
3## 0.7.6
4
5### Fixed
6
7- Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
8
9## 0.7.5
10
11### Fixed
12
13- Grid: only stretch auto tracks if content-alignment is stretch (#783)
14
15## 0.7.4
16
17### Fixed
18
19- Fix detailed grid info for empty grid (#782)
20
21## 0.7.3
22
23### Fixed
24
25- Make `TaffyTree::detailed_layout_info` take `&self` rather than `&mut self` (#779)
26
27## 0.7.2
28
29### Added
30
31- The ability to access computed track sizes and item positions of a CSS Grid layout (#772).
32  This information can be accessed using the `LayoutGridContainer::set_detailed_grid_info` method
33  in the low-level API or the `TaffyTree::detailed_layout_info` method in the high-level API.
34
35## 0.7.1
36
37### Fixed
38
39- Improve interaction of abspos children of block containers with margin collapsing (#760)
40
41### Added
42
43- Add `TaffyTree::unrounded_layout` getter (#765)
44
45### Removed
46
47- The `num-traits` dependency was removed (#761) (#762)
48
49## 0.7.0
50
51### Changed
52
53- BREAKING: The `cache_mut` method on the `LayoutPartialTree` trait has been replaced with a separate `CacheTree` trait. This allows
54  Taffy to be more easily used without caching or with a custom cache implementation.
55- BREAKING: the `TaffyTree::set_children` method now removes the children from their previous parent (if they have one).
56
57### Added
58
59- Helper methods to retrieve content-box sizes were added to `Layout`
60
61## 0.6.3
62
63### Fixes
64
65- Block: ignore margin collapsing when computing static position of abspos items (#747)
66
67## 0.6.2
68
69### Fixes
70
71- Fix: clamp indefinite available space by min- and max- size as appropriate (#742)
72
73## 0.6.1
74
75### Fixes
76
77- Fix calculation of `auto-fill`/`auto-fit` repetition count when container has a definite percentage size (#722)
78- Fix min-size style not affecting intrinsic sizes (#723)
79- Fix documentation of dirty and mark_dirty functions (#724)
80- Fix intrinsic size of scroll containers that have a small explicit flex-basis (#728)
81
82## 0.6.0
83
84### Highlights
85
86- The `Style` struct has been "traitified". This supports Taffy's integration in Servo and generally makes Taffy more flexible. The
87  `Style` struct still exists and implements the new traits so existing uses of Taffy will continue to work as before.
88- The `box-sizing` style is supported
89- Computed margins are output in `Layout`
90
91### Fixes
92
93- Fix `print_tree()` when rounding is disabled (#680)
94- Absolute Insets should be resolved against the container size minus border (#666)
95- Fix flooring hypothetical_main_size by computed min size (#689)
96- Fix flex line cross-size determination (#690)
97- Fix panics in the grid algorithm (#691)
98- Fix resolving flexible lengths (WPT css/flexbox-multiline-min-max test) (#692)
99- Fix wrapping when a max main size style is present (#694)
100- Fix case where Taffy allowed margins to collapse through an element when it shouldn't have (#695)
101
102### Added
103
104- Legacy text align (for laying out `<center>` and `<div align="..">`) is supported
105- Add `is_table` for block items (#701)
106- Impl `Debug` and `Clone` for `Cache` (#688)
107- Implement `Debug` and `PartialEq` for tree types (#697)
108
109## 0.5.2
110
111- Fix block stretch sizing (don't always apply stretch sizing to block containers) (#674)
112- Fix computation of intrinsic main size when it depends on a child's known cross size (#673)
113- Fix panic when GridLine 0 is specified (#671)
114- Docs: Document feature flags and scrape examples (#672)
115- Docs: Update cosmic-text example to cosmic-text 0.12 (#670)
116
117## 0.5.1
118
119- Fix: Clamp block item stretch widths by their min and max width (#664)
120- Fix: Auto margin computation in block layout (#663)
121
122## 0.5.0
123
124The changes in 0.5 are relatively small but the new measure function parameter is a breaking change so it requires a minor version bump.
125
126- Added: A `style: &Style` parameter has been added to measure functions.
127- Added: The `MaybeMath`, `MaybeResolve`, and `ResolveOrZero` traits have been made public.
128- Fix: use SizingMode::Inherent when sizing absolute children of flexbox nodes.
129
130## 0.4.4
131
132### Fixes
133
134- Content alignment (`align-content`/`justify-content`) behaviour was updated to match the latest spec (and Chrome 123+) (#635)
135- Ensure that root Flexbox nodes are floored by their padding-border (#651, #655)
136- Use grid area size not available space when applying aspect ratio to grid containers (#656)
137
138## 0.4.3
139
140### Fixes
141
142- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
143  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
144  but they should be able to fix on their side by clarifying the type passed in
145
146## 0.4.2
147
148- Fixed: single-line flex-container should clamp the line's cross-size (#638)
149- Reduced binary footprint of Taffy from around 300kb to around 150kb (#636)
150
151## 0.4.1
152
153- Fixed: CSS Grid track sizing not respecting growth limits in some circumstances (#624)
154
155## 0.4.0
156
157### Highlights
158
159- Support for CSS Block layout (`display: block`)
160- Support for the `overflow` property (+ `scrollbar_width` for `overflow: scroll`)
161- Improved measure function API
162- Completely refactored low-level API
163- Simplified module hierarchy (+ most types/functions are now exported from the crate root)
164- Expanded set of examples which better document integration with other layout systems (e.g. text layout)
165- Computed values for `padding` and `border` are now output into the `Layout` struct
166
167### Block layout
168
169Support for [CSS Block layout](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flow_Layout/Block_and_Inline_Layout_in_Normal_Flow#elements_participating_in_a_block_formatting_context) has been added. This can be used via the new `Display::Block` variant of the `Display` enum. Note that  full flow layout: inline, inline-block and float layout have *not* been implemented. The use case supported is block container nodes which contain block-level children.
170
171### Overflow property
172
173Support has been added for a new `overflow` style property with `Visible`, `Clip`, `Hidden`, and `Scroll` values (`Auto` is not currently implemented). Additionally a `scrollbar_width` property has been added to control the size of scrollbars for nodes with `Overflow::Scroll` set.
174
175- Overflow is settable indpendently in each axis.
176- `Visible` and `Clip` will produce layouts equivalent to the Taffy 0.3. `Clip` will affect the new `content_size` output by restricting it to the available space.
177- `Hidden` and `Scroll` affect layout by changing the automatic minimum size of Flexbox and Grid children
178- `Scroll` additionally reserves `scrollbar_width` pixels for a scrollbar in the opposite axis to which scrolling is enabled. `Scroll` with `scrollbar_width` set to zero is equivalent to `Hidden`.
179
180### Measure function changes
181
182The "measure function" API for integrating Taffy with other measurement systems (such as text layout) has been changed to be more flexible
183and to interact better with borrow checking (you can now borrow external data in your measure function!).
184
185- There are no longer per-node measure functions.
186- There is now a single "global" measure function, and a per-node "context" of a user-defined type
187- The `Taffy` tree is now a generic `TaffyTree<T>` where `T` is the "context" type.
188- The measure function is now called for all leaf nodes (nodes without children). If you wish to maintain compatibility with the previous
189  behaviour then your measure function should return `Size::ZERO` for leaf nodes whose context is `None`.
190
191If you are not using measure functions, then the only change you will need to make is from:
192
193```rust
194let mut tree = Taffy::new();
195```
196
197to
198
199```rust
200let mut tree : TaffyTree<()> = TaffyTree::new();
201```
202
203And generally update any uses of `Taffy` in your codebase to `TaffyTree<()>`.
204
205If you are using measure functions then you will need to make some bigger (but straightforward) changes. The following Taffy 0.3 code:
206
207```rust
208let mut tree = Taffy::new();
209let leaf = tree.new_leaf_with_measure(
210  Style::DEFAULT,
211  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>| Size { width: 100.0, height: 200.0 }
212);
213tree.compute_layout(leaf, Size::MAX_CONTENT);
214```
215
216Should become something like the following with Taffy 0.4:
217
218```rust
219let mut tree : TaffyTree<Size> = TaffyTree::new();
220let leaf = tree.new_leaf_with_context(Style::DEFAULT, Size { width: 100.0, height: 200.0 });
221tree.compute_layout_with_measure(
222  leaf,
223  Size::MAX_CONTENT,
224  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, node_id: NodeId, node_context: Option<Size>| {
225    node_context.unwrap_or(Size::ZERO)
226  }
227);
228```
229
230Note that:
231
232- You can choose any type instead of `Size` in the above example. This includes your own custom type (which can be an enum or a trait object).
233- If you don't need a context then you can use `()` for the context type
234- As the single "global" measure function passed to `compute_layout_with_measure` only needs to exist for the duration of a single layout run,
235  it can (mutably) borrow data from it's environment
236
237### Low-level API (`LayoutTree` trait) refactor
238
239The low-level API has been completely reworked:
240
241- The `LayoutTree` trait has been split into 5 smaller traits which live in the `taffy::tree:traits` module (along with their associated documentation)
242- The following methods have been removed from split `LayoutTree` traits entirely: `parent`, `is_childless`, `measure_node`, `needs_measure`, and `mark_dirty`.
243- `taffy::node::Node` has been replaced with `taffy::NodeId`. This should make it much easier to implement the low-level traits as the underlying type backing the node id now a `u64` rather than a `slotmap::DefaultKey`.
244- Support for running each layout algorithm individually on a single node via the following top-level functions:
245  - `compute_flexbox_layout`
246  - `compute_grid_layout`
247  - `compute_block_layout`
248  - `compute_leaf_layout`
249  - `compute_root_layout`
250  - `compute_hidden_layout`
251
252It is believed that nobody was previously using the low-level API so we are not providing a migration guide. However, along with the refactor we have greatly
253improved both the documentation and have added examples using the new API, both of which are linked to from the [main documentation page](https://docs.rs/taffy).
254
255### Module hierarchy changes
256
257The specific changes are detailed below. However for most users the most significant change will be that almost all types are now re-exported from the root module. This means that module specific imports like `use taffy::layout::Layout` can now in almost all cases be replaced with the simpler `use taffy::Layout`.
258
259Specific changes:
260
261- The `math` module has been made private
262- The `axis` module has been merged into the `geometry` module
263- The debug module is no longer public. The `print_tree` function is now accessible under `util`.
264- All types from the `node`, `data`, `layout`, `error` and `cache` modules have been moved to the  the `tree` module.
265- The `layout_flexbox()` function has been removed from the prelude. Use `taffy::compute_flexbox_layout` instead.
266
267### Many APIs have been renamed to replace `points` or `Points` with `length` or `Length`
268
269This new name better describes one-dimensional measure of space in some unspecified unit
270which is often unrelated to the PostScript point or the CSS `pt` unit.
271
272This also removes a misleading similarity with the 2D `Point`,
273whose components can have any unit and are not even necessarily absolute lengths.
274
275Example usage change:
276
277```diff
278 use taffy::prelude::*;
279
280 // …
281
282 let header_node = taffy
283     .new_leaf(
284         Style {
285-            size: Size { width: points(800.0), height: points(100.0) },
286+            size: Size { width: length(800.0), height: length(100.0) },
287             ..Default::default()
288         },
289     ).unwrap();
290```
291
292### Other Changes
293
294- The `Taffy` type was renamed to `TaffyTree` and made generic of a context parameter
295- The Flexbox algorithm has now been moved behind the `flexbox` feature. The `flexbox` feature is enabled by default.
296- The `justify_self` property has been moved behind the `grid` feature.
297- Fixed misspelling: `RunMode::PeformLayout` renamed into `RunMode::PerformLayout` (added missing `r`).
298- `serde` dependency has been made compatible with `no_std` environments
299- `slotmap` dependency has been made compatible with `no_std` environments
300- Added `insert_child_at_index()` method to the `TaffyTree`. This can be used to insert a child node at any position instead of just the end.
301- Added `total_node_count()` method to the `TaffyTree` which returns the total number of nodes in the tree.
302- Added `get_disjoint_node_context_mut()` method to the `TaffyTree`. This can be used to safely get multiple mutable borrows at the same time.
303
304## 0.3.19
305
306### Fixes
307
308- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
309  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
310  but they should be able to fix on their side by clarifying the type passed in
311
312## 0.3.18
313
314### Fixes
315
316- Fix computation of Flexbox automatic minimum size when grid or flexbox child has an explicit width/height style set (#576)
317
318## 0.3.17
319
320### Added
321
322- Added `total_node_count` method to the `Taffy` struct. Returns the total number of nodes in the tree.
323
324## 0.3.16
325
326### Fixes
327
328- Improve performance of flexbox columns
329
330## 0.3.15
331
332### Fixes
333
334- Fix justify-content and align-content when free space is negative (content overflows container) (#549) (#551)
335
336## 0.3.14
337
338### Fixes
339
340- Flex: Fix issue where constraints were not being propagated, causing nodes with inherent aspect-ratio (typically images) to not apply that aspect-ratio (#545) (Fixes bevyengine/bevy#9841)
341
342## 0.3.13
343
344### Fixes
345
346- Fix rounding accumulation bug (#521) (Fixes #501 and bevyengine/bevy#8911)
347- Flexbox: pass correct cross-axis available space when computing an item's intrinsic main size (#522)(Fixes bevyengine/bevy#9350)
348- Flexbox: Subtract child margin not parent margin when computing stretch-alignment known size
349- Grid: Make CSS Grid algorithm correctly apply max width/height and available space when it is the root node (#491)
350- Grid: Fix CSS Grid "auto track" / placement bugs #481
351  - Fix divide by zero when using grid_auto_rows/grid_auto_columns with zero negative implicit tracks
352  - Fix over counting of tracks (leading to incorrect container heights) when auto-placing in grids that contain negative implicit tracks.
353  - Fix axis conflation in auto-placement code when grid_auto_flow is column
354  - Fix assignment of auto track sizes when initializing negative implicit tracks
355- Leaf: Apply margins to leaf nodes when computing available space for measure functions
356- Leaf: Reserve space for padding/borders in nodes with measure functions (#497)
357  
358  **NOTE: This has the potential to break layouts relying on the old behaviour.** However, such layouts would be relying on a style having no effect, so it is judged that such layouts are unlikely to exist in the wild. If this turns out not to be true then this fix will be reverted on the 0.3.x branch.
359
360### Dependencies
361
362- Upgrade `grid` to `0.10`. This eliminates the transitive dependency on `no-std-compat`.
363
364## 0.3.12
365
366### Fixes
367
368- Fix caching issue when toggling `display:none` on and off
369
370## 0.3.11
371
372### Fixes
373
374- Fix exponential blowup when laying out trees containing nodes with min and max sizes.
375
376## 0.3.10
377
378### Fixes
379
380- Fix sizing of children when the available_space < min_size (#407)
381
382## 0.3.9
383
384### Fixes
385
386- Fix caching bug where a cached result would sometimes be incorrectly used when the amount of available space increased (bevyengine/bevy#8111) and (bevyengine/bevy#8124)
387
388## 0.3.8
389
390### Fixes
391
392- Fix incorrect min-content size for `flex-wrap: wrap` nodes (bevyengine/bevy#8082)
393
394## 0.3.7
395
396### Fixes
397
398- Fix: Make `padding` and `border` floor node sizes (#372)
399- Fix: Prevent percentages contributing to min-content sizes (#388) (also fixes bevyengine/bevy#8017)
400
401## 0.3.6
402
403### Fixes
404
405- Fix: Ignore `align_content` when `flex_wrap` is set to `nowrap` (#383)
406
407## 0.3.5
408
409### Fixes
410
411- Fix `display: none` when it is set on a flexbox child (#380)
412- Fix `display: none` when it is set on a grid child (#381)
413
414## 0.3.4
415
416### Fixes
417
418- Fix `display: none` when it is set for the only node in the hierarchy (#377)
419
420## 0.3.3
421
422### Added
423
424- Added `enable_rounding` and `disable_rounding` methods to the `Taffy` struct which enable consumers of Taffy to obtain unrounded `f32` values for the computed layouts if they want them. Rounding remains enabled by default.
425
426### Fixes
427
428- Fixed rounding algorithm such that it never leaves gaps between adjacent nodes (#369)
429- Fixed compiling with the `grid` feature disabled (#370)
430- Fixed compiling with the `std` feature disabled
431
432## 0.3.2
433
434### Fixes
435
436- Allow partial nested values to be deserialized into a `Style` using the `serde` feature.
437
438## 0.3.1
439
440### Fixes
441
442- The `serde` feature now works when the `grid` feature is enabled
443
444## 0.3.0
445
446### Highlights
447
448- [CSS Grid algorithm support](#new-feature-css-grid)
449- [Style helper functions](#new-feature-style-helpers)
450
451See below for details of breaking changes.
452
453### New Feature: CSS Grid
454
455We very excited to report that we now have support for CSS Grid layout. This is in addition to the existing Flexbox layout support, and the two modes interoperate. You can set a node to use Grid layout by setting the `display` property to `Display::Grid`.
456
457#### Learning Resources
458
459Taffy implements the CSS Grid specification faithfully, so documentation designed for the web should translate cleanly to Taffy's implementation. If you are interested in learning how to use CSS Grid, we would recommend the following resources:
460
461- [CSS Grid Garden](https://cssgridgarden.com/). This is an interactive tutorial/game that allows you to learn the essential parts of CSS Grid in a fun engaging way.
462- [A Complete Guide To CSS Grid](https://css-tricks.com/snippets/css/complete-guide-grid/) by CSS Tricks. This is detailed guide with illustrations and comprehensive written explanation of the different Grid properties and how they work.
463
464#### Supported Features & Properties
465
466In addition to the usual sizing/spacing properties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
467
468| Property                  | Explanation                                                                                    |
469| ---                       | ---                                                                                            |
470| [`grid-template-columns`] | The track sizing functions of the grid's explicit columns                                      |
471| [`grid-template-rows`]    | The track sizing functions of the grid's explicit rows                                         |
472| [`grid-auto-rows`]        | Track sizing functions for the grid's implicitly generated rows                                |
473| [`grid-auto-columns`]     | Track sizing functions for the grid's implicitly generated columns                             |
474| [`grid-auto-flow`]        | Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely.         |
475| [`gap`]                   | The size of the vertical and horizontal gaps between grid rows/columns                         |
476| [`align-content`]         | Align grid tracks within the container in the inline (horizontal) axis                         |
477| [`justify-content`]       | Align grid tracks within the container in the block (vertical) axis                            |
478| [`align-items`]           | Align the child items within their grid areas in the inline (horizontal) axis                  |
479| [`justify-items`]         | Align the child items within their grid areas in the block (vertical) axis                     |
480
481And the following Grid style properties are supported on Grid Items (children):
482
483| Property                  | Explanation                                                                                    |
484| ---                       | ---                                                                                            |
485| [`grid-row`]              | The (row) grid line the item starts at (or a span)                                             |
486| [`grid-column`]           | The (column) grid line the item end at (or a span)                                             |
487| [`align-self`]            | Align the item within it's grid area in the inline (horizontal) axis. Overrides `align-items`. |
488| [`justify-self`]          | Align the item within it's grid area in the block (vertical) axis. Overrides `justify-items`.  |
489
490[`grid-template-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-columns
491[`grid-template-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-rows
492[`grid-auto-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-rows
493[`grid-auto-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-columns
494[`grid-auto-flow`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-flow
495[`gap`]: https://developer.mozilla.org/en-US/docs/Web/CSS/gap
496[`align-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align_content
497[`justify-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify_content
498[`align-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-items
499[`justify-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-items
500[`grid-row`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
501[`grid-column`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-column
502[`align-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-self
503[`justify-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-self
504
505The following properties and features are not currently supported:
506
507- Subgrids
508- Masonry grid layout
509- Named grid lines
510- Named areas: `grid-template-areas` and `grid-area`
511- `grid-template` or `grid` shorthand
512
513#### Example
514
515See [examples/grid_holy_grail.rs](https://github.com/DioxusLabs/taffy/blob/main/examples/grid_holy_grail.rs) for an example using Taffy to implement the so-called [Holy Grail Layout](https://en.wikipedia.org/wiki/Holy_grail_(web_design)). If you want to run this example, the don't forget the enable the CSS Grid cargo feature:
516
517```bash
518cargo run --example grid_holy_grail --features grid
519```
520
521### New Feature: Style Helpers
522
523Ten new helper functions have added to the taffy prelude. These helper functions have short, intuitive names, and have generic return types which allow them to magically return the correct type depending on context. They make defining styles much easier, and means you won't typically need to use types like `Dimension` or `TrackSizingFunction` directly.
524
525For example, instead of:
526
527```rust
528let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };
529```
530
531you can now write
532
533```rust
534let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };
535```
536
537And that same helper function will work other types like `LengthPercentage` and `MinTrackSizingFunction` that also have a `Points` variant. There are also generic impl's for `Size<T>`, `Rect<T>` and `Line<T>` which means if your node is the same size in all dimensions you can even write
538
539```rust
540let size : Size<Dimension> = points(100.0);
541```
542
543Available style helpers:
544
545<table>
546  <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead>
547  <tbody>
548    <tr>
549      <td rowspan="3"><code>LengthPercentage</code></td>
550      <td><code>zero()</code></td>
551      <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td>
552    </tr>
553    <tr>
554      <td><code>points(val:&nbsp;f32)</code></td>
555      <td>Generates a <code>Points</code> variant with the specified value</td>
556    </tr>
557    <tr>
558      <td><code>percent(val:&nbsp;f32)</code></td>
559      <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td>
560    </tr>
561    <tr>
562      <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td>
563      <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td>
564    </tr>
565    <tr>
566      <td><code>auto()</code></td>
567      <td>Generates an <code>Auto</code> variant</td>
568    </tr>
569    <tr>
570      <td rowspan="3"><code>MinTrackSizingFunction</code></td>
571      <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td>
572    </tr>
573    <tr>
574      <td><code>min_content()</code></td>
575      <td>Generates an <code>MinContent</code> variant</td>
576    </tr>
577      <tr>
578      <td><code>max_content()</code></td>
579      <td>Generates an <code>MinContent</code> variant</td>
580    </tr>
581    <tr>
582      <td rowspan="3"><code>MaxTrackSizingFunction</code></td>
583      <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td>
584    </tr>
585    <tr>
586      <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td>
587      <td>Generates a <code>FitContent</code> variant with the specified limit.<br />Nest the <code>points</code> or <code>percent</code> helper inside this function to specified the limit.</td>
588    </tr>
589      <tr>
590      <td><code>fr(fraction:&nbsp;f32)</code></td>
591      <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td>
592    </tr>
593    <tr>
594      <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td>
595      <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td>
596    </tr>
597    <tr>
598      <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td>
599      <td>Equivalent to CSS <code>minmax()</code> function.</td>
600    </tr>
601    <tr>
602      <td><code>flex(fraction:&nbsp;f32)</code></td>
603      <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td>
604    </tr>
605    <tr>
606      <td rowspan="2"><code>TrackSizingFunction</code></td>
607      <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td>
608    </tr>
609    <tr>
610      <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td>
611      <td>Equivalent to css <code>repeat()</code> function.</td>
612    </tr>
613    <tr>
614      <td><code>Vec&lt;TrackSizingFunction&gt;</code></td>
615      <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td>
616      <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td>
617    </tr>
618    <tr>
619      <td rowspan="3"><code>AvailableSpace</code></td>
620      <td><code>auto()</code></td>
621      <td>Generates an <code>Auto</code> variant</td>
622    </tr>
623    <tr>
624      <td><code>min_content()</code></td>
625      <td>Generates an <code>MinContent</code> variant</td>
626    </tr>
627      <tr>
628      <td><code>max_content()</code></td>
629      <td>Generates an <code>MinContent</code> variant</td>
630    </tr>
631    <tr>
632      <td><code>Size&lt;T&gt;</code></td>
633      <td colspan="2">Any helper that works for <code>T</code> will also work for <code>Size&lt;T&gt;</code> and will set both <code>width</code> and <code>height</code> to that value</td>
634    </tr>
635    <tr>
636      <td><code>Rect&lt;T&gt;</code></td>
637      <td colspan="2">Any helper that works for <code>T</code> will also work for <code>Rect&lt;T&gt;</code> and will set <code>top</code>, <code>left</code>, <code>bottom</code>, and <code>right</code> to that value</td>
638    </tr>
639  </tbody>
640</table>
641
642### Breaking API changes
643
644#### Changes to alignment style types
645
646- `AlignContent` and `JustifyContent` has been merged.
647  - `JustifyContent` is now an alias of `AlignContent` and contains the `Stretch` variant.
648  - This variant will be *ignored* (falling back to `Start`) when applied Flexbox containers. It is valid value for Grid containers.
649- `AlignItems` and `AlignSelf` have been merged.
650  - The `Auto` variant of `AlignSelf` has been removed. You should now use `Option::None` if you wish to specify `AlignSelf::Auto`.
651  - `AlignSelf` is now an alias of `AlignItems`.
652  - `JustifyItems` and `JustifySelf` aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.
653- `Default` impls have been removed from all alignment types. This is because the correct default varies by property, and the types are now shared between multiple properties. The `Style` struct still has a default for each alignment property, so this is considered unlikely to affect you in practice.
654
655#### Strict style types
656
657- New types `LengthPercentage` and `LengthPercentageAuto` have been added.
658  - `LengthPercentage` is like `Dimension` but only contains the `Points` and `Percent` variants, which allows us to increase type safety for properties that don't support the `Auto` value.
659  - `LengthPercentageAuto` is currently identical to `Dimension` but will allow us to expand dimension in future to support values like `MinContent`, `MaxContent` and `FitContent`.
660- Some style properties have been updated to use either `LengthPercentage` or `LengthPercentageAuto` instead of `Dimension`. You will need to update your code, but it is recommended that you use the new style helpers (see above) rather than using the new types directly (although you certainly can use them directly if you want to).
661
662#### Position properties renamed
663
664- The `position` property is now renamed to `inset` and is now in line with [CSS inset specs](https://developer.mozilla.org/en-US/docs/Web/CSS/inset)
665- The `position_type` property is now renamed to `position` and is now in line with [CSS position specs](https://developer.mozilla.org/en-US/docs/Web/CSS/position). The `PositionType` enum has been similarly renamed to `Position`.
666
667#### Changes to `LayoutTree`
668
669- Added generic associated type to `LayoutTree` for a `ChildIter`, an iterator on the children of a given node.
670- Changed the `children` method of `LayoutTree` to return the `ChildIter` generic associated type to allow for custom tree storage implementations which do not store the children of a node contiguously.
671- Added `child_count`  method to `LayoutTree` for querying the number of children of a node. Required because the `children` method now returns an iterator instead of an array.
672- Added `is_childless` method to `LayoutTree` for querying whether a node has no children.
673
674#### `AvailableSpace` has been moved
675
676The `AvailableSpace` enum has been moved from the `layout` module to the `style` module. If you are importing it via the prelude then you will unaffected by the change.
677
678### Fixes
679
680- Flexbox nodes sized under a min-content constraint now size correctly (#291)
681- Aspect ratio is now applied correctly in many circumstances
682- Absolutely positioned items now apply margins correctly
683- Min/max size are now applied correctly
684- Inset applied incorrectly to relatively positioned flexbox children when both `top` and `bottom` or `left` and `right` were specified (#348)
685- Fix case where column-gap style could be used in place of row-gap style (when using a percentage gap with an indefinite container size)
686
687### Removed
688
689- Removed `top_from_points`, `bot_from_points`, `top_from_percent`, and `bot_from_percent` methods removed from `Rect<Dimension>`. These functions were incredibly specific for an unusual use case, so we would be surprised if anyone was using them. Please use the new style helpers instead.
690- Removed `min_main_size`, `max_main_size`, `min_cross_size`, `max_cross_size`, and `cross_size` methods from `Style`. Use the more general `cross` and `main` methods directly on the `size`, `min_size`, and `max_size` properties instead.
691- Removed `main_margin_start`, `main_margin_end`, `cross_margin_start`, `cross_margin_end` from `Style`. Use the more general `main_start`, `main_end`, `cross_start`, and `cross_end` on the `margin` property instead.
692
693## 0.2.2
694
695### Fixes
696
697- Border or padding on the horizontal axis could, in some cases, increase the height of nodes.
698
699## 0.2.1
700
701### Fixes
702
703- In case of conflicts, `min_size` now overrides `max_size` which overrides `size` (#261). This is the behaviour specified in the CSS specification, and was also the behaviour in Taffy `v0.1.0`, but a regression was introduced in Taffy `v0.2.0`.
704- `taffy::compute_layout` has been made public allowing Taffy to be used with custom storage (#263)
705
706## 0.2.0
707
708### New features
709
710#### Flexbox "gap" and `AlignContent::SpaceEvenly`
711
712The [gap](https://developer.mozilla.org/en-US/docs/Web/CSS/gap) property is now supported on flex containers. This can make it much easier to create even spacing or "gutters" between nodes.
713
714Additionally we have a `SpaceEvenly` variant to the `AlignContent` enum to support evenly spaced justification in the cross axis (equivalent to  `align-content: space-evenly` in CSS)
715
716#### Debug module and cargo feature
717
718Two debugging features have been added:
719
720- `taffy::debug::print_tree(&Taffy, root)` - This will print a debug representation of the computed layout of an entire node tree (starting at `root`), which can be useful for debugging layouts.
721- A cargo feature `debug`. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).
722
723### Performance improvements
724
725A number of performance improvements have landed since taffy 0.1:
726
727- Firstly, our custom `taffy::forest` storage implementation was ripped out and replaced with a much simpler implementation using the `slotmap` crate. This led to performance increases of up to 90%.
728- Secondly, the caching implementation was improved by upping the number of cache slots from 2 to 4 and tweaking how computed results are allocated to cache slots to better match the actual usage patterns of the flexbox layout algorithm. This had a particularly dramatic effect on deep hierarchies (which often involve recomputing the same results repeatedly), fixing the exponential blowup that was previously exhibited on these trees and improving performance by over 1000x in some cases!
729
730#### Benchmarks vs. Taffy 0.1
731
732| Benchmark                                 | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
733| ---                                       | ---       | ---       | ---                   |
734| wide/1_000 nodes (2-level hierarchy)      | 699.18 µs | 445.01 µs | -36.279%              |
735| wide/10_000 nodes (2-level hierarchy)     | 8.8244 ms | 7.1313 ms | -16.352%              |
736| wide/100_000 nodes (2-level hierarchy)    | 204.48 ms | 242.93 ms | +18.803%              |
737| deep/4000 nodes (12-level hierarchy))     | 5.2320 s  | 2.7363 ms | -99.947%              |
738| deep/10_000 nodes (14-level hierarchy)    | 75.207 s  | 6.9415 ms | -99.991%              |
739| deep/100_000 nodes (17-level hierarchy)   | -         | 102.72 ms | -                     |
740| deep/1_000_000 nodes (20-level hierarchy) | -         | 799.35 ms | -                     |
741
742(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
743
744As you can see, we have actually regressed slightly in the "wide" benchmarks (where all nodes are siblings of a single parent node). Although it should be noted our results in these benchmarks are still very fast, especially on the 10,000 node benchmark which we consider to be the most realistic size where the result is measured in microseconds.
745
746However, in the "deep" benchmarks we see dramatic improvements. The previous version of Taffy suffered from exponential blowup in the case of deeply nested hierarchies. This has resulted in somewhat silly improvements like the 10,000 node (14-level) hierarchy where Taffy 0.2 is a full 1 million times faster than Taffy 0.1. We've also included results with larger numbers of nodes (although you're unlikely to need that many) to demonstrate that this scalability continues up to even deeper levels of nesting.
747
748#### Benchmarks vs. [Yoga](https://github.com/facebook/yoga)
749
750Yoga benchmarks run via it's node.js bindings (the `yoga-layout-prebuilt` npm package), they were run a few times manually and it was verified that variance in the numbers of each run was minimal. It should be noted that this is using an old version of Yoga.
751
752| Benchmark | Yoga | Taffy 0.2 |
753| --- | --- | --- |
754| yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
755| yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
756| yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
757| yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
758| yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 ms |
759
760(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
761
762While we're trying not to get too excited (there could easily be an issue with our benchmarking methodology which make this an unfair comparison), we are pleased to see that we seem to be anywhere between 100x and 1000x times faster depending on the node count!
763
764### Breaking API changes
765
766#### Node creation changes
767
768- `taffy::Node` is now unique only to the Taffy instance from which it was created.
769- Renamed `Taffy.new_node(..)` -> `Taffy.new_with_children(..)`
770- Renamed `Taffy.new_leaf()` -> `Taffy.new_leaf_with_measure()`
771- Added `taffy::node::Taffy.new_leaf()` which allows the creation of new leaf-nodes without having to supply a measure function
772
773#### Error handling/representation improvements
774
775- Renamed `taffy::Error` -> `taffy::error::TaffyError`
776- Replaced `taffy::error::InvalidChild` with a new `InvalidChild` variant of `taffy::error::TaffyError`
777- Replaced `taffy::error::InvalidNode` with a new `InvalidNode` variant of `taffy::error::TaffyError`
778- The following method new return `Err(TaffyError::ChildIndexOutOfBounds)` instead of panicking:
779  - `taffy::Taffy::remove_child_at_index`
780  - `taffy::Taffy::replace_child_at_index`
781  - `taffy::Taffy::child_at_index`
782- `Taffy::remove` now returns a `Result<usize, Error>`, to indicate if the operation was successful (and if it was, which ID was invalidated).
783
784#### Some uses of `Option<f32>` replaced with a new `AvailableSpace` enum
785
786A new enum `Taffy::layout::AvailableSpace` has been added.
787
788The definition looks like this:
789
790```rust
791/// The amount of space available to a node in a given axis
792pub enum AvailableSpace {
793    /// The amount of space available is the specified number of pixels
794    Definite(f32),
795    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
796    MinContent,
797    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
798    MaxContent,
799}
800```
801
802This enum is now used instead of `Option<f32>` when calling `Taffy.compute_layout` (if you previously passing `Size::NONE` to `compute_layout`, then you will need to change this to `Size::MAX_CONTENT`).
803
804And a different instance of it is passed as a new second parameter to `MeasureFunc`. `MeasureFunc`s may choose to use this parameter in their computation or ignore it as they see fit. The canonical example of when it makes sense to use it is when laying out text. If `MinContent` has been passed in the axis in which the text is flowing (i.e. the horizontal axis for left-to-right text), then you should line-break at every possible opportunity (e.g. all word boundaries), whereas if `MaxContent` has been passed then you shouldn't line break at all..
805
806#### Builder methods are now `const` where possible
807
808- Several convenience constants have been defined: notably `Style::DEFAULT`
809- `Size<f32>.zero()` is now `Size::<f32>::ZERO`
810- `Point<f32>.zero()` is now  `Point::<f32>::ZERO`
811- `Size::undefined()` is now `Size::NONE`
812
813#### Removals
814
815- Removed `taffy::forest::Forest`. `taffy::node::Taffy` now handles it's own storage using a slotmap (which comes with a performance boost up to 90%).
816- Removed `taffy::number::Number`. Use `Option<f32>` is used instead
817  - the associated public `MinMax` and `OrElse` traits have also been removed; these should never have been public
818- Removed unused dependencies `hashbrown`, `hash32`, and `typenum`. `slotmap` is now the only required dependency (`num_traits` and `arrayvec` are also required if you wish to use taffy in a `no_std` environment).
819
820### Fixes
821
822- Miscellaneous correctness fixes which align our implementation with Chrome:
823
824  - Nodes can only ever have one parent
825  - Fixed rounding of fractional values to follow latest Chrome - values are now rounded the same regardless of their position
826  - Fixed computing free space when using both `flex-grow` and a minimum size
827  - Padding is now only subtracted when determining the available space if the node size is unspecified, following [section 9.2.2 of the flexbox spec](https://www.w3.org/TR/css-flexbox-1/#line-sizing)
828  - `MeasureFunc` (and hence `NodeData` and hence `Forest` and hence the public `Taffy` type) are now `Send` and `Sync`, enabling their use in async and parallel applications
829- Taffy can now be vendored using `cargo-vendor` (README.md is now included in package).
830
831## 0.1.0
832
833### 0.1.0 Changed
834
835- the `order` field of `Layout` is now public, and describes the relative z-ordering of nodes
836- renamed crate from `stretch2` to `taffy`
837- updated to the latest version of all dependencies to reduce upstream pain caused by duplicate dependencies
838- renamed `stretch::node::Stretch` -> `taffy::node::Taffy`
839
840### 0.1.0 Fixed
841
842- fixed feature strategy for `alloc` and `std`: these can now be compiled together, with `std`'s types taking priority
843
844### 0.1.0 Removed
845
846- removed Javascript / Kotlin / Swift bindings
847  - the maintainer team lacks expertise to keep these working
848  - more serious refactors are planned, and this will be challenging to keep working through that process
849  - if you are interested in helping us maintain bindings to other languages, [get in touch](https://github.com/DioxusLabs/taffy/discussions)!
850- the `serde_camel_case` and `serde_kebab_case` features have been removed: they were poorly motivated and were not correctly additive (if both were enabled compilation would fail)
851- removed the `Direction` and `Overflow` structs, and the corresponding `direction` and `overflow` fields from `Style`
852  - these had no effect in the current code base and were actively misleading
853
854## stretch2 0.4.3
855
856This is the final release of `stretch`: migrate to the crate named `taffy` for future fixes and features!
857
858These notes describe the differences between this release and `stretch` 0.3.2, the abandoned crate from which this library was forked.
859
860### Changed
861
862- updated [assorted dependencies](https://github.com/vislyhq/stretch/commit/a6491117379cea52dedc9584d892594a143e8cb0)
863
864### Fixed
865
866- fixed an exponential performance blow-up with deep nesting
867- fixed percent height values, which were using parent width
868- recomputing layout no longer moves children of non-zero-positioned parent
869- fixed broken Swift bindings