1# Changelog
2
3## 0.7.7
4
5### Fixed
6
7- Add `#[inline]` annotation to some methods on `TaffyTree` (#802)
8- Add `TaffyTree::remove_children_range` method (#802)
9
10## 0.7.6
11
12### Fixed
13
14- Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
15
16## 0.7.5
17
18### Fixed
19
20- Grid: only stretch auto tracks if content-alignment is stretch (#783)
21
22## 0.7.4
23
24### Fixed
25
26- Fix detailed grid info for empty grid (#782)
27
28## 0.7.3
29
30### Fixed
31
32- Make `TaffyTree::detailed_layout_info` take `&self` rather than `&mut self` (#779)
33
34## 0.7.2
35
36### Added
37
38- The ability to access computed track sizes and item positions of a CSS Grid layout (#772).
39  This information can be accessed using the `LayoutGridContainer::set_detailed_grid_info` method
40  in the low-level API or the `TaffyTree::detailed_layout_info` method in the high-level API.
41
42## 0.7.1
43
44### Fixed
45
46- Improve interaction of abspos children of block containers with margin collapsing (#760)
47
48### Added
49
50- Add `TaffyTree::unrounded_layout` getter (#765)
51
52### Removed
53
54- The `num-traits` dependency was removed (#761) (#762)
55
56## 0.7.0
57
58### Changed
59
60- BREAKING: The `cache_mut` method on the `LayoutPartialTree` trait has been replaced with a separate `CacheTree` trait. This allows
61  Taffy to be more easily used without caching or with a custom cache implementation.
62- BREAKING: the `TaffyTree::set_children` method now removes the children from their previous parent (if they have one).
63
64### Added
65
66- Helper methods to retrieve content-box sizes were added to `Layout`
67
68## 0.6.3
69
70### Fixes
71
72- Block: ignore margin collapsing when computing static position of abspos items (#747)
73
74## 0.6.2
75
76### Fixes
77
78- Fix: clamp indefinite available space by min- and max- size as appropriate (#742)
79
80## 0.6.1
81
82### Fixes
83
84- Fix calculation of `auto-fill`/`auto-fit` repetition count when container has a definite percentage size (#722)
85- Fix min-size style not affecting intrinsic sizes (#723)
86- Fix documentation of dirty and mark_dirty functions (#724)
87- Fix intrinsic size of scroll containers that have a small explicit flex-basis (#728)
88
89## 0.6.0
90
91### Highlights
92
93- The `Style` struct has been "traitified". This supports Taffy's integration in Servo and generally makes Taffy more flexible. The
94  `Style` struct still exists and implements the new traits so existing uses of Taffy will continue to work as before.
95- The `box-sizing` style is supported
96- Computed margins are output in `Layout`
97
98### Fixes
99
100- Fix `print_tree()` when rounding is disabled (#680)
101- Absolute Insets should be resolved against the container size minus border (#666)
102- Fix flooring hypothetical_main_size by computed min size (#689)
103- Fix flex line cross-size determination (#690)
104- Fix panics in the grid algorithm (#691)
105- Fix resolving flexible lengths (WPT css/flexbox-multiline-min-max test) (#692)
106- Fix wrapping when a max main size style is present (#694)
107- Fix case where Taffy allowed margins to collapse through an element when it shouldn't have (#695)
108
109### Added
110
111- Legacy text align (for laying out `<center>` and `<div align="..">`) is supported
112- Add `is_table` for block items (#701)
113- Impl `Debug` and `Clone` for `Cache` (#688)
114- Implement `Debug` and `PartialEq` for tree types (#697)
115
116## 0.5.2
117
118- Fix block stretch sizing (don't always apply stretch sizing to block containers) (#674)
119- Fix computation of intrinsic main size when it depends on a child's known cross size (#673)
120- Fix panic when GridLine 0 is specified (#671)
121- Docs: Document feature flags and scrape examples (#672)
122- Docs: Update cosmic-text example to cosmic-text 0.12 (#670)
123
124## 0.5.1
125
126- Fix: Clamp block item stretch widths by their min and max width (#664)
127- Fix: Auto margin computation in block layout (#663)
128
129## 0.5.0
130
131The changes in 0.5 are relatively small but the new measure function parameter is a breaking change so it requires a minor version bump.
132
133- Added: A `style: &Style` parameter has been added to measure functions.
134- Added: The `MaybeMath`, `MaybeResolve`, and `ResolveOrZero` traits have been made public.
135- Fix: use SizingMode::Inherent when sizing absolute children of flexbox nodes.
136
137## 0.4.4
138
139### Fixes
140
141- Content alignment (`align-content`/`justify-content`) behaviour was updated to match the latest spec (and Chrome 123+) (#635)
142- Ensure that root Flexbox nodes are floored by their padding-border (#651, #655)
143- Use grid area size not available space when applying aspect ratio to grid containers (#656)
144
145## 0.4.3
146
147### Fixes
148
149- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
150  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
151  but they should be able to fix on their side by clarifying the type passed in
152
153## 0.4.2
154
155- Fixed: single-line flex-container should clamp the line's cross-size (#638)
156- Reduced binary footprint of Taffy from around 300kb to around 150kb (#636)
157
158## 0.4.1
159
160- Fixed: CSS Grid track sizing not respecting growth limits in some circumstances (#624)
161
162## 0.4.0
163
164### Highlights
165
166- Support for CSS Block layout (`display: block`)
167- Support for the `overflow` property (+ `scrollbar_width` for `overflow: scroll`)
168- Improved measure function API
169- Completely refactored low-level API
170- Simplified module hierarchy (+ most types/functions are now exported from the crate root)
171- Expanded set of examples which better document integration with other layout systems (e.g. text layout)
172- Computed values for `padding` and `border` are now output into the `Layout` struct
173
174### Block layout
175
176Support 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.
177
178### Overflow property
179
180Support 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.
181
182- Overflow is settable indpendently in each axis.
183- `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.
184- `Hidden` and `Scroll` affect layout by changing the automatic minimum size of Flexbox and Grid children
185- `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`.
186
187### Measure function changes
188
189The "measure function" API for integrating Taffy with other measurement systems (such as text layout) has been changed to be more flexible
190and to interact better with borrow checking (you can now borrow external data in your measure function!).
191
192- There are no longer per-node measure functions.
193- There is now a single "global" measure function, and a per-node "context" of a user-defined type
194- The `Taffy` tree is now a generic `TaffyTree<T>` where `T` is the "context" type.
195- The measure function is now called for all leaf nodes (nodes without children). If you wish to maintain compatibility with the previous
196  behaviour then your measure function should return `Size::ZERO` for leaf nodes whose context is `None`.
197
198If you are not using measure functions, then the only change you will need to make is from:
199
200```rust
201let mut tree = Taffy::new();
202```
203
204to
205
206```rust
207let mut tree : TaffyTree<()> = TaffyTree::new();
208```
209
210And generally update any uses of `Taffy` in your codebase to `TaffyTree<()>`.
211
212If you are using measure functions then you will need to make some bigger (but straightforward) changes. The following Taffy 0.3 code:
213
214```rust
215let mut tree = Taffy::new();
216let leaf = tree.new_leaf_with_measure(
217  Style::DEFAULT,
218  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>| Size { width: 100.0, height: 200.0 }
219);
220tree.compute_layout(leaf, Size::MAX_CONTENT);
221```
222
223Should become something like the following with Taffy 0.4:
224
225```rust
226let mut tree : TaffyTree<Size> = TaffyTree::new();
227let leaf = tree.new_leaf_with_context(Style::DEFAULT, Size { width: 100.0, height: 200.0 });
228tree.compute_layout_with_measure(
229  leaf,
230  Size::MAX_CONTENT,
231  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, node_id: NodeId, node_context: Option<Size>| {
232    node_context.unwrap_or(Size::ZERO)
233  }
234);
235```
236
237Note that:
238
239- 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).
240- If you don't need a context then you can use `()` for the context type
241- As the single "global" measure function passed to `compute_layout_with_measure` only needs to exist for the duration of a single layout run,
242  it can (mutably) borrow data from it's environment
243
244### Low-level API (`LayoutTree` trait) refactor
245
246The low-level API has been completely reworked:
247
248- The `LayoutTree` trait has been split into 5 smaller traits which live in the `taffy::tree:traits` module (along with their associated documentation)
249- The following methods have been removed from split `LayoutTree` traits entirely: `parent`, `is_childless`, `measure_node`, `needs_measure`, and `mark_dirty`.
250- `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`.
251- Support for running each layout algorithm individually on a single node via the following top-level functions:
252  - `compute_flexbox_layout`
253  - `compute_grid_layout`
254  - `compute_block_layout`
255  - `compute_leaf_layout`
256  - `compute_root_layout`
257  - `compute_hidden_layout`
258
259It 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
260improved 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).
261
262### Module hierarchy changes
263
264The 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`.
265
266Specific changes:
267
268- The `math` module has been made private
269- The `axis` module has been merged into the `geometry` module
270- The debug module is no longer public. The `print_tree` function is now accessible under `util`.
271- All types from the `node`, `data`, `layout`, `error` and `cache` modules have been moved to the  the `tree` module.
272- The `layout_flexbox()` function has been removed from the prelude. Use `taffy::compute_flexbox_layout` instead.
273
274### Many APIs have been renamed to replace `points` or `Points` with `length` or `Length`
275
276This new name better describes one-dimensional measure of space in some unspecified unit
277which is often unrelated to the PostScript point or the CSS `pt` unit.
278
279This also removes a misleading similarity with the 2D `Point`,
280whose components can have any unit and are not even necessarily absolute lengths.
281
282Example usage change:
283
284```diff
285 use taffy::prelude::*;
286
287 // …
288
289 let header_node = taffy
290     .new_leaf(
291         Style {
292-            size: Size { width: points(800.0), height: points(100.0) },
293+            size: Size { width: length(800.0), height: length(100.0) },
294             ..Default::default()
295         },
296     ).unwrap();
297```
298
299### Other Changes
300
301- The `Taffy` type was renamed to `TaffyTree` and made generic of a context parameter
302- The Flexbox algorithm has now been moved behind the `flexbox` feature. The `flexbox` feature is enabled by default.
303- The `justify_self` property has been moved behind the `grid` feature.
304- Fixed misspelling: `RunMode::PeformLayout` renamed into `RunMode::PerformLayout` (added missing `r`).
305- `serde` dependency has been made compatible with `no_std` environments
306- `slotmap` dependency has been made compatible with `no_std` environments
307- 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.
308- Added `total_node_count()` method to the `TaffyTree` which returns the total number of nodes in the tree.
309- Added `get_disjoint_node_context_mut()` method to the `TaffyTree`. This can be used to safely get multiple mutable borrows at the same time.
310
311## 0.3.19
312
313### Fixes
314
315- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
316  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
317  but they should be able to fix on their side by clarifying the type passed in
318
319## 0.3.18
320
321### Fixes
322
323- Fix computation of Flexbox automatic minimum size when grid or flexbox child has an explicit width/height style set (#576)
324
325## 0.3.17
326
327### Added
328
329- Added `total_node_count` method to the `Taffy` struct. Returns the total number of nodes in the tree.
330
331## 0.3.16
332
333### Fixes
334
335- Improve performance of flexbox columns
336
337## 0.3.15
338
339### Fixes
340
341- Fix justify-content and align-content when free space is negative (content overflows container) (#549) (#551)
342
343## 0.3.14
344
345### Fixes
346
347- 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)
348
349## 0.3.13
350
351### Fixes
352
353- Fix rounding accumulation bug (#521) (Fixes #501 and bevyengine/bevy#8911)
354- Flexbox: pass correct cross-axis available space when computing an item's intrinsic main size (#522)(Fixes bevyengine/bevy#9350)
355- Flexbox: Subtract child margin not parent margin when computing stretch-alignment known size
356- Grid: Make CSS Grid algorithm correctly apply max width/height and available space when it is the root node (#491)
357- Grid: Fix CSS Grid "auto track" / placement bugs #481
358  - Fix divide by zero when using grid_auto_rows/grid_auto_columns with zero negative implicit tracks
359  - Fix over counting of tracks (leading to incorrect container heights) when auto-placing in grids that contain negative implicit tracks.
360  - Fix axis conflation in auto-placement code when grid_auto_flow is column
361  - Fix assignment of auto track sizes when initializing negative implicit tracks
362- Leaf: Apply margins to leaf nodes when computing available space for measure functions
363- Leaf: Reserve space for padding/borders in nodes with measure functions (#497)
364  
365  **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.
366
367### Dependencies
368
369- Upgrade `grid` to `0.10`. This eliminates the transitive dependency on `no-std-compat`.
370
371## 0.3.12
372
373### Fixes
374
375- Fix caching issue when toggling `display:none` on and off
376
377## 0.3.11
378
379### Fixes
380
381- Fix exponential blowup when laying out trees containing nodes with min and max sizes.
382
383## 0.3.10
384
385### Fixes
386
387- Fix sizing of children when the available_space < min_size (#407)
388
389## 0.3.9
390
391### Fixes
392
393- 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)
394
395## 0.3.8
396
397### Fixes
398
399- Fix incorrect min-content size for `flex-wrap: wrap` nodes (bevyengine/bevy#8082)
400
401## 0.3.7
402
403### Fixes
404
405- Fix: Make `padding` and `border` floor node sizes (#372)
406- Fix: Prevent percentages contributing to min-content sizes (#388) (also fixes bevyengine/bevy#8017)
407
408## 0.3.6
409
410### Fixes
411
412- Fix: Ignore `align_content` when `flex_wrap` is set to `nowrap` (#383)
413
414## 0.3.5
415
416### Fixes
417
418- Fix `display: none` when it is set on a flexbox child (#380)
419- Fix `display: none` when it is set on a grid child (#381)
420
421## 0.3.4
422
423### Fixes
424
425- Fix `display: none` when it is set for the only node in the hierarchy (#377)
426
427## 0.3.3
428
429### Added
430
431- 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.
432
433### Fixes
434
435- Fixed rounding algorithm such that it never leaves gaps between adjacent nodes (#369)
436- Fixed compiling with the `grid` feature disabled (#370)
437- Fixed compiling with the `std` feature disabled
438
439## 0.3.2
440
441### Fixes
442
443- Allow partial nested values to be deserialized into a `Style` using the `serde` feature.
444
445## 0.3.1
446
447### Fixes
448
449- The `serde` feature now works when the `grid` feature is enabled
450
451## 0.3.0
452
453### Highlights
454
455- [CSS Grid algorithm support](#new-feature-css-grid)
456- [Style helper functions](#new-feature-style-helpers)
457
458See below for details of breaking changes.
459
460### New Feature: CSS Grid
461
462We 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`.
463
464#### Learning Resources
465
466Taffy 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:
467
468- [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.
469- [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.
470
471#### Supported Features & Properties
472
473In addition to the usual sizing/spacing properties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
474
475| Property                  | Explanation                                                                                    |
476| ---                       | ---                                                                                            |
477| [`grid-template-columns`] | The track sizing functions of the grid's explicit columns                                      |
478| [`grid-template-rows`]    | The track sizing functions of the grid's explicit rows                                         |
479| [`grid-auto-rows`]        | Track sizing functions for the grid's implicitly generated rows                                |
480| [`grid-auto-columns`]     | Track sizing functions for the grid's implicitly generated columns                             |
481| [`grid-auto-flow`]        | Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely.         |
482| [`gap`]                   | The size of the vertical and horizontal gaps between grid rows/columns                         |
483| [`align-content`]         | Align grid tracks within the container in the inline (horizontal) axis                         |
484| [`justify-content`]       | Align grid tracks within the container in the block (vertical) axis                            |
485| [`align-items`]           | Align the child items within their grid areas in the inline (horizontal) axis                  |
486| [`justify-items`]         | Align the child items within their grid areas in the block (vertical) axis                     |
487
488And the following Grid style properties are supported on Grid Items (children):
489
490| Property                  | Explanation                                                                                    |
491| ---                       | ---                                                                                            |
492| [`grid-row`]              | The (row) grid line the item starts at (or a span)                                             |
493| [`grid-column`]           | The (column) grid line the item end at (or a span)                                             |
494| [`align-self`]            | Align the item within it's grid area in the inline (horizontal) axis. Overrides `align-items`. |
495| [`justify-self`]          | Align the item within it's grid area in the block (vertical) axis. Overrides `justify-items`.  |
496
497[`grid-template-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-columns
498[`grid-template-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-rows
499[`grid-auto-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-rows
500[`grid-auto-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-columns
501[`grid-auto-flow`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-flow
502[`gap`]: https://developer.mozilla.org/en-US/docs/Web/CSS/gap
503[`align-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align_content
504[`justify-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify_content
505[`align-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-items
506[`justify-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-items
507[`grid-row`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
508[`grid-column`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-column
509[`align-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-self
510[`justify-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-self
511
512The following properties and features are not currently supported:
513
514- Subgrids
515- Masonry grid layout
516- Named grid lines
517- Named areas: `grid-template-areas` and `grid-area`
518- `grid-template` or `grid` shorthand
519
520#### Example
521
522See [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:
523
524```bash
525cargo run --example grid_holy_grail --features grid
526```
527
528### New Feature: Style Helpers
529
530Ten 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.
531
532For example, instead of:
533
534```rust
535let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };
536```
537
538you can now write
539
540```rust
541let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };
542```
543
544And 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
545
546```rust
547let size : Size<Dimension> = points(100.0);
548```
549
550Available style helpers:
551
552<table>
553  <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead>
554  <tbody>
555    <tr>
556      <td rowspan="3"><code>LengthPercentage</code></td>
557      <td><code>zero()</code></td>
558      <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td>
559    </tr>
560    <tr>
561      <td><code>points(val:&nbsp;f32)</code></td>
562      <td>Generates a <code>Points</code> variant with the specified value</td>
563    </tr>
564    <tr>
565      <td><code>percent(val:&nbsp;f32)</code></td>
566      <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td>
567    </tr>
568    <tr>
569      <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td>
570      <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td>
571    </tr>
572    <tr>
573      <td><code>auto()</code></td>
574      <td>Generates an <code>Auto</code> variant</td>
575    </tr>
576    <tr>
577      <td rowspan="3"><code>MinTrackSizingFunction</code></td>
578      <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td>
579    </tr>
580    <tr>
581      <td><code>min_content()</code></td>
582      <td>Generates an <code>MinContent</code> variant</td>
583    </tr>
584      <tr>
585      <td><code>max_content()</code></td>
586      <td>Generates an <code>MinContent</code> variant</td>
587    </tr>
588    <tr>
589      <td rowspan="3"><code>MaxTrackSizingFunction</code></td>
590      <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td>
591    </tr>
592    <tr>
593      <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td>
594      <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>
595    </tr>
596      <tr>
597      <td><code>fr(fraction:&nbsp;f32)</code></td>
598      <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td>
599    </tr>
600    <tr>
601      <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td>
602      <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td>
603    </tr>
604    <tr>
605      <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td>
606      <td>Equivalent to CSS <code>minmax()</code> function.</td>
607    </tr>
608    <tr>
609      <td><code>flex(fraction:&nbsp;f32)</code></td>
610      <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td>
611    </tr>
612    <tr>
613      <td rowspan="2"><code>TrackSizingFunction</code></td>
614      <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td>
615    </tr>
616    <tr>
617      <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td>
618      <td>Equivalent to css <code>repeat()</code> function.</td>
619    </tr>
620    <tr>
621      <td><code>Vec&lt;TrackSizingFunction&gt;</code></td>
622      <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td>
623      <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td>
624    </tr>
625    <tr>
626      <td rowspan="3"><code>AvailableSpace</code></td>
627      <td><code>auto()</code></td>
628      <td>Generates an <code>Auto</code> variant</td>
629    </tr>
630    <tr>
631      <td><code>min_content()</code></td>
632      <td>Generates an <code>MinContent</code> variant</td>
633    </tr>
634      <tr>
635      <td><code>max_content()</code></td>
636      <td>Generates an <code>MinContent</code> variant</td>
637    </tr>
638    <tr>
639      <td><code>Size&lt;T&gt;</code></td>
640      <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>
641    </tr>
642    <tr>
643      <td><code>Rect&lt;T&gt;</code></td>
644      <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>
645    </tr>
646  </tbody>
647</table>
648
649### Breaking API changes
650
651#### Changes to alignment style types
652
653- `AlignContent` and `JustifyContent` has been merged.
654  - `JustifyContent` is now an alias of `AlignContent` and contains the `Stretch` variant.
655  - This variant will be *ignored* (falling back to `Start`) when applied Flexbox containers. It is valid value for Grid containers.
656- `AlignItems` and `AlignSelf` have been merged.
657  - The `Auto` variant of `AlignSelf` has been removed. You should now use `Option::None` if you wish to specify `AlignSelf::Auto`.
658  - `AlignSelf` is now an alias of `AlignItems`.
659  - `JustifyItems` and `JustifySelf` aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.
660- `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.
661
662#### Strict style types
663
664- New types `LengthPercentage` and `LengthPercentageAuto` have been added.
665  - `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.
666  - `LengthPercentageAuto` is currently identical to `Dimension` but will allow us to expand dimension in future to support values like `MinContent`, `MaxContent` and `FitContent`.
667- 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).
668
669#### Position properties renamed
670
671- 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)
672- 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`.
673
674#### Changes to `LayoutTree`
675
676- Added generic associated type to `LayoutTree` for a `ChildIter`, an iterator on the children of a given node.
677- 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.
678- 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.
679- Added `is_childless` method to `LayoutTree` for querying whether a node has no children.
680
681#### `AvailableSpace` has been moved
682
683The `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.
684
685### Fixes
686
687- Flexbox nodes sized under a min-content constraint now size correctly (#291)
688- Aspect ratio is now applied correctly in many circumstances
689- Absolutely positioned items now apply margins correctly
690- Min/max size are now applied correctly
691- Inset applied incorrectly to relatively positioned flexbox children when both `top` and `bottom` or `left` and `right` were specified (#348)
692- 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)
693
694### Removed
695
696- 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.
697- 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.
698- 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.
699
700## 0.2.2
701
702### Fixes
703
704- Border or padding on the horizontal axis could, in some cases, increase the height of nodes.
705
706## 0.2.1
707
708### Fixes
709
710- 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`.
711- `taffy::compute_layout` has been made public allowing Taffy to be used with custom storage (#263)
712
713## 0.2.0
714
715### New features
716
717#### Flexbox "gap" and `AlignContent::SpaceEvenly`
718
719The [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.
720
721Additionally 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)
722
723#### Debug module and cargo feature
724
725Two debugging features have been added:
726
727- `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.
728- A cargo feature `debug`. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).
729
730### Performance improvements
731
732A number of performance improvements have landed since taffy 0.1:
733
734- 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%.
735- 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!
736
737#### Benchmarks vs. Taffy 0.1
738
739| Benchmark                                 | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
740| ---                                       | ---       | ---       | ---                   |
741| wide/1_000 nodes (2-level hierarchy)      | 699.18 µs | 445.01 µs | -36.279%              |
742| wide/10_000 nodes (2-level hierarchy)     | 8.8244 ms | 7.1313 ms | -16.352%              |
743| wide/100_000 nodes (2-level hierarchy)    | 204.48 ms | 242.93 ms | +18.803%              |
744| deep/4000 nodes (12-level hierarchy))     | 5.2320 s  | 2.7363 ms | -99.947%              |
745| deep/10_000 nodes (14-level hierarchy)    | 75.207 s  | 6.9415 ms | -99.991%              |
746| deep/100_000 nodes (17-level hierarchy)   | -         | 102.72 ms | -                     |
747| deep/1_000_000 nodes (20-level hierarchy) | -         | 799.35 ms | -                     |
748
749(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
750
751As 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.
752
753However, 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.
754
755#### Benchmarks vs. [Yoga](https://github.com/facebook/yoga)
756
757Yoga 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.
758
759| Benchmark | Yoga | Taffy 0.2 |
760| --- | --- | --- |
761| yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
762| yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
763| yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
764| yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
765| yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 ms |
766
767(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
768
769While 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!
770
771### Breaking API changes
772
773#### Node creation changes
774
775- `taffy::Node` is now unique only to the Taffy instance from which it was created.
776- Renamed `Taffy.new_node(..)` -> `Taffy.new_with_children(..)`
777- Renamed `Taffy.new_leaf()` -> `Taffy.new_leaf_with_measure()`
778- Added `taffy::node::Taffy.new_leaf()` which allows the creation of new leaf-nodes without having to supply a measure function
779
780#### Error handling/representation improvements
781
782- Renamed `taffy::Error` -> `taffy::error::TaffyError`
783- Replaced `taffy::error::InvalidChild` with a new `InvalidChild` variant of `taffy::error::TaffyError`
784- Replaced `taffy::error::InvalidNode` with a new `InvalidNode` variant of `taffy::error::TaffyError`
785- The following method new return `Err(TaffyError::ChildIndexOutOfBounds)` instead of panicking:
786  - `taffy::Taffy::remove_child_at_index`
787  - `taffy::Taffy::replace_child_at_index`
788  - `taffy::Taffy::child_at_index`
789- `Taffy::remove` now returns a `Result<usize, Error>`, to indicate if the operation was successful (and if it was, which ID was invalidated).
790
791#### Some uses of `Option<f32>` replaced with a new `AvailableSpace` enum
792
793A new enum `Taffy::layout::AvailableSpace` has been added.
794
795The definition looks like this:
796
797```rust
798/// The amount of space available to a node in a given axis
799pub enum AvailableSpace {
800    /// The amount of space available is the specified number of pixels
801    Definite(f32),
802    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
803    MinContent,
804    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
805    MaxContent,
806}
807```
808
809This 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`).
810
811And 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..
812
813#### Builder methods are now `const` where possible
814
815- Several convenience constants have been defined: notably `Style::DEFAULT`
816- `Size<f32>.zero()` is now `Size::<f32>::ZERO`
817- `Point<f32>.zero()` is now  `Point::<f32>::ZERO`
818- `Size::undefined()` is now `Size::NONE`
819
820#### Removals
821
822- 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%).
823- Removed `taffy::number::Number`. Use `Option<f32>` is used instead
824  - the associated public `MinMax` and `OrElse` traits have also been removed; these should never have been public
825- 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).
826
827### Fixes
828
829- Miscellaneous correctness fixes which align our implementation with Chrome:
830
831  - Nodes can only ever have one parent
832  - Fixed rounding of fractional values to follow latest Chrome - values are now rounded the same regardless of their position
833  - Fixed computing free space when using both `flex-grow` and a minimum size
834  - 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)
835  - `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
836- Taffy can now be vendored using `cargo-vendor` (README.md is now included in package).
837
838## 0.1.0
839
840### 0.1.0 Changed
841
842- the `order` field of `Layout` is now public, and describes the relative z-ordering of nodes
843- renamed crate from `stretch2` to `taffy`
844- updated to the latest version of all dependencies to reduce upstream pain caused by duplicate dependencies
845- renamed `stretch::node::Stretch` -> `taffy::node::Taffy`
846
847### 0.1.0 Fixed
848
849- fixed feature strategy for `alloc` and `std`: these can now be compiled together, with `std`'s types taking priority
850
851### 0.1.0 Removed
852
853- removed Javascript / Kotlin / Swift bindings
854  - the maintainer team lacks expertise to keep these working
855  - more serious refactors are planned, and this will be challenging to keep working through that process
856  - if you are interested in helping us maintain bindings to other languages, [get in touch](https://github.com/DioxusLabs/taffy/discussions)!
857- 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)
858- removed the `Direction` and `Overflow` structs, and the corresponding `direction` and `overflow` fields from `Style`
859  - these had no effect in the current code base and were actively misleading
860
861## stretch2 0.4.3
862
863This is the final release of `stretch`: migrate to the crate named `taffy` for future fixes and features!
864
865These notes describe the differences between this release and `stretch` 0.3.2, the abandoned crate from which this library was forked.
866
867### Changed
868
869- updated [assorted dependencies](https://github.com/vislyhq/stretch/commit/a6491117379cea52dedc9584d892594a143e8cb0)
870
871### Fixed
872
873- fixed an exponential performance blow-up with deep nesting
874- fixed percent height values, which were using parent width
875- recomputing layout no longer moves children of non-zero-positioned parent
876- fixed broken Swift bindings