1# Changelog
2
3## 0.8.1
4
5### Added
6
7- Impl `GridItemStyle` and `BlockContainerStyle` for `Style` (#832).
8
9## 0.8.0
10
11### Highlights
12
13**The big feature in this release is support for `calc()` values in the low-level API.**
14
15To use this API:
16
17- Implement the `resolve_calc_value` method when implementing the `LayoutPartialTree` trait.
18- Pass a type-erased pointer (`*const ()`) to constructors like `LengthPercentage::calc(...)`
19
20Taffy treats the pointer as an opaque value (excepting that it uses the low 3 bits as a tag) which it will
21pass to `LayoutPartialTree::resolve_calc_value` along with a percentage resolution basis when it needs to
22resolve the value.
23
24### Changed
25
26- The representation of many "size" types is now a tagged pointer than an enum. This is to enable `calc()`.
27  The effected types are `LengthPercentage`, `LengthPercentageAuto`, `Dimension`, `MinTrackSizingFunction`, and
28`MaxTrackSizingFunction` types.
29
30### Added
31
32- Special-case "compressible replaced elements" in grid sizing algorithm (#807)
33  This allows for more correct sizing of "replaced" elements such as images that are children
34  of flexbox or grid containers.
35
36### Fixed
37
38- Grid: Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
39- Grid: Fix removed wrong addition, causing items to be misplaced. (#817)
40- Grid: Fix grid placement for items with fixed primary axis (#818)
41- Leaf layout: don't set available space to max-size (#819)
42
43## 0.7.7
44
45### Fixed
46
47- Add `#[inline]` annotation to some methods on `TaffyTree` (#802)
48- Add `TaffyTree::remove_children_range` method (#802)
49
50## 0.7.6
51
52### Fixed
53
54- Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
55
56## 0.7.5
57
58### Fixed
59
60- Grid: only stretch auto tracks if content-alignment is stretch (#783)
61
62## 0.7.4
63
64### Fixed
65
66- Fix detailed grid info for empty grid (#782)
67
68## 0.7.3
69
70### Fixed
71
72- Make `TaffyTree::detailed_layout_info` take `&self` rather than `&mut self` (#779)
73
74## 0.7.2
75
76### Added
77
78- The ability to access computed track sizes and item positions of a CSS Grid layout (#772).
79  This information can be accessed using the `LayoutGridContainer::set_detailed_grid_info` method
80  in the low-level API or the `TaffyTree::detailed_layout_info` method in the high-level API.
81
82## 0.7.1
83
84### Fixed
85
86- Improve interaction of abspos children of block containers with margin collapsing (#760)
87
88### Added
89
90- Add `TaffyTree::unrounded_layout` getter (#765)
91
92### Removed
93
94- The `num-traits` dependency was removed (#761) (#762)
95
96## 0.7.0
97
98### Changed
99
100- BREAKING: The `cache_mut` method on the `LayoutPartialTree` trait has been replaced with a separate `CacheTree` trait. This allows
101  Taffy to be more easily used without caching or with a custom cache implementation.
102- BREAKING: the `TaffyTree::set_children` method now removes the children from their previous parent (if they have one).
103
104### Added
105
106- Helper methods to retrieve content-box sizes were added to `Layout`
107
108## 0.6.3
109
110### Fixes
111
112- Block: ignore margin collapsing when computing static position of abspos items (#747)
113
114## 0.6.2
115
116### Fixes
117
118- Fix: clamp indefinite available space by min- and max- size as appropriate (#742)
119
120## 0.6.1
121
122### Fixes
123
124- Fix calculation of `auto-fill`/`auto-fit` repetition count when container has a definite percentage size (#722)
125- Fix min-size style not affecting intrinsic sizes (#723)
126- Fix documentation of dirty and mark_dirty functions (#724)
127- Fix intrinsic size of scroll containers that have a small explicit flex-basis (#728)
128
129## 0.6.0
130
131### Highlights
132
133- The `Style` struct has been "traitified". This supports Taffy's integration in Servo and generally makes Taffy more flexible. The
134  `Style` struct still exists and implements the new traits so existing uses of Taffy will continue to work as before.
135- The `box-sizing` style is supported
136- Computed margins are output in `Layout`
137
138### Fixes
139
140- Fix `print_tree()` when rounding is disabled (#680)
141- Absolute Insets should be resolved against the container size minus border (#666)
142- Fix flooring hypothetical_main_size by computed min size (#689)
143- Fix flex line cross-size determination (#690)
144- Fix panics in the grid algorithm (#691)
145- Fix resolving flexible lengths (WPT css/flexbox-multiline-min-max test) (#692)
146- Fix wrapping when a max main size style is present (#694)
147- Fix case where Taffy allowed margins to collapse through an element when it shouldn't have (#695)
148
149### Added
150
151- Legacy text align (for laying out `<center>` and `<div align="..">`) is supported
152- Add `is_table` for block items (#701)
153- Impl `Debug` and `Clone` for `Cache` (#688)
154- Implement `Debug` and `PartialEq` for tree types (#697)
155
156## 0.5.2
157
158- Fix block stretch sizing (don't always apply stretch sizing to block containers) (#674)
159- Fix computation of intrinsic main size when it depends on a child's known cross size (#673)
160- Fix panic when GridLine 0 is specified (#671)
161- Docs: Document feature flags and scrape examples (#672)
162- Docs: Update cosmic-text example to cosmic-text 0.12 (#670)
163
164## 0.5.1
165
166- Fix: Clamp block item stretch widths by their min and max width (#664)
167- Fix: Auto margin computation in block layout (#663)
168
169## 0.5.0
170
171The changes in 0.5 are relatively small but the new measure function parameter is a breaking change so it requires a minor version bump.
172
173- Added: A `style: &Style` parameter has been added to measure functions.
174- Added: The `MaybeMath`, `MaybeResolve`, and `ResolveOrZero` traits have been made public.
175- Fix: use SizingMode::Inherent when sizing absolute children of flexbox nodes.
176
177## 0.4.4
178
179### Fixes
180
181- Content alignment (`align-content`/`justify-content`) behaviour was updated to match the latest spec (and Chrome 123+) (#635)
182- Ensure that root Flexbox nodes are floored by their padding-border (#651, #655)
183- Use grid area size not available space when applying aspect ratio to grid containers (#656)
184
185## 0.4.3
186
187### Fixes
188
189- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
190  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
191  but they should be able to fix on their side by clarifying the type passed in
192
193## 0.4.2
194
195- Fixed: single-line flex-container should clamp the line's cross-size (#638)
196- Reduced binary footprint of Taffy from around 300kb to around 150kb (#636)
197
198## 0.4.1
199
200- Fixed: CSS Grid track sizing not respecting growth limits in some circumstances (#624)
201
202## 0.4.0
203
204### Highlights
205
206- Support for CSS Block layout (`display: block`)
207- Support for the `overflow` property (+ `scrollbar_width` for `overflow: scroll`)
208- Improved measure function API
209- Completely refactored low-level API
210- Simplified module hierarchy (+ most types/functions are now exported from the crate root)
211- Expanded set of examples which better document integration with other layout systems (e.g. text layout)
212- Computed values for `padding` and `border` are now output into the `Layout` struct
213
214### Block layout
215
216Support 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.
217
218### Overflow property
219
220Support 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.
221
222- Overflow is settable indpendently in each axis.
223- `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.
224- `Hidden` and `Scroll` affect layout by changing the automatic minimum size of Flexbox and Grid children
225- `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`.
226
227### Measure function changes
228
229The "measure function" API for integrating Taffy with other measurement systems (such as text layout) has been changed to be more flexible
230and to interact better with borrow checking (you can now borrow external data in your measure function!).
231
232- There are no longer per-node measure functions.
233- There is now a single "global" measure function, and a per-node "context" of a user-defined type
234- The `Taffy` tree is now a generic `TaffyTree<T>` where `T` is the "context" type.
235- The measure function is now called for all leaf nodes (nodes without children). If you wish to maintain compatibility with the previous
236  behaviour then your measure function should return `Size::ZERO` for leaf nodes whose context is `None`.
237
238If you are not using measure functions, then the only change you will need to make is from:
239
240```rust
241let mut tree = Taffy::new();
242```
243
244to
245
246```rust
247let mut tree : TaffyTree<()> = TaffyTree::new();
248```
249
250And generally update any uses of `Taffy` in your codebase to `TaffyTree<()>`.
251
252If you are using measure functions then you will need to make some bigger (but straightforward) changes. The following Taffy 0.3 code:
253
254```rust
255let mut tree = Taffy::new();
256let leaf = tree.new_leaf_with_measure(
257  Style::DEFAULT,
258  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>| Size { width: 100.0, height: 200.0 }
259);
260tree.compute_layout(leaf, Size::MAX_CONTENT);
261```
262
263Should become something like the following with Taffy 0.4:
264
265```rust
266let mut tree : TaffyTree<Size> = TaffyTree::new();
267let leaf = tree.new_leaf_with_context(Style::DEFAULT, Size { width: 100.0, height: 200.0 });
268tree.compute_layout_with_measure(
269  leaf,
270  Size::MAX_CONTENT,
271  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, node_id: NodeId, node_context: Option<Size>| {
272    node_context.unwrap_or(Size::ZERO)
273  }
274);
275```
276
277Note that:
278
279- 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).
280- If you don't need a context then you can use `()` for the context type
281- As the single "global" measure function passed to `compute_layout_with_measure` only needs to exist for the duration of a single layout run,
282  it can (mutably) borrow data from it's environment
283
284### Low-level API (`LayoutTree` trait) refactor
285
286The low-level API has been completely reworked:
287
288- The `LayoutTree` trait has been split into 5 smaller traits which live in the `taffy::tree:traits` module (along with their associated documentation)
289- The following methods have been removed from split `LayoutTree` traits entirely: `parent`, `is_childless`, `measure_node`, `needs_measure`, and `mark_dirty`.
290- `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`.
291- Support for running each layout algorithm individually on a single node via the following top-level functions:
292  - `compute_flexbox_layout`
293  - `compute_grid_layout`
294  - `compute_block_layout`
295  - `compute_leaf_layout`
296  - `compute_root_layout`
297  - `compute_hidden_layout`
298
299It 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
300improved 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).
301
302### Module hierarchy changes
303
304The 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`.
305
306Specific changes:
307
308- The `math` module has been made private
309- The `axis` module has been merged into the `geometry` module
310- The debug module is no longer public. The `print_tree` function is now accessible under `util`.
311- All types from the `node`, `data`, `layout`, `error` and `cache` modules have been moved to the  the `tree` module.
312- The `layout_flexbox()` function has been removed from the prelude. Use `taffy::compute_flexbox_layout` instead.
313
314### Many APIs have been renamed to replace `points` or `Points` with `length` or `Length`
315
316This new name better describes one-dimensional measure of space in some unspecified unit
317which is often unrelated to the PostScript point or the CSS `pt` unit.
318
319This also removes a misleading similarity with the 2D `Point`,
320whose components can have any unit and are not even necessarily absolute lengths.
321
322Example usage change:
323
324```diff
325 use taffy::prelude::*;
326
327 // …
328
329 let header_node = taffy
330     .new_leaf(
331         Style {
332-            size: Size { width: points(800.0), height: points(100.0) },
333+            size: Size { width: length(800.0), height: length(100.0) },
334             ..Default::default()
335         },
336     ).unwrap();
337```
338
339### Other Changes
340
341- The `Taffy` type was renamed to `TaffyTree` and made generic of a context parameter
342- The Flexbox algorithm has now been moved behind the `flexbox` feature. The `flexbox` feature is enabled by default.
343- The `justify_self` property has been moved behind the `grid` feature.
344- Fixed misspelling: `RunMode::PeformLayout` renamed into `RunMode::PerformLayout` (added missing `r`).
345- `serde` dependency has been made compatible with `no_std` environments
346- `slotmap` dependency has been made compatible with `no_std` environments
347- 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.
348- Added `total_node_count()` method to the `TaffyTree` which returns the total number of nodes in the tree.
349- Added `get_disjoint_node_context_mut()` method to the `TaffyTree`. This can be used to safely get multiple mutable borrows at the same time.
350
351## 0.3.19
352
353### Fixes
354
355- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
356  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
357  but they should be able to fix on their side by clarifying the type passed in
358
359## 0.3.18
360
361### Fixes
362
363- Fix computation of Flexbox automatic minimum size when grid or flexbox child has an explicit width/height style set (#576)
364
365## 0.3.17
366
367### Added
368
369- Added `total_node_count` method to the `Taffy` struct. Returns the total number of nodes in the tree.
370
371## 0.3.16
372
373### Fixes
374
375- Improve performance of flexbox columns
376
377## 0.3.15
378
379### Fixes
380
381- Fix justify-content and align-content when free space is negative (content overflows container) (#549) (#551)
382
383## 0.3.14
384
385### Fixes
386
387- 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)
388
389## 0.3.13
390
391### Fixes
392
393- Fix rounding accumulation bug (#521) (Fixes #501 and bevyengine/bevy#8911)
394- Flexbox: pass correct cross-axis available space when computing an item's intrinsic main size (#522)(Fixes bevyengine/bevy#9350)
395- Flexbox: Subtract child margin not parent margin when computing stretch-alignment known size
396- Grid: Make CSS Grid algorithm correctly apply max width/height and available space when it is the root node (#491)
397- Grid: Fix CSS Grid "auto track" / placement bugs #481
398  - Fix divide by zero when using grid_auto_rows/grid_auto_columns with zero negative implicit tracks
399  - Fix over counting of tracks (leading to incorrect container heights) when auto-placing in grids that contain negative implicit tracks.
400  - Fix axis conflation in auto-placement code when grid_auto_flow is column
401  - Fix assignment of auto track sizes when initializing negative implicit tracks
402- Leaf: Apply margins to leaf nodes when computing available space for measure functions
403- Leaf: Reserve space for padding/borders in nodes with measure functions (#497)
404  
405  **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.
406
407### Dependencies
408
409- Upgrade `grid` to `0.10`. This eliminates the transitive dependency on `no-std-compat`.
410
411## 0.3.12
412
413### Fixes
414
415- Fix caching issue when toggling `display:none` on and off
416
417## 0.3.11
418
419### Fixes
420
421- Fix exponential blowup when laying out trees containing nodes with min and max sizes.
422
423## 0.3.10
424
425### Fixes
426
427- Fix sizing of children when the available_space < min_size (#407)
428
429## 0.3.9
430
431### Fixes
432
433- 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)
434
435## 0.3.8
436
437### Fixes
438
439- Fix incorrect min-content size for `flex-wrap: wrap` nodes (bevyengine/bevy#8082)
440
441## 0.3.7
442
443### Fixes
444
445- Fix: Make `padding` and `border` floor node sizes (#372)
446- Fix: Prevent percentages contributing to min-content sizes (#388) (also fixes bevyengine/bevy#8017)
447
448## 0.3.6
449
450### Fixes
451
452- Fix: Ignore `align_content` when `flex_wrap` is set to `nowrap` (#383)
453
454## 0.3.5
455
456### Fixes
457
458- Fix `display: none` when it is set on a flexbox child (#380)
459- Fix `display: none` when it is set on a grid child (#381)
460
461## 0.3.4
462
463### Fixes
464
465- Fix `display: none` when it is set for the only node in the hierarchy (#377)
466
467## 0.3.3
468
469### Added
470
471- 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.
472
473### Fixes
474
475- Fixed rounding algorithm such that it never leaves gaps between adjacent nodes (#369)
476- Fixed compiling with the `grid` feature disabled (#370)
477- Fixed compiling with the `std` feature disabled
478
479## 0.3.2
480
481### Fixes
482
483- Allow partial nested values to be deserialized into a `Style` using the `serde` feature.
484
485## 0.3.1
486
487### Fixes
488
489- The `serde` feature now works when the `grid` feature is enabled
490
491## 0.3.0
492
493### Highlights
494
495- [CSS Grid algorithm support](#new-feature-css-grid)
496- [Style helper functions](#new-feature-style-helpers)
497
498See below for details of breaking changes.
499
500### New Feature: CSS Grid
501
502We 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`.
503
504#### Learning Resources
505
506Taffy 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:
507
508- [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.
509- [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.
510
511#### Supported Features & Properties
512
513In addition to the usual sizing/spacing properties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
514
515| Property                  | Explanation                                                                                    |
516| ---                       | ---                                                                                            |
517| [`grid-template-columns`] | The track sizing functions of the grid's explicit columns                                      |
518| [`grid-template-rows`]    | The track sizing functions of the grid's explicit rows                                         |
519| [`grid-auto-rows`]        | Track sizing functions for the grid's implicitly generated rows                                |
520| [`grid-auto-columns`]     | Track sizing functions for the grid's implicitly generated columns                             |
521| [`grid-auto-flow`]        | Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely.         |
522| [`gap`]                   | The size of the vertical and horizontal gaps between grid rows/columns                         |
523| [`align-content`]         | Align grid tracks within the container in the inline (horizontal) axis                         |
524| [`justify-content`]       | Align grid tracks within the container in the block (vertical) axis                            |
525| [`align-items`]           | Align the child items within their grid areas in the inline (horizontal) axis                  |
526| [`justify-items`]         | Align the child items within their grid areas in the block (vertical) axis                     |
527
528And the following Grid style properties are supported on Grid Items (children):
529
530| Property                  | Explanation                                                                                    |
531| ---                       | ---                                                                                            |
532| [`grid-row`]              | The (row) grid line the item starts at (or a span)                                             |
533| [`grid-column`]           | The (column) grid line the item end at (or a span)                                             |
534| [`align-self`]            | Align the item within it's grid area in the inline (horizontal) axis. Overrides `align-items`. |
535| [`justify-self`]          | Align the item within it's grid area in the block (vertical) axis. Overrides `justify-items`.  |
536
537[`grid-template-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-columns
538[`grid-template-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-rows
539[`grid-auto-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-rows
540[`grid-auto-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-columns
541[`grid-auto-flow`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-flow
542[`gap`]: https://developer.mozilla.org/en-US/docs/Web/CSS/gap
543[`align-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align_content
544[`justify-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify_content
545[`align-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-items
546[`justify-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-items
547[`grid-row`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
548[`grid-column`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-column
549[`align-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-self
550[`justify-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-self
551
552The following properties and features are not currently supported:
553
554- Subgrids
555- Masonry grid layout
556- Named grid lines
557- Named areas: `grid-template-areas` and `grid-area`
558- `grid-template` or `grid` shorthand
559
560#### Example
561
562See [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:
563
564```bash
565cargo run --example grid_holy_grail --features grid
566```
567
568### New Feature: Style Helpers
569
570Ten 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.
571
572For example, instead of:
573
574```rust
575let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };
576```
577
578you can now write
579
580```rust
581let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };
582```
583
584And 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
585
586```rust
587let size : Size<Dimension> = points(100.0);
588```
589
590Available style helpers:
591
592<table>
593  <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead>
594  <tbody>
595    <tr>
596      <td rowspan="3"><code>LengthPercentage</code></td>
597      <td><code>zero()</code></td>
598      <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td>
599    </tr>
600    <tr>
601      <td><code>points(val:&nbsp;f32)</code></td>
602      <td>Generates a <code>Points</code> variant with the specified value</td>
603    </tr>
604    <tr>
605      <td><code>percent(val:&nbsp;f32)</code></td>
606      <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td>
607    </tr>
608    <tr>
609      <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td>
610      <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td>
611    </tr>
612    <tr>
613      <td><code>auto()</code></td>
614      <td>Generates an <code>Auto</code> variant</td>
615    </tr>
616    <tr>
617      <td rowspan="3"><code>MinTrackSizingFunction</code></td>
618      <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td>
619    </tr>
620    <tr>
621      <td><code>min_content()</code></td>
622      <td>Generates an <code>MinContent</code> variant</td>
623    </tr>
624      <tr>
625      <td><code>max_content()</code></td>
626      <td>Generates an <code>MinContent</code> variant</td>
627    </tr>
628    <tr>
629      <td rowspan="3"><code>MaxTrackSizingFunction</code></td>
630      <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td>
631    </tr>
632    <tr>
633      <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td>
634      <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>
635    </tr>
636      <tr>
637      <td><code>fr(fraction:&nbsp;f32)</code></td>
638      <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td>
639    </tr>
640    <tr>
641      <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td>
642      <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td>
643    </tr>
644    <tr>
645      <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td>
646      <td>Equivalent to CSS <code>minmax()</code> function.</td>
647    </tr>
648    <tr>
649      <td><code>flex(fraction:&nbsp;f32)</code></td>
650      <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td>
651    </tr>
652    <tr>
653      <td rowspan="2"><code>TrackSizingFunction</code></td>
654      <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td>
655    </tr>
656    <tr>
657      <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td>
658      <td>Equivalent to css <code>repeat()</code> function.</td>
659    </tr>
660    <tr>
661      <td><code>Vec&lt;TrackSizingFunction&gt;</code></td>
662      <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td>
663      <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td>
664    </tr>
665    <tr>
666      <td rowspan="3"><code>AvailableSpace</code></td>
667      <td><code>auto()</code></td>
668      <td>Generates an <code>Auto</code> variant</td>
669    </tr>
670    <tr>
671      <td><code>min_content()</code></td>
672      <td>Generates an <code>MinContent</code> variant</td>
673    </tr>
674      <tr>
675      <td><code>max_content()</code></td>
676      <td>Generates an <code>MinContent</code> variant</td>
677    </tr>
678    <tr>
679      <td><code>Size&lt;T&gt;</code></td>
680      <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>
681    </tr>
682    <tr>
683      <td><code>Rect&lt;T&gt;</code></td>
684      <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>
685    </tr>
686  </tbody>
687</table>
688
689### Breaking API changes
690
691#### Changes to alignment style types
692
693- `AlignContent` and `JustifyContent` has been merged.
694  - `JustifyContent` is now an alias of `AlignContent` and contains the `Stretch` variant.
695  - This variant will be *ignored* (falling back to `Start`) when applied Flexbox containers. It is valid value for Grid containers.
696- `AlignItems` and `AlignSelf` have been merged.
697  - The `Auto` variant of `AlignSelf` has been removed. You should now use `Option::None` if you wish to specify `AlignSelf::Auto`.
698  - `AlignSelf` is now an alias of `AlignItems`.
699  - `JustifyItems` and `JustifySelf` aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.
700- `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.
701
702#### Strict style types
703
704- New types `LengthPercentage` and `LengthPercentageAuto` have been added.
705  - `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.
706  - `LengthPercentageAuto` is currently identical to `Dimension` but will allow us to expand dimension in future to support values like `MinContent`, `MaxContent` and `FitContent`.
707- 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).
708
709#### Position properties renamed
710
711- 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)
712- 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`.
713
714#### Changes to `LayoutTree`
715
716- Added generic associated type to `LayoutTree` for a `ChildIter`, an iterator on the children of a given node.
717- 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.
718- 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.
719- Added `is_childless` method to `LayoutTree` for querying whether a node has no children.
720
721#### `AvailableSpace` has been moved
722
723The `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.
724
725### Fixes
726
727- Flexbox nodes sized under a min-content constraint now size correctly (#291)
728- Aspect ratio is now applied correctly in many circumstances
729- Absolutely positioned items now apply margins correctly
730- Min/max size are now applied correctly
731- Inset applied incorrectly to relatively positioned flexbox children when both `top` and `bottom` or `left` and `right` were specified (#348)
732- 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)
733
734### Removed
735
736- 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.
737- 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.
738- 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.
739
740## 0.2.2
741
742### Fixes
743
744- Border or padding on the horizontal axis could, in some cases, increase the height of nodes.
745
746## 0.2.1
747
748### Fixes
749
750- 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`.
751- `taffy::compute_layout` has been made public allowing Taffy to be used with custom storage (#263)
752
753## 0.2.0
754
755### New features
756
757#### Flexbox "gap" and `AlignContent::SpaceEvenly`
758
759The [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.
760
761Additionally 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)
762
763#### Debug module and cargo feature
764
765Two debugging features have been added:
766
767- `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.
768- A cargo feature `debug`. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).
769
770### Performance improvements
771
772A number of performance improvements have landed since taffy 0.1:
773
774- 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%.
775- 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!
776
777#### Benchmarks vs. Taffy 0.1
778
779| Benchmark                                 | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
780| ---                                       | ---       | ---       | ---                   |
781| wide/1_000 nodes (2-level hierarchy)      | 699.18 µs | 445.01 µs | -36.279%              |
782| wide/10_000 nodes (2-level hierarchy)     | 8.8244 ms | 7.1313 ms | -16.352%              |
783| wide/100_000 nodes (2-level hierarchy)    | 204.48 ms | 242.93 ms | +18.803%              |
784| deep/4000 nodes (12-level hierarchy))     | 5.2320 s  | 2.7363 ms | -99.947%              |
785| deep/10_000 nodes (14-level hierarchy)    | 75.207 s  | 6.9415 ms | -99.991%              |
786| deep/100_000 nodes (17-level hierarchy)   | -         | 102.72 ms | -                     |
787| deep/1_000_000 nodes (20-level hierarchy) | -         | 799.35 ms | -                     |
788
789(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
790
791As 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.
792
793However, 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.
794
795#### Benchmarks vs. [Yoga](https://github.com/facebook/yoga)
796
797Yoga 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.
798
799| Benchmark | Yoga | Taffy 0.2 |
800| --- | --- | --- |
801| yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
802| yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
803| yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
804| yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
805| yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 ms |
806
807(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
808
809While 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!
810
811### Breaking API changes
812
813#### Node creation changes
814
815- `taffy::Node` is now unique only to the Taffy instance from which it was created.
816- Renamed `Taffy.new_node(..)` -> `Taffy.new_with_children(..)`
817- Renamed `Taffy.new_leaf()` -> `Taffy.new_leaf_with_measure()`
818- Added `taffy::node::Taffy.new_leaf()` which allows the creation of new leaf-nodes without having to supply a measure function
819
820#### Error handling/representation improvements
821
822- Renamed `taffy::Error` -> `taffy::error::TaffyError`
823- Replaced `taffy::error::InvalidChild` with a new `InvalidChild` variant of `taffy::error::TaffyError`
824- Replaced `taffy::error::InvalidNode` with a new `InvalidNode` variant of `taffy::error::TaffyError`
825- The following method new return `Err(TaffyError::ChildIndexOutOfBounds)` instead of panicking:
826  - `taffy::Taffy::remove_child_at_index`
827  - `taffy::Taffy::replace_child_at_index`
828  - `taffy::Taffy::child_at_index`
829- `Taffy::remove` now returns a `Result<usize, Error>`, to indicate if the operation was successful (and if it was, which ID was invalidated).
830
831#### Some uses of `Option<f32>` replaced with a new `AvailableSpace` enum
832
833A new enum `Taffy::layout::AvailableSpace` has been added.
834
835The definition looks like this:
836
837```rust
838/// The amount of space available to a node in a given axis
839pub enum AvailableSpace {
840    /// The amount of space available is the specified number of pixels
841    Definite(f32),
842    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
843    MinContent,
844    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
845    MaxContent,
846}
847```
848
849This 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`).
850
851And 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..
852
853#### Builder methods are now `const` where possible
854
855- Several convenience constants have been defined: notably `Style::DEFAULT`
856- `Size<f32>.zero()` is now `Size::<f32>::ZERO`
857- `Point<f32>.zero()` is now  `Point::<f32>::ZERO`
858- `Size::undefined()` is now `Size::NONE`
859
860#### Removals
861
862- 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%).
863- Removed `taffy::number::Number`. Use `Option<f32>` is used instead
864  - the associated public `MinMax` and `OrElse` traits have also been removed; these should never have been public
865- 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).
866
867### Fixes
868
869- Miscellaneous correctness fixes which align our implementation with Chrome:
870
871  - Nodes can only ever have one parent
872  - Fixed rounding of fractional values to follow latest Chrome - values are now rounded the same regardless of their position
873  - Fixed computing free space when using both `flex-grow` and a minimum size
874  - 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)
875  - `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
876- Taffy can now be vendored using `cargo-vendor` (README.md is now included in package).
877
878## 0.1.0
879
880### 0.1.0 Changed
881
882- the `order` field of `Layout` is now public, and describes the relative z-ordering of nodes
883- renamed crate from `stretch2` to `taffy`
884- updated to the latest version of all dependencies to reduce upstream pain caused by duplicate dependencies
885- renamed `stretch::node::Stretch` -> `taffy::node::Taffy`
886
887### 0.1.0 Fixed
888
889- fixed feature strategy for `alloc` and `std`: these can now be compiled together, with `std`'s types taking priority
890
891### 0.1.0 Removed
892
893- removed Javascript / Kotlin / Swift bindings
894  - the maintainer team lacks expertise to keep these working
895  - more serious refactors are planned, and this will be challenging to keep working through that process
896  - if you are interested in helping us maintain bindings to other languages, [get in touch](https://github.com/DioxusLabs/taffy/discussions)!
897- 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)
898- removed the `Direction` and `Overflow` structs, and the corresponding `direction` and `overflow` fields from `Style`
899  - these had no effect in the current code base and were actively misleading
900
901## stretch2 0.4.3
902
903This is the final release of `stretch`: migrate to the crate named `taffy` for future fixes and features!
904
905These notes describe the differences between this release and `stretch` 0.3.2, the abandoned crate from which this library was forked.
906
907### Changed
908
909- updated [assorted dependencies](https://github.com/vislyhq/stretch/commit/a6491117379cea52dedc9584d892594a143e8cb0)
910
911### Fixed
912
913- fixed an exponential performance blow-up with deep nesting
914- fixed percent height values, which were using parent width
915- recomputing layout no longer moves children of non-zero-positioned parent
916- fixed broken Swift bindings