1# Changelog
2
3## 0.9.2
4
5### Fixed
6
7- Fix wrong size propogation for absolute elements (#878)
8- Fix bounds check in CellOccupancyMatrix::last_of_type (#890)
9- Use doc_cfg instead of doc_auto_cfg (#868)
10
11### Changed
12
13- Upgraded grid dependency from 0.18 to 1.0 (#864)
14
15## 0.9.1
16
17### Fixed
18
19- Flexbox: don't apply cross-axis stretch alignment to children with auto margins (#861)
20
21## 0.9.0
22
23### Support for named grid lines and grid areas
24
25Taffy now supports named grid lines and areas.
26
27As these rely on arbitrary user-provided strings, Taffy's `Style` struct is now generic
28over a string-like type (via the `CheapCloneStr` trait). Additionally as the `grid` feature is optional,
29it has a `PhantomData` field of that type to make type inference work.
30
31### Changed
32
33- `PrintTree` and `RoundTree`: use `Layout` instead of `&Layout` (#849).
34- Renamed `TrackSizingFunction` to `GridTemplateComponent`
35- Renamed `NonRepeatedTrackSizingFunction` to `TrackSizingFunction`
36- The `Repeat` variant of `GridTemplateComponent` now contains a new `GridTemplateRepetition` struct, which allows
37  line names to be specifed in addition to tracks.
38- The way that grid styles are exposed in the low-level API is now a lot more generic with many associated types.
39
40### Added
41
42- `GridTemplateArea` struct and `Style::grid_template_areas` field
43- `Style::grid_template_column_names` and `Style::grid_template_row_names` fields. If non-empty, these
44  should have length of exactly one greater than the corresponding `grid_template_column`/`grid_template_rows` style.
45
46## 0.8.3
47
48### Fixed
49
50- Fix `serde` feature on 32bit targets (#845)
51
52## 0.8.2
53
54### Fixed
55
56- Fix: Calculate correct new grid size when expanding cell_occupancy_matrix in the negative direction (#843)
57
58## 0.8.1
59
60### Added
61
62- Impl `GridItemStyle` and `BlockContainerStyle` for `Style` (#832).
63
64## 0.8.0
65
66### Highlights
67
68**The big feature in this release is support for `calc()` values in the low-level API.**
69
70To use this API:
71
72- Implement the `resolve_calc_value` method when implementing the `LayoutPartialTree` trait.
73- Pass a type-erased pointer (`*const ()`) to constructors like `LengthPercentage::calc(...)`
74
75Taffy treats the pointer as an opaque value (excepting that it uses the low 3 bits as a tag) which it will
76pass to `LayoutPartialTree::resolve_calc_value` along with a percentage resolution basis when it needs to
77resolve the value.
78
79### Changed
80
81- The representation of many "size" types is now a tagged pointer than an enum. This is to enable `calc()`.
82  The effected types are `LengthPercentage`, `LengthPercentageAuto`, `Dimension`, `MinTrackSizingFunction`, and
83`MaxTrackSizingFunction` types.
84
85### Added
86
87- Special-case "compressible replaced elements" in grid sizing algorithm (#807)
88  This allows for more correct sizing of "replaced" elements such as images that are children
89  of flexbox or grid containers.
90
91### Fixed
92
93- Grid: Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
94- Grid: Fix removed wrong addition, causing items to be misplaced. (#817)
95- Grid: Fix grid placement for items with fixed primary axis (#818)
96- Leaf layout: don't set available space to max-size (#819)
97
98## 0.7.7
99
100### Fixed
101
102- Add `#[inline]` annotation to some methods on `TaffyTree` (#802)
103- Add `TaffyTree::remove_children_range` method (#802)
104
105## 0.7.6
106
107### Fixed
108
109- Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
110
111## 0.7.5
112
113### Fixed
114
115- Grid: only stretch auto tracks if content-alignment is stretch (#783)
116
117## 0.7.4
118
119### Fixed
120
121- Fix detailed grid info for empty grid (#782)
122
123## 0.7.3
124
125### Fixed
126
127- Make `TaffyTree::detailed_layout_info` take `&self` rather than `&mut self` (#779)
128
129## 0.7.2
130
131### Added
132
133- The ability to access computed track sizes and item positions of a CSS Grid layout (#772).
134  This information can be accessed using the `LayoutGridContainer::set_detailed_grid_info` method
135  in the low-level API or the `TaffyTree::detailed_layout_info` method in the high-level API.
136
137## 0.7.1
138
139### Fixed
140
141- Improve interaction of abspos children of block containers with margin collapsing (#760)
142
143### Added
144
145- Add `TaffyTree::unrounded_layout` getter (#765)
146
147### Removed
148
149- The `num-traits` dependency was removed (#761) (#762)
150
151## 0.7.0
152
153### Changed
154
155- BREAKING: The `cache_mut` method on the `LayoutPartialTree` trait has been replaced with a separate `CacheTree` trait. This allows
156  Taffy to be more easily used without caching or with a custom cache implementation.
157- BREAKING: the `TaffyTree::set_children` method now removes the children from their previous parent (if they have one).
158
159### Added
160
161- Helper methods to retrieve content-box sizes were added to `Layout`
162
163## 0.6.3
164
165### Fixes
166
167- Block: ignore margin collapsing when computing static position of abspos items (#747)
168
169## 0.6.2
170
171### Fixes
172
173- Fix: clamp indefinite available space by min- and max- size as appropriate (#742)
174
175## 0.6.1
176
177### Fixes
178
179- Fix calculation of `auto-fill`/`auto-fit` repetition count when container has a definite percentage size (#722)
180- Fix min-size style not affecting intrinsic sizes (#723)
181- Fix documentation of dirty and mark_dirty functions (#724)
182- Fix intrinsic size of scroll containers that have a small explicit flex-basis (#728)
183
184## 0.6.0
185
186### Highlights
187
188- The `Style` struct has been "traitified". This supports Taffy's integration in Servo and generally makes Taffy more flexible. The
189  `Style` struct still exists and implements the new traits so existing uses of Taffy will continue to work as before.
190- The `box-sizing` style is supported
191- Computed margins are output in `Layout`
192
193### Fixes
194
195- Fix `print_tree()` when rounding is disabled (#680)
196- Absolute Insets should be resolved against the container size minus border (#666)
197- Fix flooring hypothetical_main_size by computed min size (#689)
198- Fix flex line cross-size determination (#690)
199- Fix panics in the grid algorithm (#691)
200- Fix resolving flexible lengths (WPT css/flexbox-multiline-min-max test) (#692)
201- Fix wrapping when a max main size style is present (#694)
202- Fix case where Taffy allowed margins to collapse through an element when it shouldn't have (#695)
203
204### Added
205
206- Legacy text align (for laying out `<center>` and `<div align="..">`) is supported
207- Add `is_table` for block items (#701)
208- Impl `Debug` and `Clone` for `Cache` (#688)
209- Implement `Debug` and `PartialEq` for tree types (#697)
210
211## 0.5.2
212
213- Fix block stretch sizing (don't always apply stretch sizing to block containers) (#674)
214- Fix computation of intrinsic main size when it depends on a child's known cross size (#673)
215- Fix panic when GridLine 0 is specified (#671)
216- Docs: Document feature flags and scrape examples (#672)
217- Docs: Update cosmic-text example to cosmic-text 0.12 (#670)
218
219## 0.5.1
220
221- Fix: Clamp block item stretch widths by their min and max width (#664)
222- Fix: Auto margin computation in block layout (#663)
223
224## 0.5.0
225
226The changes in 0.5 are relatively small but the new measure function parameter is a breaking change so it requires a minor version bump.
227
228- Added: A `style: &Style` parameter has been added to measure functions.
229- Added: The `MaybeMath`, `MaybeResolve`, and `ResolveOrZero` traits have been made public.
230- Fix: use SizingMode::Inherent when sizing absolute children of flexbox nodes.
231
232## 0.4.4
233
234### Fixes
235
236- Content alignment (`align-content`/`justify-content`) behaviour was updated to match the latest spec (and Chrome 123+) (#635)
237- Ensure that root Flexbox nodes are floored by their padding-border (#651, #655)
238- Use grid area size not available space when applying aspect ratio to grid containers (#656)
239
240## 0.4.3
241
242### Fixes
243
244- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
245  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
246  but they should be able to fix on their side by clarifying the type passed in
247
248## 0.4.2
249
250- Fixed: single-line flex-container should clamp the line's cross-size (#638)
251- Reduced binary footprint of Taffy from around 300kb to around 150kb (#636)
252
253## 0.4.1
254
255- Fixed: CSS Grid track sizing not respecting growth limits in some circumstances (#624)
256
257## 0.4.0
258
259### Highlights
260
261- Support for CSS Block layout (`display: block`)
262- Support for the `overflow` property (+ `scrollbar_width` for `overflow: scroll`)
263- Improved measure function API
264- Completely refactored low-level API
265- Simplified module hierarchy (+ most types/functions are now exported from the crate root)
266- Expanded set of examples which better document integration with other layout systems (e.g. text layout)
267- Computed values for `padding` and `border` are now output into the `Layout` struct
268
269### Block layout
270
271Support 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.
272
273### Overflow property
274
275Support 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.
276
277- Overflow is settable indpendently in each axis.
278- `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.
279- `Hidden` and `Scroll` affect layout by changing the automatic minimum size of Flexbox and Grid children
280- `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`.
281
282### Measure function changes
283
284The "measure function" API for integrating Taffy with other measurement systems (such as text layout) has been changed to be more flexible
285and to interact better with borrow checking (you can now borrow external data in your measure function!).
286
287- There are no longer per-node measure functions.
288- There is now a single "global" measure function, and a per-node "context" of a user-defined type
289- The `Taffy` tree is now a generic `TaffyTree<T>` where `T` is the "context" type.
290- The measure function is now called for all leaf nodes (nodes without children). If you wish to maintain compatibility with the previous
291  behaviour then your measure function should return `Size::ZERO` for leaf nodes whose context is `None`.
292
293If you are not using measure functions, then the only change you will need to make is from:
294
295```rust
296let mut tree = Taffy::new();
297```
298
299to
300
301```rust
302let mut tree : TaffyTree<()> = TaffyTree::new();
303```
304
305And generally update any uses of `Taffy` in your codebase to `TaffyTree<()>`.
306
307If you are using measure functions then you will need to make some bigger (but straightforward) changes. The following Taffy 0.3 code:
308
309```rust
310let mut tree = Taffy::new();
311let leaf = tree.new_leaf_with_measure(
312  Style::DEFAULT,
313  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>| Size { width: 100.0, height: 200.0 }
314);
315tree.compute_layout(leaf, Size::MAX_CONTENT);
316```
317
318Should become something like the following with Taffy 0.4:
319
320```rust
321let mut tree : TaffyTree<Size> = TaffyTree::new();
322let leaf = tree.new_leaf_with_context(Style::DEFAULT, Size { width: 100.0, height: 200.0 });
323tree.compute_layout_with_measure(
324  leaf,
325  Size::MAX_CONTENT,
326  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, node_id: NodeId, node_context: Option<Size>| {
327    node_context.unwrap_or(Size::ZERO)
328  }
329);
330```
331
332Note that:
333
334- 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).
335- If you don't need a context then you can use `()` for the context type
336- As the single "global" measure function passed to `compute_layout_with_measure` only needs to exist for the duration of a single layout run,
337  it can (mutably) borrow data from it's environment
338
339### Low-level API (`LayoutTree` trait) refactor
340
341The low-level API has been completely reworked:
342
343- The `LayoutTree` trait has been split into 5 smaller traits which live in the `taffy::tree:traits` module (along with their associated documentation)
344- The following methods have been removed from split `LayoutTree` traits entirely: `parent`, `is_childless`, `measure_node`, `needs_measure`, and `mark_dirty`.
345- `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`.
346- Support for running each layout algorithm individually on a single node via the following top-level functions:
347  - `compute_flexbox_layout`
348  - `compute_grid_layout`
349  - `compute_block_layout`
350  - `compute_leaf_layout`
351  - `compute_root_layout`
352  - `compute_hidden_layout`
353
354It 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
355improved 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).
356
357### Module hierarchy changes
358
359The 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`.
360
361Specific changes:
362
363- The `math` module has been made private
364- The `axis` module has been merged into the `geometry` module
365- The debug module is no longer public. The `print_tree` function is now accessible under `util`.
366- All types from the `node`, `data`, `layout`, `error` and `cache` modules have been moved to the  the `tree` module.
367- The `layout_flexbox()` function has been removed from the prelude. Use `taffy::compute_flexbox_layout` instead.
368
369### Many APIs have been renamed to replace `points` or `Points` with `length` or `Length`
370
371This new name better describes one-dimensional measure of space in some unspecified unit
372which is often unrelated to the PostScript point or the CSS `pt` unit.
373
374This also removes a misleading similarity with the 2D `Point`,
375whose components can have any unit and are not even necessarily absolute lengths.
376
377Example usage change:
378
379```diff
380 use taffy::prelude::*;
381
382 // …
383
384 let header_node = taffy
385     .new_leaf(
386         Style {
387-            size: Size { width: points(800.0), height: points(100.0) },
388+            size: Size { width: length(800.0), height: length(100.0) },
389             ..Default::default()
390         },
391     ).unwrap();
392```
393
394### Other Changes
395
396- The `Taffy` type was renamed to `TaffyTree` and made generic of a context parameter
397- The Flexbox algorithm has now been moved behind the `flexbox` feature. The `flexbox` feature is enabled by default.
398- The `justify_self` property has been moved behind the `grid` feature.
399- Fixed misspelling: `RunMode::PeformLayout` renamed into `RunMode::PerformLayout` (added missing `r`).
400- `serde` dependency has been made compatible with `no_std` environments
401- `slotmap` dependency has been made compatible with `no_std` environments
402- 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.
403- Added `total_node_count()` method to the `TaffyTree` which returns the total number of nodes in the tree.
404- Added `get_disjoint_node_context_mut()` method to the `TaffyTree`. This can be used to safely get multiple mutable borrows at the same time.
405
406## 0.3.19
407
408### Fixes
409
410- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
411  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
412  but they should be able to fix on their side by clarifying the type passed in
413
414## 0.3.18
415
416### Fixes
417
418- Fix computation of Flexbox automatic minimum size when grid or flexbox child has an explicit width/height style set (#576)
419
420## 0.3.17
421
422### Added
423
424- Added `total_node_count` method to the `Taffy` struct. Returns the total number of nodes in the tree.
425
426## 0.3.16
427
428### Fixes
429
430- Improve performance of flexbox columns
431
432## 0.3.15
433
434### Fixes
435
436- Fix justify-content and align-content when free space is negative (content overflows container) (#549) (#551)
437
438## 0.3.14
439
440### Fixes
441
442- 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)
443
444## 0.3.13
445
446### Fixes
447
448- Fix rounding accumulation bug (#521) (Fixes #501 and bevyengine/bevy#8911)
449- Flexbox: pass correct cross-axis available space when computing an item's intrinsic main size (#522)(Fixes bevyengine/bevy#9350)
450- Flexbox: Subtract child margin not parent margin when computing stretch-alignment known size
451- Grid: Make CSS Grid algorithm correctly apply max width/height and available space when it is the root node (#491)
452- Grid: Fix CSS Grid "auto track" / placement bugs #481
453  - Fix divide by zero when using grid_auto_rows/grid_auto_columns with zero negative implicit tracks
454  - Fix over counting of tracks (leading to incorrect container heights) when auto-placing in grids that contain negative implicit tracks.
455  - Fix axis conflation in auto-placement code when grid_auto_flow is column
456  - Fix assignment of auto track sizes when initializing negative implicit tracks
457- Leaf: Apply margins to leaf nodes when computing available space for measure functions
458- Leaf: Reserve space for padding/borders in nodes with measure functions (#497)
459  
460  **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.
461
462### Dependencies
463
464- Upgrade `grid` to `0.10`. This eliminates the transitive dependency on `no-std-compat`.
465
466## 0.3.12
467
468### Fixes
469
470- Fix caching issue when toggling `display:none` on and off
471
472## 0.3.11
473
474### Fixes
475
476- Fix exponential blowup when laying out trees containing nodes with min and max sizes.
477
478## 0.3.10
479
480### Fixes
481
482- Fix sizing of children when the available_space < min_size (#407)
483
484## 0.3.9
485
486### Fixes
487
488- 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)
489
490## 0.3.8
491
492### Fixes
493
494- Fix incorrect min-content size for `flex-wrap: wrap` nodes (bevyengine/bevy#8082)
495
496## 0.3.7
497
498### Fixes
499
500- Fix: Make `padding` and `border` floor node sizes (#372)
501- Fix: Prevent percentages contributing to min-content sizes (#388) (also fixes bevyengine/bevy#8017)
502
503## 0.3.6
504
505### Fixes
506
507- Fix: Ignore `align_content` when `flex_wrap` is set to `nowrap` (#383)
508
509## 0.3.5
510
511### Fixes
512
513- Fix `display: none` when it is set on a flexbox child (#380)
514- Fix `display: none` when it is set on a grid child (#381)
515
516## 0.3.4
517
518### Fixes
519
520- Fix `display: none` when it is set for the only node in the hierarchy (#377)
521
522## 0.3.3
523
524### Added
525
526- 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.
527
528### Fixes
529
530- Fixed rounding algorithm such that it never leaves gaps between adjacent nodes (#369)
531- Fixed compiling with the `grid` feature disabled (#370)
532- Fixed compiling with the `std` feature disabled
533
534## 0.3.2
535
536### Fixes
537
538- Allow partial nested values to be deserialized into a `Style` using the `serde` feature.
539
540## 0.3.1
541
542### Fixes
543
544- The `serde` feature now works when the `grid` feature is enabled
545
546## 0.3.0
547
548### Highlights
549
550- [CSS Grid algorithm support](#new-feature-css-grid)
551- [Style helper functions](#new-feature-style-helpers)
552
553See below for details of breaking changes.
554
555### New Feature: CSS Grid
556
557We 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`.
558
559#### Learning Resources
560
561Taffy 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:
562
563- [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.
564- [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.
565
566#### Supported Features & Properties
567
568In addition to the usual sizing/spacing properties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
569
570| Property                  | Explanation                                                                                    |
571| ---                       | ---                                                                                            |
572| [`grid-template-columns`] | The track sizing functions of the grid's explicit columns                                      |
573| [`grid-template-rows`]    | The track sizing functions of the grid's explicit rows                                         |
574| [`grid-auto-rows`]        | Track sizing functions for the grid's implicitly generated rows                                |
575| [`grid-auto-columns`]     | Track sizing functions for the grid's implicitly generated columns                             |
576| [`grid-auto-flow`]        | Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely.         |
577| [`gap`]                   | The size of the vertical and horizontal gaps between grid rows/columns                         |
578| [`align-content`]         | Align grid tracks within the container in the inline (horizontal) axis                         |
579| [`justify-content`]       | Align grid tracks within the container in the block (vertical) axis                            |
580| [`align-items`]           | Align the child items within their grid areas in the inline (horizontal) axis                  |
581| [`justify-items`]         | Align the child items within their grid areas in the block (vertical) axis                     |
582
583And the following Grid style properties are supported on Grid Items (children):
584
585| Property                  | Explanation                                                                                    |
586| ---                       | ---                                                                                            |
587| [`grid-row`]              | The (row) grid line the item starts at (or a span)                                             |
588| [`grid-column`]           | The (column) grid line the item end at (or a span)                                             |
589| [`align-self`]            | Align the item within it's grid area in the inline (horizontal) axis. Overrides `align-items`. |
590| [`justify-self`]          | Align the item within it's grid area in the block (vertical) axis. Overrides `justify-items`.  |
591
592[`grid-template-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-columns
593[`grid-template-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-rows
594[`grid-auto-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-rows
595[`grid-auto-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-columns
596[`grid-auto-flow`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-flow
597[`gap`]: https://developer.mozilla.org/en-US/docs/Web/CSS/gap
598[`align-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align_content
599[`justify-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify_content
600[`align-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-items
601[`justify-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-items
602[`grid-row`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
603[`grid-column`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-column
604[`align-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-self
605[`justify-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-self
606
607The following properties and features are not currently supported:
608
609- Subgrids
610- Masonry grid layout
611- Named grid lines
612- Named areas: `grid-template-areas` and `grid-area`
613- `grid-template` or `grid` shorthand
614
615#### Example
616
617See [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:
618
619```bash
620cargo run --example grid_holy_grail --features grid
621```
622
623### New Feature: Style Helpers
624
625Ten 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.
626
627For example, instead of:
628
629```rust
630let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };
631```
632
633you can now write
634
635```rust
636let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };
637```
638
639And 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
640
641```rust
642let size : Size<Dimension> = points(100.0);
643```
644
645Available style helpers:
646
647<table>
648  <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead>
649  <tbody>
650    <tr>
651      <td rowspan="3"><code>LengthPercentage</code></td>
652      <td><code>zero()</code></td>
653      <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td>
654    </tr>
655    <tr>
656      <td><code>points(val:&nbsp;f32)</code></td>
657      <td>Generates a <code>Points</code> variant with the specified value</td>
658    </tr>
659    <tr>
660      <td><code>percent(val:&nbsp;f32)</code></td>
661      <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td>
662    </tr>
663    <tr>
664      <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td>
665      <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td>
666    </tr>
667    <tr>
668      <td><code>auto()</code></td>
669      <td>Generates an <code>Auto</code> variant</td>
670    </tr>
671    <tr>
672      <td rowspan="3"><code>MinTrackSizingFunction</code></td>
673      <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td>
674    </tr>
675    <tr>
676      <td><code>min_content()</code></td>
677      <td>Generates an <code>MinContent</code> variant</td>
678    </tr>
679      <tr>
680      <td><code>max_content()</code></td>
681      <td>Generates an <code>MinContent</code> variant</td>
682    </tr>
683    <tr>
684      <td rowspan="3"><code>MaxTrackSizingFunction</code></td>
685      <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td>
686    </tr>
687    <tr>
688      <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td>
689      <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>
690    </tr>
691      <tr>
692      <td><code>fr(fraction:&nbsp;f32)</code></td>
693      <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td>
694    </tr>
695    <tr>
696      <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td>
697      <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td>
698    </tr>
699    <tr>
700      <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td>
701      <td>Equivalent to CSS <code>minmax()</code> function.</td>
702    </tr>
703    <tr>
704      <td><code>flex(fraction:&nbsp;f32)</code></td>
705      <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td>
706    </tr>
707    <tr>
708      <td rowspan="2"><code>TrackSizingFunction</code></td>
709      <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td>
710    </tr>
711    <tr>
712      <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td>
713      <td>Equivalent to css <code>repeat()</code> function.</td>
714    </tr>
715    <tr>
716      <td><code>Vec&lt;TrackSizingFunction&gt;</code></td>
717      <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td>
718      <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td>
719    </tr>
720    <tr>
721      <td rowspan="3"><code>AvailableSpace</code></td>
722      <td><code>auto()</code></td>
723      <td>Generates an <code>Auto</code> variant</td>
724    </tr>
725    <tr>
726      <td><code>min_content()</code></td>
727      <td>Generates an <code>MinContent</code> variant</td>
728    </tr>
729      <tr>
730      <td><code>max_content()</code></td>
731      <td>Generates an <code>MinContent</code> variant</td>
732    </tr>
733    <tr>
734      <td><code>Size&lt;T&gt;</code></td>
735      <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>
736    </tr>
737    <tr>
738      <td><code>Rect&lt;T&gt;</code></td>
739      <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>
740    </tr>
741  </tbody>
742</table>
743
744### Breaking API changes
745
746#### Changes to alignment style types
747
748- `AlignContent` and `JustifyContent` has been merged.
749  - `JustifyContent` is now an alias of `AlignContent` and contains the `Stretch` variant.
750  - This variant will be *ignored* (falling back to `Start`) when applied Flexbox containers. It is valid value for Grid containers.
751- `AlignItems` and `AlignSelf` have been merged.
752  - The `Auto` variant of `AlignSelf` has been removed. You should now use `Option::None` if you wish to specify `AlignSelf::Auto`.
753  - `AlignSelf` is now an alias of `AlignItems`.
754  - `JustifyItems` and `JustifySelf` aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.
755- `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.
756
757#### Strict style types
758
759- New types `LengthPercentage` and `LengthPercentageAuto` have been added.
760  - `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.
761  - `LengthPercentageAuto` is currently identical to `Dimension` but will allow us to expand dimension in future to support values like `MinContent`, `MaxContent` and `FitContent`.
762- 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).
763
764#### Position properties renamed
765
766- 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)
767- 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`.
768
769#### Changes to `LayoutTree`
770
771- Added generic associated type to `LayoutTree` for a `ChildIter`, an iterator on the children of a given node.
772- 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.
773- 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.
774- Added `is_childless` method to `LayoutTree` for querying whether a node has no children.
775
776#### `AvailableSpace` has been moved
777
778The `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.
779
780### Fixes
781
782- Flexbox nodes sized under a min-content constraint now size correctly (#291)
783- Aspect ratio is now applied correctly in many circumstances
784- Absolutely positioned items now apply margins correctly
785- Min/max size are now applied correctly
786- Inset applied incorrectly to relatively positioned flexbox children when both `top` and `bottom` or `left` and `right` were specified (#348)
787- 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)
788
789### Removed
790
791- 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.
792- 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.
793- 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.
794
795## 0.2.2
796
797### Fixes
798
799- Border or padding on the horizontal axis could, in some cases, increase the height of nodes.
800
801## 0.2.1
802
803### Fixes
804
805- 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`.
806- `taffy::compute_layout` has been made public allowing Taffy to be used with custom storage (#263)
807
808## 0.2.0
809
810### New features
811
812#### Flexbox "gap" and `AlignContent::SpaceEvenly`
813
814The [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.
815
816Additionally 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)
817
818#### Debug module and cargo feature
819
820Two debugging features have been added:
821
822- `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.
823- A cargo feature `debug`. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).
824
825### Performance improvements
826
827A number of performance improvements have landed since taffy 0.1:
828
829- 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%.
830- 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!
831
832#### Benchmarks vs. Taffy 0.1
833
834| Benchmark                                 | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
835| ---                                       | ---       | ---       | ---                   |
836| wide/1_000 nodes (2-level hierarchy)      | 699.18 µs | 445.01 µs | -36.279%              |
837| wide/10_000 nodes (2-level hierarchy)     | 8.8244 ms | 7.1313 ms | -16.352%              |
838| wide/100_000 nodes (2-level hierarchy)    | 204.48 ms | 242.93 ms | +18.803%              |
839| deep/4000 nodes (12-level hierarchy))     | 5.2320 s  | 2.7363 ms | -99.947%              |
840| deep/10_000 nodes (14-level hierarchy)    | 75.207 s  | 6.9415 ms | -99.991%              |
841| deep/100_000 nodes (17-level hierarchy)   | -         | 102.72 ms | -                     |
842| deep/1_000_000 nodes (20-level hierarchy) | -         | 799.35 ms | -                     |
843
844(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
845
846As 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.
847
848However, 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.
849
850#### Benchmarks vs. [Yoga](https://github.com/facebook/yoga)
851
852Yoga 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.
853
854| Benchmark | Yoga | Taffy 0.2 |
855| --- | --- | --- |
856| yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
857| yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
858| yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
859| yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
860| yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 ms |
861
862(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
863
864While 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!
865
866### Breaking API changes
867
868#### Node creation changes
869
870- `taffy::Node` is now unique only to the Taffy instance from which it was created.
871- Renamed `Taffy.new_node(..)` -> `Taffy.new_with_children(..)`
872- Renamed `Taffy.new_leaf()` -> `Taffy.new_leaf_with_measure()`
873- Added `taffy::node::Taffy.new_leaf()` which allows the creation of new leaf-nodes without having to supply a measure function
874
875#### Error handling/representation improvements
876
877- Renamed `taffy::Error` -> `taffy::error::TaffyError`
878- Replaced `taffy::error::InvalidChild` with a new `InvalidChild` variant of `taffy::error::TaffyError`
879- Replaced `taffy::error::InvalidNode` with a new `InvalidNode` variant of `taffy::error::TaffyError`
880- The following method new return `Err(TaffyError::ChildIndexOutOfBounds)` instead of panicking:
881  - `taffy::Taffy::remove_child_at_index`
882  - `taffy::Taffy::replace_child_at_index`
883  - `taffy::Taffy::child_at_index`
884- `Taffy::remove` now returns a `Result<usize, Error>`, to indicate if the operation was successful (and if it was, which ID was invalidated).
885
886#### Some uses of `Option<f32>` replaced with a new `AvailableSpace` enum
887
888A new enum `Taffy::layout::AvailableSpace` has been added.
889
890The definition looks like this:
891
892```rust
893/// The amount of space available to a node in a given axis
894pub enum AvailableSpace {
895    /// The amount of space available is the specified number of pixels
896    Definite(f32),
897    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
898    MinContent,
899    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
900    MaxContent,
901}
902```
903
904This 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`).
905
906And 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..
907
908#### Builder methods are now `const` where possible
909
910- Several convenience constants have been defined: notably `Style::DEFAULT`
911- `Size<f32>.zero()` is now `Size::<f32>::ZERO`
912- `Point<f32>.zero()` is now  `Point::<f32>::ZERO`
913- `Size::undefined()` is now `Size::NONE`
914
915#### Removals
916
917- 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%).
918- Removed `taffy::number::Number`. Use `Option<f32>` is used instead
919  - the associated public `MinMax` and `OrElse` traits have also been removed; these should never have been public
920- 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).
921
922### Fixes
923
924- Miscellaneous correctness fixes which align our implementation with Chrome:
925
926  - Nodes can only ever have one parent
927  - Fixed rounding of fractional values to follow latest Chrome - values are now rounded the same regardless of their position
928  - Fixed computing free space when using both `flex-grow` and a minimum size
929  - 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)
930  - `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
931- Taffy can now be vendored using `cargo-vendor` (README.md is now included in package).
932
933## 0.1.0
934
935### 0.1.0 Changed
936
937- the `order` field of `Layout` is now public, and describes the relative z-ordering of nodes
938- renamed crate from `stretch2` to `taffy`
939- updated to the latest version of all dependencies to reduce upstream pain caused by duplicate dependencies
940- renamed `stretch::node::Stretch` -> `taffy::node::Taffy`
941
942### 0.1.0 Fixed
943
944- fixed feature strategy for `alloc` and `std`: these can now be compiled together, with `std`'s types taking priority
945
946### 0.1.0 Removed
947
948- removed Javascript / Kotlin / Swift bindings
949  - the maintainer team lacks expertise to keep these working
950  - more serious refactors are planned, and this will be challenging to keep working through that process
951  - if you are interested in helping us maintain bindings to other languages, [get in touch](https://github.com/DioxusLabs/taffy/discussions)!
952- 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)
953- removed the `Direction` and `Overflow` structs, and the corresponding `direction` and `overflow` fields from `Style`
954  - these had no effect in the current code base and were actively misleading
955
956## stretch2 0.4.3
957
958This is the final release of `stretch`: migrate to the crate named `taffy` for future fixes and features!
959
960These notes describe the differences between this release and `stretch` 0.3.2, the abandoned crate from which this library was forked.
961
962### Changed
963
964- updated [assorted dependencies](https://github.com/vislyhq/stretch/commit/a6491117379cea52dedc9584d892594a143e8cb0)
965
966### Fixed
967
968- fixed an exponential performance blow-up with deep nesting
969- fixed percent height values, which were using parent width
970- recomputing layout no longer moves children of non-zero-positioned parent
971- fixed broken Swift bindings