1# Changelog
2
3## 0.9.3
4
5### Added
6
7- Added write_tree method to utils.
8
9## 0.9.2
10
11### Fixed
12
13- Fix wrong size propogation for absolute elements (#878)
14- Fix bounds check in CellOccupancyMatrix::last_of_type (#890)
15- Use doc_cfg instead of doc_auto_cfg (#868)
16
17### Changed
18
19- Upgraded grid dependency from 0.18 to 1.0 (#864)
20
21## 0.9.1
22
23### Fixed
24
25- Flexbox: don't apply cross-axis stretch alignment to children with auto margins (#861)
26
27## 0.9.0
28
29### Support for named grid lines and grid areas
30
31Taffy now supports named grid lines and areas.
32
33As these rely on arbitrary user-provided strings, Taffy's `Style` struct is now generic
34over a string-like type (via the `CheapCloneStr` trait). Additionally as the `grid` feature is optional,
35it has a `PhantomData` field of that type to make type inference work.
36
37### Changed
38
39- `PrintTree` and `RoundTree`: use `Layout` instead of `&Layout` (#849).
40- Renamed `TrackSizingFunction` to `GridTemplateComponent`
41- Renamed `NonRepeatedTrackSizingFunction` to `TrackSizingFunction`
42- The `Repeat` variant of `GridTemplateComponent` now contains a new `GridTemplateRepetition` struct, which allows
43  line names to be specifed in addition to tracks.
44- The way that grid styles are exposed in the low-level API is now a lot more generic with many associated types.
45
46### Added
47
48- `GridTemplateArea` struct and `Style::grid_template_areas` field
49- `Style::grid_template_column_names` and `Style::grid_template_row_names` fields. If non-empty, these
50  should have length of exactly one greater than the corresponding `grid_template_column`/`grid_template_rows` style.
51
52## 0.8.3
53
54### Fixed
55
56- Fix `serde` feature on 32bit targets (#845)
57
58## 0.8.2
59
60### Fixed
61
62- Fix: Calculate correct new grid size when expanding cell_occupancy_matrix in the negative direction (#843)
63
64## 0.8.1
65
66### Added
67
68- Impl `GridItemStyle` and `BlockContainerStyle` for `Style` (#832).
69
70## 0.8.0
71
72### Highlights
73
74**The big feature in this release is support for `calc()` values in the low-level API.**
75
76To use this API:
77
78- Implement the `resolve_calc_value` method when implementing the `LayoutPartialTree` trait.
79- Pass a type-erased pointer (`*const ()`) to constructors like `LengthPercentage::calc(...)`
80
81Taffy treats the pointer as an opaque value (excepting that it uses the low 3 bits as a tag) which it will
82pass to `LayoutPartialTree::resolve_calc_value` along with a percentage resolution basis when it needs to
83resolve the value.
84
85### Changed
86
87- The representation of many "size" types is now a tagged pointer than an enum. This is to enable `calc()`.
88  The effected types are `LengthPercentage`, `LengthPercentageAuto`, `Dimension`, `MinTrackSizingFunction`, and
89`MaxTrackSizingFunction` types.
90
91### Added
92
93- Special-case "compressible replaced elements" in grid sizing algorithm (#807)
94  This allows for more correct sizing of "replaced" elements such as images that are children
95  of flexbox or grid containers.
96
97### Fixed
98
99- Grid: Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
100- Grid: Fix removed wrong addition, causing items to be misplaced. (#817)
101- Grid: Fix grid placement for items with fixed primary axis (#818)
102- Leaf layout: don't set available space to max-size (#819)
103
104## 0.7.7
105
106### Fixed
107
108- Add `#[inline]` annotation to some methods on `TaffyTree` (#802)
109- Add `TaffyTree::remove_children_range` method (#802)
110
111## 0.7.6
112
113### Fixed
114
115- Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
116
117## 0.7.5
118
119### Fixed
120
121- Grid: only stretch auto tracks if content-alignment is stretch (#783)
122
123## 0.7.4
124
125### Fixed
126
127- Fix detailed grid info for empty grid (#782)
128
129## 0.7.3
130
131### Fixed
132
133- Make `TaffyTree::detailed_layout_info` take `&self` rather than `&mut self` (#779)
134
135## 0.7.2
136
137### Added
138
139- The ability to access computed track sizes and item positions of a CSS Grid layout (#772).
140  This information can be accessed using the `LayoutGridContainer::set_detailed_grid_info` method
141  in the low-level API or the `TaffyTree::detailed_layout_info` method in the high-level API.
142
143## 0.7.1
144
145### Fixed
146
147- Improve interaction of abspos children of block containers with margin collapsing (#760)
148
149### Added
150
151- Add `TaffyTree::unrounded_layout` getter (#765)
152
153### Removed
154
155- The `num-traits` dependency was removed (#761) (#762)
156
157## 0.7.0
158
159### Changed
160
161- BREAKING: The `cache_mut` method on the `LayoutPartialTree` trait has been replaced with a separate `CacheTree` trait. This allows
162  Taffy to be more easily used without caching or with a custom cache implementation.
163- BREAKING: the `TaffyTree::set_children` method now removes the children from their previous parent (if they have one).
164
165### Added
166
167- Helper methods to retrieve content-box sizes were added to `Layout`
168
169## 0.6.3
170
171### Fixes
172
173- Block: ignore margin collapsing when computing static position of abspos items (#747)
174
175## 0.6.2
176
177### Fixes
178
179- Fix: clamp indefinite available space by min- and max- size as appropriate (#742)
180
181## 0.6.1
182
183### Fixes
184
185- Fix calculation of `auto-fill`/`auto-fit` repetition count when container has a definite percentage size (#722)
186- Fix min-size style not affecting intrinsic sizes (#723)
187- Fix documentation of dirty and mark_dirty functions (#724)
188- Fix intrinsic size of scroll containers that have a small explicit flex-basis (#728)
189
190## 0.6.0
191
192### Highlights
193
194- The `Style` struct has been "traitified". This supports Taffy's integration in Servo and generally makes Taffy more flexible. The
195  `Style` struct still exists and implements the new traits so existing uses of Taffy will continue to work as before.
196- The `box-sizing` style is supported
197- Computed margins are output in `Layout`
198
199### Fixes
200
201- Fix `print_tree()` when rounding is disabled (#680)
202- Absolute Insets should be resolved against the container size minus border (#666)
203- Fix flooring hypothetical_main_size by computed min size (#689)
204- Fix flex line cross-size determination (#690)
205- Fix panics in the grid algorithm (#691)
206- Fix resolving flexible lengths (WPT css/flexbox-multiline-min-max test) (#692)
207- Fix wrapping when a max main size style is present (#694)
208- Fix case where Taffy allowed margins to collapse through an element when it shouldn't have (#695)
209
210### Added
211
212- Legacy text align (for laying out `<center>` and `<div align="..">`) is supported
213- Add `is_table` for block items (#701)
214- Impl `Debug` and `Clone` for `Cache` (#688)
215- Implement `Debug` and `PartialEq` for tree types (#697)
216
217## 0.5.2
218
219- Fix block stretch sizing (don't always apply stretch sizing to block containers) (#674)
220- Fix computation of intrinsic main size when it depends on a child's known cross size (#673)
221- Fix panic when GridLine 0 is specified (#671)
222- Docs: Document feature flags and scrape examples (#672)
223- Docs: Update cosmic-text example to cosmic-text 0.12 (#670)
224
225## 0.5.1
226
227- Fix: Clamp block item stretch widths by their min and max width (#664)
228- Fix: Auto margin computation in block layout (#663)
229
230## 0.5.0
231
232The changes in 0.5 are relatively small but the new measure function parameter is a breaking change so it requires a minor version bump.
233
234- Added: A `style: &Style` parameter has been added to measure functions.
235- Added: The `MaybeMath`, `MaybeResolve`, and `ResolveOrZero` traits have been made public.
236- Fix: use SizingMode::Inherent when sizing absolute children of flexbox nodes.
237
238## 0.4.4
239
240### Fixes
241
242- Content alignment (`align-content`/`justify-content`) behaviour was updated to match the latest spec (and Chrome 123+) (#635)
243- Ensure that root Flexbox nodes are floored by their padding-border (#651, #655)
244- Use grid area size not available space when applying aspect ratio to grid containers (#656)
245
246## 0.4.3
247
248### Fixes
249
250- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
251  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
252  but they should be able to fix on their side by clarifying the type passed in
253
254## 0.4.2
255
256- Fixed: single-line flex-container should clamp the line's cross-size (#638)
257- Reduced binary footprint of Taffy from around 300kb to around 150kb (#636)
258
259## 0.4.1
260
261- Fixed: CSS Grid track sizing not respecting growth limits in some circumstances (#624)
262
263## 0.4.0
264
265### Highlights
266
267- Support for CSS Block layout (`display: block`)
268- Support for the `overflow` property (+ `scrollbar_width` for `overflow: scroll`)
269- Improved measure function API
270- Completely refactored low-level API
271- Simplified module hierarchy (+ most types/functions are now exported from the crate root)
272- Expanded set of examples which better document integration with other layout systems (e.g. text layout)
273- Computed values for `padding` and `border` are now output into the `Layout` struct
274
275### Block layout
276
277Support 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.
278
279### Overflow property
280
281Support 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.
282
283- Overflow is settable indpendently in each axis.
284- `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.
285- `Hidden` and `Scroll` affect layout by changing the automatic minimum size of Flexbox and Grid children
286- `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`.
287
288### Measure function changes
289
290The "measure function" API for integrating Taffy with other measurement systems (such as text layout) has been changed to be more flexible
291and to interact better with borrow checking (you can now borrow external data in your measure function!).
292
293- There are no longer per-node measure functions.
294- There is now a single "global" measure function, and a per-node "context" of a user-defined type
295- The `Taffy` tree is now a generic `TaffyTree<T>` where `T` is the "context" type.
296- The measure function is now called for all leaf nodes (nodes without children). If you wish to maintain compatibility with the previous
297  behaviour then your measure function should return `Size::ZERO` for leaf nodes whose context is `None`.
298
299If you are not using measure functions, then the only change you will need to make is from:
300
301```rust
302let mut tree = Taffy::new();
303```
304
305to
306
307```rust
308let mut tree : TaffyTree<()> = TaffyTree::new();
309```
310
311And generally update any uses of `Taffy` in your codebase to `TaffyTree<()>`.
312
313If you are using measure functions then you will need to make some bigger (but straightforward) changes. The following Taffy 0.3 code:
314
315```rust
316let mut tree = Taffy::new();
317let leaf = tree.new_leaf_with_measure(
318  Style::DEFAULT,
319  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>| Size { width: 100.0, height: 200.0 }
320);
321tree.compute_layout(leaf, Size::MAX_CONTENT);
322```
323
324Should become something like the following with Taffy 0.4:
325
326```rust
327let mut tree : TaffyTree<Size> = TaffyTree::new();
328let leaf = tree.new_leaf_with_context(Style::DEFAULT, Size { width: 100.0, height: 200.0 });
329tree.compute_layout_with_measure(
330  leaf,
331  Size::MAX_CONTENT,
332  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, node_id: NodeId, node_context: Option<Size>| {
333    node_context.unwrap_or(Size::ZERO)
334  }
335);
336```
337
338Note that:
339
340- 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).
341- If you don't need a context then you can use `()` for the context type
342- As the single "global" measure function passed to `compute_layout_with_measure` only needs to exist for the duration of a single layout run,
343  it can (mutably) borrow data from it's environment
344
345### Low-level API (`LayoutTree` trait) refactor
346
347The low-level API has been completely reworked:
348
349- The `LayoutTree` trait has been split into 5 smaller traits which live in the `taffy::tree:traits` module (along with their associated documentation)
350- The following methods have been removed from split `LayoutTree` traits entirely: `parent`, `is_childless`, `measure_node`, `needs_measure`, and `mark_dirty`.
351- `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`.
352- Support for running each layout algorithm individually on a single node via the following top-level functions:
353  - `compute_flexbox_layout`
354  - `compute_grid_layout`
355  - `compute_block_layout`
356  - `compute_leaf_layout`
357  - `compute_root_layout`
358  - `compute_hidden_layout`
359
360It 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
361improved 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).
362
363### Module hierarchy changes
364
365The 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`.
366
367Specific changes:
368
369- The `math` module has been made private
370- The `axis` module has been merged into the `geometry` module
371- The debug module is no longer public. The `print_tree` function is now accessible under `util`.
372- All types from the `node`, `data`, `layout`, `error` and `cache` modules have been moved to the  the `tree` module.
373- The `layout_flexbox()` function has been removed from the prelude. Use `taffy::compute_flexbox_layout` instead.
374
375### Many APIs have been renamed to replace `points` or `Points` with `length` or `Length`
376
377This new name better describes one-dimensional measure of space in some unspecified unit
378which is often unrelated to the PostScript point or the CSS `pt` unit.
379
380This also removes a misleading similarity with the 2D `Point`,
381whose components can have any unit and are not even necessarily absolute lengths.
382
383Example usage change:
384
385```diff
386 use taffy::prelude::*;
387
388 // …
389
390 let header_node = taffy
391     .new_leaf(
392         Style {
393-            size: Size { width: points(800.0), height: points(100.0) },
394+            size: Size { width: length(800.0), height: length(100.0) },
395             ..Default::default()
396         },
397     ).unwrap();
398```
399
400### Other Changes
401
402- The `Taffy` type was renamed to `TaffyTree` and made generic of a context parameter
403- The Flexbox algorithm has now been moved behind the `flexbox` feature. The `flexbox` feature is enabled by default.
404- The `justify_self` property has been moved behind the `grid` feature.
405- Fixed misspelling: `RunMode::PeformLayout` renamed into `RunMode::PerformLayout` (added missing `r`).
406- `serde` dependency has been made compatible with `no_std` environments
407- `slotmap` dependency has been made compatible with `no_std` environments
408- 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.
409- Added `total_node_count()` method to the `TaffyTree` which returns the total number of nodes in the tree.
410- Added `get_disjoint_node_context_mut()` method to the `TaffyTree`. This can be used to safely get multiple mutable borrows at the same time.
411
412## 0.3.19
413
414### Fixes
415
416- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
417  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
418  but they should be able to fix on their side by clarifying the type passed in
419
420## 0.3.18
421
422### Fixes
423
424- Fix computation of Flexbox automatic minimum size when grid or flexbox child has an explicit width/height style set (#576)
425
426## 0.3.17
427
428### Added
429
430- Added `total_node_count` method to the `Taffy` struct. Returns the total number of nodes in the tree.
431
432## 0.3.16
433
434### Fixes
435
436- Improve performance of flexbox columns
437
438## 0.3.15
439
440### Fixes
441
442- Fix justify-content and align-content when free space is negative (content overflows container) (#549) (#551)
443
444## 0.3.14
445
446### Fixes
447
448- 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)
449
450## 0.3.13
451
452### Fixes
453
454- Fix rounding accumulation bug (#521) (Fixes #501 and bevyengine/bevy#8911)
455- Flexbox: pass correct cross-axis available space when computing an item's intrinsic main size (#522)(Fixes bevyengine/bevy#9350)
456- Flexbox: Subtract child margin not parent margin when computing stretch-alignment known size
457- Grid: Make CSS Grid algorithm correctly apply max width/height and available space when it is the root node (#491)
458- Grid: Fix CSS Grid "auto track" / placement bugs #481
459  - Fix divide by zero when using grid_auto_rows/grid_auto_columns with zero negative implicit tracks
460  - Fix over counting of tracks (leading to incorrect container heights) when auto-placing in grids that contain negative implicit tracks.
461  - Fix axis conflation in auto-placement code when grid_auto_flow is column
462  - Fix assignment of auto track sizes when initializing negative implicit tracks
463- Leaf: Apply margins to leaf nodes when computing available space for measure functions
464- Leaf: Reserve space for padding/borders in nodes with measure functions (#497)
465  
466  **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.
467
468### Dependencies
469
470- Upgrade `grid` to `0.10`. This eliminates the transitive dependency on `no-std-compat`.
471
472## 0.3.12
473
474### Fixes
475
476- Fix caching issue when toggling `display:none` on and off
477
478## 0.3.11
479
480### Fixes
481
482- Fix exponential blowup when laying out trees containing nodes with min and max sizes.
483
484## 0.3.10
485
486### Fixes
487
488- Fix sizing of children when the available_space < min_size (#407)
489
490## 0.3.9
491
492### Fixes
493
494- 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)
495
496## 0.3.8
497
498### Fixes
499
500- Fix incorrect min-content size for `flex-wrap: wrap` nodes (bevyengine/bevy#8082)
501
502## 0.3.7
503
504### Fixes
505
506- Fix: Make `padding` and `border` floor node sizes (#372)
507- Fix: Prevent percentages contributing to min-content sizes (#388) (also fixes bevyengine/bevy#8017)
508
509## 0.3.6
510
511### Fixes
512
513- Fix: Ignore `align_content` when `flex_wrap` is set to `nowrap` (#383)
514
515## 0.3.5
516
517### Fixes
518
519- Fix `display: none` when it is set on a flexbox child (#380)
520- Fix `display: none` when it is set on a grid child (#381)
521
522## 0.3.4
523
524### Fixes
525
526- Fix `display: none` when it is set for the only node in the hierarchy (#377)
527
528## 0.3.3
529
530### Added
531
532- 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.
533
534### Fixes
535
536- Fixed rounding algorithm such that it never leaves gaps between adjacent nodes (#369)
537- Fixed compiling with the `grid` feature disabled (#370)
538- Fixed compiling with the `std` feature disabled
539
540## 0.3.2
541
542### Fixes
543
544- Allow partial nested values to be deserialized into a `Style` using the `serde` feature.
545
546## 0.3.1
547
548### Fixes
549
550- The `serde` feature now works when the `grid` feature is enabled
551
552## 0.3.0
553
554### Highlights
555
556- [CSS Grid algorithm support](#new-feature-css-grid)
557- [Style helper functions](#new-feature-style-helpers)
558
559See below for details of breaking changes.
560
561### New Feature: CSS Grid
562
563We 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`.
564
565#### Learning Resources
566
567Taffy 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:
568
569- [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.
570- [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.
571
572#### Supported Features & Properties
573
574In addition to the usual sizing/spacing properties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
575
576| Property                  | Explanation                                                                                    |
577| ---                       | ---                                                                                            |
578| [`grid-template-columns`] | The track sizing functions of the grid's explicit columns                                      |
579| [`grid-template-rows`]    | The track sizing functions of the grid's explicit rows                                         |
580| [`grid-auto-rows`]        | Track sizing functions for the grid's implicitly generated rows                                |
581| [`grid-auto-columns`]     | Track sizing functions for the grid's implicitly generated columns                             |
582| [`grid-auto-flow`]        | Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely.         |
583| [`gap`]                   | The size of the vertical and horizontal gaps between grid rows/columns                         |
584| [`align-content`]         | Align grid tracks within the container in the inline (horizontal) axis                         |
585| [`justify-content`]       | Align grid tracks within the container in the block (vertical) axis                            |
586| [`align-items`]           | Align the child items within their grid areas in the inline (horizontal) axis                  |
587| [`justify-items`]         | Align the child items within their grid areas in the block (vertical) axis                     |
588
589And the following Grid style properties are supported on Grid Items (children):
590
591| Property                  | Explanation                                                                                    |
592| ---                       | ---                                                                                            |
593| [`grid-row`]              | The (row) grid line the item starts at (or a span)                                             |
594| [`grid-column`]           | The (column) grid line the item end at (or a span)                                             |
595| [`align-self`]            | Align the item within it's grid area in the inline (horizontal) axis. Overrides `align-items`. |
596| [`justify-self`]          | Align the item within it's grid area in the block (vertical) axis. Overrides `justify-items`.  |
597
598[`grid-template-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-columns
599[`grid-template-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-rows
600[`grid-auto-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-rows
601[`grid-auto-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-columns
602[`grid-auto-flow`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-flow
603[`gap`]: https://developer.mozilla.org/en-US/docs/Web/CSS/gap
604[`align-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align_content
605[`justify-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify_content
606[`align-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-items
607[`justify-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-items
608[`grid-row`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
609[`grid-column`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-column
610[`align-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-self
611[`justify-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-self
612
613The following properties and features are not currently supported:
614
615- Subgrids
616- Masonry grid layout
617- Named grid lines
618- Named areas: `grid-template-areas` and `grid-area`
619- `grid-template` or `grid` shorthand
620
621#### Example
622
623See [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:
624
625```bash
626cargo run --example grid_holy_grail --features grid
627```
628
629### New Feature: Style Helpers
630
631Ten 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.
632
633For example, instead of:
634
635```rust
636let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };
637```
638
639you can now write
640
641```rust
642let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };
643```
644
645And 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
646
647```rust
648let size : Size<Dimension> = points(100.0);
649```
650
651Available style helpers:
652
653<table>
654  <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead>
655  <tbody>
656    <tr>
657      <td rowspan="3"><code>LengthPercentage</code></td>
658      <td><code>zero()</code></td>
659      <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td>
660    </tr>
661    <tr>
662      <td><code>points(val:&nbsp;f32)</code></td>
663      <td>Generates a <code>Points</code> variant with the specified value</td>
664    </tr>
665    <tr>
666      <td><code>percent(val:&nbsp;f32)</code></td>
667      <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td>
668    </tr>
669    <tr>
670      <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td>
671      <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td>
672    </tr>
673    <tr>
674      <td><code>auto()</code></td>
675      <td>Generates an <code>Auto</code> variant</td>
676    </tr>
677    <tr>
678      <td rowspan="3"><code>MinTrackSizingFunction</code></td>
679      <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td>
680    </tr>
681    <tr>
682      <td><code>min_content()</code></td>
683      <td>Generates an <code>MinContent</code> variant</td>
684    </tr>
685      <tr>
686      <td><code>max_content()</code></td>
687      <td>Generates an <code>MinContent</code> variant</td>
688    </tr>
689    <tr>
690      <td rowspan="3"><code>MaxTrackSizingFunction</code></td>
691      <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td>
692    </tr>
693    <tr>
694      <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td>
695      <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>
696    </tr>
697      <tr>
698      <td><code>fr(fraction:&nbsp;f32)</code></td>
699      <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td>
700    </tr>
701    <tr>
702      <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td>
703      <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td>
704    </tr>
705    <tr>
706      <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td>
707      <td>Equivalent to CSS <code>minmax()</code> function.</td>
708    </tr>
709    <tr>
710      <td><code>flex(fraction:&nbsp;f32)</code></td>
711      <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td>
712    </tr>
713    <tr>
714      <td rowspan="2"><code>TrackSizingFunction</code></td>
715      <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td>
716    </tr>
717    <tr>
718      <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td>
719      <td>Equivalent to css <code>repeat()</code> function.</td>
720    </tr>
721    <tr>
722      <td><code>Vec&lt;TrackSizingFunction&gt;</code></td>
723      <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td>
724      <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td>
725    </tr>
726    <tr>
727      <td rowspan="3"><code>AvailableSpace</code></td>
728      <td><code>auto()</code></td>
729      <td>Generates an <code>Auto</code> variant</td>
730    </tr>
731    <tr>
732      <td><code>min_content()</code></td>
733      <td>Generates an <code>MinContent</code> variant</td>
734    </tr>
735      <tr>
736      <td><code>max_content()</code></td>
737      <td>Generates an <code>MinContent</code> variant</td>
738    </tr>
739    <tr>
740      <td><code>Size&lt;T&gt;</code></td>
741      <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>
742    </tr>
743    <tr>
744      <td><code>Rect&lt;T&gt;</code></td>
745      <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>
746    </tr>
747  </tbody>
748</table>
749
750### Breaking API changes
751
752#### Changes to alignment style types
753
754- `AlignContent` and `JustifyContent` has been merged.
755  - `JustifyContent` is now an alias of `AlignContent` and contains the `Stretch` variant.
756  - This variant will be *ignored* (falling back to `Start`) when applied Flexbox containers. It is valid value for Grid containers.
757- `AlignItems` and `AlignSelf` have been merged.
758  - The `Auto` variant of `AlignSelf` has been removed. You should now use `Option::None` if you wish to specify `AlignSelf::Auto`.
759  - `AlignSelf` is now an alias of `AlignItems`.
760  - `JustifyItems` and `JustifySelf` aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.
761- `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.
762
763#### Strict style types
764
765- New types `LengthPercentage` and `LengthPercentageAuto` have been added.
766  - `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.
767  - `LengthPercentageAuto` is currently identical to `Dimension` but will allow us to expand dimension in future to support values like `MinContent`, `MaxContent` and `FitContent`.
768- 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).
769
770#### Position properties renamed
771
772- 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)
773- 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`.
774
775#### Changes to `LayoutTree`
776
777- Added generic associated type to `LayoutTree` for a `ChildIter`, an iterator on the children of a given node.
778- 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.
779- 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.
780- Added `is_childless` method to `LayoutTree` for querying whether a node has no children.
781
782#### `AvailableSpace` has been moved
783
784The `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.
785
786### Fixes
787
788- Flexbox nodes sized under a min-content constraint now size correctly (#291)
789- Aspect ratio is now applied correctly in many circumstances
790- Absolutely positioned items now apply margins correctly
791- Min/max size are now applied correctly
792- Inset applied incorrectly to relatively positioned flexbox children when both `top` and `bottom` or `left` and `right` were specified (#348)
793- 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)
794
795### Removed
796
797- 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.
798- 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.
799- 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.
800
801## 0.2.2
802
803### Fixes
804
805- Border or padding on the horizontal axis could, in some cases, increase the height of nodes.
806
807## 0.2.1
808
809### Fixes
810
811- 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`.
812- `taffy::compute_layout` has been made public allowing Taffy to be used with custom storage (#263)
813
814## 0.2.0
815
816### New features
817
818#### Flexbox "gap" and `AlignContent::SpaceEvenly`
819
820The [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.
821
822Additionally 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)
823
824#### Debug module and cargo feature
825
826Two debugging features have been added:
827
828- `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.
829- A cargo feature `debug`. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).
830
831### Performance improvements
832
833A number of performance improvements have landed since taffy 0.1:
834
835- 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%.
836- 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!
837
838#### Benchmarks vs. Taffy 0.1
839
840| Benchmark                                 | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
841| ---                                       | ---       | ---       | ---                   |
842| wide/1_000 nodes (2-level hierarchy)      | 699.18 µs | 445.01 µs | -36.279%              |
843| wide/10_000 nodes (2-level hierarchy)     | 8.8244 ms | 7.1313 ms | -16.352%              |
844| wide/100_000 nodes (2-level hierarchy)    | 204.48 ms | 242.93 ms | +18.803%              |
845| deep/4000 nodes (12-level hierarchy))     | 5.2320 s  | 2.7363 ms | -99.947%              |
846| deep/10_000 nodes (14-level hierarchy)    | 75.207 s  | 6.9415 ms | -99.991%              |
847| deep/100_000 nodes (17-level hierarchy)   | -         | 102.72 ms | -                     |
848| deep/1_000_000 nodes (20-level hierarchy) | -         | 799.35 ms | -                     |
849
850(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
851
852As 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.
853
854However, 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.
855
856#### Benchmarks vs. [Yoga](https://github.com/facebook/yoga)
857
858Yoga 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.
859
860| Benchmark | Yoga | Taffy 0.2 |
861| --- | --- | --- |
862| yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
863| yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
864| yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
865| yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
866| yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 ms |
867
868(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
869
870While 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!
871
872### Breaking API changes
873
874#### Node creation changes
875
876- `taffy::Node` is now unique only to the Taffy instance from which it was created.
877- Renamed `Taffy.new_node(..)` -> `Taffy.new_with_children(..)`
878- Renamed `Taffy.new_leaf()` -> `Taffy.new_leaf_with_measure()`
879- Added `taffy::node::Taffy.new_leaf()` which allows the creation of new leaf-nodes without having to supply a measure function
880
881#### Error handling/representation improvements
882
883- Renamed `taffy::Error` -> `taffy::error::TaffyError`
884- Replaced `taffy::error::InvalidChild` with a new `InvalidChild` variant of `taffy::error::TaffyError`
885- Replaced `taffy::error::InvalidNode` with a new `InvalidNode` variant of `taffy::error::TaffyError`
886- The following method new return `Err(TaffyError::ChildIndexOutOfBounds)` instead of panicking:
887  - `taffy::Taffy::remove_child_at_index`
888  - `taffy::Taffy::replace_child_at_index`
889  - `taffy::Taffy::child_at_index`
890- `Taffy::remove` now returns a `Result<usize, Error>`, to indicate if the operation was successful (and if it was, which ID was invalidated).
891
892#### Some uses of `Option<f32>` replaced with a new `AvailableSpace` enum
893
894A new enum `Taffy::layout::AvailableSpace` has been added.
895
896The definition looks like this:
897
898```rust
899/// The amount of space available to a node in a given axis
900pub enum AvailableSpace {
901    /// The amount of space available is the specified number of pixels
902    Definite(f32),
903    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
904    MinContent,
905    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
906    MaxContent,
907}
908```
909
910This 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`).
911
912And 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..
913
914#### Builder methods are now `const` where possible
915
916- Several convenience constants have been defined: notably `Style::DEFAULT`
917- `Size<f32>.zero()` is now `Size::<f32>::ZERO`
918- `Point<f32>.zero()` is now  `Point::<f32>::ZERO`
919- `Size::undefined()` is now `Size::NONE`
920
921#### Removals
922
923- 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%).
924- Removed `taffy::number::Number`. Use `Option<f32>` is used instead
925  - the associated public `MinMax` and `OrElse` traits have also been removed; these should never have been public
926- 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).
927
928### Fixes
929
930- Miscellaneous correctness fixes which align our implementation with Chrome:
931
932  - Nodes can only ever have one parent
933  - Fixed rounding of fractional values to follow latest Chrome - values are now rounded the same regardless of their position
934  - Fixed computing free space when using both `flex-grow` and a minimum size
935  - 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)
936  - `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
937- Taffy can now be vendored using `cargo-vendor` (README.md is now included in package).
938
939## 0.1.0
940
941### 0.1.0 Changed
942
943- the `order` field of `Layout` is now public, and describes the relative z-ordering of nodes
944- renamed crate from `stretch2` to `taffy`
945- updated to the latest version of all dependencies to reduce upstream pain caused by duplicate dependencies
946- renamed `stretch::node::Stretch` -> `taffy::node::Taffy`
947
948### 0.1.0 Fixed
949
950- fixed feature strategy for `alloc` and `std`: these can now be compiled together, with `std`'s types taking priority
951
952### 0.1.0 Removed
953
954- removed Javascript / Kotlin / Swift bindings
955  - the maintainer team lacks expertise to keep these working
956  - more serious refactors are planned, and this will be challenging to keep working through that process
957  - if you are interested in helping us maintain bindings to other languages, [get in touch](https://github.com/DioxusLabs/taffy/discussions)!
958- 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)
959- removed the `Direction` and `Overflow` structs, and the corresponding `direction` and `overflow` fields from `Style`
960  - these had no effect in the current code base and were actively misleading
961
962## stretch2 0.4.3
963
964This is the final release of `stretch`: migrate to the crate named `taffy` for future fixes and features!
965
966These notes describe the differences between this release and `stretch` 0.3.2, the abandoned crate from which this library was forked.
967
968### Changed
969
970- updated [assorted dependencies](https://github.com/vislyhq/stretch/commit/a6491117379cea52dedc9584d892594a143e8cb0)
971
972### Fixed
973
974- fixed an exponential performance blow-up with deep nesting
975- fixed percent height values, which were using parent width
976- recomputing layout no longer moves children of non-zero-positioned parent
977- fixed broken Swift bindings