1# Changelog
2
3## 0.10.0
4
5The MSRV for this release is 1.71.
6
7### Support for `direction`
8
9The `direction` property is now supported, allowing for RTL layout of boxes in Block, Flexbox, and CSS Grid layout modes.
10
11### Support for floats
12
13The `float` and `clear` properties are now supported. Support consists of a general-purpose `FloatContext` in the `compute` module, and integration of float layout into Block layout. Block layout now also has a `BlockContext` that allows a `FloatContext` to be shared across an entire Block formatting context.
14
15Float support is feature flagged by the `float_layout` feature.
16
17### Support for parsing styles from CSS string (#929)
18
19All of Taffy's style types (except the top-level `Style` struct) now have `FromStr` implementations that parses the type from the CSS representation of that value (e.g. `30px` or `50%` for `LengthPercentage`. A future version of Taffy will likely add support for parsing `Style` from `;`-seperated CSS.
20
21CSS parsing is feature flagged by the `parse` feature.
22
23### Changed
24
25- Make DetailedGridTracksInfo accessible from a public module (#899)
26- Add `TaffyTree::write_tree` method to debug print the tree into an arbitrary writer (#925)
27- The cache `set` and `set` APIs now take `&LayoutInput` rather than individual values (#933)
28
29### Fixed
30
31- Flexbox: apply gap even when there are auto margins (#938)
32
33## 0.9.3
34
35### Added
36
37- Added write_tree method to utils.
38
39## 0.9.2
40
41### Fixed
42
43- Fix wrong size propogation for absolute elements (#878)
44- Fix bounds check in CellOccupancyMatrix::last_of_type (#890)
45- Use doc_cfg instead of doc_auto_cfg (#868)
46
47### Changed
48
49- Upgraded grid dependency from 0.18 to 1.0 (#864)
50
51## 0.9.1
52
53### Fixed
54
55- Flexbox: don't apply cross-axis stretch alignment to children with auto margins (#861)
56
57## 0.9.0
58
59The MSRV for this release is 1.65.
60
61### Support for named grid lines and grid areas
62
63Taffy now supports named grid lines and areas.
64
65As these rely on arbitrary user-provided strings, Taffy's `Style` struct is now generic
66over a string-like type (via the `CheapCloneStr` trait). Additionally as the `grid` feature is optional,
67it has a `PhantomData` field of that type to make type inference work.
68
69### Changed
70
71- `PrintTree` and `RoundTree`: use `Layout` instead of `&Layout` (#849).
72- Renamed `TrackSizingFunction` to `GridTemplateComponent`
73- Renamed `NonRepeatedTrackSizingFunction` to `TrackSizingFunction`
74- The `Repeat` variant of `GridTemplateComponent` now contains a new `GridTemplateRepetition` struct, which allows
75  line names to be specifed in addition to tracks.
76- The way that grid styles are exposed in the low-level API is now a lot more generic with many associated types.
77
78### Added
79
80- `GridTemplateArea` struct and `Style::grid_template_areas` field
81- `Style::grid_template_column_names` and `Style::grid_template_row_names` fields. If non-empty, these
82  should have length of exactly one greater than the corresponding `grid_template_column`/`grid_template_rows` style.
83
84## 0.8.3
85
86### Fixed
87
88- Fix `serde` feature on 32bit targets (#845)
89
90## 0.8.2
91
92### Fixed
93
94- Fix: Calculate correct new grid size when expanding cell_occupancy_matrix in the negative direction (#843)
95
96## 0.8.1
97
98### Added
99
100- Impl `GridItemStyle` and `BlockContainerStyle` for `Style` (#832).
101
102## 0.8.0
103
104### Highlights
105
106**The big feature in this release is support for `calc()` values in the low-level API.**
107
108To use this API:
109
110- Implement the `resolve_calc_value` method when implementing the `LayoutPartialTree` trait.
111- Pass a type-erased pointer (`*const ()`) to constructors like `LengthPercentage::calc(...)`
112
113Taffy treats the pointer as an opaque value (excepting that it uses the low 3 bits as a tag) which it will
114pass to `LayoutPartialTree::resolve_calc_value` along with a percentage resolution basis when it needs to
115resolve the value.
116
117### Changed
118
119- The representation of many "size" types is now a tagged pointer than an enum. This is to enable `calc()`.
120  The effected types are `LengthPercentage`, `LengthPercentageAuto`, `Dimension`, `MinTrackSizingFunction`, and
121`MaxTrackSizingFunction` types.
122
123### Added
124
125- Special-case "compressible replaced elements" in grid sizing algorithm (#807)
126  This allows for more correct sizing of "replaced" elements such as images that are children
127  of flexbox or grid containers.
128
129### Fixed
130
131- Grid: Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
132- Grid: Fix removed wrong addition, causing items to be misplaced. (#817)
133- Grid: Fix grid placement for items with fixed primary axis (#818)
134- Leaf layout: don't set available space to max-size (#819)
135
136## 0.7.7
137
138### Fixed
139
140- Add `#[inline]` annotation to some methods on `TaffyTree` (#802)
141- Add `TaffyTree::remove_children_range` method (#802)
142
143## 0.7.6
144
145### Fixed
146
147- Fix infinite loop due to float precision in grid layout maximise tracks step (#792)
148
149## 0.7.5
150
151### Fixed
152
153- Grid: only stretch auto tracks if content-alignment is stretch (#783)
154
155## 0.7.4
156
157### Fixed
158
159- Fix detailed grid info for empty grid (#782)
160
161## 0.7.3
162
163### Fixed
164
165- Make `TaffyTree::detailed_layout_info` take `&self` rather than `&mut self` (#779)
166
167## 0.7.2
168
169### Added
170
171- The ability to access computed track sizes and item positions of a CSS Grid layout (#772).
172  This information can be accessed using the `LayoutGridContainer::set_detailed_grid_info` method
173  in the low-level API or the `TaffyTree::detailed_layout_info` method in the high-level API.
174
175## 0.7.1
176
177### Fixed
178
179- Improve interaction of abspos children of block containers with margin collapsing (#760)
180
181### Added
182
183- Add `TaffyTree::unrounded_layout` getter (#765)
184
185### Removed
186
187- The `num-traits` dependency was removed (#761) (#762)
188
189## 0.7.0
190
191### Changed
192
193- BREAKING: The `cache_mut` method on the `LayoutPartialTree` trait has been replaced with a separate `CacheTree` trait. This allows
194  Taffy to be more easily used without caching or with a custom cache implementation.
195- BREAKING: the `TaffyTree::set_children` method now removes the children from their previous parent (if they have one).
196
197### Added
198
199- Helper methods to retrieve content-box sizes were added to `Layout`
200
201## 0.6.3
202
203### Fixes
204
205- Block: ignore margin collapsing when computing static position of abspos items (#747)
206
207## 0.6.2
208
209### Fixes
210
211- Fix: clamp indefinite available space by min- and max- size as appropriate (#742)
212
213## 0.6.1
214
215### Fixes
216
217- Fix calculation of `auto-fill`/`auto-fit` repetition count when container has a definite percentage size (#722)
218- Fix min-size style not affecting intrinsic sizes (#723)
219- Fix documentation of dirty and mark_dirty functions (#724)
220- Fix intrinsic size of scroll containers that have a small explicit flex-basis (#728)
221
222## 0.6.0
223
224### Highlights
225
226- The `Style` struct has been "traitified". This supports Taffy's integration in Servo and generally makes Taffy more flexible. The
227  `Style` struct still exists and implements the new traits so existing uses of Taffy will continue to work as before.
228- The `box-sizing` style is supported
229- Computed margins are output in `Layout`
230
231### Fixes
232
233- Fix `print_tree()` when rounding is disabled (#680)
234- Absolute Insets should be resolved against the container size minus border (#666)
235- Fix flooring hypothetical_main_size by computed min size (#689)
236- Fix flex line cross-size determination (#690)
237- Fix panics in the grid algorithm (#691)
238- Fix resolving flexible lengths (WPT css/flexbox-multiline-min-max test) (#692)
239- Fix wrapping when a max main size style is present (#694)
240- Fix case where Taffy allowed margins to collapse through an element when it shouldn't have (#695)
241
242### Added
243
244- Legacy text align (for laying out `<center>` and `<div align="..">`) is supported
245- Add `is_table` for block items (#701)
246- Impl `Debug` and `Clone` for `Cache` (#688)
247- Implement `Debug` and `PartialEq` for tree types (#697)
248
249## 0.5.2
250
251- Fix block stretch sizing (don't always apply stretch sizing to block containers) (#674)
252- Fix computation of intrinsic main size when it depends on a child's known cross size (#673)
253- Fix panic when GridLine 0 is specified (#671)
254- Docs: Document feature flags and scrape examples (#672)
255- Docs: Update cosmic-text example to cosmic-text 0.12 (#670)
256
257## 0.5.1
258
259- Fix: Clamp block item stretch widths by their min and max width (#664)
260- Fix: Auto margin computation in block layout (#663)
261
262## 0.5.0
263
264The changes in 0.5 are relatively small but the new measure function parameter is a breaking change so it requires a minor version bump.
265
266- Added: A `style: &Style` parameter has been added to measure functions.
267- Added: The `MaybeMath`, `MaybeResolve`, and `ResolveOrZero` traits have been made public.
268- Fix: use SizingMode::Inherent when sizing absolute children of flexbox nodes.
269
270## 0.4.4
271
272### Fixes
273
274- Content alignment (`align-content`/`justify-content`) behaviour was updated to match the latest spec (and Chrome 123+) (#635)
275- Ensure that root Flexbox nodes are floored by their padding-border (#651, #655)
276- Use grid area size not available space when applying aspect ratio to grid containers (#656)
277
278## 0.4.3
279
280### Fixes
281
282- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
283  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
284  but they should be able to fix on their side by clarifying the type passed in
285
286## 0.4.2
287
288- Fixed: single-line flex-container should clamp the line's cross-size (#638)
289- Reduced binary footprint of Taffy from around 300kb to around 150kb (#636)
290
291## 0.4.1
292
293- Fixed: CSS Grid track sizing not respecting growth limits in some circumstances (#624)
294
295## 0.4.0
296
297### Highlights
298
299- Support for CSS Block layout (`display: block`)
300- Support for the `overflow` property (+ `scrollbar_width` for `overflow: scroll`)
301- Improved measure function API
302- Completely refactored low-level API
303- Simplified module hierarchy (+ most types/functions are now exported from the crate root)
304- Expanded set of examples which better document integration with other layout systems (e.g. text layout)
305- Computed values for `padding` and `border` are now output into the `Layout` struct
306
307### Block layout
308
309Support 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.
310
311### Overflow property
312
313Support 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.
314
315- Overflow is settable indpendently in each axis.
316- `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.
317- `Hidden` and `Scroll` affect layout by changing the automatic minimum size of Flexbox and Grid children
318- `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`.
319
320### Measure function changes
321
322The "measure function" API for integrating Taffy with other measurement systems (such as text layout) has been changed to be more flexible
323and to interact better with borrow checking (you can now borrow external data in your measure function!).
324
325- There are no longer per-node measure functions.
326- There is now a single "global" measure function, and a per-node "context" of a user-defined type
327- The `Taffy` tree is now a generic `TaffyTree<T>` where `T` is the "context" type.
328- The measure function is now called for all leaf nodes (nodes without children). If you wish to maintain compatibility with the previous
329  behaviour then your measure function should return `Size::ZERO` for leaf nodes whose context is `None`.
330
331If you are not using measure functions, then the only change you will need to make is from:
332
333```rust
334let mut tree = Taffy::new();
335```
336
337to
338
339```rust
340let mut tree : TaffyTree<()> = TaffyTree::new();
341```
342
343And generally update any uses of `Taffy` in your codebase to `TaffyTree<()>`.
344
345If you are using measure functions then you will need to make some bigger (but straightforward) changes. The following Taffy 0.3 code:
346
347```rust
348let mut tree = Taffy::new();
349let leaf = tree.new_leaf_with_measure(
350  Style::DEFAULT,
351  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>| Size { width: 100.0, height: 200.0 }
352);
353tree.compute_layout(leaf, Size::MAX_CONTENT);
354```
355
356Should become something like the following with Taffy 0.4:
357
358```rust
359let mut tree : TaffyTree<Size> = TaffyTree::new();
360let leaf = tree.new_leaf_with_context(Style::DEFAULT, Size { width: 100.0, height: 200.0 });
361tree.compute_layout_with_measure(
362  leaf,
363  Size::MAX_CONTENT,
364  |known_dimensions: Size<Option<f32>>, available_space: Size<AvailableSpace>, node_id: NodeId, node_context: Option<Size>| {
365    node_context.unwrap_or(Size::ZERO)
366  }
367);
368```
369
370Note that:
371
372- 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).
373- If you don't need a context then you can use `()` for the context type
374- As the single "global" measure function passed to `compute_layout_with_measure` only needs to exist for the duration of a single layout run,
375  it can (mutably) borrow data from it's environment
376
377### Low-level API (`LayoutTree` trait) refactor
378
379The low-level API has been completely reworked:
380
381- The `LayoutTree` trait has been split into 5 smaller traits which live in the `taffy::tree:traits` module (along with their associated documentation)
382- The following methods have been removed from split `LayoutTree` traits entirely: `parent`, `is_childless`, `measure_node`, `needs_measure`, and `mark_dirty`.
383- `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`.
384- Support for running each layout algorithm individually on a single node via the following top-level functions:
385  - `compute_flexbox_layout`
386  - `compute_grid_layout`
387  - `compute_block_layout`
388  - `compute_leaf_layout`
389  - `compute_root_layout`
390  - `compute_hidden_layout`
391
392It 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
393improved 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).
394
395### Module hierarchy changes
396
397The 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`.
398
399Specific changes:
400
401- The `math` module has been made private
402- The `axis` module has been merged into the `geometry` module
403- The debug module is no longer public. The `print_tree` function is now accessible under `util`.
404- All types from the `node`, `data`, `layout`, `error` and `cache` modules have been moved to the  the `tree` module.
405- The `layout_flexbox()` function has been removed from the prelude. Use `taffy::compute_flexbox_layout` instead.
406
407### Many APIs have been renamed to replace `points` or `Points` with `length` or `Length`
408
409This new name better describes one-dimensional measure of space in some unspecified unit
410which is often unrelated to the PostScript point or the CSS `pt` unit.
411
412This also removes a misleading similarity with the 2D `Point`,
413whose components can have any unit and are not even necessarily absolute lengths.
414
415Example usage change:
416
417```diff
418 use taffy::prelude::*;
419
420 // …
421
422 let header_node = taffy
423     .new_leaf(
424         Style {
425-            size: Size { width: points(800.0), height: points(100.0) },
426+            size: Size { width: length(800.0), height: length(100.0) },
427             ..Default::default()
428         },
429     ).unwrap();
430```
431
432### Other Changes
433
434- The `Taffy` type was renamed to `TaffyTree` and made generic of a context parameter
435- The Flexbox algorithm has now been moved behind the `flexbox` feature. The `flexbox` feature is enabled by default.
436- The `justify_self` property has been moved behind the `grid` feature.
437- Fixed misspelling: `RunMode::PeformLayout` renamed into `RunMode::PerformLayout` (added missing `r`).
438- `serde` dependency has been made compatible with `no_std` environments
439- `slotmap` dependency has been made compatible with `no_std` environments
440- 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.
441- Added `total_node_count()` method to the `TaffyTree` which returns the total number of nodes in the tree.
442- Added `get_disjoint_node_context_mut()` method to the `TaffyTree`. This can be used to safely get multiple mutable borrows at the same time.
443
444## 0.3.19
445
446### Fixes
447
448- Fix compilation error in `evenly_sized_tracks` style helper in recent versions of rustc caused by a change/regression in type
449  inference (#643). Note that 3rd-party code that call style helpers that take an `Into<f32>` parameter may still be affected by this issue,
450  but they should be able to fix on their side by clarifying the type passed in
451
452## 0.3.18
453
454### Fixes
455
456- Fix computation of Flexbox automatic minimum size when grid or flexbox child has an explicit width/height style set (#576)
457
458## 0.3.17
459
460### Added
461
462- Added `total_node_count` method to the `Taffy` struct. Returns the total number of nodes in the tree.
463
464## 0.3.16
465
466### Fixes
467
468- Improve performance of flexbox columns
469
470## 0.3.15
471
472### Fixes
473
474- Fix justify-content and align-content when free space is negative (content overflows container) (#549) (#551)
475
476## 0.3.14
477
478### Fixes
479
480- 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)
481
482## 0.3.13
483
484### Fixes
485
486- Fix rounding accumulation bug (#521) (Fixes #501 and bevyengine/bevy#8911)
487- Flexbox: pass correct cross-axis available space when computing an item's intrinsic main size (#522)(Fixes bevyengine/bevy#9350)
488- Flexbox: Subtract child margin not parent margin when computing stretch-alignment known size
489- Grid: Make CSS Grid algorithm correctly apply max width/height and available space when it is the root node (#491)
490- Grid: Fix CSS Grid "auto track" / placement bugs #481
491  - Fix divide by zero when using grid_auto_rows/grid_auto_columns with zero negative implicit tracks
492  - Fix over counting of tracks (leading to incorrect container heights) when auto-placing in grids that contain negative implicit tracks.
493  - Fix axis conflation in auto-placement code when grid_auto_flow is column
494  - Fix assignment of auto track sizes when initializing negative implicit tracks
495- Leaf: Apply margins to leaf nodes when computing available space for measure functions
496- Leaf: Reserve space for padding/borders in nodes with measure functions (#497)
497  
498  **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.
499
500### Dependencies
501
502- Upgrade `grid` to `0.10`. This eliminates the transitive dependency on `no-std-compat`.
503
504## 0.3.12
505
506### Fixes
507
508- Fix caching issue when toggling `display:none` on and off
509
510## 0.3.11
511
512### Fixes
513
514- Fix exponential blowup when laying out trees containing nodes with min and max sizes.
515
516## 0.3.10
517
518### Fixes
519
520- Fix sizing of children when the available_space < min_size (#407)
521
522## 0.3.9
523
524### Fixes
525
526- 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)
527
528## 0.3.8
529
530### Fixes
531
532- Fix incorrect min-content size for `flex-wrap: wrap` nodes (bevyengine/bevy#8082)
533
534## 0.3.7
535
536### Fixes
537
538- Fix: Make `padding` and `border` floor node sizes (#372)
539- Fix: Prevent percentages contributing to min-content sizes (#388) (also fixes bevyengine/bevy#8017)
540
541## 0.3.6
542
543### Fixes
544
545- Fix: Ignore `align_content` when `flex_wrap` is set to `nowrap` (#383)
546
547## 0.3.5
548
549### Fixes
550
551- Fix `display: none` when it is set on a flexbox child (#380)
552- Fix `display: none` when it is set on a grid child (#381)
553
554## 0.3.4
555
556### Fixes
557
558- Fix `display: none` when it is set for the only node in the hierarchy (#377)
559
560## 0.3.3
561
562### Added
563
564- 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.
565
566### Fixes
567
568- Fixed rounding algorithm such that it never leaves gaps between adjacent nodes (#369)
569- Fixed compiling with the `grid` feature disabled (#370)
570- Fixed compiling with the `std` feature disabled
571
572## 0.3.2
573
574### Fixes
575
576- Allow partial nested values to be deserialized into a `Style` using the `serde` feature.
577
578## 0.3.1
579
580### Fixes
581
582- The `serde` feature now works when the `grid` feature is enabled
583
584## 0.3.0
585
586### Highlights
587
588- [CSS Grid algorithm support](#new-feature-css-grid)
589- [Style helper functions](#new-feature-style-helpers)
590
591See below for details of breaking changes.
592
593### New Feature: CSS Grid
594
595We 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`.
596
597#### Learning Resources
598
599Taffy 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:
600
601- [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.
602- [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.
603
604#### Supported Features & Properties
605
606In addition to the usual sizing/spacing properties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
607
608| Property                  | Explanation                                                                                    |
609| ---                       | ---                                                                                            |
610| [`grid-template-columns`] | The track sizing functions of the grid's explicit columns                                      |
611| [`grid-template-rows`]    | The track sizing functions of the grid's explicit rows                                         |
612| [`grid-auto-rows`]        | Track sizing functions for the grid's implicitly generated rows                                |
613| [`grid-auto-columns`]     | Track sizing functions for the grid's implicitly generated columns                             |
614| [`grid-auto-flow`]        | Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely.         |
615| [`gap`]                   | The size of the vertical and horizontal gaps between grid rows/columns                         |
616| [`align-content`]         | Align grid tracks within the container in the inline (horizontal) axis                         |
617| [`justify-content`]       | Align grid tracks within the container in the block (vertical) axis                            |
618| [`align-items`]           | Align the child items within their grid areas in the inline (horizontal) axis                  |
619| [`justify-items`]         | Align the child items within their grid areas in the block (vertical) axis                     |
620
621And the following Grid style properties are supported on Grid Items (children):
622
623| Property                  | Explanation                                                                                    |
624| ---                       | ---                                                                                            |
625| [`grid-row`]              | The (row) grid line the item starts at (or a span)                                             |
626| [`grid-column`]           | The (column) grid line the item end at (or a span)                                             |
627| [`align-self`]            | Align the item within it's grid area in the inline (horizontal) axis. Overrides `align-items`. |
628| [`justify-self`]          | Align the item within it's grid area in the block (vertical) axis. Overrides `justify-items`.  |
629
630[`grid-template-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-columns
631[`grid-template-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-rows
632[`grid-auto-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-rows
633[`grid-auto-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-columns
634[`grid-auto-flow`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-flow
635[`gap`]: https://developer.mozilla.org/en-US/docs/Web/CSS/gap
636[`align-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align_content
637[`justify-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify_content
638[`align-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-items
639[`justify-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-items
640[`grid-row`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
641[`grid-column`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-column
642[`align-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-self
643[`justify-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-self
644
645The following properties and features are not currently supported:
646
647- Subgrids
648- Masonry grid layout
649- Named grid lines
650- Named areas: `grid-template-areas` and `grid-area`
651- `grid-template` or `grid` shorthand
652
653#### Example
654
655See [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:
656
657```bash
658cargo run --example grid_holy_grail --features grid
659```
660
661### New Feature: Style Helpers
662
663Ten 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.
664
665For example, instead of:
666
667```rust
668let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };
669```
670
671you can now write
672
673```rust
674let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };
675```
676
677And 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
678
679```rust
680let size : Size<Dimension> = points(100.0);
681```
682
683Available style helpers:
684
685<table>
686  <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead>
687  <tbody>
688    <tr>
689      <td rowspan="3"><code>LengthPercentage</code></td>
690      <td><code>zero()</code></td>
691      <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td>
692    </tr>
693    <tr>
694      <td><code>points(val:&nbsp;f32)</code></td>
695      <td>Generates a <code>Points</code> variant with the specified value</td>
696    </tr>
697    <tr>
698      <td><code>percent(val:&nbsp;f32)</code></td>
699      <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td>
700    </tr>
701    <tr>
702      <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td>
703      <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td>
704    </tr>
705    <tr>
706      <td><code>auto()</code></td>
707      <td>Generates an <code>Auto</code> variant</td>
708    </tr>
709    <tr>
710      <td rowspan="3"><code>MinTrackSizingFunction</code></td>
711      <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td>
712    </tr>
713    <tr>
714      <td><code>min_content()</code></td>
715      <td>Generates an <code>MinContent</code> variant</td>
716    </tr>
717      <tr>
718      <td><code>max_content()</code></td>
719      <td>Generates an <code>MinContent</code> variant</td>
720    </tr>
721    <tr>
722      <td rowspan="3"><code>MaxTrackSizingFunction</code></td>
723      <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td>
724    </tr>
725    <tr>
726      <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td>
727      <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>
728    </tr>
729      <tr>
730      <td><code>fr(fraction:&nbsp;f32)</code></td>
731      <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td>
732    </tr>
733    <tr>
734      <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td>
735      <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td>
736    </tr>
737    <tr>
738      <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td>
739      <td>Equivalent to CSS <code>minmax()</code> function.</td>
740    </tr>
741    <tr>
742      <td><code>flex(fraction:&nbsp;f32)</code></td>
743      <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td>
744    </tr>
745    <tr>
746      <td rowspan="2"><code>TrackSizingFunction</code></td>
747      <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td>
748    </tr>
749    <tr>
750      <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td>
751      <td>Equivalent to css <code>repeat()</code> function.</td>
752    </tr>
753    <tr>
754      <td><code>Vec&lt;TrackSizingFunction&gt;</code></td>
755      <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td>
756      <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td>
757    </tr>
758    <tr>
759      <td rowspan="3"><code>AvailableSpace</code></td>
760      <td><code>auto()</code></td>
761      <td>Generates an <code>Auto</code> variant</td>
762    </tr>
763    <tr>
764      <td><code>min_content()</code></td>
765      <td>Generates an <code>MinContent</code> variant</td>
766    </tr>
767      <tr>
768      <td><code>max_content()</code></td>
769      <td>Generates an <code>MinContent</code> variant</td>
770    </tr>
771    <tr>
772      <td><code>Size&lt;T&gt;</code></td>
773      <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>
774    </tr>
775    <tr>
776      <td><code>Rect&lt;T&gt;</code></td>
777      <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>
778    </tr>
779  </tbody>
780</table>
781
782### Breaking API changes
783
784#### Changes to alignment style types
785
786- `AlignContent` and `JustifyContent` has been merged.
787  - `JustifyContent` is now an alias of `AlignContent` and contains the `Stretch` variant.
788  - This variant will be *ignored* (falling back to `Start`) when applied Flexbox containers. It is valid value for Grid containers.
789- `AlignItems` and `AlignSelf` have been merged.
790  - The `Auto` variant of `AlignSelf` has been removed. You should now use `Option::None` if you wish to specify `AlignSelf::Auto`.
791  - `AlignSelf` is now an alias of `AlignItems`.
792  - `JustifyItems` and `JustifySelf` aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.
793- `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.
794
795#### Strict style types
796
797- New types `LengthPercentage` and `LengthPercentageAuto` have been added.
798  - `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.
799  - `LengthPercentageAuto` is currently identical to `Dimension` but will allow us to expand dimension in future to support values like `MinContent`, `MaxContent` and `FitContent`.
800- 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).
801
802#### Position properties renamed
803
804- 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)
805- 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`.
806
807#### Changes to `LayoutTree`
808
809- Added generic associated type to `LayoutTree` for a `ChildIter`, an iterator on the children of a given node.
810- 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.
811- 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.
812- Added `is_childless` method to `LayoutTree` for querying whether a node has no children.
813
814#### `AvailableSpace` has been moved
815
816The `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.
817
818### Fixes
819
820- Flexbox nodes sized under a min-content constraint now size correctly (#291)
821- Aspect ratio is now applied correctly in many circumstances
822- Absolutely positioned items now apply margins correctly
823- Min/max size are now applied correctly
824- Inset applied incorrectly to relatively positioned flexbox children when both `top` and `bottom` or `left` and `right` were specified (#348)
825- 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)
826
827### Removed
828
829- 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.
830- 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.
831- 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.
832
833## 0.2.2
834
835### Fixes
836
837- Border or padding on the horizontal axis could, in some cases, increase the height of nodes.
838
839## 0.2.1
840
841### Fixes
842
843- 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`.
844- `taffy::compute_layout` has been made public allowing Taffy to be used with custom storage (#263)
845
846## 0.2.0
847
848### New features
849
850#### Flexbox "gap" and `AlignContent::SpaceEvenly`
851
852The [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.
853
854Additionally 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)
855
856#### Debug module and cargo feature
857
858Two debugging features have been added:
859
860- `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.
861- A cargo feature `debug`. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).
862
863### Performance improvements
864
865A number of performance improvements have landed since taffy 0.1:
866
867- 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%.
868- 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!
869
870#### Benchmarks vs. Taffy 0.1
871
872| Benchmark                                 | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
873| ---                                       | ---       | ---       | ---                   |
874| wide/1_000 nodes (2-level hierarchy)      | 699.18 µs | 445.01 µs | -36.279%              |
875| wide/10_000 nodes (2-level hierarchy)     | 8.8244 ms | 7.1313 ms | -16.352%              |
876| wide/100_000 nodes (2-level hierarchy)    | 204.48 ms | 242.93 ms | +18.803%              |
877| deep/4000 nodes (12-level hierarchy))     | 5.2320 s  | 2.7363 ms | -99.947%              |
878| deep/10_000 nodes (14-level hierarchy)    | 75.207 s  | 6.9415 ms | -99.991%              |
879| deep/100_000 nodes (17-level hierarchy)   | -         | 102.72 ms | -                     |
880| deep/1_000_000 nodes (20-level hierarchy) | -         | 799.35 ms | -                     |
881
882(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
883
884As 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.
885
886However, 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.
887
888#### Benchmarks vs. [Yoga](https://github.com/facebook/yoga)
889
890Yoga 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.
891
892| Benchmark | Yoga | Taffy 0.2 |
893| --- | --- | --- |
894| yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
895| yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
896| yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
897| yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
898| yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 ms |
899
900(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
901
902While 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!
903
904### Breaking API changes
905
906#### Node creation changes
907
908- `taffy::Node` is now unique only to the Taffy instance from which it was created.
909- Renamed `Taffy.new_node(..)` -> `Taffy.new_with_children(..)`
910- Renamed `Taffy.new_leaf()` -> `Taffy.new_leaf_with_measure()`
911- Added `taffy::node::Taffy.new_leaf()` which allows the creation of new leaf-nodes without having to supply a measure function
912
913#### Error handling/representation improvements
914
915- Renamed `taffy::Error` -> `taffy::error::TaffyError`
916- Replaced `taffy::error::InvalidChild` with a new `InvalidChild` variant of `taffy::error::TaffyError`
917- Replaced `taffy::error::InvalidNode` with a new `InvalidNode` variant of `taffy::error::TaffyError`
918- The following method new return `Err(TaffyError::ChildIndexOutOfBounds)` instead of panicking:
919  - `taffy::Taffy::remove_child_at_index`
920  - `taffy::Taffy::replace_child_at_index`
921  - `taffy::Taffy::child_at_index`
922- `Taffy::remove` now returns a `Result<usize, Error>`, to indicate if the operation was successful (and if it was, which ID was invalidated).
923
924#### Some uses of `Option<f32>` replaced with a new `AvailableSpace` enum
925
926A new enum `Taffy::layout::AvailableSpace` has been added.
927
928The definition looks like this:
929
930```rust
931/// The amount of space available to a node in a given axis
932pub enum AvailableSpace {
933    /// The amount of space available is the specified number of pixels
934    Definite(f32),
935    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
936    MinContent,
937    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
938    MaxContent,
939}
940```
941
942This 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`).
943
944And 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..
945
946#### Builder methods are now `const` where possible
947
948- Several convenience constants have been defined: notably `Style::DEFAULT`
949- `Size<f32>.zero()` is now `Size::<f32>::ZERO`
950- `Point<f32>.zero()` is now  `Point::<f32>::ZERO`
951- `Size::undefined()` is now `Size::NONE`
952
953#### Removals
954
955- 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%).
956- Removed `taffy::number::Number`. Use `Option<f32>` is used instead
957  - the associated public `MinMax` and `OrElse` traits have also been removed; these should never have been public
958- 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).
959
960### Fixes
961
962- Miscellaneous correctness fixes which align our implementation with Chrome:
963
964  - Nodes can only ever have one parent
965  - Fixed rounding of fractional values to follow latest Chrome - values are now rounded the same regardless of their position
966  - Fixed computing free space when using both `flex-grow` and a minimum size
967  - 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)
968  - `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
969- Taffy can now be vendored using `cargo-vendor` (README.md is now included in package).
970
971## 0.1.0
972
973### 0.1.0 Changed
974
975- the `order` field of `Layout` is now public, and describes the relative z-ordering of nodes
976- renamed crate from `stretch2` to `taffy`
977- updated to the latest version of all dependencies to reduce upstream pain caused by duplicate dependencies
978- renamed `stretch::node::Stretch` -> `taffy::node::Taffy`
979
980### 0.1.0 Fixed
981
982- fixed feature strategy for `alloc` and `std`: these can now be compiled together, with `std`'s types taking priority
983
984### 0.1.0 Removed
985
986- removed Javascript / Kotlin / Swift bindings
987  - the maintainer team lacks expertise to keep these working
988  - more serious refactors are planned, and this will be challenging to keep working through that process
989  - if you are interested in helping us maintain bindings to other languages, [get in touch](https://github.com/DioxusLabs/taffy/discussions)!
990- 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)
991- removed the `Direction` and `Overflow` structs, and the corresponding `direction` and `overflow` fields from `Style`
992  - these had no effect in the current code base and were actively misleading
993
994## stretch2 0.4.3
995
996This is the final release of `stretch`: migrate to the crate named `taffy` for future fixes and features!
997
998These notes describe the differences between this release and `stretch` 0.3.2, the abandoned crate from which this library was forked.
999
1000### Changed
1001
1002- updated [assorted dependencies](https://github.com/vislyhq/stretch/commit/a6491117379cea52dedc9584d892594a143e8cb0)
1003
1004### Fixed
1005
1006- fixed an exponential performance blow-up with deep nesting
1007- fixed percent height values, which were using parent width
1008- recomputing layout no longer moves children of non-zero-positioned parent
1009- fixed broken Swift bindings