1# Release Notes
2
3## 0.3.16
4
5### Fixes
6
7- Improve performance of flexbox columns
8
9## 0.3.15
10
11### Fixes
12
13- Fix justify-content and align-content when free space is negative (content overflows container) (#549) (#551)
14
15## 0.3.14
16
17### Fixes
18
19- Flexbox: 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)
20
21## 0.3.13
22
23### Fixes
24
25- Fix rounding accumulation bug (#521) (Fixes #501 and bevyengine/bevy#8911)
26- Flexbox: pass correct cross-axis available space when computing an item's intrinsic main size (#522)(Fixes bevyengine/bevy#9350)
27- Flexbox: Subtract child margin not parent margin when computing stretch-alignment known size
28- Grid: Make CSS Grid algorithm correctly apply max width/height and available space when it is the root node (#491)
29- Grid: Fix CSS Grid "auto track" / placement bugs #481
30  - Fix divide by zero when using grid_auto_rows/grid_auto_columns with zero negative implicit tracks
31  - Fix over counting of tracks (leading to incorrect container heights) when auto-placing in grids that contain negative implicit tracks.
32  - Fix axis conflation in auto-placement code when grid_auto_flow is column
33  - Fix assignment of auto track sizes when initializing negative implicit tracks
34- Leaf: Apply margins to leaf nodes when computing available space for measure functions
35- Leaf: Reserve space for padding/borders in nodes with measure functions (#497)
36  
37  **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.
38
39### Dependencies
40
41- Upgrade `grid` to `0.10`. This eliminates the transitive dependency on `no-std-compat`.
42
43## 0.3.12
44
45### Fixes
46
47- Fix caching issue when toggling `display:none` on and off
48
49## 0.3.11
50
51### Fixes
52
53- Fix exponential blowup when laying out trees containing nodes with min and max sizes.
54
55## 0.3.10
56
57### Fixes
58
59- Fix sizing of children when the available_space < min_size (#407)
60
61## 0.3.9
62
63### Fixes
64
65- 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)
66
67## 0.3.8
68
69### Fixes
70
71- Fix incorrect min-content size for `flex-wrap: wrap` nodes (bevyengine/bevy#8082)
72
73## 0.3.7
74
75### Fixes
76
77- Fix: Make `padding` and `border` floor node sizes (#372)
78- Fix: Prevent percentages contributing to min-content sizes (#388) (also fixes bevyengine/bevy#8017)
79
80## 0.3.6
81
82### Fixes
83
84- Fix: Ignore `align_content` when `flex_wrap` is set to `nowrap` (#383)
85
86## 0.3.5
87
88### Fixes
89
90- Fix `display: none` when it is set on a flexbox child (#380)
91- Fix `display: none` when it is set on a grid child (#381)
92
93## 0.3.4
94
95### Fixes
96
97- Fix `display: none` when it is set for the only node in the hierarchy (#377)
98
99## 0.3.3
100
101### Added
102
103- 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.
104
105### Fixes
106
107- Fixed rounding algorithm such that it never leaves gaps between adjacent nodes (#369)
108- Fixed compiling with the `grid` feature disabled (#370)
109- Fixed compiling with the `std` feature disabled
110
111## 0.3.2
112
113### Fixes
114
115- Allow partial nested values to be deserialized into a `Style` using the `serde` feature.
116
117## 0.3.1
118
119### Fixes
120
121- The `serde` feature now works when the `grid` feature is enabled
122
123## 0.3.0
124
125### Highlights
126
127- [CSS Grid algorithm support](#new-feature-css-grid)
128- [Style helper functions](#new-feature-style-helpers)
129
130See below for details of breaking changes.
131
132### New Feature: CSS Grid
133
134We 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`.
135
136#### Learning Resources
137
138Taffy 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:
139
140- [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.
141- [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 comphrehensive written explanation of the different Grid propertie and how they work.
142
143#### Supported Features & Properties
144
145In addition to the usual sizing/spacing proerties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
146
147| Property                  | Explanation                                                                                    |
148| ---                       | ---                                                                                            |
149| [`grid-template-columns`] | The track sizing functions of the grid's explicit columns                                      |
150| [`grid-template-rows`]    | The track sizing functions of the grid's explicit rows                                         |
151| [`grid-auto-rows`]        | Track sizing functions for the grid's implicitly generated rows                                |
152| [`grid-auto-columns`]     | Track sizing functions for the grid's implicitly generated columns                             |
153| [`grid-auto-flow`]        | Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely.         |
154| [`gap`]                   | The size of the vertical and horizontal gaps between grid rows/columns                         |
155| [`align-content`]         | Align grid tracks within the container in the inline (horizontal) axis                         |
156| [`justify-content`]       | Align grid tracks within the container in the block (vertical) axis                            |
157| [`align-items`]           | Align the child items within their grid areas in the inline (horizontal) axis                  |
158| [`justify-items`]         | Align the child items within their grid areas in the block (vertical) axis                     |
159
160And the following Grid style properties are supported on Grid Items (children):
161
162| Property                  | Explanation                                                                                    |
163| ---                       | ---                                                                                            |
164| [`grid-row`]              | The (row) grid line the item starts at (or a span)                                             |
165| [`grid-column`]           | The (column) grid line the item end at (or a span)                                             |
166| [`align-self`]            | Align the item within it's grid area in the inline (horizontal) axis. Overrides `align-items`. |
167| [`justify-self`]          | Align the item within it's grid area in the block (vertical) axis. Overrides `justify-items`.  |
168
169[`grid-template-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-columns
170[`grid-template-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-template-rows
171[`grid-auto-rows`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-rows
172[`grid-auto-columns`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-columns
173[`grid-auto-flow`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-auto-flow
174[`gap`]: https://developer.mozilla.org/en-US/docs/Web/CSS/gap
175[`align-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align_content
176[`justify-content`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify_content
177[`align-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-items
178[`justify-items`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-items
179[`grid-row`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
180[`grid-column`]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-column
181[`align-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/align-self
182[`justify-self`]: https://developer.mozilla.org/en-US/docs/Web/CSS/justify-self
183
184The following properties and features are not currently supported:
185
186- Subgrids
187- Masonry grid layout
188- Named grid lines
189- Named areas: `grid-template-areas` and `grid-area`
190- `grid-template` or `grid` shorthand
191
192#### Example
193
194See [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:
195
196```bash
197cargo run --example grid_holy_grail --features grid
198```
199
200### New Feature: Style Helpers
201
202Ten 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.
203
204For example, instead of:
205
206```rust
207let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };
208```
209
210you can now write
211
212```rust
213let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };
214```
215
216And 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
217
218```rust
219let size : Size<Dimension> = points(100.0);
220```
221
222Available style helpers:
223
224<table>
225  <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead>
226  <tbody>
227    <tr>
228      <td rowspan="3"><code>LengthPercentage</code></td>
229      <td><code>zero()</code></td>
230      <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td>
231    </tr>
232    <tr>
233      <td><code>points(val:&nbsp;f32)</code></td>
234      <td>Generates a <code>Points</code> variant with the specified value</td>
235    </tr>
236    <tr>
237      <td><code>percent(val:&nbsp;f32)</code></td>
238      <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td>
239    </tr>
240    <tr>
241      <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td>
242      <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td>
243    </tr>
244    <tr>
245      <td><code>auto()</code></td>
246      <td>Generates an <code>Auto</code> variant</td>
247    </tr>
248    <tr>
249      <td rowspan="3"><code>MinTrackSizingFunction</code></td>
250      <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td>
251    </tr>
252    <tr>
253      <td><code>min_content()</code></td>
254      <td>Generates an <code>MinContent</code> variant</td>
255    </tr>
256      <tr>
257      <td><code>max_content()</code></td>
258      <td>Generates an <code>MinContent</code> variant</td>
259    </tr>
260    <tr>
261      <td rowspan="3"><code>MaxTrackSizingFunction</code></td>
262      <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td>
263    </tr>
264    <tr>
265      <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td>
266      <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>
267    </tr>
268      <tr>
269      <td><code>fr(fraction:&nbsp;f32)</code></td>
270      <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td>
271    </tr>
272    <tr>
273      <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td>
274      <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td>
275    </tr>
276    <tr>
277      <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td>
278      <td>Equivalent to CSS <code>minmax()</code> function.</td>
279    </tr>
280    <tr>
281      <td><code>flex(fraction:&nbsp;f32)</code></td>
282      <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td>
283    </tr>
284    <tr>
285      <td rowspan="2"><code>TrackSizingFunction</code></td>
286      <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td>
287    </tr>
288    <tr>
289      <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td>
290      <td>Equivalent to css <code>repeat()</code> function.</td>
291    </tr>
292    <tr>
293      <td><code>Vec&lt;TrackSizingFunction&gt;</code></td>
294      <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td>
295      <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td>
296    </tr>
297    <tr>
298      <td rowspan="3"><code>AvailableSpace</code></td>
299      <td><code>auto()</code></td>
300      <td>Generates an <code>Auto</code> variant</td>
301    </tr>
302    <tr>
303      <td><code>min_content()</code></td>
304      <td>Generates an <code>MinContent</code> variant</td>
305    </tr>
306      <tr>
307      <td><code>max_content()</code></td>
308      <td>Generates an <code>MinContent</code> variant</td>
309    </tr>
310    <tr>
311      <td><code>Size&lt;T&gt;</code></td>
312      <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>
313    </tr>
314    <tr>
315      <td><code>Rect&lt;T&gt;</code></td>
316      <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>
317    </tr>
318  </tbody>
319</table>
320
321### Breaking API changes
322
323#### Changes to alignment style types
324
325- `AlignContent` and `JustifyContent` has been merged.
326  - `JustifyContent` is now an alias of `AlignContent` and contains the `Stretch` variant.
327  - This variant will be *ignored* (falling back to `Start`) when applied Flexbox containers. It is valid value for Grid containers.
328- `AlignItems` and `AlignSelf` have been merged.
329  - The `Auto` variant of `AlignSelf` has been removed. You should now use `Option::None` if you wish to specify `AlignSelf::Auto`.
330  - `AlignSelf` is now an alias of `AlignItems`.
331  - `JustifyItems` and `JustifySelf` aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.
332- `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.
333
334#### Strict style types
335
336- New types `LengthPercentage` and `LengthPercentageAuto` have been added.
337  - `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.
338  - `LengthPercentageAuto` is currently identical to `Dimension` but will allow us to expand dimension in future to support values like `MinContent`, `MaxContent` and `FitContent`.
339- 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).
340
341#### Position properties renamed
342
343- 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)
344- 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`.
345
346#### Changes to `LayoutTree`
347
348- Added generic associated type to `LayoutTree` for a `ChildIter`, an iterator on the children of a given node.
349- 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.
350- 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.
351- Added `is_childless` method to `LayoutTree` for querying whether a node has no children.
352
353#### `AvailableSpace` has been moved
354
355The `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.
356
357### Fixes
358
359- Flexbox nodes sized under a min-content constraint now size correctly (#291)
360- Aspect ratio is now applied correctly in many circumstances
361- Absolutely positioned items now apply margins correctly
362- Min/max size are now applied correctly
363- Inset applied incorrectly to relatively positioned flexbox children when both `top` and `bottom` or `left` and `right` were specified (#348)
364- 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)
365
366### Removed
367
368- 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.
369- 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.
370- 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.
371
372## 0.2.2
373
374### Fixes
375
376- Border or padding on the horizontal axis could, in some cases, increase the height of nodes.
377
378## 0.2.1
379
380### Fixes
381
382- 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`.
383- `taffy::compute_layout` has been made public allowing Taffy to be used with custom storage (#263)
384
385## 0.2.0
386
387### New features
388
389#### Flexbox "gap" and `AlignContent::SpaceEvenly`
390
391The [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.
392
393Additionally 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)
394
395#### Debug module and cargo feature
396
397Two debugging features have been added:
398
399- `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.
400- A cargo feature `debug`. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).
401
402### Performance improvements
403
404A number of performance improvements have landed since taffy 0.1:
405
406- 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%.
407- 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 chache slots to better match the actual usage patterns of the flexbox layout algorithm. This had a particularly dramatic effect on deep hierachies (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!
408
409#### Benchmarks vs. Taffy 0.1
410
411| Benchmark                                 | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
412| ---                                       | ---       | ---       | ---                   |
413| wide/1_000 nodes (2-level hierarchy)      | 699.18 µs | 445.01 µs | -36.279%              |
414| wide/10_000 nodes (2-level hierarchy)     | 8.8244 ms | 7.1313 ms | -16.352%              |
415| wide/100_000 nodes (2-level hierarchy)    | 204.48 ms | 242.93 ms | +18.803%              |
416| deep/4000 nodes (12-level hierarchy))     | 5.2320 s  | 2.7363 ms | -99.947%              |
417| deep/10_000 nodes (14-level hierarchy)    | 75.207 s  | 6.9415 ms | -99.991%              |
418| deep/100_000 nodes (17-level hierarchy)   | -         | 102.72 ms | -                     |
419| deep/1_000_000 nodes (20-level hierarchy) | -         | 799.35 ms | -                     |
420
421(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
422
423As 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.
424
425However, in the "deep" benchmarks we see dramatic improvements. The previous version of Taffy suffered from exponential blowup in the case of deeply nested hierachies. This has resulted in somewhat silly improvements like the 10,000 node (14-level) hierachy 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.
426
427#### Benchmarks vs. [Yoga](https://github.com/facebook/yoga)
428
429Yoga 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.
430
431| Benchmark | Yoga | Taffy 0.2 |
432| --- | --- | --- |
433| yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
434| yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
435| yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
436| yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
437| yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 ms |
438
439(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))
440
441While 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!
442
443### Breaking API changes
444
445#### Node creation changes
446
447- `taffy::Node` is now unique only to the Taffy instance from which it was created.
448- Renamed `Taffy.new_node(..)` -> `Taffy.new_with_children(..)`
449- Renamed `Taffy.new_leaf()` -> `Taffy.new_leaf_with_measure()`
450- Added `taffy::node::Taffy.new_leaf()` which allows the creation of new leaf-nodes without having to supply a measure function
451
452#### Error handling/representation improvements
453
454- Renamed `taffy::Error` -> `taffy::error::TaffyError`
455- Replaced `taffy::error::InvalidChild` with a new `InvalidChild` variant of `taffy::error::TaffyError`
456- Replaced `taffy::error::InvalidNode` with a new `InvalidNode` variant of `taffy::error::TaffyError`
457- The following method new return `Err(TaffyError::ChildIndexOutOfBounds)` instead of panicking:
458  - `taffy::Taffy::remove_child_at_index`
459  - `taffy::Taffy::replace_child_at_index`
460  - `taffy::Taffy::child_at_index`
461- `Taffy::remove` now returns a `Result<usize, Error>`, to indicate if the operation was sucessful (and if it was, which ID was invalidated).
462
463#### Some uses of `Option<f32>` replaced with a new `AvailableSpace` enum
464
465A new enum `Taffy::layout::AvailableSpace` has been added.
466
467The definition looks like this:
468
469```rust
470/// The amount of space available to a node in a given axis
471pub enum AvailableSpace {
472    /// The amount of space available is the specified number of pixels
473    Definite(f32),
474    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
475    MinContent,
476    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
477    MaxContent,
478}
479```
480
481This 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`).
482
483And 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..
484
485#### Builder methods are now `const` where possible
486
487- Several convenience constants have been defined: notably `Style::DEFAULT`
488- `Size<f32>.zero()` is now `Size::<f32>::ZERO`
489- `Point<f32>.zero()` is now  `Point::<f32>::ZERO`
490- `Size::undefined()` is now `Size::NONE`
491
492#### Removals
493
494- 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%).
495- Removed `taffy::number::Number`. Use `Option<f32>` is used instead
496  - the associated public `MinMax` and `OrElse` traits have also been removed; these should never have been public
497- 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).
498
499### Fixes
500
501- Miscellaneous correctness fixes which align our implementation with Chrome:
502
503  - Nodes can only ever have one parent
504  - Fixed rounding of fractional values to follow latest Chrome - values are now rounded the same regardless of their position
505  - Fixed computing free space when using both `flex-grow` and a minimum size
506  - 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)
507  - `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
508- Taffy can now be vendored using `cargo-vendor` (README.md is now included in package).
509
510## 0.1.0
511
512### 0.1.0 Changed
513
514- the `order` field of `Layout` is now public, and describes the relative z-ordering of nodes
515- renamed crate from `stretch2` to `taffy`
516- updated to the latest version of all dependencies to reduce upstream pain caused by duplicate dependencies
517- renamed `stretch::node::Strech` -> `taffy::node::Taffy`
518
519### 0.1.0 Fixed
520
521- fixed feature strategy for `alloc` and `std`: these can now be compiled together, with `std`'s types taking priority
522
523### 0.1.0 Removed
524
525- removed Javascript / Kotlin / Swift bindings
526  - the maintainer team lacks expertise to keep these working
527  - more serious refactors are planned, and this will be challenging to keep working through that process
528  - if you are interested in helping us maintain bindings to other languages, [get in touch](https://github.com/DioxusLabs/taffy/discussions)!
529- 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)
530- removed the `Direction` and `Overflow` structs, and the corresponding `direction` and `overflow` fields from `Style`
531  - these had no effect in the current code base and were actively misleading
532
533## stretch2 0.4.3
534
535This is the final release of `stretch`: migrate to the crate named `taffy` for future fixes and features!
536
537These notes describe the differences between this release and `stretch` 0.3.2, the abandoned crate from which this library was forked.
538
539### Changed
540
541- updated [assorted dependencies](https://github.com/vislyhq/stretch/commit/a6491117379cea52dedc9584d892594a143e8cb0)
542
543### Fixed
544
545- fixed an exponential performance blow-up with deep nesting
546- fixed percent height values, which were using parent width
547- recomputing layout no longer moves children of non-zero-positioned parent
548- fixed broken Swift bindings