gioser

tawasuyu/taffy

A high performance rust-powered UI layout library

HTML 5544Rust 88Markdown 11TOML 91926 Sutichaykuna

⎇ cd0c4403a09b47837719a8ee201808ca253cdefb RELEASES.md Markdown · 508 siq'ikuna · 27.2 KB Ñawpa willay ch'uya

Prepare for 0.3.12 release (#458) f58f642fa · Nico Burns ·

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

RELEASES.md

Release Notes

0.3.12

Fixes

0.3.11

Fixes

0.3.10

Fixes

0.3.9

Fixes

0.3.8

Fixes

0.3.7

Fixes

0.3.6

Fixes

0.3.5

Fixes

0.3.4

Fixes

0.3.3

Added

Fixes

0.3.2

Fixes

0.3.1

Fixes

0.3.0

Highlights

See below for details of breaking changes.

New Feature: CSS Grid

We 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.

Learning Resources

Taffy 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:

Supported Features & Properties

In addition to the usual sizing/spacing proerties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:

PropertyExplanation
grid-template-columnsThe track sizing functions of the grid's explicit columns
grid-template-rowsThe track sizing functions of the grid's explicit rows
grid-auto-rowsTrack sizing functions for the grid's implicitly generated rows
grid-auto-columnsTrack sizing functions for the grid's implicitly generated columns
grid-auto-flowWhether auto-placed items are placed row-wise or column-wise. And sparsely or densely.
gapThe size of the vertical and horizontal gaps between grid rows/columns
align-contentAlign grid tracks within the container in the inline (horizontal) axis
justify-contentAlign grid tracks within the container in the block (vertical) axis
align-itemsAlign the child items within their grid areas in the inline (horizontal) axis
justify-itemsAlign the child items within their grid areas in the block (vertical) axis

And the following Grid style properties are supported on Grid Items (children):

PropertyExplanation
grid-rowThe (row) grid line the item starts at (or a span)
grid-columnThe (column) grid line the item end at (or a span)
align-selfAlign the item within it's grid area in the inline (horizontal) axis. Overrides align-items.
justify-selfAlign the item within it's grid area in the block (vertical) axis. Overrides justify-items.

The following properties and features are not currently supported:

Example

See examples/grid_holy_grail.rs for an example using Taffy to implement the so-called Holy Grail Layout. If you want to run this example, the don't forget the enable the CSS Grid cargo feature:

cargo run --example grid_holy_grail --features grid

New Feature: Style Helpers

Ten 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.

For example, instead of:

let size : Size<Dimension> = Size { width: Dimension::Points(100.0), height: Dimension::Percent(50.0) };

you can now write

let size : Size<Dimension> = Size { width: points(100.0), height: percent(50.0) };

And 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

let size : Size<Dimension> = points(100.0);

Available style helpers:

<table> <thead><tr><th>Type(s)</th><th colspan="2">Helpers that work with that type</th></tr></thead> <tbody> <tr> <td rowspan="3"><code>LengthPercentage</code></td> <td><code>zero()</code></td> <td>Generates a <code>Points</code> variant with the value <code>0.0</code></td> </tr> <tr> <td><code>points(val:&nbsp;f32)</code></td> <td>Generates a <code>Points</code> variant with the specified value</td> </tr> <tr> <td><code>percent(val:&nbsp;f32)</code></td> <td>Generates a <code>Percent</code> variant with the specified value.<br />Note that the scale of 0-1 not 0-100.</td> </tr> <tr> <td rowspan="2"><code>LengthPercentageAuto</code><br /><code>Dimension</code></td> <td colspan="2"><i>All helpers from <code>LengthPercentage</code> and...</i></td> </tr> <tr> <td><code>auto()</code></td> <td>Generates an <code>Auto</code> variant</td> </tr> <tr> <td rowspan="3"><code>MinTrackSizingFunction</code></td> <td colspan="2"><i>All helpers from <code>LengthPercentageAuto</code>/<code>Dimension</code> and...</i></td> </tr> <tr> <td><code>min_content()</code></td> <td>Generates an <code>MinContent</code> variant</td> </tr> <tr> <td><code>max_content()</code></td> <td>Generates an <code>MinContent</code> variant</td> </tr> <tr> <td rowspan="3"><code>MaxTrackSizingFunction</code></td> <td colspan="2"><i>All helpers from <code>MinTrackSizingFunction</code> and...</i></td> </tr> <tr> <td><code>fit_content(limit:&nbsp;LengthPercentage)</code></td> <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> </tr> <tr> <td><code>fr(fraction:&nbsp;f32)</code></td> <td>Generates a <code>Fraction</code> (<code>fr</code>) variant with the specified flex fraction </td> </tr> <tr> <td rowspan="3"><code>NonRepeatingTrackSizingFunction</code></td> <td colspan="2"><i>All helpers from <code>MaxTrackSizingFunction</code> and...</i></td> </tr> <tr> <td><code>minmax(min: MinTrackSizingFunction, max: MaxTrackSizingFunction)</code></td> <td>Equivalent to CSS <code>minmax()</code> function.</td> </tr> <tr> <td><code>flex(fraction:&nbsp;f32)</code></td> <td>Equivalent to CSS <code>minmax(0px, 1fr)</code>. This is likely what you want if you want evenly sized rows/columns.</td> </tr> <tr> <td rowspan="2"><code>TrackSizingFunction</code></td> <td colspan="2"><i>All helpers from <code>NonRepeatingTrackSizingFunction</code> and...</i></td> </tr> <tr> <td><code>repeat(rep: GridTrackRepetition, tracks: Vec&lt;TrackSizingFunction&gt;)</code></td> <td>Equivalent to css <code>repeat()</code> function.</td> </tr> <tr> <td><code>Vec&lt;TrackSizingFunction&gt;</code></td> <td><code>evenly_sized_tracks(count:&nbsp;u16)</code></td> <td>Equivalent to CSS <code>repeat(count, minmax(0px, 1fr)</code></td> </tr> <tr> <td rowspan="3"><code>AvailableSpace</code></td> <td><code>auto()</code></td> <td>Generates an <code>Auto</code> variant</td> </tr> <tr> <td><code>min_content()</code></td> <td>Generates an <code>MinContent</code> variant</td> </tr> <tr> <td><code>max_content()</code></td> <td>Generates an <code>MinContent</code> variant</td> </tr> <tr> <td><code>Size&lt;T&gt;</code></td> <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> </tr> <tr> <td><code>Rect&lt;T&gt;</code></td> <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> </tr> </tbody> </table>

Breaking API changes

Changes to alignment style types

Strict style types

Position properties renamed

Changes to LayoutTree

AvailableSpace has been moved

The 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.

Fixes

Removed

0.2.2

Fixes

0.2.1

Fixes

0.2.0

New features

Flexbox "gap" and AlignContent::SpaceEvenly

The gap property is now supported on flex containers. This can make it much easier to create even spacing or "gutters" between nodes.

Additionally 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)

Debug module and cargo feature

Two debugging features have been added:

Performance improvements

A number of performance improvements have landed since taffy 0.1:

Benchmarks vs. Taffy 0.1

BenchmarkTaffy 0.1Taffy 0.2% change (0.1 -> 0.2)
wide/1_000 nodes (2-level hierarchy)699.18 µs445.01 µs-36.279%
wide/10_000 nodes (2-level hierarchy)8.8244 ms7.1313 ms-16.352%
wide/100_000 nodes (2-level hierarchy)204.48 ms242.93 ms+18.803%
deep/4000 nodes (12-level hierarchy))5.2320 s2.7363 ms-99.947%
deep/10_000 nodes (14-level hierarchy)75.207 s6.9415 ms-99.991%
deep/100_000 nodes (17-level hierarchy)-102.72 ms-
deep/1_000_000 nodes (20-level hierarchy)-799.35 ms-

(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))

As 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.

However, 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.

Benchmarks vs. Yoga

Yoga 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.

BenchmarkYogaTaffy 0.2
yoga/10 nodes (1-level hierarchy)45.1670 µs33.297 ns
yoga/100 nodes (2-level hierarchy)134.1250 µs336.53 ns
yoga/1_000 nodes (3-level hierarchy)1.2221 ms3.8928 µs
yoga/10_000 nodes (4-level hierarchy)13.8672 ms36.162 µs
yoga/100_000 nodes (5-level hierarchy)141.5307 ms1.6404 ms

(note that the table above contains multiple different units (milliseconds vs. microseconds vs. nanoseconds))

While 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!

Breaking API changes

Node creation changes

Error handling/representation improvements

Some uses of Option<f32> replaced with a new AvailableSpace enum

A new enum Taffy::layout::AvailableSpace has been added.

The definition looks like this:

/// The amount of space available to a node in a given axis
pub enum AvailableSpace {
    /// The amount of space available is the specified number of pixels
    Definite(f32),
    /// The amount of space available is indefinite and the node should be laid out under a min-content constraint
    MinContent,
    /// The amount of space available is indefinite and the node should be laid out under a max-content constraint
    MaxContent,
}

This 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).

And a different instance of it is passed as a new second parameter to MeasureFunc. MeasureFuncs 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..

Builder methods are now const where possible

Removals

Fixes

0.1.0

0.1.0 Changed

0.1.0 Fixed

0.1.0 Removed

stretch2 0.4.3

This is the final release of stretch: migrate to the crate named taffy for future fixes and features!

These notes describe the differences between this release and stretch 0.3.2, the abandoned crate from which this library was forked.

Changed

Fixed