A high performance rust-powered UI layout library
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Published by nicoburns over 1 year ago
align_content
when flex_wrap
is set to nowrap
(#383)Published by nicoburns over 1 year ago
display: none
when it is set on a flexbox child (#380)display: none
when it is set on a grid child (#381)Published by nicoburns over 1 year ago
display: none
when it is set for the only node in the hierarchy (#377)Published by nicoburns over 1 year ago
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.grid
feature disabled (#370)std
feature disabledPublished by nicoburns over 1 year ago
Style
using the serde
feature.Published by nicoburns over 1 year ago
A small bugfix for the 0.3.0 release
serde
feature now works when the grid
feature is enabledPublished by nicoburns over 1 year ago
See below for details of breaking changes.
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
.
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:
In addition to the usual sizing/spacing proerties (size, min_size, padding, margin, etc), the following Grid style properties are supported on Grid Containers:
Property | Explanation |
---|---|
grid-template-columns |
The track sizing functions of the grid's explicit columns |
grid-template-rows |
The track sizing functions of the grid's explicit rows |
grid-auto-rows |
Track sizing functions for the grid's implicitly generated rows |
grid-auto-columns |
Track sizing functions for the grid's implicitly generated columns |
grid-auto-flow |
Whether auto-placed items are placed row-wise or column-wise. And sparsely or densely. |
gap |
The size of the vertical and horizontal gaps between grid rows/columns |
align-content |
Align grid tracks within the container in the inline (horizontal) axis |
justify-content |
Align grid tracks within the container in the block (vertical) axis |
align-items |
Align the child items within their grid areas in the inline (horizontal) axis |
justify-items |
Align the child items within their grid areas in the block (vertical) axis |
And the following Grid style properties are supported on Grid Items (children):
Property | Explanation |
---|---|
grid-row |
The (row) grid line the item starts at (or a span) |
grid-column |
The (column) grid line the item end at (or a span) |
align-self |
Align the item within it's grid area in the inline (horizontal) axis. Overrides align-items . |
justify-self |
Align the item within it's grid area in the block (vertical) axis. Overrides justify-items . |
The following properties and features are not currently supported:
grid-template-areas
and grid-area
grid-template
or grid
shorthandSee 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
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:
AlignContent
and JustifyContent
has been merged.
JustifyContent
is now an alias of AlignContent
and contains the Stretch
variant.Start
) when applied Flexbox containers. It is valid value for Grid containers.AlignItems
and AlignSelf
have been merged.
Auto
variant of AlignSelf
has been removed. You should now use Option::None
if you wish to specify AlignSelf::Auto
.AlignSelf
is now an alias of AlignItems
.JustifyItems
and JustifySelf
aliases have been added. These properties have no affect on Flexbox containers, but apply to Grid containers.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.LengthPercentage
and LengthPercentageAuto
have been added.
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.LengthPercentageAuto
is currently identical to Dimension
but will allow us to expand dimension in future to support values like MinContent
, MaxContent
and FitContent
.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).position
property is now renamed to inset
and is now in line with CSS inset specs
position_type
property is now renamed to position
and is now in line with CSS position specs. The PositionType
enum has been similarly renamed to Position
.LayoutTree
LayoutTree
for a ChildIter
, an iterator on the children of a given node.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.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.is_childless
method to LayoutTree
for querying whether a node has no children.AvailableSpace
has been movedThe 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.
top
and bottom
or left
and right
were specified (#348)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.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.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.Published by nicoburns over 1 year ago
Published by nicoburns over 1 year ago
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
.taffy::compute_layout
has been made public allowing Taffy to be used with custom storage (#263)Published by nicoburns over 1 year ago
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)
Two debugging features have been added:
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.debug
. This enabled debug logging of the layout computation process itself (this is probably mainly useful for those working taffy itself).A number of performance improvements have landed since taffy 0.1:
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%.Benchmark | Taffy 0.1 | Taffy 0.2 | % change (0.1 -> 0.2) |
---|---|---|---|
wide/1_000 nodes (2-level hierarchy) | 699.18 µs | 445.01 µs | -36.279% |
wide/10_000 nodes (2-level hierarchy) | 8.8244 ms | 7.1313 ms | -16.352% |
wide/100_000 nodes (2-level hierarchy) | 204.48 ms | 242.93 ms | +18.803% |
deep/4000 nodes (12-level hierarchy)) | 5.2320 s | 2.7363 ms | -99.947% |
deep/10_000 nodes (14-level hierarchy) | 75.207 s | 6.9415 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.
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.
Benchmark | Yoga | Taffy 0.2 |
---|---|---|
yoga/10 nodes (1-level hierarchy) | 45.1670 µs | 33.297 ns |
yoga/100 nodes (2-level hierarchy) | 134.1250 µs | 336.53 ns |
yoga/1_000 nodes (3-level hierarchy) | 1.2221 ms | 3.8928 µs |
yoga/10_000 nodes (4-level hierarchy) | 13.8672 ms | 36.162 µs |
yoga/100_000 nodes (5-level hierarchy) | 141.5307 ms | 1.6404 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!
taffy::Node
is now unique only to the Taffy instance from which it was created.Taffy.new_node(..)
-> Taffy.new_with_children(..)
Taffy.new_leaf()
-> Taffy.new_leaf_with_measure()
taffy::node::Taffy.new_leaf()
which allows the creation of new leaf-nodes without having to supply a measure functiontaffy::Error
-> taffy::error::TaffyError
taffy::error::InvalidChild
with a new InvalidChild
variant of taffy::error::TaffyError
taffy::error::InvalidNode
with a new InvalidNode
variant of taffy::error::TaffyError
Err(TaffyError::ChildIndexOutOfBounds)
instead of panicking:
taffy::Taffy::remove_child_at_index
taffy::Taffy::replace_child_at_index
taffy::Taffy::child_at_index
Taffy::remove
now returns a Result<usize, Error>
, to indicate if the operation was sucessful (and if it was, which ID was invalidated).Option<f32>
replaced with a new AvailableSpace
enumA 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
. 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..
const
where possibleStyle::DEFAULT
Size<f32>.zero()
is now Size::<f32>::ZERO
Point<f32>.zero()
is now Point::<f32>::ZERO
Size::undefined()
is now Size::NONE
taffy::forest::Forest
. taffy::node::Taffy
now handles it's own storage using a slotmap (which comes with a performance boost up to 90%).taffy::number::Number
. Use Option<f32>
is used instead
MinMax
and OrElse
traits have also been removed; these should never have been publichashbrown
, 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).Miscellaneous correctness fixes which align our implementation with Chrome:
flex-grow
and a minimum sizeMeasureFunc
(and hence NodeData
and hence Forest
and hence the public Taffy
type) are now Send
and Sync
, enabling their use in async and parallel applicationsTaffy can now be vendored using cargo-vendor
(README.md is now included in package).
Published by nicoburns over 1 year ago
This is the first release of Taffy
, but Taffy is a continuation of an older abandoned library stretch
order
field of Layout
is now public, and describes the relative z-ordering of nodesstretch2
to taffy
stretch::node::Strech
-> taffy::node::Taffy
alloc
and std
: these can now be compiled together, with std
's types taking priorityserde_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)Direction
and Overflow
structs, and the corresponding direction
and overflow
fields from Style
A version of this library was also released as stretch2
. The following notes describe the differences between this release and stretch
0.3.2, the abandoned crate from which this library was forked.