nite/crates/ming/src/taffy.rs
2024-05-13 22:41:30 +03:00

498 lines
16 KiB
Rust

use crate::{
AbsoluteLength, Bounds, DefiniteLength, Edges, Length, Pixels, Point, Size, Style,
WindowContext,
};
use collections::{FxHashMap, FxHashSet};
use smallvec::SmallVec;
use std::fmt::Debug;
use taffy::{
geometry::{Point as TaffyPoint, Rect as TaffyRect, Size as TaffySize},
style::AvailableSpace as TaffyAvailableSpace,
tree::NodeId,
TaffyTree, TraversePartialTree as _,
};
type NodeMeasureFn =
Box<dyn FnMut(Size<Option<Pixels>>, Size<AvailableSpace>, &mut WindowContext) -> Size<Pixels>>;
pub struct TaffyLayoutEngine {
taffy: TaffyTree<()>,
styles: FxHashMap<LayoutId, Style>,
children_to_parents: FxHashMap<LayoutId, LayoutId>,
absolute_layout_bounds: FxHashMap<LayoutId, Bounds<Pixels>>,
computed_layouts: FxHashSet<LayoutId>,
nodes_to_measure: FxHashMap<LayoutId, NodeMeasureFn>,
}
static EXPECT_MESSAGE: &str = "we should avoid taffy layout errors by construction if possible";
impl TaffyLayoutEngine {
pub fn new() -> Self {
TaffyLayoutEngine {
taffy: TaffyTree::new(),
styles: FxHashMap::default(),
children_to_parents: FxHashMap::default(),
absolute_layout_bounds: FxHashMap::default(),
computed_layouts: FxHashSet::default(),
nodes_to_measure: FxHashMap::default(),
}
}
pub fn clear(&mut self) {
self.taffy.clear();
self.children_to_parents.clear();
self.absolute_layout_bounds.clear();
self.computed_layouts.clear();
self.nodes_to_measure.clear();
self.styles.clear();
}
pub fn request_layout(
&mut self,
style: Style,
rem_size: Pixels,
children: &[LayoutId],
) -> LayoutId {
let taffy_style = style.to_taffy(rem_size);
let layout_id = if children.is_empty() {
self.taffy
.new_leaf(taffy_style)
.expect(EXPECT_MESSAGE)
.into()
} else {
let parent_id = self
.taffy
// This is safe because LayoutId is repr(transparent) to taffy::tree::NodeId.
.new_with_children(taffy_style, unsafe { std::mem::transmute(children) })
.expect(EXPECT_MESSAGE)
.into();
self.children_to_parents
.extend(children.into_iter().map(|child_id| (*child_id, parent_id)));
parent_id
};
self.styles.insert(layout_id, style);
layout_id
}
pub fn request_measured_layout(
&mut self,
style: Style,
rem_size: Pixels,
measure: impl FnMut(Size<Option<Pixels>>, Size<AvailableSpace>, &mut WindowContext) -> Size<Pixels>
+ 'static,
) -> LayoutId {
let taffy_style = style.to_taffy(rem_size);
let layout_id = self
.taffy
.new_leaf_with_context(taffy_style, ())
.expect(EXPECT_MESSAGE)
.into();
self.nodes_to_measure.insert(layout_id, Box::new(measure));
self.styles.insert(layout_id, style);
layout_id
}
// Used to understand performance
#[allow(dead_code)]
fn count_all_children(&self, parent: LayoutId) -> anyhow::Result<u32> {
let mut count = 0;
for child in self.taffy.children(parent.0)? {
// Count this child.
count += 1;
// Count all of this child's children.
count += self.count_all_children(LayoutId(child))?
}
Ok(count)
}
// Used to understand performance
#[allow(dead_code)]
fn max_depth(&self, depth: u32, parent: LayoutId) -> anyhow::Result<u32> {
println!(
"{parent:?} at depth {depth} has {} children",
self.taffy.child_count(parent.0)
);
let mut max_child_depth = 0;
for child in self.taffy.children(parent.0)? {
max_child_depth = std::cmp::max(max_child_depth, self.max_depth(0, LayoutId(child))?);
}
Ok(depth + 1 + max_child_depth)
}
// Used to understand performance
#[allow(dead_code)]
fn get_edges(&self, parent: LayoutId) -> anyhow::Result<Vec<(LayoutId, LayoutId)>> {
let mut edges = Vec::new();
for child in self.taffy.children(parent.0)? {
edges.push((parent, LayoutId(child)));
edges.extend(self.get_edges(LayoutId(child))?);
}
Ok(edges)
}
pub fn compute_layout(
&mut self,
id: LayoutId,
available_space: Size<AvailableSpace>,
cx: &mut WindowContext,
) {
// Leaving this here until we have a better instrumentation approach.
// println!("Laying out {} children", self.count_all_children(id)?);
// println!("Max layout depth: {}", self.max_depth(0, id)?);
// Output the edges (branches) of the tree in Mermaid format for visualization.
// println!("Edges:");
// for (a, b) in self.get_edges(id)? {
// println!("N{} --> N{}", u64::from(a), u64::from(b));
// }
// println!("");
//
if !self.computed_layouts.insert(id) {
let mut stack = SmallVec::<[LayoutId; 64]>::new();
stack.push(id);
while let Some(id) = stack.pop() {
self.absolute_layout_bounds.remove(&id);
stack.extend(
self.taffy
.children(id.into())
.expect(EXPECT_MESSAGE)
.into_iter()
.map(Into::into),
);
}
}
// let started_at = std::time::Instant::now();
self.taffy
.compute_layout_with_measure(
id.into(),
available_space.into(),
|known_dimensions, available_space, node_id, _context| {
let Some(measure) = self.nodes_to_measure.get_mut(&node_id.into()) else {
return taffy::geometry::Size::default();
};
let known_dimensions = Size {
width: known_dimensions.width.map(Pixels),
height: known_dimensions.height.map(Pixels),
};
measure(known_dimensions, available_space.into(), cx).into()
},
)
.expect(EXPECT_MESSAGE);
// println!("compute_layout took {:?}", started_at.elapsed());
}
pub fn layout_bounds(&mut self, id: LayoutId) -> Bounds<Pixels> {
if let Some(layout) = self.absolute_layout_bounds.get(&id).cloned() {
return layout;
}
let layout = self.taffy.layout(id.into()).expect(EXPECT_MESSAGE);
let mut bounds = Bounds {
origin: layout.location.into(),
size: layout.size.into(),
};
if let Some(parent_id) = self.children_to_parents.get(&id).copied() {
let parent_bounds = self.layout_bounds(parent_id);
bounds.origin += parent_bounds.origin;
}
self.absolute_layout_bounds.insert(id, bounds);
bounds
}
}
/// A unique identifier for a layout node, generated when requesting a layout from Taffy
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
#[repr(transparent)]
pub struct LayoutId(NodeId);
impl std::hash::Hash for LayoutId {
fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
u64::from(self.0).hash(state);
}
}
impl From<NodeId> for LayoutId {
fn from(node_id: NodeId) -> Self {
Self(node_id)
}
}
impl From<LayoutId> for NodeId {
fn from(layout_id: LayoutId) -> NodeId {
layout_id.0
}
}
trait ToTaffy<Output> {
fn to_taffy(&self, rem_size: Pixels) -> Output;
}
impl ToTaffy<taffy::style::Style> for Style {
fn to_taffy(&self, rem_size: Pixels) -> taffy::style::Style {
taffy::style::Style {
display: self.display,
overflow: self.overflow.into(),
scrollbar_width: self.scrollbar_width,
position: self.position,
inset: self.inset.to_taffy(rem_size),
size: self.size.to_taffy(rem_size),
min_size: self.min_size.to_taffy(rem_size),
max_size: self.max_size.to_taffy(rem_size),
aspect_ratio: self.aspect_ratio,
margin: self.margin.to_taffy(rem_size),
padding: self.padding.to_taffy(rem_size),
border: self.border_widths.to_taffy(rem_size),
align_items: self.align_items,
align_self: self.align_self,
align_content: self.align_content,
justify_content: self.justify_content,
gap: self.gap.to_taffy(rem_size),
flex_direction: self.flex_direction,
flex_wrap: self.flex_wrap,
flex_basis: self.flex_basis.to_taffy(rem_size),
flex_grow: self.flex_grow,
flex_shrink: self.flex_shrink,
..Default::default() // Ignore grid properties for now
}
}
}
impl ToTaffy<taffy::style::LengthPercentageAuto> for Length {
fn to_taffy(&self, rem_size: Pixels) -> taffy::prelude::LengthPercentageAuto {
match self {
Length::Definite(length) => length.to_taffy(rem_size),
Length::Auto => taffy::prelude::LengthPercentageAuto::Auto,
}
}
}
impl ToTaffy<taffy::style::Dimension> for Length {
fn to_taffy(&self, rem_size: Pixels) -> taffy::prelude::Dimension {
match self {
Length::Definite(length) => length.to_taffy(rem_size),
Length::Auto => taffy::prelude::Dimension::Auto,
}
}
}
impl ToTaffy<taffy::style::LengthPercentage> for DefiniteLength {
fn to_taffy(&self, rem_size: Pixels) -> taffy::style::LengthPercentage {
match self {
DefiniteLength::Absolute(length) => match length {
AbsoluteLength::Pixels(pixels) => {
taffy::style::LengthPercentage::Length(pixels.into())
}
AbsoluteLength::Rems(rems) => {
taffy::style::LengthPercentage::Length((*rems * rem_size).into())
}
},
DefiniteLength::Fraction(fraction) => {
taffy::style::LengthPercentage::Percent(*fraction)
}
}
}
}
impl ToTaffy<taffy::style::LengthPercentageAuto> for DefiniteLength {
fn to_taffy(&self, rem_size: Pixels) -> taffy::style::LengthPercentageAuto {
match self {
DefiniteLength::Absolute(length) => match length {
AbsoluteLength::Pixels(pixels) => {
taffy::style::LengthPercentageAuto::Length(pixels.into())
}
AbsoluteLength::Rems(rems) => {
taffy::style::LengthPercentageAuto::Length((*rems * rem_size).into())
}
},
DefiniteLength::Fraction(fraction) => {
taffy::style::LengthPercentageAuto::Percent(*fraction)
}
}
}
}
impl ToTaffy<taffy::style::Dimension> for DefiniteLength {
fn to_taffy(&self, rem_size: Pixels) -> taffy::style::Dimension {
match self {
DefiniteLength::Absolute(length) => match length {
AbsoluteLength::Pixels(pixels) => taffy::style::Dimension::Length(pixels.into()),
AbsoluteLength::Rems(rems) => {
taffy::style::Dimension::Length((*rems * rem_size).into())
}
},
DefiniteLength::Fraction(fraction) => taffy::style::Dimension::Percent(*fraction),
}
}
}
impl ToTaffy<taffy::style::LengthPercentage> for AbsoluteLength {
fn to_taffy(&self, rem_size: Pixels) -> taffy::style::LengthPercentage {
match self {
AbsoluteLength::Pixels(pixels) => taffy::style::LengthPercentage::Length(pixels.into()),
AbsoluteLength::Rems(rems) => {
taffy::style::LengthPercentage::Length((*rems * rem_size).into())
}
}
}
}
impl<T, T2> From<TaffyPoint<T>> for Point<T2>
where
T: Into<T2>,
T2: Clone + Default + Debug,
{
fn from(point: TaffyPoint<T>) -> Point<T2> {
Point {
x: point.x.into(),
y: point.y.into(),
}
}
}
impl<T, T2> From<Point<T>> for TaffyPoint<T2>
where
T: Into<T2> + Clone + Default + Debug,
{
fn from(val: Point<T>) -> Self {
TaffyPoint {
x: val.x.into(),
y: val.y.into(),
}
}
}
impl<T, U> ToTaffy<TaffySize<U>> for Size<T>
where
T: ToTaffy<U> + Clone + Default + Debug,
{
fn to_taffy(&self, rem_size: Pixels) -> TaffySize<U> {
TaffySize {
width: self.width.to_taffy(rem_size),
height: self.height.to_taffy(rem_size),
}
}
}
impl<T, U> ToTaffy<TaffyRect<U>> for Edges<T>
where
T: ToTaffy<U> + Clone + Default + Debug,
{
fn to_taffy(&self, rem_size: Pixels) -> TaffyRect<U> {
TaffyRect {
top: self.top.to_taffy(rem_size),
right: self.right.to_taffy(rem_size),
bottom: self.bottom.to_taffy(rem_size),
left: self.left.to_taffy(rem_size),
}
}
}
impl<T, U> From<TaffySize<T>> for Size<U>
where
T: Into<U>,
U: Clone + Default + Debug,
{
fn from(taffy_size: TaffySize<T>) -> Self {
Size {
width: taffy_size.width.into(),
height: taffy_size.height.into(),
}
}
}
impl<T, U> From<Size<T>> for TaffySize<U>
where
T: Into<U> + Clone + Default + Debug,
{
fn from(size: Size<T>) -> Self {
TaffySize {
width: size.width.into(),
height: size.height.into(),
}
}
}
/// The space available for an element to be laid out in
#[derive(Copy, Clone, Default, Debug, Eq, PartialEq)]
pub enum AvailableSpace {
/// The amount of space available is the specified number of pixels
Definite(Pixels),
/// The amount of space available is indefinite and the node should be laid out under a min-content constraint
#[default]
MinContent,
/// The amount of space available is indefinite and the node should be laid out under a max-content constraint
MaxContent,
}
impl AvailableSpace {
/// Returns a `Size` with both width and height set to `AvailableSpace::MinContent`.
///
/// This function is useful when you want to create a `Size` with the minimum content constraints
/// for both dimensions.
///
/// # Examples
///
/// ```
/// let min_content_size = AvailableSpace::min_size();
/// assert_eq!(min_content_size.width, AvailableSpace::MinContent);
/// assert_eq!(min_content_size.height, AvailableSpace::MinContent);
/// ```
pub const fn min_size() -> Size<Self> {
Size {
width: Self::MinContent,
height: Self::MinContent,
}
}
}
impl From<AvailableSpace> for TaffyAvailableSpace {
fn from(space: AvailableSpace) -> TaffyAvailableSpace {
match space {
AvailableSpace::Definite(Pixels(value)) => TaffyAvailableSpace::Definite(value),
AvailableSpace::MinContent => TaffyAvailableSpace::MinContent,
AvailableSpace::MaxContent => TaffyAvailableSpace::MaxContent,
}
}
}
impl From<TaffyAvailableSpace> for AvailableSpace {
fn from(space: TaffyAvailableSpace) -> AvailableSpace {
match space {
TaffyAvailableSpace::Definite(value) => AvailableSpace::Definite(Pixels(value)),
TaffyAvailableSpace::MinContent => AvailableSpace::MinContent,
TaffyAvailableSpace::MaxContent => AvailableSpace::MaxContent,
}
}
}
impl From<Pixels> for AvailableSpace {
fn from(pixels: Pixels) -> Self {
AvailableSpace::Definite(pixels)
}
}
impl From<Size<Pixels>> for Size<AvailableSpace> {
fn from(size: Size<Pixels>) -> Self {
Size {
width: AvailableSpace::Definite(size.width),
height: AvailableSpace::Definite(size.height),
}
}
}