servo/components/style/values/animated/grid.rs
2019-01-13 21:59:35 +01:00

171 lines
6.6 KiB
Rust

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
//! Animation implementation for various grid-related types.
// Note: we can implement Animate on their generic types directly, but in this case we need to
// make sure two trait bounds, L: Clone and I: PartialEq, are satisfied on almost all the
// grid-related types and their other trait implementations because Animate needs them. So in
// order to avoid adding these two trait bounds (or maybe more..) everywhere, we implement
// Animate for the computed types, instead of the generic types.
use super::{Animate, Procedure, ToAnimatedZero};
use crate::values::computed::Integer;
use crate::values::computed::LengthPercentage;
use crate::values::computed::{GridTemplateComponent, TrackList, TrackSize};
use crate::values::distance::{ComputeSquaredDistance, SquaredDistance};
use crate::values::generics::grid as generics;
fn discrete<T: Clone>(from: &T, to: &T, procedure: Procedure) -> Result<T, ()> {
if let Procedure::Interpolate { progress } = procedure {
Ok(if progress < 0.5 {
from.clone()
} else {
to.clone()
})
} else {
Err(())
}
}
fn animate_with_discrete_fallback<T: Animate + Clone>(
from: &T,
to: &T,
procedure: Procedure,
) -> Result<T, ()> {
from.animate(to, procedure)
.or_else(|_| discrete(from, to, procedure))
}
impl Animate for TrackSize {
fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
match (self, other) {
(&generics::TrackSize::Breadth(ref from), &generics::TrackSize::Breadth(ref to)) => {
animate_with_discrete_fallback(from, to, procedure)
.map(generics::TrackSize::Breadth)
},
(
&generics::TrackSize::Minmax(ref from_min, ref from_max),
&generics::TrackSize::Minmax(ref to_min, ref to_max),
) => Ok(generics::TrackSize::Minmax(
animate_with_discrete_fallback(from_min, to_min, procedure)?,
animate_with_discrete_fallback(from_max, to_max, procedure)?,
)),
(
&generics::TrackSize::FitContent(ref from),
&generics::TrackSize::FitContent(ref to),
) => animate_with_discrete_fallback(from, to, procedure)
.map(generics::TrackSize::FitContent),
(_, _) => discrete(self, other, procedure),
}
}
}
impl Animate for generics::TrackRepeat<LengthPercentage, Integer>
where
generics::RepeatCount<Integer>: PartialEq,
{
fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
// If the keyword, auto-fit/fill, is the same it can result in different
// number of tracks. For both auto-fit/fill, the number of columns isn't
// known until you do layout since it depends on the container size, item
// placement and other factors, so we cannot do the correct interpolation
// by computed values. Therefore, return Err(()) if it's keywords. If it
// is Number, we support animation only if the count is the same and the
// length of track_sizes is the same.
// https://github.com/w3c/csswg-drafts/issues/3503
match (&self.count, &other.count) {
(&generics::RepeatCount::Number(from), &generics::RepeatCount::Number(to))
if from == to =>
{
()
},
(_, _) => return Err(()),
}
// The length of track_sizes should be matched.
if self.track_sizes.len() != other.track_sizes.len() {
return Err(());
}
let count = self.count;
let track_sizes = self
.track_sizes
.iter()
.zip(other.track_sizes.iter())
.map(|(a, b)| a.animate(b, procedure))
.collect::<Result<Vec<_>, _>>()?;
// The length of |line_names| is always 0 or N+1, where N is the length
// of |track_sizes|. Besides, <line-names> is always discrete.
let line_names = discrete(&self.line_names, &other.line_names, procedure)?;
Ok(generics::TrackRepeat {
count,
line_names,
track_sizes,
})
}
}
impl Animate for TrackList {
// Based on https://github.com/w3c/csswg-drafts/issues/3201:
// 1. Check interpolation type per track, so we need to handle discrete animations
// in TrackSize, so any Err(()) returned from TrackSize doesn't make all TrackSize
// fallback to discrete animation.
// 2. line-names is always discrete.
fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
if self.values.len() != other.values.len() {
return Err(());
}
if self.list_type != other.list_type {
return Err(());
}
// For now, repeat(auto-fill/auto-fit, ...) is not animatable. TrackRepeat will
// return Err(()) if we use keywords. Therefore, we can early return here to avoid
// traversing |values| in <auto-track-list>. This may be updated in the future.
// https://github.com/w3c/csswg-drafts/issues/3503
if let generics::TrackListType::Auto(_) = self.list_type {
return Err(());
}
let list_type = self.list_type;
let auto_repeat = self.auto_repeat.animate(&other.auto_repeat, procedure)?;
let values = self
.values
.iter()
.zip(other.values.iter())
.map(|(a, b)| a.animate(b, procedure))
.collect::<Result<Vec<_>, _>>()?;
// The length of |line_names| is always 0 or N+1, where N is the length
// of |track_sizes|. Besides, <line-names> is always discrete.
let line_names = discrete(&self.line_names, &other.line_names, procedure)?;
Ok(TrackList {
list_type,
values,
line_names,
auto_repeat,
})
}
}
impl ComputeSquaredDistance for GridTemplateComponent {
#[inline]
fn compute_squared_distance(&self, _other: &Self) -> Result<SquaredDistance, ()> {
// TODO: Bug 1518585, we should implement ComputeSquaredDistance.
Err(())
}
}
impl ToAnimatedZero for GridTemplateComponent {
#[inline]
fn to_animated_zero(&self) -> Result<Self, ()> {
// It's not clear to get a zero grid track list based on the current definition
// of spec, so we return Err(()) directly.
Err(())
}
}