/* 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 {
// The discrete animation is not additive, so per spec [1] we should use the |from|, which
// is the underlying value. However this mismatches our animation mechanism (see
// composite_endpoint() in servo/ports/geckolib/glues.rs), which uses the effect value
// (i.e. |to| value here) [2]. So in order to match the behavior of other properties and
// other browsers, we use |to| value for addition and accumulation, i.e. Vresult = Vb.
//
// [1]
https://drafts.csswg.org/css-values-4/#not-additive
// [2]
https://github.com/w3c/csswg-drafts/issues/9070
Ok(to.clone())
}
}
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> {
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(()),
}
let count = self.count;
let track_sizes = super::lists::by_computed_value::animate(
&self.track_sizes,
&other.track_sizes,
procedure,
)?;
// 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.is_explicit() != other.is_explicit() {
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 self.has_auto_repeat() || other.has_auto_repeat() {
return Err(());
}
let values =
super::lists::by_computed_value::animate(&self.values, &other.values, procedure)?;
// 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 {
values,
line_names,
auto_repeat_index: self.auto_repeat_index,
})
}
}
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(())
}
}
