/* 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 http://mozilla.org/MPL/2.0/. */
//! CSS transitions and animations.
#![deny(missing_docs)]
use Atom;
use bezier::Bezier;
use context::SharedStyleContext;
use dom::{OpaqueNode, TElement};
use font_metrics::FontMetricsProvider;
use properties::{self, CascadeFlags, ComputedValues, LonghandId};
use properties::animated_properties::{AnimatedProperty, TransitionProperty};
use properties::longhands::animation_direction::computed_value::single_value::T as AnimationDirection;
use properties::longhands::animation_play_state::computed_value::single_value::T as AnimationPlayState;
use rule_tree::CascadeLevel;
use servo_arc::Arc;
use std::sync::mpsc::Sender;
use stylesheets::keyframes_rule::{KeyframesStep, KeyframesStepValue};
use timer::Timer;
use values::computed::Time;
use values::computed::transform::TimingFunction;
use values::generics::box_::AnimationIterationCount;
use values::generics::transform::{StepPosition, TimingFunction as GenericTimingFunction};
/// This structure represents a keyframes animation current iteration state.
///
/// If the iteration count is infinite, there's no other state, otherwise we
/// have to keep track the current iteration and the max iteration count.
#[derive(Clone, Debug)]
pub enum KeyframesIterationState {
/// Infinite iterations, so no need to track a state.
Infinite,
/// Current and max iterations.
Finite(f32, f32),
}
/// This structure represents wether an animation is actually running.
///
/// An animation can be running, or paused at a given time.
#[derive(Clone, Debug)]
pub enum KeyframesRunningState {
/// This animation is paused. The inner field is the percentage of progress
/// when it was paused, from 0 to 1.
Paused(f64),
/// This animation is actually running.
Running,
}
/// This structure represents the current keyframe animation state, i.e., the
/// duration, the current and maximum iteration count, and the state (either
/// playing or paused).
// TODO: unify the use of f32/f64 in this file.
#[derive(Clone, Debug)]
pub struct KeyframesAnimationState {
/// The time this animation started at.
pub started_at: f64,
/// The duration of this animation.
pub duration: f64,
/// The delay of the animation.
pub delay: f64,
/// The current iteration state for the animation.
pub iteration_state: KeyframesIterationState,
/// Werther this animation is paused.
pub running_state: KeyframesRunningState,
/// The declared animation direction of this animation.
pub direction: AnimationDirection,
/// The current animation direction. This can only be `normal` or `reverse`.
pub current_direction: AnimationDirection,
/// Werther this keyframe animation is outdated due to a restyle.
pub expired: bool,
/// The original cascade style, needed to compute the generated keyframes of
/// the animation.
pub cascade_style: Arc<ComputedValues>,
}
impl KeyframesAnimationState {
/// Performs a tick in the animation state, i.e., increments the counter of
/// the current iteration count, updates times and then toggles the
/// direction if appropriate.
///
/// Returns true if the animation should keep running.
pub fn tick(&mut self) -> bool {
debug!("KeyframesAnimationState::tick");
debug_assert!(!self.expired);
self.started_at += self.duration + self.delay;
match self.running_state {
// If it's paused, don't update direction or iteration count.
KeyframesRunningState::Paused(_) => return true,
KeyframesRunningState::Running => {},
}
if let KeyframesIterationState::Finite(ref mut current, ref max) = self.iteration_state {
*current += 1.0;
// NB: This prevent us from updating the direction, which might be
// needed for the correct handling of animation-fill-mode.
if *current >= *max {
return false;
}
}
// Update the next iteration direction if applicable.
match self.direction {
AnimationDirection::Alternate |
AnimationDirection::AlternateReverse => {
self.current_direction = match self.current_direction {
AnimationDirection::Normal => AnimationDirection::Reverse,
AnimationDirection::Reverse => AnimationDirection::Normal,
_ => unreachable!(),
};
}
_ => {},
}
true
}
/// Updates the appropiate state from other animation.
///
/// This happens when an animation is re-submitted to layout, presumably
/// because of an state change.
///
/// There are some bits of state we can't just replace, over all taking in
/// account times, so here's that logic.
pub fn update_from_other(&mut self,
other: &Self,
timer: &Timer) {
use self::KeyframesRunningState::*;
debug!("KeyframesAnimationState::update_from_other({:?}, {:?})", self, other);
// NB: We shall not touch the started_at field, since we don't want to
// restart the animation.
let old_started_at = self.started_at;
let old_duration = self.duration;
let old_direction = self.current_direction;
let old_running_state = self.running_state.clone();
let old_iteration_state = self.iteration_state.clone();
*self = other.clone();
let mut new_started_at = old_started_at;
// If we're unpausing the animation, fake the start time so we seem to
// restore it.
//
// If the animation keeps paused, keep the old value.
//
// If we're pausing the animation, compute the progress value.
match (&mut self.running_state, old_running_state) {
(&mut Running, Paused(progress))
=> new_started_at = timer.seconds() - (self.duration * progress),
(&mut Paused(ref mut new), Paused(old))
=> *new = old,
(&mut Paused(ref mut progress), Running)
=> *progress = (timer.seconds() - old_started_at) / old_duration,
_ => {},
}
// Don't update the iteration count, just the iteration limit.
// TODO: see how changing the limit affects rendering in other browsers.
// We might need to keep the iteration count even when it's infinite.
match (&mut self.iteration_state, old_iteration_state) {
(&mut KeyframesIterationState::Finite(ref mut iters, _), KeyframesIterationState::Finite(old_iters, _))
=> *iters = old_iters,
_ => {}
}
self.current_direction = old_direction;
self.started_at = new_started_at;
}
#[inline]
fn is_paused(&self) -> bool {
match self.running_state {
KeyframesRunningState::Paused(..) => true,
KeyframesRunningState::Running => false,
}
}
}
/// State relating to an animation.
#[derive(Clone, Debug)]
pub enum Animation {
/// A transition is just a single frame triggered at a time, with a reflow.
///
/// the f64 field is the start time as returned by `time::precise_time_s()`.
///
/// The `bool` field is werther this animation should no longer run.
Transition(OpaqueNode, f64, AnimationFrame, bool),
/// A keyframes animation is identified by a name, and can have a
/// node-dependent state (i.e. iteration count, etc.).
Keyframes(OpaqueNode, Atom, KeyframesAnimationState),
}
impl Animation {
/// Mark this animation as expired.
#[inline]
pub fn mark_as_expired(&mut self) {
debug_assert!(!self.is_expired());
match *self {
Animation::Transition(_, _, _, ref mut expired) => *expired = true,
Animation::Keyframes(_, _, ref mut state) => state.expired = true,
}
}
/// Whether this animation is expired.
#[inline]
pub fn is_expired(&self) -> bool {
match *self {
Animation::Transition(_, _, _, expired) => expired,
Animation::Keyframes(_, _, ref state) => state.expired,
}
}
/// The opaque node that owns the animation.
#[inline]
pub fn node(&self) -> &OpaqueNode {
match *self {
Animation::Transition(ref node, _, _, _) => node,
Animation::Keyframes(ref node, _, _) => node,
}
}
/// Whether this animation is paused. A transition can never be paused.
#[inline]
pub fn is_paused(&self) -> bool {
match *self {
Animation::Transition(..) => false,
Animation::Keyframes(_, _, ref state) => state.is_paused(),
}
}
/// Whether this animation is a transition.
#[inline]
pub fn is_transition(&self) -> bool {
match *self {
Animation::Transition(..) => true,
Animation::Keyframes(..) => false,
}
}
}
/// A single animation frame of a single property.
#[derive(Clone, Debug)]
pub struct AnimationFrame {
/// A description of the property animation that is occurring.
pub property_animation: PropertyAnimation,
/// The duration of the animation. This is either relative in the keyframes
/// case (a number between 0 and 1), or absolute in the transition case.
pub duration: f64,
}
/// Represents an animation for a given property.
#[derive(Clone, Debug)]
pub struct PropertyAnimation {
property: AnimatedProperty,
timing_function: TimingFunction,
duration: Time, // TODO: isn't this just repeated?
}
impl PropertyAnimation {
/// Returns the given property name.
pub fn property_name(&self) -> &'static str {
self.property.name()
}
/// Creates a new property animation for the given transition index and old
/// and new styles. Any number of animations may be returned, from zero (if
/// the property did not animate) to one (for a single transition property)
/// to arbitrarily many (for `all`).
pub fn from_transition(
transition_index: usize,
old_style: &ComputedValues,
new_style: &mut ComputedValues,
) -> Vec<PropertyAnimation> {
let mut result = vec![];
let box_style = new_style.get_box();
let transition_property = box_style.transition_property_at(transition_index);
let timing_function = box_style.transition_timing_function_mod(transition_index);
let duration = box_style.transition_duration_mod(transition_index);
match transition_property {
TransitionProperty::Unsupported(_) => result,
TransitionProperty::Shorthand(ref shorthand_id) => {
shorthand_id.longhands().filter_map(|longhand| {
PropertyAnimation::from_longhand(
longhand,
timing_function,
duration,
old_style,
new_style,
)
}).collect()
}
TransitionProperty::Longhand(longhand_id) => {
let animation = PropertyAnimation::from_longhand(
longhand_id,
timing_function,
duration,
old_style,
new_style,
);
if let Some(animation) = animation {
result.push(animation);
}
result
}
}
}
fn from_longhand(
longhand: LonghandId,
timing_function: TimingFunction,
duration: Time,
old_style: &ComputedValues,
new_style: &ComputedValues,
) -> Option<PropertyAnimation> {
let animated_property = AnimatedProperty::from_longhand(
longhand,
old_style,
new_style,
)?;
let property_animation = PropertyAnimation {
property: animated_property,
timing_function: timing_function,
duration: duration,
};
if property_animation.does_animate() {
Some(property_animation)
} else {
None
}
}
/// Update the given animation at a given point of progress.
pub fn update(&self, style: &mut ComputedValues, time: f64) {
let epsilon = 1. / (200. * (self.duration.seconds() as f64));
let progress = match self.timing_function {
GenericTimingFunction::CubicBezier { x1, y1, x2, y2 } => {
Bezier::new(x1, y1, x2, y2).solve(time, epsilon)
},
GenericTimingFunction::Steps(steps, StepPosition::Start) => {
(time * (steps as f64)).ceil() / (steps as f64)
},
GenericTimingFunction::Steps(steps, StepPosition::End) => {
(time * (steps as f64)).floor() / (steps as f64)
},
GenericTimingFunction::Frames(frames) => {
// https://drafts.csswg.org/css-timing/#frames-timing-functions
let mut out = (time * (frames as f64)).floor() / ((frames - 1) as f64);
if out > 1.0 {
// FIXME: Basically, during the animation sampling process, the input progress
// should be in the range of [0, 1]. However, |time| is not accurate enough
// here, which means |time| could be larger than 1.0 in the last animation
// frame. (It should be equal to 1.0 exactly.) This makes the output of frames
// timing function jumps to the next frame/level.
// However, this solution is still not correct because |time| is possible
// outside the range of [0, 1] after introducing Web Animations. We should fix
// this problem when implementing web animations.
out = 1.0;
}
out
},
GenericTimingFunction::Keyword(keyword) => {
let (x1, x2, y1, y2) = keyword.to_bezier();
Bezier::new(x1, x2, y1, y2).solve(time, epsilon)
},
};
self.property.update(style, progress);
}
#[inline]
fn does_animate(&self) -> bool {
self.property.does_animate() && self.duration.seconds() != 0.0
}
/// Whether this animation has the same end value as another one.
#[inline]
pub fn has_the_same_end_value_as(&self, other: &Self) -> bool {
self.property.has_the_same_end_value_as(&other.property)
}
}
/// Inserts transitions into the queue of running animations as applicable for
/// the given style difference. This is called from the layout worker threads.
/// Returns true if any animations were kicked off and false otherwise.
#[cfg(feature = "servo")]
pub fn start_transitions_if_applicable(
new_animations_sender: &Sender<Animation>,
opaque_node: OpaqueNode,
old_style: &ComputedValues,
new_style: &mut Arc<ComputedValues>,
timer: &Timer,
possibly_expired_animations: &[PropertyAnimation]
) -> bool {
let mut had_animations = false;
for i in 0..new_style.get_box().transition_property_count() {
// Create any property animations, if applicable.
let property_animations = PropertyAnimation::from_transition(i,
old_style,
Arc::make_mut(new_style));
for property_animation in property_animations {
// Set the property to the initial value.
//
// NB: get_mut is guaranteed to succeed since we called make_mut()
// above.
property_animation.update(Arc::get_mut(new_style).unwrap(), 0.0);
// Per [1], don't trigger a new transition if the end state for that
// transition is the same as that of a transition that's already
// running on the same node.
//
// [1]: https://drafts.csswg.org/css-transitions/#starting
if possibly_expired_animations.iter().any(|animation| {
animation.has_the_same_end_value_as(&property_animation)
}) {
continue
}
// Kick off the animation.
let box_style = new_style.get_box();
let now = timer.seconds();
let start_time =
now + (box_style.transition_delay_mod(i).seconds() as f64);
new_animations_sender
.send(Animation::Transition(opaque_node, start_time, AnimationFrame {
duration: box_style.transition_duration_mod(i).seconds() as f64,
property_animation: property_animation,
}, /* is_expired = */ false)).unwrap();
had_animations = true;
}
}
had_animations
}
fn compute_style_for_animation_step<E>(
context: &SharedStyleContext,
step: &KeyframesStep,
previous_style: &ComputedValues,
style_from_cascade: &Arc<ComputedValues>,
font_metrics_provider: &FontMetricsProvider,
) -> Arc<ComputedValues>
where
E: TElement,
{
match step.value {
KeyframesStepValue::ComputedValues => style_from_cascade.clone(),
KeyframesStepValue::Declarations { block: ref declarations } => {
let guard = declarations.read_with(context.guards.author);
let iter = || {
// It's possible to have !important properties in keyframes
// so we have to filter them out.
// See the spec issue https://github.com/w3c/csswg-drafts/issues/1824
// Also we filter our non-animatable properties.
guard.normal_declaration_iter()
.filter(|declaration| declaration.is_animatable())
.map(|decl| (decl, CascadeLevel::Animations))
};
// This currently ignores visited styles, which seems acceptable,
// as existing browsers don't appear to animate visited styles.
let computed =
properties::apply_declarations::<E, _, _>(
context.stylist.device(),
/* pseudo = */ None,
previous_style.rules(),
&context.guards,
iter,
Some(previous_style),
Some(previous_style),
Some(previous_style),
/* visited_style = */ None,
font_metrics_provider,
CascadeFlags::empty(),
context.quirks_mode(),
/* rule_cache = */ None,
&mut Default::default(),
/* element = */ None,
);
computed
}
}
}
/// Triggers animations for a given node looking at the animation property
/// values.
pub fn maybe_start_animations(
context: &SharedStyleContext,
new_animations_sender: &Sender<Animation>,
node: OpaqueNode,
new_style: &Arc<ComputedValues>,
) -> bool {
let mut had_animations = false;
let box_style = new_style.get_box();
for (i, name) in box_style.animation_name_iter().enumerate() {
let name = if let Some(atom) = name.as_atom() {
atom
} else {
continue
};
debug!("maybe_start_animations: name={}", name);
let total_duration = box_style.animation_duration_mod(i).seconds();
if total_duration == 0. {
continue
}
if let Some(ref anim) = context.stylist.get_animation(name) {
debug!("maybe_start_animations: animation {} found", name);
// If this animation doesn't have any keyframe, we can just continue
// without submitting it to the compositor, since both the first and
// the second keyframes would be synthetised from the computed
// values.
if anim.steps.is_empty() {
continue;
}
let delay = box_style.animation_delay_mod(i).seconds();
let now = context.timer.seconds();
let animation_start = now + delay as f64;
let duration = box_style.animation_duration_mod(i).seconds();
let iteration_state = match box_style.animation_iteration_count_mod(i) {
AnimationIterationCount::Infinite => KeyframesIterationState::Infinite,
AnimationIterationCount::Number(n) => KeyframesIterationState::Finite(0.0, n),
};
let animation_direction = box_style.animation_direction_mod(i);
let initial_direction = match animation_direction {
AnimationDirection::Normal |
AnimationDirection::Alternate => AnimationDirection::Normal,
AnimationDirection::Reverse |
AnimationDirection::AlternateReverse => AnimationDirection::Reverse,
};
let running_state = match box_style.animation_play_state_mod(i) {
AnimationPlayState::Paused => KeyframesRunningState::Paused(0.),
AnimationPlayState::Running => KeyframesRunningState::Running,
};
new_animations_sender
.send(Animation::Keyframes(node, name.clone(), KeyframesAnimationState {
started_at: animation_start,
duration: duration as f64,
delay: delay as f64,
iteration_state: iteration_state,
running_state: running_state,
direction: animation_direction,
current_direction: initial_direction,
expired: false,
cascade_style: new_style.clone(),
})).unwrap();
had_animations = true;
}
}
had_animations
}
/// Updates a given computed style for a given animation frame. Returns a bool
/// representing if the style was indeed updated.
pub fn update_style_for_animation_frame(mut new_style: &mut Arc<ComputedValues>,
now: f64,
start_time: f64,
frame: &AnimationFrame) -> bool {
let mut progress = (now - start_time) / frame.duration;
if progress > 1.0 {
progress = 1.0
}
if progress <= 0.0 {
return false;
}
frame.property_animation.update(Arc::make_mut(&mut new_style), progress);
true
}
/// Updates a single animation and associated style based on the current time.
pub fn update_style_for_animation<E>(
context: &SharedStyleContext,
animation: &Animation,
style: &mut Arc<ComputedValues>,
font_metrics_provider: &FontMetricsProvider,
)
where
E: TElement,
{
debug!("update_style_for_animation: entering");
debug_assert!(!animation.is_expired());
match *animation {
Animation::Transition(_, start_time, ref frame, _) => {
debug!("update_style_for_animation: transition found");
let now = context.timer.seconds();
let mut new_style = (*style).clone();
let updated_style = update_style_for_animation_frame(&mut new_style,
now, start_time,
frame);
if updated_style {
*style = new_style
}
}
Animation::Keyframes(_, ref name, ref state) => {
debug!("update_style_for_animation: animation found: \"{}\", {:?}", name, state);
let duration = state.duration;
let started_at = state.started_at;
let now = match state.running_state {
KeyframesRunningState::Running => context.timer.seconds(),
KeyframesRunningState::Paused(progress) => started_at + duration * progress,
};
let animation = match context.stylist.get_animation(name) {
None => {
warn!("update_style_for_animation: Animation {:?} not found", name);
return;
}
Some(animation) => animation,
};
debug_assert!(!animation.steps.is_empty());
let maybe_index = style
.get_box()
.animation_name_iter()
.position(|animation_name| Some(name) == animation_name.as_atom());
let index = match maybe_index {
Some(index) => index,
None => {
warn!("update_style_for_animation: Animation {:?} not found in style", name);
return;
}
};
let total_duration = style.get_box().animation_duration_mod(index).seconds() as f64;
if total_duration == 0. {
debug!("update_style_for_animation: zero duration for animation {:?}", name);
return;
}
let mut total_progress = (now - started_at) / total_duration;
if total_progress < 0. {
warn!("Negative progress found for animation {:?}", name);
return;
}
if total_progress > 1. {
total_progress = 1.;
}
debug!("update_style_for_animation: anim \"{}\", steps: {:?}, state: {:?}, progress: {}",
name, animation.steps, state, total_progress);
// Get the target and the last keyframe position.
let last_keyframe_position;
let target_keyframe_position;
match state.current_direction {
AnimationDirection::Normal => {
target_keyframe_position =
animation.steps.iter().position(|step| {
total_progress as f32 <= step.start_percentage.0
});
last_keyframe_position = target_keyframe_position.and_then(|pos| {
if pos != 0 { Some(pos - 1) } else { None }
}).unwrap_or(0);
}
AnimationDirection::Reverse => {
target_keyframe_position =
animation.steps.iter().rev().position(|step| {
total_progress as f32 <= 1. - step.start_percentage.0
}).map(|pos| animation.steps.len() - pos - 1);
last_keyframe_position = target_keyframe_position.and_then(|pos| {
if pos != animation.steps.len() - 1 { Some(pos + 1) } else { None }
}).unwrap_or(animation.steps.len() - 1);
}
_ => unreachable!(),
}
debug!("update_style_for_animation: keyframe from {:?} to {:?}",
last_keyframe_position, target_keyframe_position);
let target_keyframe = match target_keyframe_position {
Some(target) => &animation.steps[target],
None => {
warn!("update_style_for_animation: No current keyframe found for animation \"{}\" at progress {}",
name, total_progress);
return;
}
};
let last_keyframe = &animation.steps[last_keyframe_position];
let relative_timespan = (target_keyframe.start_percentage.0 - last_keyframe.start_percentage.0).abs();
let relative_duration = relative_timespan as f64 * duration;
let last_keyframe_ended_at = match state.current_direction {
AnimationDirection::Normal => {
state.started_at + (total_duration * last_keyframe.start_percentage.0 as f64)
}
AnimationDirection::Reverse => {
state.started_at + (total_duration * (1. - last_keyframe.start_percentage.0 as f64))
}
_ => unreachable!(),
};
let relative_progress = (now - last_keyframe_ended_at) / relative_duration;
// TODO: How could we optimise it? Is it such a big deal?
let from_style = compute_style_for_animation_step::<E>(
context,
last_keyframe,
&**style,
&state.cascade_style,
font_metrics_provider,
);
// NB: The spec says that the timing function can be overwritten
// from the keyframe style.
let mut timing_function = style.get_box().animation_timing_function_mod(index);
if last_keyframe.declared_timing_function {
// NB: animation_timing_function can never be empty, always has
// at least the default value (`ease`).
timing_function = from_style.get_box().animation_timing_function_at(0);
}
let target_style = compute_style_for_animation_step::<E>(
context,
target_keyframe,
&from_style,
&state.cascade_style,
font_metrics_provider,
);
let mut new_style = (*style).clone();
for property in animation.properties_changed.iter() {
debug!("update_style_for_animation: scanning prop {:?} for animation \"{}\"",
property, name);
let animation = PropertyAnimation::from_longhand(
property,
timing_function,
Time::from_seconds(relative_duration as f32),
&from_style,
&target_style
);
match animation {
Some(property_animation) => {
debug!("update_style_for_animation: got property animation for prop {:?}", property);
debug!("update_style_for_animation: {:?}", property_animation);
property_animation.update(Arc::make_mut(&mut new_style), relative_progress);
}
None => {
debug!("update_style_for_animation: property animation {:?} not animating",
property);
}
}
}
debug!("update_style_for_animation: got style change in animation \"{}\"", name);
*style = new_style;
}
}
}
/// Update the style in the node when it finishes.
#[cfg(feature = "servo")]
pub fn complete_expired_transitions(
node: OpaqueNode,
style: &mut Arc<ComputedValues>,
context: &SharedStyleContext,
) -> bool {
let had_animations_to_expire;
{
let all_expired_animations = context.expired_animations.read();
let animations_to_expire = all_expired_animations.get(&node);
had_animations_to_expire = animations_to_expire.is_some();
if let Some(ref animations) = animations_to_expire {
for animation in *animations {
// TODO: support animation-fill-mode
if let Animation::Transition(_, _, ref frame, _) = *animation {
frame.property_animation.update(Arc::make_mut(style), 1.0);
}
}
}
}
if had_animations_to_expire {
context.expired_animations.write().remove(&node);
}
had_animations_to_expire
}