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use std::{mem, thread::ThreadId, time::Duration};
use zng_app_context::{app_local, context_local};
use zng_time::INSTANT_APP;
use crate::animation::AnimationTimer;
use self::types::ArcCowVar;
use super::{
animation::{Animations, ModifyInfo},
*,
};
/// Represents the last time a variable was mutated or the current update cycle.
#[derive(Debug, Clone, Copy, PartialEq, Eq, bytemuck::NoUninit)]
#[repr(transparent)]
pub struct VarUpdateId(u32);
impl VarUpdateId {
/// ID that is never new.
pub const fn never() -> Self {
VarUpdateId(0)
}
fn next(&mut self) {
if self.0 == u32::MAX {
self.0 = 1;
} else {
self.0 += 1;
}
}
}
impl Default for VarUpdateId {
fn default() -> Self {
Self::never()
}
}
pub(super) type VarUpdateFn = Box<dyn FnOnce() + Send>;
app_local! {
pub(crate) static VARS_SV: VarsService = VarsService::new();
}
context_local! {
pub(crate) static VARS_MODIFY_CTX: Option<ModifyInfo> = None;
}
pub(crate) struct VarsService {
pub(super) ans: Animations,
update_id: VarUpdateId,
updates: Mutex<Vec<(ModifyInfo, VarUpdateFn)>>,
updating_thread: Option<ThreadId>,
updates_after: Mutex<Vec<(ModifyInfo, VarUpdateFn)>>,
app_waker: Option<Box<dyn Fn() + Send + Sync>>,
modify_trace: Option<Box<dyn Fn(&'static str) + Send + Sync>>,
perm: Mutex<Vec<Box<dyn Any + Send>>>,
}
impl VarsService {
pub(crate) fn new() -> Self {
Self {
ans: Animations::new(),
update_id: VarUpdateId(1),
updates: Mutex::new(vec![]),
updating_thread: None,
updates_after: Mutex::new(vec![]),
app_waker: None,
modify_trace: None,
perm: Mutex::new(vec![]),
}
}
pub(crate) fn wake_app(&self) {
if let Some(w) = &self.app_waker {
w()
}
}
}
/// Variable updates and animation service.
pub struct VARS;
impl VARS {
/// Id of the current vars update in the app scope.
///
/// Variable with [`AnyVar::last_update`] equal to this are *new*.
pub fn update_id(&self) -> VarUpdateId {
VARS_SV.read().update_id
}
/// Read-write that defines if animations are enabled on the app.
///
/// The value is the same as [`sys_animations_enabled`], if set the variable disconnects from system config.
///
/// [`sys_animations_enabled`]: Self::sys_animations_enabled
pub fn animations_enabled(&self) -> ArcCowVar<bool, ArcVar<bool>> {
VARS_SV.read().ans.animations_enabled.clone()
}
/// Read-only that tracks if animations are enabled in the operating system.
///
/// This is `true` by default, it updates when the operating system config changes.
pub fn sys_animations_enabled(&self) -> ReadOnlyArcVar<bool> {
VARS_SV.read().ans.sys_animations_enabled.read_only()
}
/// Variable that defines the global frame duration, the default is 60fps `(1.0 / 60.0).secs()`.
pub fn frame_duration(&self) -> ArcVar<Duration> {
VARS_SV.read().ans.frame_duration.clone()
}
/// Variable that defines a global scale for the elapsed time of animations.
pub fn animation_time_scale(&self) -> ArcVar<Factor> {
VARS_SV.read().ans.animation_time_scale.clone()
}
/// Info about the current context when requesting variable modification.
///
/// If is currently inside a [`VARS.animate`] closure, or inside a [`Var::modify`] closure requested by an animation, or inside
/// an [`AnimationController`], returns the info that was collected at the moment the animation was requested. Outside of animations
/// gets an info with [`importance`] guaranteed to override the [`modify_importance`].
///
/// [`importance`]: ModifyInfo::importance
/// [`modify_importance`]: AnyVar::modify_importance
/// [`AnimationController`]: animation::AnimationController
/// [`VARS.animate`]: VARS::animate
pub fn current_modify(&self) -> ModifyInfo {
match VARS_MODIFY_CTX.get_clone() {
Some(current) => current, // override set by modify and animation closures.
None => VARS_SV.read().ans.current_modify.clone(),
}
}
/// Adds an `animation` closure that is called every frame to update captured variables, starting after next frame.
///
/// This is used to implement all [`Var<T>`] animations, it enables any kind of variable animation,
/// including multiple variables.
///
/// Returns an [`AnimationHandle`] that can be used to monitor the animation status and to [`stop`] or to
/// make the animation [`perm`].
///
/// # Variable Control
///
/// Animations assume *control* of a variable on the first time they cause its value to be new, after this
/// moment the [`AnyVar::is_animating`] value is `true` and [`AnyVar::modify_importance`] is the animation's importance,
/// until the animation stops. Only one animation can control a variable at a time, if an animation loses control of a
/// variable all attempts to modify it from inside the animation are ignored.
///
/// Later started animations steal control from previous animations, update, modify or set calls also remove the variable
/// from being affected by a running animation, even if just set to an equal value, that is, not actually updated.
///
/// # Nested Animations
///
/// Other animations can be started from inside the animation closure, these *nested* animations have the same importance
/// as the *parent* animation, the animation handle is different and [`AnyVar::is_animating`] is `false` if the nested animation
/// is dropped before the *parent* animation. But because the animations share the same importance the parent animation can
/// set the variable again.
///
/// # Examples
///
/// The example animates a `text` variable from `"Animation at 0%"` to `"Animation at 100%"`, when the animation
/// stops the `completed` variable is set to `true`.
///
/// ```
/// # use zng_var::{*, animation::easing};
/// # use zng_txt::*;
/// # use zng_unit::*;
/// # use zng_clone_move::*;
/// #
/// fn animate_text(text: &impl Var<Txt>, completed: &impl Var<bool>) {
/// let transition = animation::Transition::new(0u8, 100);
/// let mut prev_value = 101;
/// VARS.animate(clmv!(text, completed, |animation| {
/// let step = easing::expo(animation.elapsed_stop(1.secs()));
/// let value = transition.sample(step);
/// if value != prev_value {
/// if value == 100 {
/// animation.stop();
/// let _ = completed.set(true);
/// }
/// let _ = text.set(formatx!("Animation at {value}%"));
/// prev_value = value;
/// }
/// }))
/// .perm()
/// }
/// ```
///
/// Note that the animation can be stopped from the inside, the closure parameter is an [`Animation`]. In
/// the example this is the only way to stop the animation, because [`perm`] was called. Animations hold a clone
/// of the variables they affect and exist for the duration of the app if not stopped, causing the app to wake and call the
/// animation closure for every frame.
///
/// This method is the most basic animation interface, used to build all other animations, its rare that you
/// will need to use it directly, most of the time animation effects can be composted using the [`Var`] easing and mapping
/// methods.
///
/// ```
/// # use zng_var::{*, animation::easing};
/// # use zng_txt::*;
/// # use zng_unit::*;
/// # fn demo() {
/// let value = var(0u8);
/// let text = value.map(|v| formatx!("Animation at {v}%"));
/// value.ease(100, 1.secs(), easing::expo);
/// # }
/// ```
///
/// # Optimization Tips
///
/// When no animation is running the app *sleeps* awaiting for an external event, update request or timer elapse, when at least one
/// animation is running the app awakes every [`VARS.frame_duration`]. You can use [`Animation::sleep`] to *pause* the animation
/// for a duration, if all animations are sleeping the app is also sleeping.
///
/// Animations lose control over a variable permanently when a newer animation modifies the var or
/// the var is modified directly, but even if the animation can't control any variables **it keeps running**.
/// This happens because the system has no insight of all side effects caused by the `animation` closure. You
/// can use the [`VARS.current_modify`] and [`AnyVar::modify_importance`] to detect when the animation no longer affects
/// any variables and stop the animation to avoid awaking the app for no reason.
///
/// These optimizations are already implemented by the animations provided as methods of [`Var<T>`].
///
/// # External Controller
///
/// The animation can be controlled from the inside using the [`Animation`] reference, it can be stopped using the returned
/// [`AnimationHandle`], and it can also be controlled by a registered [`AnimationController`] that can manage multiple
/// animations at the same time, see [`with_animation_controller`] for more details.
///
/// [`AnimationHandle`]: animation::AnimationHandle
/// [`AnimationController`]: animation::AnimationController
/// [`Animation`]: animation::Animation
/// [`Animation::sleep`]: animation::Animation::sleep
/// [`stop`]: animation::AnimationHandle::stop
/// [`perm`]: animation::AnimationHandle::perm
/// [`with_animation_controller`]: Self::with_animation_controller
/// [`VARS.frame_duration`]: VARS::frame_duration
/// [`VARS.current_modify`]: VARS::current_modify
pub fn animate<A>(&self, animation: A) -> animation::AnimationHandle
where
A: FnMut(&animation::Animation) + Send + 'static,
{
Animations::animate(animation)
}
/// Calls `animate` while `controller` is registered as the animation controller.
///
/// The `controller` is notified of animation events for each animation spawned by `animate` and can affect then with the same
/// level of access as [`VARS.animate`]. Only one controller can affect animations at a time.
///
/// This can be used to manage multiple animations at the same time, or to get [`VARS.animate`] level of access to an animation
/// that is not implemented to allow such access. Note that animation implementers are not required to support the full
/// [`Animation`] API, for example, there is no guarantee that a restart requested by the controller will repeat the same animation.
///
/// The controller can start new animations, these animations will have the same controller if not overridden, you can
/// use this method and the `()` controller to avoid this behavior.
///
/// [`Animation`]: animation::Animation
/// [`VARS.animate`]: VARS::animate
pub fn with_animation_controller<R>(&self, controller: impl animation::AnimationController, animate: impl FnOnce() -> R) -> R {
let controller: Box<dyn animation::AnimationController> = Box::new(controller);
let mut opt = Some(Arc::new(controller));
animation::VARS_ANIMATION_CTRL_CTX.with_context(&mut opt, animate)
}
pub(super) fn schedule_update(&self, update: VarUpdateFn, type_name: &'static str) {
let vars = VARS_SV.read();
if let Some(trace) = &vars.modify_trace {
trace(type_name);
}
let cur_modify = match VARS_MODIFY_CTX.get_clone() {
Some(current) => current, // override set by modify and animation closures.
None => vars.ans.current_modify.clone(),
};
if let Some(id) = vars.updating_thread {
if std::thread::current().id() == id {
// is binding request, enqueue for immediate exec.
vars.updates.lock().push((cur_modify, update));
} else {
// is request from app task thread when we are already updating, enqueue for exec after current update.
vars.updates_after.lock().push((cur_modify, update));
}
} else {
// request from any app thread,
vars.updates.lock().push((cur_modify, update));
vars.wake_app();
}
}
/// Keep the `value` alive for the app lifetime.
pub fn perm(&self, value: impl Any + Send) {
let value = Box::new(value);
VARS_SV.read().perm.lock().push(value);
}
pub(crate) fn wake_app(&self) {
VARS_SV.read().wake_app();
}
}
/// VARS APP integration.
#[expect(non_camel_case_types)]
pub struct VARS_APP;
impl VARS_APP {
/// Register a closure called when [`apply_updates`] should be called because there are changes pending.
///
/// # Panics
///
/// Panics if already called for the current app. This must be called by app framework implementers only.
///
/// [`apply_updates`]: Self::apply_updates
pub fn init_app_waker(&self, waker: impl Fn() + Send + Sync + 'static) {
let mut vars = VARS_SV.write();
assert!(vars.app_waker.is_none());
vars.app_waker = Some(Box::new(waker));
}
/// Register a closure called when a variable modify is about to be scheduled. The
/// closure parameter is the type name of the variable type.
///
/// # Panics
///
/// Panics if already called for the current app. This must be called by app framework implementers only.
pub fn init_modify_trace(&self, trace: impl Fn(&'static str) + Send + Sync + 'static) {
let mut vars = VARS_SV.write();
assert!(vars.modify_trace.is_none());
vars.modify_trace = Some(Box::new(trace));
}
/// If [`apply_updates`] will do anything.
///
/// [`apply_updates`]: Self::apply_updates
pub fn has_pending_updates(&self) -> bool {
!VARS_SV.write().updates.get_mut().is_empty()
}
/// Sets the `sys_animations_enabled` read-only variable.
pub fn set_sys_animations_enabled(&self, enabled: bool) {
VARS_SV.read().ans.sys_animations_enabled.set(enabled);
}
/// Apply all pending updates, call hooks and update bindings.
///
/// This must be called by app framework implementers only.
pub fn apply_updates(&self) {
let _s = tracing::trace_span!("VARS").entered();
let _t = INSTANT_APP.pause_for_update();
Self::apply_updates_and_after(0)
}
fn apply_updates_and_after(depth: u8) {
let mut vars = VARS_SV.write();
match depth {
0 => {
vars.update_id.next();
vars.ans.animation_start_time = None;
}
10 => {
// high-pressure from worker threads, skip
return;
}
_ => {}
}
// updates requested by other threads while was applying updates
let mut updates = mem::take(vars.updates_after.get_mut());
// normal updates
if updates.is_empty() {
updates = mem::take(vars.updates.get_mut());
} else {
updates.append(vars.updates.get_mut());
}
// apply pending updates
if !updates.is_empty() {
debug_assert!(vars.updating_thread.is_none());
vars.updating_thread = Some(std::thread::current().id());
drop(vars);
update_each_and_bindings(updates, 0);
vars = VARS_SV.write();
vars.updating_thread = None;
if !vars.updates_after.get_mut().is_empty() {
drop(vars);
Self::apply_updates_and_after(depth + 1)
}
}
fn update_each_and_bindings(updates: Vec<(ModifyInfo, VarUpdateFn)>, depth: u16) {
if depth == 1000 {
tracing::error!(
"updated variable bindings 1000 times, probably stuck in an infinite loop\n\
will skip next updates"
);
return;
}
for (info, update) in updates {
VARS_MODIFY_CTX.with_context(&mut Some(Arc::new(Some(info))), update);
let mut vars = VARS_SV.write();
let updates = mem::take(vars.updates.get_mut());
if !updates.is_empty() {
drop(vars);
update_each_and_bindings(updates, depth + 1);
}
}
}
}
/// Does one animation frame if the frame duration has elapsed.
///
/// This must be called by app framework implementers only.
pub fn update_animations(&self, timer: &mut impl AnimationTimer) {
Animations::update_animations(timer)
}
/// Register the next animation frame, if there are any active animations.
///
/// This must be called by app framework implementers only.
pub fn next_deadline(&self, timer: &mut impl AnimationTimer) {
Animations::next_deadline(timer)
}
}