Web Animations Module Level 1

所与の時点での`~animation$ %~animation の `現-時刻@ は、 次に従って計算される： ◎ The current time is calculated from the first matching condition below:

1. ~IF［ %~animation の`保持-時刻$ ~NEQ `未解決$ ］ ⇒ ~RET %~animation の`保持-時刻$ ◎ If the animation’s hold time is resolved, • The current time is the animation’s hold time.
2. ~IF［ %~animation の`時列線~現-時刻$ ~EQ `未解決$ ］~OR［ %~animation の`開始-時刻$ ~EQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If any of the following are true: • the animation has no associated timeline, or • the associated timeline is inactive, or • the animation’s start time is unresolved, • The current time is an unresolved time value.

3. ~RET ( %~animation の`時列線~現-時刻$ ~MINUS %~animation の`開始-時刻$ ) ~MUL `再生~rate$ ◎ Otherwise, • current time = (timeline time − start time) × playback rate

   `再生~rate$ 値は、 `§ 速度~制御＠#speed-control$ にて定義される。 ◎ Where timeline time is the current time value of the associated timeline. The playback rate value is defined in § 4.5.15 Speed control.

`時列線を設定する@ 手続-は、 所与の ( %~animation, %新-時列線 （ ~NULL もとり得る） ) に対し： ◎ The procedure to set the timeline of an animation, animation, to new timeline which may be null, is as follows:

1. %旧-時列線 ~LET %~animation の`時列線$An ◎ Let old timeline be the current timeline of animation, if any.
2. ~IF［ %新-時列線 ~EQ %旧-時列線 ］ ⇒ ~RET ◎ If new timeline is the same object as old timeline, abort this procedure.
3. %~animation の`時列線$An ~LET %新-時列線 ◎ Let the timeline of animation be new timeline.

4. ~IF［ %~animation の`開始-時刻$ ~NEQ `未解決$ ］ ⇒ %~animation の`保持-時刻$ ~SET `未解決$ ◎ If the start time of animation is resolved, make animation’s hold time unresolved.

   注記： この段は、 次を確保する ⇒ %~animation の再生-状態は — `完遂d$i に “貼り付き続ける” ことなく — `現-時刻$の更新に基づいて評価し直される。 ◎ Note: This step ensures that the finished play state of animation is not “sticky”, but is re-evaluated based on its updated current time.

5. `完遂d状態を更新する$( %~animation ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to false, and the synchronously notify flag set to false.

`結付けられる効果を設定する@ 手続-は、 所与の ( %~animation, %新-効果 （ ~NULL もとり得る） ) に対し： ◎ The procedure to set the associated effect of an animation, animation, to new effect which may be null, is as follows:

1. %旧-効果 ~LET %~animation に`結付けられた効果$ ◎ Let old effect be the current associated effect of animation, if any.
2. ~IF［ %新-効果 ~EQ %旧-効果 【！same object as】 ］ ⇒ ~RET ◎ If new effect is the same object as old effect, abort this procedure.

3. ~IF［ %新-効果 ~NEQ ~NULL ］：

   1. ~IF［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］ ⇒ その~taskを，次が満たされた時点で走るように~scheduleし直す ⇒ %~animation は %新-効果 に関して`準備済み$である ◎ If animation has a pending pause task, reschedule that task to run as soon as animation is ready.
   2. ~IF［ %~animation の`処理待ち再生-~task$ ~NEQ ε ］ ⇒ その~taskを，次が満たされた時点で走るように~scheduleし直す ⇒ %~animation は %新-効果 に関して`準備済み$である ◎ If animation has a pending play task, reschedule that task to run as soon as animation is ready to play new effect.
   3. ~IF［ %新-効果 を`結付けた~animation$ %A ~NEQ ε ］ ⇒ `結付けられる効果を設定する$( %A, ~NULL ) ◎ If new effect is not null and if new effect is the associated effect of another animation, previous animation, run the procedure to set the associated effect of an animation (this procedure) on previous animation, passing null as new effect.
4. %~animation に`結付けられた効果$ ~LET %新-効果 ◎ Let the associated effect of animation be new effect.
5. `完遂d状態を更新する$( %~animation ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to false, and the synchronously notify flag set to false.

`現-時刻を~silentに設定する@ 手続-は、 所与の ( %~animation, %~seek時刻 ) に対し： ◎ The procedure to silently set the current time of an animation, animation, to seek time is as follows:

1. ~IF［ %~seek時刻 ~EQ `未解決$ ］： ◎ If seek time is an unresolved time value, then perform the following steps.

   1. ~IF［ %~animation の`現-時刻$ ~NEQ `未解決$ ］ ⇒ ~THROW `TypeError^E ◎ If the current time is resolved, then throw a TypeError.
   2. ~RET ◎ Abort these steps.

2. ~IF［ %~animation は ~OR↓ を満たす ］… ◎ Update either animation’s hold time or start time as follows: ◎ If any of the following conditions are true:

   • `保持-時刻$ ~NEQ `未解決$ ◎ animation’s hold time is resolved, or
   • `開始-時刻$ ~EQ `未解決$ ◎ animation’s start time is unresolved, or
   • `時列線~現-時刻$ ~EQ `未解決$ ◎ animation has no associated timeline or the associated timeline is inactive, or
   • `再生~rate$ ~EQ 0 ◎ animation’s playback rate is 0,

   …ならば ⇒ %~animation の`保持-時刻$ ~SET %~seek時刻 ◎ Set animation’s hold time to seek time.

3. ~ELSE ⇒ %~animation の`開始-時刻$ ~SET ( %~animation の`時列線~現-時刻$ ) ~MINUS ( %~seek時刻 ~DIV `再生~rate$ ) ◎ Otherwise, • Set animation’s start time to the result of evaluating timeline time − (seek time / playback rate) where timeline time is the current time value of the timeline associated with animation.

4. ~IF［ %~animation の`時列線~現-時刻$ ~EQ `未解決$ ］ ⇒ %~animation の`開始-時刻$ ~SET `未解決$ ◎ If animation has no associated timeline or the associated timeline is inactive, make animation’s start time unresolved.

   注記： これは、 次の不変則を保全する ⇒ ［ %~animation の`時列線~現-時刻$ ~EQ `未解決$ ］になる間は、 その［ `開始-時刻$／`現-時刻$ ］に限り，設定-可能になる。 ◎ Note: This preserves the invariant that when we don’t have an active timeline it is only possible to set either the start time or the animation’s current time.

5. %~animation の`前回の現-時刻$ ~SET `未解決$ ◎ Make animation’s previous current time unresolved.

`現-時刻を設定する@ 手続-は、 所与の ( %~animation, %~seek時刻 ) に対し： ◎ The procedure to set the current time of an animation, animation, to seek time is as follows:

1. `現-時刻を~silentに設定する$( %~animation, %~seek時刻 ) ◎ Run the steps to silently set the current time of animation to seek time.

2. ~IF［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］（この段は、静止-演算を同期的に完了させる）： ◎ If animation has a pending pause task, synchronously complete the pause operation by performing the following steps:

   1. %~animation の`保持-時刻$ ~SET %~seek時刻 ◎ Set animation’s hold time to seek time.
   2. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate to animation.
   3. %~animation の`開始-時刻$ ~SET `未解決$ ◎ Make animation’s start time unresolved.
   4. %~animation の`処理待ち静止-~task$を取消す ◎ Cancel the pending pause task.
   5. `~promiseを解決する$( %~animation の`現在の準備済み~promise$, %~animation ) ◎ Resolve animation’s current ready promise with animation.
3. `完遂d状態を更新する$( %~animation, `~seekした^i ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to true, and the synchronously notify flag set to false.

`開始-時刻を設定する@ 手続-は、 所与の ( `~animation$ %~animation, %新-開始-時刻 ) に対し： ◎ The procedure to set the start time of an animation, animation, to new start time is as follows:

1. %時列線 ~LET %~animation の`時列線$An ◎ ↓
2. %時列線~時刻 ~LET %~animation の`時列線~現-時刻$ ◎ Let timeline time be the current time value of the timeline that animation is associated with. If there is no timeline associated with animation or the associated timeline is inactive, let the timeline time be unresolved.

3. ~IF［ %時列線~時刻 ~EQ `未解決$ ］~AND［ %新-開始-時刻 ~NEQ `未解決$ ］ ⇒ %~animation の`保持-時刻$ ~SET `未解決$ ◎ If timeline time is unresolved and new start time is resolved, make animation’s hold time unresolved.

   注記： これは、 次の不変則を保全する ⇒ ［ %~animation の`時列線~現-時刻$ ~EQ `未解決$ ］になる間は、 その［ `開始-時刻$／`現-時刻$ ］に限り，設定-可能になる。 ◎ Note: This preserves the invariant that when we don’t have an active timeline it is only possible to set either the start time or the animation’s current time.

4. %前回の現-時刻 ~LET %~animation の`現-時刻$ ◎ Let previous current time be animation’s current time.

   注記： これは、 前~段による変更により`未解決$になることもある。 ◎ Note: This is the current time after applying the changes from the previous step, which can cause the current time to become unresolved.

5. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate on animation.
6. %~animation の`開始-時刻$ ~SET %新-開始-時刻 ◎ Set animation’s start time to new start time.
7. ~IF［ %新-開始-時刻 ~NEQ `未解決$ ］ ⇒ ~IF［ %~animation の`再生~rate$ ~NEQ 0 ］ ⇒ %~animation の`保持-時刻$ ~SET `未解決$ ◎ Update animation’s hold time based on the first matching condition from the following: ◎ If new start time is resolved, • If animation’s playback rate is not zero, make animation’s hold time unresolved.
8. ~ELSE ⇒ %~animation の`保持-時刻$ ~SET %前回の現-時刻 ◎ Otherwise (new start time is unresolved), • Set animation’s hold time to previous current time even if previous current time is unresolved.
9. ~IF［ %~animation の`処理待ち再生-~task$ ~NEQ ε ］~OR［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］ ⇒＃ その~taskを取消す； `~promiseを解決する$( %~animation の`現在の準備済み~promise$, %~animation ) ◎ If animation has a pending play task or a pending pause task, cancel that task and resolve animation’s current ready promise with animation.
10. `完遂d状態を更新する$( %~animation, `~seekした^i ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to true, and the synchronously notify flag set to false.

`~animationを再生する@ 手続-は、 所与の ( %~animation, %自動で巻戻すか ~IN { `自動で巻戻す^i, ε } ) に対し： ◎ The procedure to play an animation, animation, given a flag auto-rewind, is as follows:

1. %静止-は中止された ~LET ~IS［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］ ◎ Let aborted pause be a boolean flag that is true if animation has a pending pause task, and false otherwise.
2. %処理待ち準備済み~promiseは在るか ~LET ~F ◎ Let has pending ready promise be a boolean flag that is initially false.
3. %~seek時刻 ~LET `未解決$ ◎ Let seek time be a time value that is initially unresolved.
4. %現-時刻 ~LET %~animation の`現-時刻$ ◎ ↓

5. ~IF［ %自動で巻戻すか ~EQ `自動で巻戻す^i ］： ◎ If the auto-rewind flag is true, perform the steps corresponding to the first matching condition from the following, if any:

   1. %実効~再生~rate ~LET %~animation の`実効~再生~rate$ ◎ ↓
   2. %効果~終端 ~SET %~animation に`結付けられた効果の終端$ ◎ ↓

   3. ~IF［ %実効~再生~rate ~GTE 0 ］~AND［ ~OR↓ ］… ◎ If animation’s effective playback rate ≥ 0, and animation’s current time is either:

      • %現-時刻 ~EQ `未解決$ ◎ unresolved, or
      • %現-時刻 ~LT 0 ◎ less than zero, or
      • %現-時刻 ~GTE %効果~終端 ◎ greater than or equal to associated effect end,

      …ならば ⇒ %~seek時刻 ~SET 0 ◎ Set seek time to zero.

   4. ~IF［ %実効~再生~rate ~LT 0 ］~AND［ ~OR↓ ］… ◎ If animation’s effective playback rate < 0, and animation’s current time is either:

      • %現-時刻 ~EQ `未解決$ ◎ unresolved, or
      • %現-時刻 ~LTE 0 ◎ less than or equal to zero, or
      • %現-時刻 ~GT %効果~終端 ◎ greater than associated effect end,

      …ならば：

      1. ~IF［ %効果~終端 ~EQ 正な無限大 【この条件は %現-時刻 ~GT %効果~終端 と両立し得ないと思われるが？】 ］ ⇒ ~THROW `InvalidStateError$E ◎ If associated effect end is positive infinity, • throw an "InvalidStateError" DOMException and abort these steps.
      2. %~seek時刻 ~SET %効果~終端 ◎ Otherwise, • Set seek time to animation’s associated effect end.

6. ~IF［ %~animation の`開始-時刻$ ~EQ `未解決$ ］~AND［ %現-時刻 ~EQ `未解決$ ］ ⇒ %~seek時刻 ~SET 0 ◎ If the following three conditions are all satisfied: • seek time is unresolved, and • animation’s start time is unresolved, and • animation’s current time is unresolved, set seek time to zero.

   注記： この段は、 %自動で巻戻すか の設定に関わらず， この手続-が遊休~animationを再生することを確保する。 ◎ Note: The above step ensures that this procedure will play an idle animation regardless of the setting of the auto-rewind flag.

7. %時列線は有限か ~LET ~IS［ %~animation の`時列線$An ~NEQ ~NULL ］~AND［ %~animation の`時列線$Anは`単調増加-$している ］ ◎ Let has finite timeline be true if animation has an associated timeline that is not monotonically increasing.

8. ~IF［ %~seek時刻 ~NEQ `未解決$ ］： ◎ If seek time is resolved,

   1. ~IF［ %時列線は有限か ~EQ ~T ］ ⇒ ◎ If has finite timeline is true,

      1. %~animation の`開始-時刻$ ~SET %~seek時刻 ◎ Set animation’s start time to seek time.
      2. %~animation の`保持-時刻$ ~SET `未解決$ ◎ Let animation’s hold time be unresolved.
      3. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate on animation.
   2. ~ELSE ⇒ %~animation の`保持-時刻$ ~SET %~seek時刻 ◎ Otherwise, • Set animation’s hold time to seek time.
9. ~IF［ %~animation の`保持-時刻$ ~NEQ `未解決$ ］ ⇒ %~animation の`開始-時刻$ ~SET `未解決$ ◎ If animation’s hold time is resolved, let its start time be unresolved.

10. ~IF［ %~animation の`処理待ち再生-~task$ ~NEQ ε ］~OR［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］： ◎ If animation has a pending play task or a pending pause task,

    1. その~taskを取消す ◎ Cancel that task.
    2. %処理待ち準備済み~promiseは在るか ~SET ~T ◎ Set has pending ready promise to true.

11. ~IF［ ~AND↓ ］… ◎ If the following four conditions are all satisfied:

    • %~animation の`保持-時刻$ ~EQ `未解決$ ◎ animation’s hold time is unresolved, and
    • %~seek時刻 ~EQ `未解決$ ◎ seek time is unresolved, and
    • %静止-は中止された ~EQ ~F ◎ aborted pause is false, and
    • %~animation の`処理待ち再生~rate$ ~EQ ε ◎ animation does not have a pending playback rate,

    ならば… ⇒ ~RET ◎ abort this procedure.

12. ~IF［ %処理待ち準備済み~promiseは在るか ~EQ ~F ］ ⇒ %~animation の`現在の準備済み~promise$ ~SET `新たな~promise$を %~animation に`関連な~realm$内に作成した結果 ◎ If has pending ready promise is false, let animation’s current ready promise be a new promise in the relevant Realm of animation.

13. 次に与える~taskを［ %~animation が`準備済み$になり次第，走らす ］よう~scheduleする： ◎ Schedule a task to run as soon as animation is ready. The task shall perform the following steps:

    1. ~Assert： ［ %~animation の`開始-時刻$ ~NEQ `未解決$ ］~OR［ %~animation の`保持-時刻$ ~NEQ `未解決$ ］ ◎ Assert that at least one of animation’s start time or hold time is resolved.
    2. %準備済み時刻 ~LET %~animation の`時列線~現-時刻$ （すなわち、 `準備済み$になった~momentのそれ） ◎ Let ready time be the time value of the timeline associated with animation at the moment when animation became ready.
    3. %新-開始-時刻 ~LET %準備済み時刻 ◎ ↓

    4. ~IF［ %~animation の`保持-時刻$ ~EQ `未解決$ ］： ◎ Perform the steps corresponding to the first matching condition below, if any: ◎ If animation’s hold time is resolved,

       1. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate on animation.
       2. %再生~rate ~LET %~animation の`再生~rate$ ◎ ↓
       3. ~IF［ %再生~rate ~NEQ 0 ］ ⇒＃ %新-開始-時刻 ~DECBY ( %~animation の`保持-時刻$ ~DIV %再生~rate )； %~animation の`保持-時刻$ ~SET `未解決$ ◎ Let new start time be the result of evaluating ready time − hold time / playback rate for animation. If the playback rate is zero, let new start time be simply ready time. ◎ Set the start time of animation to new start time. ◎ If animation’s playback rate is not 0, make animation’s hold time unresolved.
       4. %~animation の`開始-時刻$ ~SET %新-開始-時刻 ◎ ↑

    5. ~ELSE （ %~animation の`開始-時刻$ ~NEQ `未解決$ ）： ◎ If animation’s start time is resolved＼

       1. ~IF［ %~animation の`処理待ち再生~rate$ ~NEQ ε ］： ◎ and animation has a pending playback rate,

          1. %合致させる現-時刻 ~LET ( %準備済み時刻 ~MINUS `開始-時刻$ ) ~MUL %~animation の`再生~rate$ ◎ Let current time to match be the result of evaluating (ready time − start time) × playback rate for animation.
          2. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate on animation.
          3. %再生~rate ~LET %~animation の`再生~rate$ ◎ ↓
          4. ~IF［ %再生~rate ~EQ 0 ］ ⇒ %~animation の`保持-時刻$ ~SET %合致させる現-時刻； ◎ If animation’s playback rate is zero, let animation’s hold time be current time to match.
          5. ~ELSE ⇒ %新-開始-時刻 ~DECBY %合致させる現-時刻 ~DIV %再生~rate ◎ Let new start time be the result of evaluating ready time − current time to match / playback rate for animation. If the playback rate is zero, let new start time be simply ready time.
          6. %~animation の`開始-時刻$ ~SET %新-開始-時刻 ◎ Set the start time of animation to new start time.
    6. `~promiseを解決する$( %~animation の`現在の準備済み~promise$, %~animation ) ◎ Resolve animation’s current ready promise with animation.

    7. `完遂d状態を更新する$( %~animation ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to false, and the synchronously notify flag set to false.

       注記： 上の 2 つの段の順序は重要である — それは、 ~animationに`結付けられた効果$の長さが 0 であっても［ ~animationの`現在の準備済み~promise$は， `現在の完遂d~promise$より先に解決される ］ことを意味するので。 ◎ Note: The order of the above two steps is important since it means that an animation with zero-length associated effect will resolve its current ready promise before its current finished promise.

    所与の時点における %~animation の `処理待ち再生-~task@ は、［ この段に与えた~taskが~scheduleされてから走る直前までの間は その~task ／ 他のときは ε ］とする。 ◎ So long as the above task is scheduled but has yet to run, animation is described as having a pending play task. While the task is running, however, animation does not have a pending play task.

    ~UAは %~animation は即時に`準備済み$になるものと決定する場合、 上の~taskを［ 次回に`小task~checkpointを遂行する$ときに走らすような小task ］として~scheduleしてもヨイが，同期的には遂行しないモノトスル。 ◎ If a user agent determines that animation is immediately ready, it may schedule the above task as a microtask such that it runs at the next microtask checkpoint, but it must not perform the task synchronously.

    注記： `処理待ち再生-~task$を非同期的に走らす上の要件は、 次のような~codeの挙動が各~実装~間で一貫することを確保する： ◎ The above requirement to run the pending play task asynchronously ensures that code such as the following behaves consistently between implementations:

    %animation.`play$0();
    %animation.`ready$0.then(
      () => { console.log('再生にかかります'); },
      () => { console.log('再生は取消されました'); }
    );
    /* 
    何らかの条件により，再生を取消すことが要求されるとする…
    ◎
    Suppose some condition requires playback to be canceled...
     */
    %animation.`cancel$0();
    /* 
    ~consoleには “再生は取消されました” と~printされることになる。
    ◎
    "Playback was canceled" will be printed to the console.
     */
    

    `処理待ち再生-~task$を同期的に走らせた場合、 上の~codeにおける`現在の準備済み~promise$は却下されなくなる。 ◎ In the above code, were the pending play task run synchronously, the current ready promise would not be rejected.

14. `完遂d状態を更新する$( %~animation ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to false, and the synchronously notify flag set to false.

`~animationを静止する@ 手続-は、 所与の ( %~animation ) に対し： ◎ The procedure to pause an animation, animation, is as follows:

1. ~IF［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］ ⇒ ~RET ◎ If animation has a pending pause task, abort these steps.
2. ~IF［ %~animation の`再生-状態$ ~EQ `静止中$i ］ ⇒ ~RET ◎ If the play state of animation is paused, abort these steps. ◎ ↓Let seek time be a time value that is initially unresolved.
3. %時列線は有限か ~LET ~IS［ %~animation の`時列線$An ~NEQ ~NULL ］~AND［ %~animation の`時列線$Anは`単調増加-$している ］ ◎ Let has finite timeline be true if animation has an associated timeline that is not monotonically increasing.

4. %~seek時刻 ~LET 次の手続きを走らせた結果： ◎ ↑

   1. ~IF［ %~animation の`現-時刻$ ~NEQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If the animation’s current time is unresolved, perform the steps according to the first matching condition below:
   2. ~IF［ %~animation の`再生~rate$ ~GTE 0 ］ ⇒ ~RET 0 ◎ If animation’s playback rate is ≥ 0, • Set seek time to zero.
   3. %効果~終端 ~LET %~animation に`結付けられた効果の終端$
   4. ~IF［ %効果~終端 ~EQ 正な無限大 ］ ⇒ ~THROW `InvalidStateError$E ◎ Otherwise, ◎ If associated effect end for animation is positive infinity, • throw an "InvalidStateError" DOMException and abort these steps.
   5. ~RET %効果~終端 ◎ Otherwise, • Set seek time to animation’s associated effect end.

5. ~IF［ %~seek時刻 ~NEQ `未解決$ ］： ◎ If seek time is resolved,

   1. ~IF［ %時列線は有限か ~EQ ~T ］ ⇒ %~animation の`開始-時刻$ ~SET %~seek時刻 ◎ If has finite timeline is true, • Set animation’s start time to seek time.
   2. ~ELSE ⇒ %~animation の`保持-時刻$ ~SET %~seek時刻 ◎ Otherwise, • Set animation’s hold time to seek time.
6. %処理待ち準備済み~promiseは在るか ~LET ~F ◎ Let has pending ready promise be a boolean flag that is initially false.
7. ~IF［ %~animation の`処理待ち再生-~task$ ~NEQ ε ］ ⇒＃ その~taskを取消す； %処理待ち準備済み~promiseは在るか ~SET ~T ◎ If animation has a pending play task, cancel that task and let has pending ready promise be true.
8. ~IF［ %処理待ち準備済み~promiseは在るか ~EQ ~F ］ ⇒ %~animation の`現在の準備済み~promise$ ~SET `新たな~promise$を %~animation に`関連な~realm$内に作成した結果 ◎ If has pending ready promise is false, set animation’s current ready promise to a new promise in the relevant Realm of animation.

9. ［ ~AND↓ が最初に満たされた【！possible】~moment ］に［ 条件に後続する手続きを遂行する~task ］を実行するよう~scheduleする： ◎ Schedule a task to be executed at the first possible moment where both of the following conditions are true:

   • ~UAは、 次を遂行した ⇒ %~animation に`結付けられた効果$の再生を休止するために必要yな処理 ◎ the user agent has performed any processing necessary to suspend the playback of animation’s associated effect, if any.
   • ~animationの`時列線$Anは`作動中$でない ◎ the animation is associated with a timeline that is not inactive.

   ~taskを成す手続きは： ◎ The task shall perform the following steps:

   1. %準備済み時刻 ~LET %~animation の（この~momentにおける）`時列線~現-時刻$ ◎ Let ready time be the time value of the timeline associated with animation at the moment when the user agent completed processing necessary to suspend playback of animation’s associated effect.

   2. ~IF［ %~animation の`開始-時刻$ ~NEQ `未解決$ ］~AND［ %~animation の`保持-時刻$ ~EQ `未解決$ ］ ⇒ %~animation の`保持-時刻$ ~SET ( %準備済み時刻 ~MINUS %~animation の`開始-時刻$ ) ~MUL %~animation の`再生~rate$ ◎ If animation’s start time is resolved and its hold time is not resolved, let animation’s hold time be the result of evaluating (ready time − start time) × playback rate.

      注記： `保持-時刻$は、 すでに設定-済みかもしれない — ［ %~animation は`完遂d$i ／ %~animation の`処理待ち再生-~task$ ~NEQ ε ］の場合には。 いずれの事例においても、 `静止中$i 状態に入するに伴い，`保持-時刻$を保全することが求まれる。 ◎ Note: The hold time might be already set if the animation is finished, or if the animation has a pending play task. In either case we want to preserve the hold time as we enter the paused state.

   3. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate on animation.
   4. %~animation の`開始-時刻$ ~SET `未解決$ ◎ Make animation’s start time unresolved.
   5. `~promiseを解決する$( %~animation の`現在の準備済み~promise$, %~animation ) ◎ Resolve animation’s current ready promise with animation.
   6. `完遂d状態を更新する$( %~animation ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to false, and the synchronously notify flag set to false.

   所与の時点における %~animation の `処理待ち静止-~task@ は、［ この段に与えた~taskが~scheduleされてから走る直前までの間は その~task ／ 他のときは ε ］とする。 ◎ So long as the above task is scheduled but has yet to run, animation is described as having a pending pause task. While the task is running, however, animation does not have a pending pause task.

   `処理待ち再生-~task$のときと同じく、 ~UAは，`処理待ち静止-~task$を非同期的に走らすモノトスル — それは、 次回に`小task~checkpointを遂行する$ときに走ることにもなろうが。 ◎ As with the pending play task, the user agent must run the pending pause task asynchronously, although that could be as soon as the next microtask checkpoint.

10. `完遂d状態を更新する$( %~animation ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to false, and the synchronously notify flag set to false.

`完遂d状態を更新する@ 手続-は、 所与の ( %~animation, %~seekしたか ~DF ε, %同期的に通知するか ~DF ε ) に対し： ◎ The procedure to update an animation’s finished state for animation, given＼

• %~seekしたか ~IN { `~seekした^i, ε } は、 非 ε ならば，次を指示する ⇒ この手続-は、 `現-時刻を設定する$手続-の後に遂行されている。 ◎ a flag did seek (to indicate if the update is being performed after setting the current time), and＼
• %同期的に通知するか ~IN { `同期的に通知する^i, ε } は、 非 ε ならば，次を指示する ⇒ この手続-を~callしている文脈は、 とにかく即時に［ 完遂d~eventを~queueする ／ 完遂d~promiseを解決する ］ことを期待している。 ◎ a flag synchronously notify (to indicate the update was called in a context where we expect finished event queueing and finished promise resolution to happen immediately, if at all) is as follows:

1. %旧~現-時刻 ~LET %~animation の`現-時刻$ ◎ ↓

2. ~IF［ %~seekしたか ~EQ ε ］~AND［ %~animation の`保持-時刻$ ~EQ `未解決$ ］ ⇒ %~animation の`保持-時刻$ ~SET %旧~現-時刻 ◎ Let the unconstrained current time be the result of calculating the current time, substituting an unresolved time value for the hold time if did seek is false. If did seek is true, the unconstrained current time is equal to the current time.

   注記： この段は、［ 方向が変化し得るような時列線 ］に適応するために要求される。 この定義がないと、 いったん完遂した~animationは，時列線が反対-方向へ進捗した後も完遂dのままであり続けることになる。 ◎ Note: This is required to accommodate timelines that can change direction. Without this definition, a once-finished animation would remain finished even when its timeline progresses in the opposite direction.

3. %新-保持-時刻 ~LET 次の手続きを走らせた結果： ◎ ↓

   1. ~IF［ ~OR↓ ］：

      • %旧~現-時刻 ~EQ `未解決$
      • %~animation の`開始-時刻$ ~EQ `未解決$
      • %~animation の`処理待ち再生-~task$ ~NEQ ε
      • %~animation の`処理待ち静止-~task$ ~NEQ ε

      …ならば ⇒ ~RET ε

      ◎ If all three of the following conditions are true, • the unconstrained current time is resolved, and • animation’s start time is resolved, and • animation does not have a pending play task or a pending pause task, ◎ then update animation’s hold time based on the first matching condition for animation from below, if any:
   2. %再生~rate ~LET %~animation の`再生~rate$ ◎ ↓
   3. ~IF［ %再生~rate ~EQ 0 ］ ⇒ ~RET ε ◎ ↓

   4. ~IF［ %再生~rate ~GT 0 ］~AND［ %旧~現-時刻 ~GTE %~animation に`結付けられた効果の終端$ ］： ◎ If playback rate > 0 and unconstrained current time is greater than or equal to associated effect end,

      1. ~IF［ %~seekしたか ~EQ `~seekした^i ］ ⇒ ~RET %旧~現-時刻 ◎ If did seek is true, let the hold time be the value of unconstrained current time.
      2. ~IF［ %~animation の`前回の現-時刻$ ~NEQ `未解決$ ］ ⇒ ~RET `max^op( %~animation の`前回の現-時刻$, %~animation に`結付けられた効果の終端$ ) ◎ If did seek is false, let the hold time be the maximum value of previous current time and associated effect end.＼
      3. ~RET %~animation に`結付けられた効果の終端$ ◎ If the previous current time is unresolved, let the hold time be associated effect end.

   5. ~IF［ %再生~rate ~LT 0 ］~AND［ %旧~現-時刻 ~LTE 0 ］： ◎ If playback rate < 0 and unconstrained current time is less than or equal to 0,

      1. ~IF［ %~seekしたか ~EQ `~seekした^i ］ ⇒ ~RET %旧~現-時刻 ◎ If did seek is true, let the hold time be the value of unconstrained current time.
      2. ~IF［ %~animation の`前回の現-時刻$ ~NEQ `未解決$ ］ ⇒ ~RET `min^op( %~animation の`前回の現-時刻$, 0 ) ◎ If did seek is false, let the hold time be the minimum value of previous current time and zero.＼
      3. ~RET 0 ◎ If the previous current time is unresolved, let the hold time be zero.

   6. ~IF［ %~animation の`時列線~現-時刻$ ~NEQ `未解決$ ］： ◎ If playback rate ≠ 0, and animation is associated with an active timeline, ◎ Perform the following steps:

      1. %保持-時刻 ~LET %~animation の`保持-時刻$ ◎ ↓
      2. ~IF［ %~seekしたか ~EQ `~seekした^i ］~AND［ %保持-時刻 ~NEQ `未解決$ ］ ⇒ %~animation の`開始-時刻$ ~LET %~animation の`時列線~現-時刻$ ~MINUS ( %保持-時刻 ~DIV %再生~rate ) ◎ If did seek is true and the hold time is resolved, let animation’s start time be equal to the result of evaluating timeline time − (hold time / playback rate) where timeline time is the current time value of the timeline associated with animation.
      3. ~RET `未解決$ ◎ Let the hold time be unresolved.
   7. ~RET ε ◎ ↑
4. ~IF［ %新-保持-時刻 ~NEQ ε ］ ⇒ %~animation の`保持-時刻$ ~SET %新-保持-時刻 ◎ ↑
5. %~animation の`前回の現-時刻$ ~SET %~animation の`現-時刻$ ◎ Set the previous current time of animation to be the result of calculating its current time.
6. %現-完遂d状態 ~LET ~IS［ %~animation の`再生-状態$ ~EQ `完遂d$i ］ ◎ Let current finished state be true if the play state of animation is finished. Otherwise, let it be false.

7. ~IF［ %現-完遂d状態 ~EQ ~T ］~AND［ %~animation の`現在の完遂d~promise$はまだ解決されてない ］： ◎ If current finished state is true and the current finished promise is not yet resolved, perform the following steps:

   1. この手続-における `完遂-通知~手続き@ は： ◎ Let finish notification steps refer to the following procedure:

      1. ~IF［ %~animation の`再生-状態$ ~NEQ `完遂d$i ］ ⇒ ~RET ◎ If animation’s play state is not equal to finished, abort these steps.
      2. `~promiseを解決する$( %~animation の`現在の完遂d~promise$, %~animation ) ◎ Resolve animation’s current finished promise object with animation.
      3. %~finish~event ~LET `~eventを作成する$( `AnimationPlaybackEvent$I ) ◎ Create an AnimationPlaybackEvent, finishEvent.
      4. %~finish~event の ⇒＃ `type$m 属性 ~SET `finish$et `currentTime$m 属性 ~SET %~animation の`現-時刻$ `timelineTime$m 属性 ~SET %~animation の`時列線~現-時刻$ ◎ Set finishEvent’s type attribute to finish. ◎ Set finishEvent’s currentTime attribute to the current time of animation. ◎ Set finishEvent’s timelineTime attribute to the current time of the timeline with which animation is associated. If animation is not associated with a timeline, or the timeline is inactive, let timelineTime be null.
      5. ~IF［ %~animation の`計時~用の文書$ ~NEQ ε ］ ⇒ %~animation の`計時~用の文書$の`処理待ち~animation~event~queue$に， %~finish~event に次を伴わせた上で付加する ⇒＃ `対応する~event~target$ ~SET %~animation, `~schedule済み~event時刻$ ~SET `~animation時刻を起点に相対的な時刻へ戻す$( %~animation に`結付けられた効果の終端$ ) ◎ If animation has a document for timing, then append finishEvent to its document for timing’s pending animation event queue along with its target, animation. For the scheduled event time, use the result of converting animation’s associated effect end to an origin-relative time.

      6. ~ELSE ⇒ `~taskを~queueする$( `~DOM操作~task~source$, 次の手続き )

         手続きは ⇒ `~eventを配送する$( %~animation, %~finish~event )
         ◎ Otherwise, queue a task to dispatch finishEvent at animation. The task source for this task is the DOM manipulation task source.
   2. %小task ~LET %~animation 用に`完遂-通知~手続き$を走らす小taskは［ すでに~queueされているならば それ ／ ~ELSE_ ε ］ ◎ ↓
   3. ~IF［ %同期的に通知するか ~EQ `同期的に通知する^i ］ ⇒＃ %小task ~NEQ ε ならばそれを取消す； 即時に`完遂-通知~手続き$を走らす ◎ If synchronously notify is true, cancel any queued microtask to run the finish notification steps for this animation, and run the finish notification steps immediately.
   4. ~ELIF［ %小task ~EQ ε ］ ⇒ `小taskを~queueする$( %~animation 用の`完遂-通知~手続き$ ) ◎ Otherwise, if synchronously notify is false, queue a microtask to run finish notification steps for animation unless there is already a microtask queued to run those steps for animation.
8. ~IF［ %現-完遂d状態 ~EQ ~F ］~AND［ %~animation の`現在の完遂d~promise$はすでに解決された ］ ⇒ %~animation の`現在の完遂d~promise$ ~SET `新たな~promise$を %~animation に`関連な~realm$内に作成した結果 ◎ If current finished state is false and animation’s current finished promise is already resolved, set animation’s current finished promise to a new promise in the relevant Realm of animation.

`~animationを完遂する@ 手続-は、 ~animationを現在の再生~方向にある自然な終端へ進めるために利用できる。 それは、 所与の ( %~animation ) に対し： ◎ An animation can be advanced to the natural end of its current playback direction by using the procedure to finish an animation for animation defined below:

1. %再生~rate ~LET %~animation の`実効~再生~rate$ ◎ ↓
2. ~IF［ %再生~rate ~EQ 0 ］~OR［［ %再生~rate ~GT 0 ］~AND［ `結付けられた効果の終端$ ~EQ 無限大 ］］ ⇒ ~THROW `InvalidStateError$E ◎ If animation’s effective playback rate is zero, or if animation’s effective playback rate > 0 and associated effect end is infinity, throw an "InvalidStateError" DOMException and abort these steps.
3. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate to animation.
4. ~Assert： %再生~rate ~EQ %~animation の`再生~rate$
5. %制限- ~LET ［ %再生~rate ~GT 0 ならば`結付けられた効果の終端$ ／ ~ELSE_ 0 ］ ◎ Set limit as follows: • If playback rate > 0, •• Let limit be associated effect end. • Otherwise, •• Let limit be zero.
6. `現-時刻を~silentに設定する$( %~animation, %制限- ) ◎ Silently set the current time to limit.
7. ~IF［ %~animation の`開始-時刻$ ~EQ `未解決$ ］~AND［ %~animation の`時列線~現-時刻$ ~NEQ `未解決$ ］ ⇒ %~animation の`開始-時刻$ ~LET ( %~animation の`時列線~現-時刻$ ) ~MINUS ( %制限- ~DIV %再生~rate ) ◎ If animation’s start time is unresolved and animation has an associated active timeline, let the start time be the result of evaluating timeline time − (limit / playback rate) where timeline time is the current time value of the associated timeline.

8. ~IF［ %~animation の`開始-時刻$ ~NEQ `未解決$ ］： ◎ ↓

   1. ~IF［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］： ◎ If there is a pending pause task and start time is resolved,

      1. `保持-時刻$ ~SET `未解決$ ◎ Let the hold time be unresolved.

         注記： 概して，`保持-時刻$は、 この段~以前に`未解決$になる — %~animation が `遊休中$i であった事例を除き。 ◎ Note: Typically the hold time will already be unresolved except in the case when the animation was previously idle.

      2. %~animation の`処理待ち静止-~task$を取消す ◎ Cancel the pending pause task.
      3. `~promiseを解決する$( %~animation の`現在の準備済み~promise$, %~animation ) ◎ Resolve the current ready promise of animation with animation.
   2. ~IF［ %~animation の`処理待ち再生-~task$ ~NEQ ε ］ ⇒＃ その~taskを取消す； `~promiseを解決する$( %~animation の`現在の準備済み~promise$, %~animation ) ◎ If there is a pending play task and start time is resolved, cancel that task and resolve the current ready promise of animation with animation.
9. `完遂d状態を更新する$( %~animation, `~seekした^i, `同期的に通知する^i ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to true, and the synchronously notify flag set to true.

`~animationを取消す@ 手続-は、 所与の ( %~animation ) に対し： ◎ The procedure to cancel an animation for animation is as follows:

1. ~IF［ %~animation の`再生-状態$ ~NEQ `遊休中$i ］： ◎ If animation’s play state is not idle, perform the following steps:

   1. `処理待ち~taskを再設定する$( %~animation ) ◎ Run the procedure to reset an animation’s pending tasks on animation.
   2. %完遂d~promise ~LET %~animation の`現在の完遂d~promise$ ◎ ↓
   3. `~promiseを却下する$( %完遂d~promise, `AbortError$E 例外 ) ◎ Reject the current finished promise with a DOMException named "AbortError".
   4. %完遂d~promise の `PromiseIsHandled^sl 内部~slot ~SET ~T ◎ Set the [[PromiseIsHandled]] internal slot of the current finished promise to true.
   5. %~animation の`現在の完遂d~promise$ ~SET `新たな~promise$を %~animation に`関連な~realm$内に作成した結果 ◎ Let current finished promise be a new promise in the relevant Realm of animation.
   6. %~cancel~event ~LET `~eventを作成する$( `AnimationPlaybackEvent$I ) ◎ Create an AnimationPlaybackEvent, cancelEvent.
   7. %時列線~時刻 ~LET %~animation の`時列線~現-時刻$ ◎ ↓
   8. %~cancel~event の ⇒＃ `type$m 属性 ~SET `cancel$et, `currentTime$m 属性 ~SET `未解決$, `timelineTime$m 属性 ~SET %時列線~時刻 ◎ Set cancelEvent’s type attribute to cancel. ◎ Set cancelEvent’s currentTime to null. ◎ Let timeline time be the current time of the timeline with which animation is associated. If animation is not associated with an active timeline, let timeline time be an unresolved time value. ◎ Set cancelEvent’s timelineTime to timeline time. If timeline time is unresolved, set it to null.

   9. ~IF［ %~animation の`計時~用の文書$ ~NEQ ε ］：

      1. %~schedule済み~event時刻 ~LET `未解決$
      2. ~IF［ %時列線~時刻 ~NEQ `未解決$ ］~AND［ %~animation の`時列線$An用に`起点に相対的な時刻へ変換する$手続-は定義されている ］ ⇒ %~schedule済み~event時刻 ~SET その手続-を %時列線~時刻 に適用した結果
      3. `計時~用の文書$の`処理待ち~animation~event~queue$に， %~cancel~event に次を伴わせた上で付加する ⇒＃ `対応する~event~target$ ~SET %~animation, `~schedule済み~event時刻$ ~SET %~schedule済み~event時刻
      ◎ If animation has a document for timing, then append cancelEvent to its document for timing’s pending animation event queue along with its target, animation. If animation is associated with an active timeline that defines a procedure to convert timeline times to origin-relative time, let the scheduled event time be the result of applying that procedure to timeline time. Otherwise, the scheduled event time is an unresolved time value.

   10. ~ELSE ⇒ `~taskを~queueする$( `~DOM操作~task~source$, 次の手続き )

       手続きは ⇒ `~eventを配送する$( %~animation, %~cancel~event )
       ◎ Otherwise, queue a task to dispatch cancelEvent at animation. The task source for this task is the DOM manipulation task source.
2. %~animation の`保持-時刻$ ~SET `未解決$ ◎ Make animation’s hold time unresolved.
3. %~animation の`開始-時刻$ ~SET `未解決$ ◎ Make animation’s start time unresolved.

`処理待ち~taskを再設定する@ 手続-は、 所与の ( %~animation ) に対し： ◎ The procedure to reset an animation’s pending tasks for animation is as follows:

1. ~IF［ %~animation の`処理待ち再生-~task$ ~EQ ε ］~AND［ %~animation の`処理待ち静止-~task$ ~EQ ε ］ ⇒ ~RET ◎ If animation does not have a pending play task or a pending pause task, abort this procedure.
2. ~IF［ %~animation の`処理待ち再生-~task$ ~NEQ ε ］ ⇒ その~taskを取消す ◎ If animation has a pending play task, cancel that task.
3. ~IF［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］ ⇒ その~taskを取消す ◎ If animation has a pending pause task, cancel that task.
4. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate on animation.
5. `~promiseを却下する$( %~animation の`現在の準備済み~promise$, `AbortError$E 例外 ) ◎ Reject animation’s current ready promise with a DOMException named "AbortError".
6. %~animation の`現在の準備済み~promise$の `PromiseIsHandled^sl 内部~slot ~SET ~T ◎ Set the [[PromiseIsHandled]] internal slot of animation’s current ready promise to true.
7. %~animation の`現在の準備済み~promise$ ~LET `解決される~promise$( %~animation, %~animation に`関連な~realm$ ) ◎ Let animation’s current ready promise be the result of creating a new resolved Promise object with value animation in the relevant Realm of animation.

`~animation$ %~animation の `再生~rateを設定する@ ~algoは、 所与の ( %新-再生~rate ) に対し： ◎ The procedure to set the playback rate of an animation, animation, to new playback rate is as follows:

1. %~animation の`処理待ち再生~rate$ ~SET ε ◎ Clear any pending playback rate on animation.
2. %前回の時刻 ~LET %~animation の`現-時刻$ ◎ Let previous time be the value of the current time of animation before changing the playback rate.
3. %前回の再生~rate ~LET %~animation の現在の`実効~再生~rate$ ◎ Let previous playback rate be the current effective playback rate of animation.
4. `再生~rate$ ~SET %新-再生~rate ◎ Set the playback rate to new playback rate.
5. %時列線 ~LET %~animation の`時列線$An ◎ ↓
6. ~IF［ %時列線 ~EQ ~NULL ］ ⇒ ~RET ◎ ↓
7. ~IF［ %時列線 は`単調増加-$している ］~AND［ %前回の時刻 ~NEQ `未解決$ ］ ⇒ `現-時刻を設定する$( %~animation, %前回の時刻 ) ◎ Perform the steps corresponding to the first matching condition from the following, if any: ◎ If animation is associated with a monotonically increasing timeline and the previous time is resolved, • Set the current time of animation to previous time.

8. ~ELIF［ ~AND↓ ］… ◎ ↑ If animation is associated with a non-null timeline＼

   • %時列線 は`単調増加-$していない ◎ that is not monotonically increasing,＼
   • %~animation の`開始-時刻$ ~EQ `未解決$ ◎ the start time of animation is resolved,＼
   • `結付けられた効果の終端$ ~NEQ 無限大 ◎ associated effect end is not infinity,＼

   • ~OR↓： ◎ and either:

     • ［ %前回の再生~rate ~LT 0 ］~AND［ %新-再生~rate ~GTE 0 ］ ◎ the previous playback rate < 0 and the new playback rate ≥ 0, or
     • ［ %前回の再生~rate ~GTE 0 ］~AND［ %新-再生~rate ~LT 0 ］ ◎ the previous playback rate ≥ 0 and the new playback rate < 0,

   …ならば ⇒ %~animation の`開始-時刻$ ~SET %~animation に`結付けられた効果の終端$ ~MINUS %~animation の`開始-時刻$ ◎ Set animation’s start time to the result of evaluating associated effect end − start time for animation.

   注記 この段は、 実質的に， %時列線 上で %~animation の［ 開始-時刻, 終止-時刻 ］を［ 反対~方向から相対的な開始-時刻の~offsetを保全する ］よう，入れ替える。 ◎ Note: This effectively flips the animation start/end times on non-monotonic timelines, preserving the relative offset of the start time from the other direction.

%~animation の `実効~再生~rate@ は、［ %~animation の`処理待ち再生~rate$ ~NEQ ε ならば それ ／ ~ELSE_ %~animation の`再生~rate$ ］とする。 ◎ The effective playback rate of an animation is its pending playback rate, if set, otherwise it is the animation’s playback rate.

`処理待ち再生~rateがあれば適用する@ ~algoは、 所与の ( `~animation$ %~animation ) に対し： ◎ When an animation, animation, is to apply any pending playback rate the following steps are performed:

1. ~IF［ %~animation の`処理待ち再生~rate$ ~EQ ε ］ ⇒ ~RET ◎ If animation does not have a pending playback rate, abort these steps.
2. %~animation の`再生~rate$ ~SET %~animation の`処理待ち再生~rate$ ◎ Set animation’s playback rate to its pending playback rate.
3. %~animation の`処理待ち再生~rate$ ~SET ε ◎ Clear animation’s pending playback rate.

`再生~rateを継目無く更新する@ ~algoは、 所与の ( `~animation$ %~animation, %新-再生~rate ) に対し — この手続-は、 %~animation の`現-時刻$を保全するようにふるまう： ◎ The procedure to seamlessly update the playback rate of an animation, animation, to new playback rate preserving its current time is as follows:

1. %以前の再生-状態 ~LET %~animation の`再生-状態$ ◎ Let previous play state be animation’s play state.

   注記： 再生-状態は、 %~animation の`実効~再生~rate$を更新する前に記録することが必要yである。 `この時点^emで，再生-状態が `完遂d$i である場合、 以下において`処理待ち再生~rate$を適用した後にどうなろうが， %~animation の`処理待ち再生~rate$を即時に適用することが求まれるので。 ◎ Note: It is necessary to record the play state before updating animation’s effective playback rate since, in the following logic, we want to immediately apply the pending playback rate of animation if it is currently finished regardless of whether or not it will still be finished after we apply the pending playback rate.

2. %~animation の`処理待ち再生~rate$ ~SET %新-再生~rate ◎ Let animation’s pending playback rate be new playback rate.

3. ~IF［ %~animation の`処理待ち再生-~task$ ~NEQ ε ］~OR［ %~animation の`処理待ち静止-~task$ ~NEQ ε ］ ⇒ ~RET ◎ Perform the steps corresponding to the first matching condition below: ◎ If animation has a pending play task or a pending pause task, • Abort these steps.

   注記： どちらの処理待ち~taskも，自身が走るときに`処理待ち再生~rate$を適用することになるので、 この事例においては，それ以上の動作は要求されない。 ◎ Note: The different types of pending tasks will apply the pending playback rate when they run so there is no further action required in this case.

4. %現-時刻 ~LET %~animation の`現-時刻$ ◎ ↓

5. ~IF［ %以前の再生-状態 ~IN { `遊休中$i, `静止中$i } ］~OR［ %現-時刻 ~EQ `未解決$ ］ ⇒ `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ If previous play state is idle or paused, or animation’s current time is unresolved, • Apply any pending playback rate on animation.

   注記： 上の 2 個目の条件は、 `稼働中$i にある~animationの`現-時刻$が`未解決$で，`処理待ち再生-~task$も無い場合には、 以下で再生しようと試みないようにするために要求される。 ◎ Note: The second condition above is required so that if we have a running animation with an unresolved current time and no pending play task, we do not attempt to play it below.

6. ~ELIF［ %以前の再生-状態 ~EQ `完遂d$i ］： ◎ If previous play state is finished,

   1. ~IF［ `保持-時刻$ ~EQ `未解決$ ］ ⇒ %~animation の`保持-時刻$ ~SET %現-時刻 ◎ Let the unconstrained current time be the result of calculating the current time of animation substituting an unresolved time value for the hold time.
   2. %~animation の`開始-時刻$ ~SET %~animation の`時列線~現-時刻$ ◎ ↓
   3. ~IF［ %~animation の`処理待ち再生~rate$ ~NEQ 0 ］ ⇒ %~animation の`開始-時刻$ ~DECBY ( %現-時刻 ~DIV %~animation の`処理待ち再生~rate$ ) ◎ Let animation’s start time be the result of evaluating the following expression: • timeline time − (unconstrained current time / pending playback rate) • Where timeline time is the current time value of the timeline associated with animation. ◎ If pending playback rate is zero, let animation’s start time be timeline time.
   4. `処理待ち再生~rateがあれば適用する$( %~animation ) ◎ Apply any pending playback rate on animation.
   5. `完遂d状態を更新する$( %~animation ) ◎ Run the procedure to update an animation’s finished state for animation with the did seek flag set to false, and the synchronously notify flag set to false.
7. ~ELSE ⇒ `~animationを再生する$( %~animation, ε ) ◎ Otherwise, • Run the procedure to play an animation for animation with the auto-rewind flag set to false.

`~animationを逆転する@ ~algoは、 所与の ( `~animation$ %~animation ) に対し： ◎ The procedure to reverse an animation of animation animation is as follows:

1. ~IF［ %~animation の`時列線~現-時刻$ ~EQ `未解決$ ］ ⇒ ~THROW `InvalidStateError$E ◎ If there is no timeline associated with animation, or the associated timeline is inactive throw an "InvalidStateError" DOMException and abort these steps.
2. %元の処理待ち再生~rate ~LET %~animation の`処理待ち再生~rate$ ◎ Let original pending playback rate be animation’s pending playback rate.
3. %~animation の`処理待ち再生~rate$ ~LET %~animation の`実効~再生~rate$ ~MUL −1 ◎ Let animation’s pending playback rate be the additive inverse of its effective playback rate (i.e. -effective playback rate).
4. `~animationを再生する$( %~animation, `自動で巻戻す^i ) ⇒ 例外が投出されたときは ⇒＃ %~animation の`処理待ち再生~rate$ ~SET %元の処理待ち再生~rate； ~THROW その例外 ◎ Run the steps to play an animation for animation with the auto-rewind flag set to true. ◎ If the steps to play an animation throw an exception, set animation’s pending playback rate to original pending playback rate and propagate the exception.

所与の~momentにおける`~animation$ %~animation の`再生-状態$は、 次を走らせた結果を返す： ◎ The play state of animation, animation, at a given moment is the state corresponding to the first matching condition from the following:

1. 以下に現れる次の用語は、 %~animation のそれを表すとする ⇒＃ `現-時刻$, `処理待ち再生-~task$, `処理待ち静止-~task$, `開始-時刻$, `実効~再生~rate$, `結付けられた効果の終端$

2. ~IF［ ~AND↓ ］… ◎ All of the following conditions are true:

   • `現-時刻$ ~EQ `未解決$ ◎ The current time of animation is unresolved, and
   • `開始-時刻$ ~EQ `未解決$ ◎ the start time of animation is unresolved, and
   • ［ `処理待ち再生-~task$ ~EQ ε ］~AND［ `処理待ち静止-~task$ ~EQ ε ］ ◎ animation does not have either a pending play task or a pending pause task,

   …ならば ⇒ ~RET `遊休中@i ◎ → idle

3. ~IF［ ~OR↓ ］： ◎ Either of the following conditions are true:

   • `処理待ち静止-~task$ ~NEQ ε ◎ animation has a pending pause task, or
   • ［ `開始-時刻$ ~EQ `未解決$ ］~AND［ `処理待ち再生-~task$ ~EQ ε ］ ◎ both the start time of animation is unresolved and it does not have a pending play task,

   …ならば ⇒ ~RET `静止中@i ◎ → paused

4. ~IF［ `現-時刻$ ~NEQ `未解決$ ］~AND［ ~OR↓ ］： ◎ For animation, current time is resolved and either of the following conditions are true:

   • ［ `実効~再生~rate$ ~GT 0 ］~AND［ `現-時刻$ ~GTE `結付けられた効果の終端$ ］ ◎ animation’s effective playback rate > 0 and current time ≥ associated effect end; or
   • ［ `実効~再生~rate$ ~LT 0 ］~AND［ `現-時刻$ ~LTE 0 ］ ◎ animation’s effective playback rate < 0 and current time ≤ 0,

   …ならば ⇒ ~RET `完遂d@i ◎ → finished

5. ~RET `稼働中@i ◎ Otherwise, • → running

`~animation時刻を起点に相対的な時刻へ戻す@ ~algoは、 所与の ( %~animation, %時刻 ) に対し （ %時刻 は %~animation の`開始-時刻$に相対的な`時刻~値$を表す）： ◎ ↓↓

1. %時列線~時刻 ~LET 次の手続き（ `~animation時刻から時列線~時刻へ変換する@ ）を遂行した結果： ◎ To convert an animation time to timeline time a time value, time, that is relative to the start time of an animation, animation, perform the following steps:

   1. ~IF［ %時刻 ~IN { `未解決$, 無限大 } ］ ⇒ ~RET `未解決$ ◎ If time is unresolved, return time. ◎ If time is infinity, return an unresolved time value.
   2. %再生~rate ~LET %~animation の`再生~rate$ ◎ ↓
   3. %開始-時刻 ~LET %~animation の`開始-時刻$ ◎ ↓

   4. ~IF［ %再生~rate ~EQ 0 ］~OR［ %開始-時刻 ~EQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If animation’s playback rate is zero, return an unresolved time value. ◎ If animation’s start time is unresolved, return an unresolved time value.

   5. ~RET %時刻 ~DIV %再生~rate ~PLUS %開始-時刻 ◎ Return the result of calculating time × (1 / playback rate) + start time, where playback rate and start time are the playback rate and start time of animation, respectively.
2. ~IF［ %時列線~時刻 ~EQ `未解決$ ］ ⇒ ~RET %時刻 【`未解決$ではないのか？】 ◎ ↑To convert a timeline time to an origin-relative time a time value, time, that is expressed in the same scale as the time values of a timeline, timeline, perform the following steps: ◎ ↑Let timeline time be the result of converting time from an animation time to a timeline time. ◎ If timeline time is unresolved, return time.
3. ~IF［ %~animation の`時列線~現-時刻$ ~NEQ `未解決$ ］~AND［ %~animation の`時列線$An用に`起点に相対的な時刻へ変換する$手続-は定義されている ］ ⇒ ~RET その手続-を %時列線~時刻 に適用した結果 ◎ If animation is not associated with a timeline, return an unresolved time value. ◎ If animation is associated with an inactive timeline, return an unresolved time value. ◎ If there is no procedure to convert a timeline time to an origin-relative time for the timeline associated with animation, return an unresolved time value. ◎ Return the result of converting timeline time to an origin-relative time using the procedure defined for the timeline associated with animation.
4. ~RET `未解決$ ◎ ↑

所与の時点における`~animation効果$ %効果 の `相@ は、 次の~algoに従って決定される： ◎ The phase of an animation effect depends on the following definitions:

1. %局所~時刻 ~LET %効果 の`局所~時刻$ ◎ ↓↓
2. ~IF［ %局所~時刻 ~EQ `未解決$ ］ ⇒ ~RET `遊休~相@i ◎ ↓↓
3. `~animation方向@V ~LET ［ 次が満たされるならば `後方^i ／ ~ELSE_ `前方^i ］ ⇒ %効果 を`結付けた~animation$（ ~NEQ ε ）の`再生~rate$ ~LT 0 ◎ animation direction • “backwards” if the effect is associated with an animation and the associated animation’s playback rate is less than zero; in all other cases, the animation direction is “forward”.
4. `作動~前~境界~時刻@V ~LET `max^op( `min^op( %効果 の`開始-遅延$, %効果 の`終止-時刻$ ), 0 ) ◎ before-active boundary time • max(min(start delay, end time), 0)
5. `作動~後~境界~時刻@V ~LET `max^op( `min^op( %効果 の`開始-遅延$ ~PLUS %効果 の`作動~所要時間$, %効果 の`終止-時刻$ ), 0 ) ◎ active-after boundary time • max(min(start delay + active duration, end time), 0)
6. `作動~区間に終端点を含めるか@V ~SET ~IS［［ `相$を決定するときは，この真偽-~flagは ~T をとる ］ものと指定された ］ ◎ Furthermore, an endpoint-inclusive active interval flag may be specified when determining the phase. If not specified, it is assumed to be false.

7. ~IF［ ~OR↓ ］…

   • %局所~時刻 ~LT %作動~前~境界~時刻

   • ~AND↓：

     • %~animation方向 ~EQ `後方^i
     • `作動~区間に終端点を含めるか$V ~EQ ~F
     • %局所~時刻 ~EQ %作動~前~境界~時刻

   …ならば ⇒ ~RET `事前~相@i

   ◎ An animation effect is in the before phase if the animation effect’s local time is not unresolved and either of the following conditions are met: • the local time is less than the before-active boundary time, or • the animation direction is “backwards”, the endpoint-inclusive active interval flag is false, and the local time is equal to the before-active boundary time.
8. ~IF［ %局所~時刻 ~GT %作動~後~境界~時刻 ］~OR［［ %局所~時刻 ~EQ %作動~後~境界~時刻 ］~AND［ %~animation方向 ~EQ `前方^i ］］ ⇒ ~RET `事後~相@i ◎ An animation effect is in the after phase if the animation effect’s local time is not unresolved and either of the following conditions are met: • the local time is greater than the active-after boundary time, or • the animation direction is “forwards” and the local time is equal to the active-after boundary time.
9. ~RET `作動~相@i ◎ An animation effect is in the active phase if the animation effect’s local time is not unresolved and it is not in either the before phase nor the after phase. ◎ ↑↑Furthermore, it is often convenient to refer to the case when an animation effect is in none of the above phases as being in the idle phase.

所与の［ 要素／疑似要素 ］ %~target に対し，それに `関連な~animation群@ は、 `~animation$のうち［ それに`結付けられた効果$の`効果~target$が次を満たすもの ］すべてからなる集合を返す ⇒ その`~target要素$ ~EQ %~target

所与の［ 要素／疑似要素／`文書$／`~shadow根$ ］ %~target に対し，その `下位tree用の関連な~animation群@ は、 `~animation$のうち［ それに`結付けられた効果$の`効果~target$の`~target要素$が次を満たすもの ］すべてからなる集合を返す：

• %~target は［ 要素／疑似要素 ］である場合 ⇒ %~target の`広義-子孫$である

  【 %~target が疑似要素である場合、 %~target の`出自の要素$の広義-子孫？ 】

• %~target は［ `文書$／`~shadow根$ ］である場合 ⇒ %~target の`子孫$である

`~animation効果$ %効果 の `作動~時刻@ は， %効果 の［ `局所~時刻$, `開始-遅延$ ］に基づくが、 %効果 が出力を生産するべきときに限り定義されるので， %効果 の［ `延伸~mode$, `相$ ］にも依存する — 次に従うように： ◎ The active time is based on the local time and start delay. However, it is only defined when the animation effect should produce an output and hence depends on its fill mode and phase as follows:

1. ~IF［ %効果 の`相$ ~EQ `遊休~相$i ］ ⇒ ~RET `未解決$ ◎ ↓↓
2. ~Assert： `局所~時刻$ ~NEQ `未解決$ ◎ ↓↓
3. %時刻 ~LET `局所~時刻$ ~MINUS `開始-遅延$ ◎ ↓

4. %効果 の`相$に応じて：

   • `事前~相$i： ◎ If the animation effect is in the before phase, • The result depends on the first matching condition from the following:

     1. ~IF［ `延伸~mode$ ~IN { `後方$i, `両方$i } ］ ⇒ ~RET `max^op( %時刻, 0 ) ◎ If the fill mode is backwards or both, • Return the result of evaluating max(local time − start delay, 0).
     2. ~RET `未解決$ ◎ Otherwise, • Return an unresolved time value.
   • `作動~相$i ⇒ ~RET %時刻 ◎ If the animation effect is in the active phase, • Return the result of evaluating local time − start delay.

   • `事後~相$i： ◎ If the animation effect is in the after phase, • The result depends on the first matching condition from the following:

     1. ~IF［ `延伸~mode$ ~IN { `前方$i, `両方$i } ］ ⇒ ~RET `max^op( `min^op( %時刻, `作動~所要時間$ ), 0) ◎ If the fill mode is forwards or both, • Return the result of evaluating max(min(local time − start delay, active duration), 0).
     2. ~RET `未解決$ ◎ Otherwise, • Return an unresolved time value. ◎ Otherwise (the local time is unresolved), • Return an unresolved time value.

`~animation効果$ %効果 の `総体~進捗@ は、 完了した反復~回数（部分的な反復による端数も含む）を表し， 次に従って定義される： ◎ The overall progress describes the number of iterations that have completed (including partial iterations) and is defined as follows:

1. %作動~時刻 ~LET %効果 の`作動~時刻$ ◎ ↓
2. ~IF［ %作動~時刻 ~EQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If the active time is unresolved, return unresolved.
3. %反復~所要時間 ~LET %効果 の`反復~所要時間$ ◎ ↓
4. %総体~進捗 ~LET ⇒＃ %反復~所要時間 ~NEQ 0 ならば ( %作動~時刻 ~DIV %反復~所要時間 ) ／ ~ELSE_ %効果 は `事前~相$i にあるならば 0 ／ ~ELSE_ %効果 の`反復~回数$ ◎ Calculate an initial value for overall progress based on the first matching condition below: ◎ If the iteration duration is zero, • If the animation effect is in the before phase, let overall progress be zero; otherwise, let it be equal to the iteration count. ◎ Otherwise, • Let overall progress be the result of calculating active time / iteration duration.
5. ~RET %総体~進捗 ~PLUS %効果 の`反復~始端$ ◎ Return the result of calculating overall progress + iteration start.

`~animation効果$ %効果 の `単純~反復~進捗@ は、 次に従って計算される — それは、［ 効果に適用された［ `再生~方向$ ／ `~easing関数$ ］により導入される，時刻に対する変形n ］は無視する下での，現在の反復~進捗に対する割合分を表す： ◎ The simple iteration progress is a fraction of the progress through the current iteration that ignores transformations to the time introduced by the playback direction or easing functions applied to the effect, and is calculated as follows:

1. %進捗 ~LET %効果 の`総体~進捗$ ◎ ↓
2. ~IF［ %進捗 ~EQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If the overall progress is unresolved, return unresolved.
3. ~IF［ %進捗 ~EQ 無限大 ］ ⇒ %進捗 ~SET %効果 の`反復~始端$ ◎ ↓
4. %単純~反復~進捗 ~SET %進捗 ~MINUS `floor^op( %進捗 ) 【！% 1.0】 ◎ If overall progress is infinity, let the simple iteration progress be iteration start % 1.0; otherwise, let the simple iteration progress be overall progress % 1.0.

5. ~IF［ ~AND↓ ］… ◎ If all of the following conditions are true:

   • %単純~反復~進捗 ~EQ 0 ◎ the simple iteration progress calculated above is zero, and
   • %効果 は［ `作動~相$i ／ `事後~相$i ］にある ◎ the animation effect is in the active phase or the after phase, and
   • %効果 の`作動~時刻$ ~EQ %効果 の`作動~所要時間$ ◎ the active time is equal to the active duration, and
   • %効果 の`反復~回数$ ~NEQ 0 ◎ the iteration count is not equal to zero.

   …ならば ⇒ %単純~反復~進捗 ~LET 1.0 ◎ Let the simple iteration progress be 1.0.

   注記： この段は、［ ~animationの作動~区間の終端, 反復の終端 ］が精確に一致するときの延伸の挙動を実装する — 次回の反復の始端ではなく， 最終回の反復の終端点を保持することにより。 ◎ The above step implements the behavior that when an animation’s active interval ends precisely at the end of an iteration, it fills by holding the endpoint of the final iteration rather than the start of the next iteration.

   最後の条件は、［ `反復~回数$ ~EQ 0 ］であったため ~animationの反復は決して再生されない場合に，これが適用されないようにする。 ◎ The final condition prevents this from applying when we never played any iterations of the animation to begin with because the iteration count was zero.

6. ~RET %単純~反復~進捗 ◎ Return simple iteration progress.

`~animation効果$ %効果 の `現在の反復~index@ 【 0 から数えて何回目の反復か】 は、 次の手続きで与えられ， 整数または無限大になる： ◎ The current iteration can be calculated using the following steps:

1. ~IF［ `作動~時刻$ ~EQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If the active time is unresolved, return unresolved.
2. ~IF［ %効果 は `事後~相$i にある ］~AND［ `反復~回数$ ~EQ 無限大 ］ ⇒ ~RET 無限大 ◎ If the animation effect is in the after phase and the iteration count is infinity, return infinity.
3. ~IF［ `単純~反復~進捗$ ~EQ 1.0 ］ ⇒ ~RET `floor^op( `総体~進捗$ ) ~MINUS 1 ◎ If the simple iteration progress is 1.0, return floor(overall progress) − 1.
4. ~RET `floor^op( `総体~進捗$ ) ◎ Otherwise, return floor(overall progress).

`~animation効果$ %効果 の `有向~進捗@ は、 次の手続きを利用して計算される： ◎ The directed progress is calculated from the simple iteration progress using the following steps:

1. %進捗 ~LET %効果 の`単純~反復~進捗$ ◎ ↑
2. ~IF［ %進捗 ~EQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If the simple iteration progress is unresolved, return unresolved.

3. %現在の方向 ~LET 次の手続きを走らせた結果： ◎ Calculate the current direction using the first matching condition from the following list:

   1. %再生~方向 ~LET %効果 の`再生~方向$ ◎ ↓
   2. ~IF［ %再生~方向 ~EQ `normal$v ］ ⇒ ~RET `順方向^i ◎ If playback direction is normal, • Let the current direction be forwards.
   3. ~IF［ %再生~方向 ~EQ `reverse$v ］ ⇒ ~RET `逆方向^i ◎ If playback direction is reverse, • Let the current direction be reverse.
   4. %d ~LET %効果 の`現在の反復~index$ ◎ ↓ Otherwise (the playback direction is alternate or alternate-reverse)p, ◎ Let d be the current iteration index.
   5. ~IF［ %d ~EQ 無限大 ］ ⇒ ~RET `順方向^i ◎ ↓
   6. ~IF［ %再生~方向 ~EQ `alternate-reverse$v ］ ⇒ %d ~INCBY 1 ◎ If playback direction is alternate-reverse increment d by 1.
   7. ~RET［ %d は偶数ならば `順方向^i ／ ~ELSE_ `逆方向^i ］ ◎ If d % 2 == 0, let the current direction be forwards; otherwise let the current direction be reverse. If d is infinity, let the current direction be forwards.
4. ~RET %現在の方向 に応じて ⇒＃ `順方向^i ならば %進捗 ／ `逆方向^i ならば ( 1.0 ~MINUS %進捗 ) ◎ If the current direction is forwards then return the simple iteration progress. ◎ Otherwise, return 1.0 − simple iteration progress.

`~animation効果$ %効果 の `変形d進捗@ は、 次の手続きを利用して計算される： ◎ The transformed progress is calculated from the directed progress using the following steps:

1. %有向~進捗 ~LET %効果 の`有向~進捗$ ◎ ↑
2. ~IF［ %有向~進捗 ~EQ `未解決$ ］ ⇒ ~RET `未解決$ ◎ If the directed progress is unresolved, return unresolved.
3. %現在の方向 ~LET `§ 有向~進捗の計算-法＠#calculating-the-directed-progress$ に定義される手続-の中で決定されるそれ ◎ Calculate the value of the before flag as follows: ◎ Determine the current direction using the procedure defined in § 4.7.6 Calculating the directed progress.

4. %直前~flag ~LET ~IS ~OR↓： ◎ If the current direction is forwards, let going forwards be true; otherwise it is false. ◎ The before flag is set＼

   • ［ %効果 は `事前~相$i にある ］~AND［ %現在の方向 ~EQ `順方向^i ］ ◎ if the animation effect is in the before phase and going forwards is true;＼
   • ［ %効果 は `事後~相$i にある ］~AND［ %現在の方向 ~EQ `逆方向^i ］ ◎ or if the animation effect is in the after phase and going forwards is false.
5. ~RET 次を与える下で， %効果 の`効果~easing関数$を評価した結果【`出力~進捗~値$】 ⇒＃ `入力~進捗~値$ ~SET %有向~進捗, `直前~flag$ ~SET %直前~flag ◎ Return the result of evaluating the effect easing function passing directed progress as the input progress value and before flag as the before flag.

`~prop値を算出する@ ~algoは、 所与の ( ~prop %~prop, 値 %値, `Element$I %要素 ) に対し ⇒ ~RET ［ %要素 の【他の~propたちの】`算出d値$ ］を［ 依存関係を解決するための文脈 ］として利用する下で，［ %~prop の定義~表tの “算出d値” の欄 ］に則って %値 を解決した結果 ◎ To compute a property value given a property property, a value value, and an Element element: resolve value according to the “Computed Value” line of the property’s definition table, using the computed values of element as the context for resolving dependencies, and return the result.

注記： この~algoは、 %要素 上の各~propの`算出d値$には影響しない。 ◎ Note: The computed values on element are not affected by this algorithm.

この~algoは、 ~keyframe内で指定された各~prop値に対し， 【それらを算出する】順序に依存関係が【各~propの間で】確立され得ることを含意する。 `~prop値を算出する$ときは、 `最初に^em， %値 に保持される［ `算出d値$どうしの依存関係 ］を計算するモノトスル。 ◎ This algorithm implies that property values specified in keyframes can establish order dependencies. When computing a property value, the computed values of dependencies held by value must be calculated first.

var %animation = %elem.`animate$0([{ fontSize: '10px', width: '10em' },
                              { fontSize: '20px', width: '20em' }], 1000);
%animation.`currentTime$0 = 500;
console.log(`getComputedStyle$0(%elem).fontSize); /* 
`15px^v になるべき。
◎
Should be 15px
 */
console.log(`getComputedStyle$0(%elem).width); /* 
`225px^v 【 = 15 × 15 】になるべき。
◎
Should be 225px
 */

`算出d~keyframe~offset$は、 次に定義する `欠落~keyframe~offsetを算出する@ 手続きを利用して生産される — それは、 所与の ( `~keyframe$たちが成す~list %~keyframe群 ) に対し： ◎ To produce computed keyframe offsets, we define a procedure to compute missing keyframe offsets that takes a sequence of keyframes, keyframes, and has the following steps:

1. ~IF［ %~keyframe群 は空である ］ ⇒ ~RET ◎ ↓
2. %~offset~list ~LET %~keyframe群 を成す各~keyframeの`~keyframe~offset$からなる同順の~list ◎ For each keyframe in keyframes, let the computed keyframe offset of the keyframe be equal to its keyframe offset value.
3. %終端~index ~LET %~offset~list の~size ~MINUS 1 ◎ ↓
4. ~IF［ %~offset~list[ 0 ] ~EQ ~NULL ］ ⇒ %~offset~list[ 0 ] ~SET 0 ◎ If keyframes contains more than one keyframe and the computed keyframe offset of the first keyframe in keyframes is null, set the computed keyframe offset of the first keyframe to 0.
5. ~IF［ %~offset~list[ %終端~index ] ~EQ ~NULL ］ ⇒ %~offset~list[ %終端~index ] ~SET 1 ◎ If the computed keyframe offset of the last keyframe in keyframes is null, set its computed keyframe offset to 1.
6. ( %始端~index, %始端~offset ) ~LET ( 0, %~offset~list[ 0 ] ) ◎ ↓

7. ~EACH( 整数 %~index ~IN { 1 〜 %終端~index } ) に対し，昇順に：

   1. %~offset ~LET %~offset~list[ %~index ]
   2. ~IF［ %~offset ~EQ ~NULL ］ ⇒ ~CONTINUE
   3. %n ~LET %~index ~MINUS %始端~index
   4. ~EACH( 整数 %j ~IN { 1 〜 %n ~MINUS 1 } ) に対し，昇順に ⇒ %~offset~list[ %始端~index ~PLUS %j ] ~SET %始端~offset ~PLUS ( %~offset ~MINUS %始端~offset ) ~MUL %j ~DIV %n
   5. ( %始端~index, %始端~offset ) ~SET ( %~index, %~offset )
   ◎ For each pair of keyframes A and B where: • A appears before B in keyframes, and • A and B have a computed keyframe offset that is not null, and • all keyframes between A and B have a null computed keyframe offset, ◎ calculate the computed keyframe offset of each keyframe between A and B as follows: • Let offsetk be the computed keyframe offset of a keyframe k. • Let n be the number of keyframes between and including A and B minus 1. • Let index refer to the position of keyframe in the sequence of keyframes between A and B such that the first keyframe after A has an index of 1. • Set the computed keyframe offset of keyframe to offsetA + (offsetB − offsetA) × index / n.
8. ~EACH( 整数 %~index ~IN { 0 〜 %終端~index } ) に対し ⇒ %~keyframe群[ %~index ] の`算出d~keyframe~offset$ ~SET %~offset~list[ %~index ] ◎ ↑

`算出d~keyframe~list$は、 所与の ( `~keyframe効果$ %効果 ) に対し，次の手続-を利用して生産される： ◎ Computed keyframes are produced using the following procedure.＼

1. %効果~target ~LET %効果 の`効果~target$ ◎ ↓
2. ~Assert： 以下は、 %効果~target 上で算出d~prop値を計算できる場合に限り，遂行される ◎ Note that this procedure is only performed on a keyframe effect having an effect target for which computed property values can be calculated.
3. %算出d~keyframe群 ~LET 空な~list ◎ Let computed keyframes be an empty list of keyframes.

4. %効果 上に指定された`~keyframe$たちが成す~list内の~EACH( %~keyframe ) に対し： ◎ For each keyframe in the list of keyframes specified on this keyframe effect, perform the following steps:

   1. %算出d~keyframe ~LET 新たな空`~keyframe$ ◎ ↓
   2. %算出d~keyframe群 に %算出d~keyframe を追加する ◎ Add a new empty keyframe, computed keyframe, to computed keyframes.

   3. %~keyframe 内に指定された~EACH( %~prop ) に対し，以下の規則も適用する下で ⇒ %算出d~keyframe に ( %~prop, 次の結果 ) を追加する ⇒ `~prop値を算出する$( %~prop, %~keyframe に指定された値, `~target要素$ ) ◎ For each property specified in keyframe: • Compute a property value using the value specified on keyframe as the value, and the target element as the element; then add the property and resulting value to computed keyframe.

      • %~prop が略式~propである場合、 この段は，対応する等価な下位propたちに対し遂行するとする。 ◎ For shorthand properties, add the equivalent longhand properties.
      • %~prop が論理-~prop `CSS-LOGICAL-1$r である場合、 %効果~target 上の［ `writing-mode$p ／ `direction$p ］の算出d値に基づいて，%~prop `等価な物理-~prop＠~CSSWM#logical-to-physical$ `CSS-WRITING-MODES-4$r を【代わりに】追加するとする。 ◎ For logical properties [CSS-LOGICAL-1], add the equivalent physical properties [CSS-WRITING-MODES-4] based on the computed value of writing-mode and/or direction for the effect target.

      例えば %~keyframe が `border-width$p `略式~prop$用の算出d値 `12pt^v を有する場合、 ~UAは，各~下位prop — `border-bottom-width$p, `border-left-width$p, `border-right-width$p, `border-top-width$p — 用に`~prop値を算出する$ことになる。 %算出d~keyframe に追加されるのは， `border-width$p ~prop用の値に代えて，これらの各~下位propと算出した結果の値 `16px^v になる。 ◎ For example, if keyframe has a value of 12pt for the border-width shorthand property, the user agent will compute a property value of 16px for each of the longhand properties: border-bottom-width, border-left-width, border-right-width, and border-top-width. As a result, computed keyframe would not have a value for the border-width property, but would instead include each of the longhand properties, each with the value 16px.

      ［ 略式~propを展開した ／ 論理-~propを物理-~propに置換した ］ことにより，競合が発生する場合、 次の規則を，競合が解決されるまで順に適用する： ◎ If conflicts arise when expanding shorthand properties or replacing logical properties with physical properties, apply the following rules in order until the conflict is resolved:

      1. 下位propは略式~propを上書きする （例： `border-top-color$p は `border-top$p を上書きする）。 ◎ Longhand properties override shorthand properties (e.g. border-top-color overrides border-top).
      2. 下位propの個数がより少ない略式~propは、 より多いものを上書きする （例： `border-top$p は `border-color$p を上書きする）。 ◎ Shorthand properties with fewer longhand components override those with more longhand components (e.g. border-top overrides border-color).
      3. 物理-~propは論理-~propを上書きする。 ◎ Physical properties override logical properties.
      4. 下位propの個数が互いに等しい略式~propどうしは、［ `~CSS~propから~IDL属性を得る$ ~algo `CSSOM$r により~propから得られる~IDL名 ］を比較して，~Unicode符号位置に基づく辞書式順序で先に~sortされるものが後に~sortされるものを上書きする。 ◎ For shorthand properties with an equal number of longhand components, properties whose IDL name (see the CSS property to IDL attribute algorithm [CSSOM]) appears earlier when sorted in ascending order by the Unicode codepoints that make up each IDL name, override those who appear later.
5. `欠落~keyframe~offsetを算出する$( %算出d~keyframe群 ) ◎ Apply the procedure to compute missing keyframe offsets to computed keyframes.
6. ~RET %算出d~keyframe群 ◎ Return computed keyframes.

`~keyframe効果$ %効果 の各`~target~prop$ %~prop 用の`効果~値$は、 次に従って計算される： 【！反復~indexは利用されていない】 ◎ The effect value of a single property referenced by a keyframe effect as one of its target properties, for a given iteration progress, iteration index and underlying value is calculated as follows.

1. %反復~進捗 ~LET %効果 の`反復~進捗$ ◎ ↑
2. ~IF［ %反復~進捗 ~EQ `未解決$ ］ ⇒ ~RET ε ◎ If iteration progress is unresolved abort this procedure. ◎ ↑Let target property be the longhand property for which the effect value is to be calculated.
3. ~IF［ %~prop の`~animation型$は`~animate不可$ ］ ⇒ ~RET ε — 効果は適用できない。 ◎ If animation type of the target property is not animatable abort this procedure since the effect cannot be applied.
4. ~IF［ %効果 の`効果~target$ ~EQ ~NULL ］~OR［ %効果 の`効果~target$の算出d~prop値は計算できない ］ ⇒ ~RET ε ◎ If the keyframe effect does not have an effect target, or if the effect target cannot have computed property values calculated, abort this procedure.
5. 以下に現れる `組成~用の中立~値@ とは、［ `加算-型$の組成-演算を利用して`下層~値$と結合した結果は，単にその`下層~値$になる ］ような，特別な値とする ◎ Define the neutral value for composition as a value which, when combined with an underlying value using the add composite operation, produces the underlying value.
6. %~keyframe群 ~LET `算出d~keyframe~list$( %効果 ) ◎ Let property-specific keyframes be the result of getting the set of computed keyframes for this keyframe effect.
7. %~keyframe群 から［ %~prop 用の値が無い`~keyframe$ ］をすべて除去する ◎ Remove any keyframes from property-specific keyframes that do not have a property value for target property.
8. %下層~値 ~LET %効果 の`下層~値$ ◎ ↑
9. ~IF［ %~keyframe群 は空である ］ ⇒ ~RET %下層~値 ◎ If property-specific keyframes is empty, return underlying value.
10. ~IF［ %~keyframe群 を成す どの`~keyframe$の`算出d~keyframe~offset$も 0 でない ］ ⇒ %~keyframe群 に次を伴う新たな`~keyframe$を前付加する ⇒＃ `算出d~keyframe~offset$ ~SET 0, ~prop値 ~SET `組成~用の中立~値$, `組成-演算~型$ ~SET `加算-型$ ◎ If there is no keyframe in property-specific keyframes with a computed keyframe offset of 0, create a new keyframe with a computed keyframe offset of 0, a property value set to the neutral value for composition, and a composite operation of add, and prepend it to the beginning of property-specific keyframes.
11. ~IF［ %~keyframe群 を成す どの`~keyframe$の`算出d~keyframe~offset$も 1 でない ］ ⇒ %~keyframe群 に次を伴う新たな`~keyframe$を付加する ⇒＃ `算出d~keyframe~offset$ ~SET 1, ~prop値 ~SET `組成~用の中立~値$, `組成-演算~型$ ~SET `加算-型$ ◎ Similarly, if there is no keyframe in property-specific keyframes with a computed keyframe offset of 1, create a new keyframe with a computed keyframe offset of 1, a property value set to the neutral value for composition, and a composite operation of add, and append it to the end of property-specific keyframes.
12. ( %始端~keyframe, %終端~keyframe ) ~LET ( ε, ε ) ◎ Let interval endpoints be an empty sequence of keyframes. ◎ Populate interval endpoints by following the steps from the first matching condition below:
13. ~IF［ %反復~進捗 ~LT 0 ］~AND［ %~keyframe群 を成す`~keyframe$として［ `算出d~keyframe~offset$ ~EQ 0 ］を満たすものが複数ある ］ ⇒ %始端~keyframe ~SET %~keyframe群 を成す最初の`~keyframe$ ◎ If iteration progress < 0 and there is more than one keyframe in property-specific keyframes with a computed keyframe offset of 0, • Add the first keyframe in property-specific keyframes to interval endpoints.
14. ~ELIF［ %反復~進捗 ~GTE 1 ］~AND［ %~keyframe群 を成す`~keyframe$として［ `算出d~keyframe~offset$ ~EQ 1 ］を満たすものが複数ある ］ ⇒ %始端~keyframe ~SET %~keyframe群 を成す最後の`~keyframe$ ◎ If iteration progress ≥ 1 and there is more than one keyframe in property-specific keyframes with a computed keyframe offset of 1, • Add the last keyframe in property-specific keyframes to interval endpoints.

15. ~ELSE：

    1. %始端~keyframe群 ~LET %~keyframe群 を成す`~keyframe$のうち，その`算出d~keyframe~offset$ %~offset が［ 次の条件 (1) を満たすものは在るならば それら ／ ~ELSE_ 次の条件 (2) を満たすものたち ］からなる同順の~list ⇒＃ (1)［ %~offset ~LTE %反復~進捗 ］~AND［ %~offset ~LT 1 ］ ／ (2) %~offset ~EQ 0
    2. %始端~keyframe ~SET %始端~keyframe群 を成す最後の~item
    3. %終端~keyframe ~SET %~keyframe群 内の %始端~keyframe の直後に在る~keyframe

    【 %~keyframe群 の先頭には %~offset ~EQ 0 のもの, 末尾には ~EQ 1 のものが必ず在るので、該当する 2 つの~keyframeは常に在る。 】

    ◎ Otherwise, • Append to interval endpoints the last keyframe in property-specific keyframes whose computed keyframe offset is less than or equal to iteration progress and less than 1. If there is no such keyframe (because, for example, the iteration progress is negative), add the last keyframe whose computed keyframe offset is 0. • Append to interval endpoints the next keyframe in property-specific keyframes after the one added in the previous step.
16. %~animation型 ~LET %~prop の`~animation型$ ◎ ↓

17. %~keyframeから値を得る手続き ~LET 所与の ( %~keyframe ) に対し，次を走らす手続き：

    1. %利用する組成-演算~型 ~LET %~keyframe の`~keyframeに特有な組成-演算~型$
    2. ~IF［ %利用する組成-演算~型 ~EQ ε ］ ⇒ %利用する組成-演算~型 ~SET %効果 の`組成-演算~型$
    3. %値 ~LET %~keyframe 上に指定された %~prop の値
    4. ~IF［ %利用する組成-演算~型 ~NEQ `置換-型$ ］ ⇒ %値 ~SET ［ %~animation型 に対応する， %利用する組成-演算~型 用の手続- ］を利用して，次を結合した結果 ⇒ ( %下層~値, %値 )
    5. ~RET %値
    ◎ For each keyframe in interval endpoints: ◎ If keyframe has a composite operation that is not replace, or keyframe has no composite operation and the composite operation of this keyframe effect is not replace, then perform the following steps: • Let composite operation to use be the composite operation of keyframe, or if it has none, the composite operation of this keyframe effect. • Let value to combine be the property value of target property specified on keyframe. • Replace the property value of target property on keyframe with the result of combining underlying value (Va) and value to combine (Vb) using the procedure for the composite operation to use corresponding to the target property’s animation type.
18. %始端~値 ~LET %~keyframeから値を得る手続き( %始端~keyframe ) ◎ ↑
19. ~IF［ %終端~keyframe ~EQ ε ］ ⇒ ~RET %始端~値 ◎ If there is only one keyframe in interval endpoints return the property value of target property on that keyframe.
20. %終端~値 ~LET %~keyframeから値を得る手続き( %終端~keyframe ) ◎ ↑
21. %始端~offset ~LET %始端~keyframe の`算出d~keyframe~offset$ ◎ Let start offset be the computed keyframe offset of the first keyframe in interval endpoints.
22. %終端~offset ~LET %終端~keyframe の`算出d~keyframe~offset$ ◎ Let end offset be the computed keyframe offset of last keyframe in interval endpoints.
23. %区間~距離 ~LET ( %反復~進捗 ~MINUS %始端~offset ) ~DIV ( %終端~offset ~MINUS %始端~offset ) ◎ Let interval distance be the result of evaluating (iteration progress − start offset) / (end offset − start offset).
24. %変形d距離 ~LET %始端~keyframe に結付けられた`~easing関数$を［ 入力~進捗として %区間~距離 ］を渡して評価した結果 ◎ Let transformed distance be the result of evaluating the easing function associated with the first keyframe in interval endpoints passing interval distance as the input progress.
25. ~RET 次を与える下で， %~animation型 により定義される`補間$手続-を適用した結果 ⇒＃ ( 値A, 値B ) ~SET ( %始端~値, %終端~値 ), 補間~parameter %p ~SET %変形d距離 ◎ Return the result of applying the interpolation procedure defined by the animation type of the target property, to the values of the target property specified on the two keyframes in interval endpoints, taking the first such value as Vstart and the second as Vend and using transformed distance as the interpolation parameter p.

`効果~stack$の結果を与える `組成d値@ は、 所与の ( %~stack, 初期`下層~値$ %下層~値 ) から，次に従って計算される： ◎ In order to calculate the final value of an effect stack, the effect values of each keyframe effect in the stack are combined in composite order.

1. %~stack 内の~EACH( `~keyframe効果$ %効果 ) に対し，`組成-順序$で ⇒ %下層~値 ~SET `§ 効果の組成＠#effect-composition$ に従って， ( %下層~値, %効果 の`効果~値$ ) を結合した結果

   この段の各~反復における［ %効果 を結合する前の %下層~値 ］は、 %効果 の `下層~値@ と呼ばれる。

   ◎ Each step in the process of evaluating an effect stack takes an underlying value as input. ◎ For each keyframe effect in the stack, the appropriate effect value from the keyframe effect is combined with the underlying value to produce a new value. This resulting value becomes the underlying value for combining the next keyframe effect in the stack.
2. ~RET %下層~値 ◎ The final value of an effect stack, called the composited value, is simply the result of combining the effect value of the final (highest composite order) keyframe effect in the stack with the underlying value at that point.

`置換された~animationを除去する@ ~algoは、 所与の ( `文書$, %文書 ), に対し， ~AND↓ を満たす ~EACH( `~animation$ %~animation ) に対し…： ◎ When asked to remove replaced animations for a Document, doc, then for every animation, animation, that:

• それに`結付けられた効果$ %効果 【！`~animation効果$】 ~NEQ ~NULL ◎ has an associated animation effect＼
• %効果 の`効果~target$【の`~target要素$】は %文書 の`子孫$である ◎ whose effect target is a descendant of doc, and
• `置換-可能$である ◎ is replaceable, and
• `置換-状態$ ~EQ `作動中$i ◎ has a replace state of active, and
• %効果 のどの`~target~prop$ %~prop に対しても、 ある`置換-可能$な`~animation$が在って， それに`結付けられた効果$【！~animation効果】 %別の効果 は次を満たす ⇒ ［ %~prop は %別の効果 の`~target~prop$である ］~AND［ %別の効果 の`組成-順序$は %効果 より後 ］ ◎ for which there exists for each target property of every animation effect associated with animation, an animation effect associated with a replaceable animation with a higher composite order than animation that includes the same target property

…次の手続きを遂行する： ◎ perform the following steps:

1. %~animation の`置換-状態$ ~SET `除去-済み$i ◎ Set animation’s replace state to removed.
2. %~remove~event ~LET `~eventを作成する$( `AnimationPlaybackEvent$I ) ◎ Create an AnimationPlaybackEvent, removeEvent.
3. %時列線~時刻 ~LET %~animation の`時列線~現-時刻$ ◎ ↓
4. %~remove~event の ⇒＃ `type$m 属性 ~SET `remove$et, `currentTime$m 属性 ~SET %~animation の`現-時刻$, `timelineTime$m 属性 ~SET %時列線~時刻 ◎ Set removeEvent’s type attribute to remove. ◎ Set removeEvent’s currentTime attribute to the current time of animation. ◎ Set removeEvent’s timelineTime attribute to the current time of the timeline with which animation is associated.
5. ~IF［ %~animation の`計時~用の文書$ ~NEQ ε ］ ⇒ `計時~用の文書$の`処理待ち~animation~event~queue$に， %~remove~event に次を伴わせた上で付加する ⇒＃ `対応する~event~target$ ~SET %~animation, `~schedule済み~event時刻$ ~SET `起点に相対的な時刻へ変換する$( %時列線~時刻 ) ◎ If animation has a document for timing, then append removeEvent to its document for timing’s pending animation event queue along with its target, animation. For the scheduled event time, use the result of applying the procedure to convert timeline time to origin-relative time to the current time of the timeline with which animation is associated.

6. ~ELSE ⇒ `~taskを~queueする$( `~DOM操作~task~source$, 次の手続き )

   手続きは ⇒ `~eventを配送する$( %~animation, %~remove~event )
   ◎ Otherwise, queue a task to dispatch removeEvent at animation. The task source for this task is the DOM manipulation task source.