AnimationClockObservable.kt
/*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.compose.animation.core
/**
* This interface allows AnimationClock to be subscribed and unsubscribed.
*/
// TODO: This is a temporary design for Animation Clock. In long term, we may use a Flow<Long>
// or some other data structure that takes care of the subscribing and unsubscribing
// implementation out of the box.
interface AnimationClockObservable {
/**
* Subscribes an observer to the animation clock source.
*
* Observers may only be added to a clock once. Calls to add the same observer more than
* once will be ignored, and a single call to [unsubscribe] will unregister from further
* callbacks.
*
* @param observer The observer that will be notified when animation clock time is updated.
*/
fun subscribe(observer: AnimationClockObserver)
/**
* Unsubscribes an observer from the animation clock.
*
* Observers may only be added to a clock once. If [subscribe] has been called multiple times
* with the same observer, a single call to this method will unregister the observer completely.
*
* @param observer The observer to be removed from the subscription list.
*/
fun unsubscribe(observer: AnimationClockObserver)
}
/**
* Observer for animation clock changes. The observers will be notified via [onAnimationFrame] when
* the frame time has been updated in animation clock
*/
interface AnimationClockObserver {
/**
* This gets called when animation clock ticks.
*
* @param frameTimeMillis The frame time of the new tick in milliseconds
*/
fun onAnimationFrame(frameTimeMillis: Long)
}