1 /*
2  * Copyright 2022 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package androidx.compose.ui
18 
19 import androidx.compose.runtime.Stable
20 import kotlin.coroutines.CoroutineContext
21 
22 /**
23  * Provides a duration scale for motion such as animations. When the duration [scaleFactor] is 0,
24  * the motion will end in the next frame callback. Otherwise, the duration [scaleFactor] will be
25  * used as a multiplier to scale the duration of the motion. The larger the scale, the longer the
26  * motion will take to finish, and therefore the slower it will be perceived.
27  *
28  * ## Testing
29  *
30  * To control the motion duration scale in tests, create an implementation of this interface and
31  * pass it to the `effectContext` parameter either where you call `runComposeUiTest` or where you
32  * create your test rule.
33  */
34 @Stable
35 interface MotionDurationScale : CoroutineContext.Element {
36     /**
37      * Defines the multiplier for the duration of the motion. This value should be non-negative.
38      *
39      * A [scaleFactor] of 1.0f would play the motion in real time. 0f would cause motion to finish
40      * in the next frame callback. Larger [scaleFactor] will result in longer durations for the
41      * motion/animation (i.e. slower animation). For example, a [scaleFactor] of 10f would cause an
42      * animation with a duration of 100ms to finish in 1000ms.
43      */
44     val scaleFactor: Float
45 
46     override val key: CoroutineContext.Key<*>
47         get() = Key
48 
49     companion object Key : CoroutineContext.Key<MotionDurationScale>
50 }
51