1 /*
2  * Copyright 2024 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.foundation.gestures
18 
19 import androidx.compose.runtime.Stable
20 
21 /** Interface to specify fling behavior with additional information about its animation target. */
22 @Stable
23 interface TargetedFlingBehavior : FlingBehavior {
24 
25     /**
26      * Perform settling via fling animation with given velocity and suspend until fling has
27      * finished. Use [onRemainingDistanceUpdated] to report the status of the ongoing fling
28      * animation and the remaining amount of scroll offset.
29      *
30      * This functions is called with [ScrollScope] to drive the state change of the
31      * [androidx.compose.foundation.gestures.ScrollableState] via [ScrollScope.scrollBy].
32      *
33      * This function must return the correct velocity left after it is finished flinging in order to
34      * guarantee proper nested scroll support.
35      *
36      * @param initialVelocity velocity available for fling in the orientation specified in
37      *   [androidx.compose.foundation.gestures.scrollable] that invoked this method.
38      * @param onRemainingDistanceUpdated a lambda that will be called anytime the distance to the
39      *   settling offset is updated. The settling offset in pixels is passed to this lambda an it
40      *   represents the final offset where this fling will stop and may change depending on the
41      *   snapping animation progression.
42      * @return remaining velocity after fling operation has ended
43      */
performFlingnull44     suspend fun ScrollScope.performFling(
45         initialVelocity: Float,
46         onRemainingDistanceUpdated: (Float) -> Unit
47     ): Float
48 
49     override suspend fun ScrollScope.performFling(initialVelocity: Float): Float =
50         performFling(initialVelocity, NoOnReport)
51 }
52 
53 private val NoOnReport: (Float) -> Unit = {}
54