1 /*
2  * Copyright 2023 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 com.android.compose.animation.scene.transformation
18 
19 import com.android.compose.animation.scene.ContentKey
20 import com.android.compose.animation.scene.ElementKey
21 import com.android.compose.animation.scene.content.state.TransitionState
22 
23 /** Fade an element in or out. */
24 internal object Fade : InterpolatedPropertyTransformation<Float> {
25     override val property = PropertyTransformation.Property.Alpha
26 
transformnull27     override fun PropertyTransformationScope.transform(
28         content: ContentKey,
29         element: ElementKey,
30         transition: TransitionState.Transition,
31         idleValue: Float,
32     ): Float {
33         // Return the alpha value of [element] either when it starts fading in or when it finished
34         // fading out, which is `0` in both cases.
35         return 0f
36     }
37 
38     object Factory : Transformation.Factory {
createnull39         override fun create(): Transformation = Fade
40     }
41 }
42