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.foundation.lazy.grid
18 
19 import androidx.compose.animation.core.FiniteAnimationSpec
20 import androidx.compose.animation.core.Spring
21 import androidx.compose.animation.core.VisibilityThreshold
22 import androidx.compose.animation.core.spring
23 import androidx.compose.runtime.Stable
24 import androidx.compose.ui.Modifier
25 import androidx.compose.ui.unit.IntOffset
26 
27 /** Receiver scope being used by the item content parameter of [LazyVerticalGrid]. */
28 @Stable
29 @LazyGridScopeMarker
30 sealed interface LazyGridItemScope {
31     /**
32      * This modifier animates the item appearance (fade in), disappearance (fade out) and placement
33      * changes (such as an item reordering).
34      *
35      * You should also provide a key via [LazyGridScope.item]/[LazyGridScope.items] for this
36      * modifier to enable animations.
37      *
38      * @sample androidx.compose.foundation.samples.GridAnimateItemSample
39      * @param fadeInSpec an animation specs to use for animating the item appearance. When null is
40      *   provided the item will be appearing without animations.
41      * @param placementSpec an animation specs that will be used to animate the item placement.
42      *   Aside from item reordering all other position changes caused by events like arrangement or
43      *   alignment changes will also be animated. When null is provided no animations will happen.
44      * @param fadeOutSpec an animation specs to use for animating the item disappearance. When null
45      *   is provided the item will be disappearance without animations.
46      */
animateItemnull47     fun Modifier.animateItem(
48         fadeInSpec: FiniteAnimationSpec<Float>? = spring(stiffness = Spring.StiffnessMediumLow),
49         placementSpec: FiniteAnimationSpec<IntOffset>? =
50             spring(
51                 stiffness = Spring.StiffnessMediumLow,
52                 visibilityThreshold = IntOffset.VisibilityThreshold
53             ),
54         fadeOutSpec: FiniteAnimationSpec<Float>? = spring(stiffness = Spring.StiffnessMediumLow),
55     ): Modifier
56 }
57