Compose 动画 (四) : AnimatedVisibility 各种入场和出场动画效果

AnimatedVisibility中的EnterTransition 和 ExitTransition ，用来配置入场/出场时候的动画效果。

默认的入场效果是 fadeIn() + expandVertically()
默认的出场效果是 fadeOut() + shrinkVertically()

1. EnterTransition和ExitTransition支持的动画

enter的参数类型是EnterTransition，支持这些动画

• 淡入 : fade: fadeIn
• 缩放 : scale: scaleIn
• 滑动 : slide: slideIn, slideInHorizontally, slideInVertically
• 展开 : expand: expandIn, expandHorizontally, expandVertically

exit的参数类型是EnterTransition，支持这些动画

• 淡出 : fade: fadeOut
• 缩放 : scale: scaleOut
• 滑动 : slide: slideOut, slideOutHorizontally, slideOutVertically
• 收缩 : shrink: shrinkOut, shrinkHorizontally, shrinkVertically

可以看到EnterTransition和ExitTransition支持的动画只有expand和shrink命名上有区别，
其他都是对应的 fadeIn 和 fadeOut，scaleIn 和 scaleOut，slideIn 和 slideOut。
expand和shrink命名上做区分，是因为expand就是展开的意思，而shrink是收缩的意思，它们其实就是相对应的。

2. fadeIn / fadeOut

fadeIn / fadeOut是淡出淡出的效果

我们使用上篇文章中的那段代码

@Composable
fun AnimatedVisibilityPage() {Column(horizontalAlignment = Alignment.CenterHorizontally) {var visible by remember {mutableStateOf(true)}AnimatedVisibility(visible = visible) {MyImage()}Spacer(modifier = Modifier.height(10.dp))Button(onClick = { visible = !visible }) {Text(text = "显示/隐藏")}}
}@Composable
private fun MyImage() {Image(painter = painterResource(id = R.mipmap.photot1),modifier = Modifier.width(300.dp),contentDescription = null)
}

然后修改AnimatedVisibility，配置enter和exit

AnimatedVisibility(visible = visible,enter = fadeIn(),exit = fadeOut()
) {MyImage()
}

效果如下所示

3. scaleIn / scaleOut

scaleIn / scaleOut是缩放的效果

AnimatedVisibility(visible = visible,enter = scaleIn(),exit = scaleOut()
) {MyImage()
}

效果如下所示

4. slideIn / SlideOut

slideIn / SlideOut是滑动的效果，这里进入的初始位置和退出的目标位置都设置为了(300,-150)，所以会从右上角进入/退出

AnimatedVisibility(visible = visible,enter = slideIn(initialOffset = {IntOffset(300, -150) }),exit = slideOut(targetOffset = {IntOffset(300,-150) })
) {MyImage()
}

效果如下所示

5. slideInVertically / slideOutVertically

slideInVertically / slideOutVertically是垂直方向滑动进入/退出

AnimatedVisibility(visible = visible,enter = slideInVertically(),exit = slideOutVertically()
) {MyImage()
}

效果如下所示

5.1 slideInHorizontally / slideOutHorizontally

slideInHorizontally / slideOutHorizontally是从横向方向滑动进入/退出

AnimatedVisibility(visible = visible,enter = slideInHorizontally(),exit = slideOutHorizontally()
) {MyImage()
}

效果如下所示

6. expandIn / shrinkOut

expandIn / shrinkOut是展开/收缩的效果

AnimatedVisibility(visible = visible,enter = expandIn(),exit = shrinkOut()
) {MyImage()
}

效果如下所示

6.1 expandVertically / shrinkVertically

expandVertically / shrinkVertically是从垂直方向展开/收缩

AnimatedVisibility(visible = visible,enter = expandVertically(),exit = shrinkVertically()
) {MyImage()
}

效果如下所示

6.2 expandHorizontally / shrinkHorizontally

expandHorizontally / shrinkHorizontally是从横向方向展开/收缩

AnimatedVisibility(visible = visible,enter = expandHorizontally(),exit = shrinkHorizontally()
) {MyImage()
}

效果如下所示

7. 其他

7.1 Compose动画系列

Compose 动画系列，后续持续更新，可以先关注
Compose 动画 (一) : animateXxxAsState 实现放大/缩小/渐变等效果
Compose 动画 (二) : 为什么animateDpAsState要用val ? MutableState和State有什么区别 ?
Compose 动画 (三) : AnimatedVisibility 从入门到深入

7.2 参考

关于EnterTransition 和 ExitTransition 示例也可以看这里