Jetpack Compose動畫詳解-帶效果圖

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項目git地址：github.com/ananananzhu…android

概述

compose 爲支持動畫提供了大量的 api，經過這些 api 咱們能夠輕鬆實現動畫效果git

ps：這些 api 的原理與 Flutter 很接近，與原生的 api 相去甚遠github

你能夠提早看看用 compose 實現的一個放大縮小動畫，總的來講仍是比較流暢： spring

低級別動畫 API

animate*AsState

所能處理屬性的種類：Float、Color、Dp、Size、Bounds、Offset、Rect、Int、IntOffset 和 IntSize後端

經過 animate*AsState 咱們能夠實現單一屬性的動畫效果,咱們只須要提供目標值就能夠自動從當前進度動畫過渡到目標值api

實現放大動畫

代碼

@Composable
fun animSize() {
    val enable = remember {
        mutableStateOf(true)
    }
    val size =
        animateSizeAsState(targetValue = if (enable.value) Size(50f, 50f) else Size(300f, 300f))
    Column(
        modifier = Modifier.fillMaxSize(1f),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center
    ) {
        Image(
            modifier = Modifier
                .size(size.value.width.dp, size.value.height.dp)
                .clickable {
                    enable.value = !enable.value
                },
            painter = painterResource(id = R.drawable.apple),
            contentDescription = ""
        )
    }
}
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實現效果

實現顏色變化動畫

代碼

@Composable
fun animColor() {
    val enable = remember {
        mutableStateOf(true)
    }
    val colors = animateColorAsState(targetValue = if (enable.value) Color.Green else Color.Red)
    val size = animateIntSizeAsState(
        targetValue = if (enable.value) IntSize(100, 100) else IntSize(
            300,
            300
        )
    )
    Column(
        modifier = Modifier.fillMaxWidth(1f),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center
    ) {
        Box(
            modifier = Modifier
                .size(size.value.width.dp, size.value.height.dp)
                .height(400.dp)
                .background(
                    color = colors.value,
                    shape = if (enable.value) RectangleShape else CircleShape
                )
        ) {

        }
    }
}
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效果

使用 Animatable 實現顏色變化效果

Animatable 是一個值容器，咱們能夠經過調用 animateTo 實現動畫效果。動畫執行過程當中若是再次開啓動畫會中斷當前動畫。markdown

Animatable 動畫執行過程當中值的變化是在協程中執行的，因此 animateTo 是一個掛起操做app

代碼

@Composable
fun animChangeColor() {
    val color = remember {
        Animatable(Color.Red)
    }
    val state = remember {
        mutableStateOf(true)
    }
    LaunchedEffect(state.value) {
        color.animateTo(if (state.value) Color.Red else Color.Magenta)
    }
    Box(Modifier.fillMaxSize(1f), contentAlignment = Alignment.Center) {
        Box(
            modifier = Modifier
                .background(color.value, shape = RoundedCornerShape(30.dp))
                .size(200.dp)
                .clickable {
                    state.value = !state.value
                }, contentAlignment = Alignment.Center
        ) {
            Text(
                text = "顏色動畫",
                style = TextStyle(color = Color.White, fontSize = 40.sp)
            )
        }
    }
}
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效果

使用 updateTransition 實現顏色和圓角動畫

使用 updateTransition 能夠實現多個動畫組合的效果。oop

例如：咱們能夠在動畫執行過程當中同時執行大小和顏色變化效果

本例中咱們定義了一個枚舉用來控制動畫，枚舉能夠定義多個，分別用來對應動畫的多個狀態

代碼

@Composable
fun animupdateTransition() {
    var state by remember {
        mutableStateOf(BoxState.Collapsed)
    }
    val transition = updateTransition(targetState = state, label = "")

    val round = transition.animateDp(label = "") {
        when (it) {
            BoxState.Collapsed -> 40.dp
            BoxState.Expanded -> 100.dp
        }
    }
    val color = transition.animateColor(label = "") {
        when (it) {
            BoxState.Collapsed -> Color.Red
            BoxState.Expanded -> Color.Green
        }
    }
    Box(Modifier.fillMaxSize(1f),contentAlignment = Alignment.Center) {
        Box(
            modifier = Modifier
                .size(300.dp)
                .background(
                    color.value,
                    shape = RoundedCornerShape(corner = CornerSize(round.value))
                )
                .clickable {
                    state =
                        if (state == BoxState.Collapsed) BoxState.Expanded else BoxState.Collapsed
                },contentAlignment = Alignment.Center
        ) {
            Text(text = "點擊開始動畫",style = TextStyle(color = Color.White,fontSize = 20.sp))
        }
    }
}
private enum class BoxState {
    Collapsed,
    Expanded
}
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效果

rememberInfiniteTransition

rememberInfiniteTransition 的使用和 updateTransition 基本同樣，不一樣的是 rememberInfiniteTransition 的動畫一旦開始便會一直反覆運行下去，只有被移除動畫才能結束

代碼

@Composable
fun rememberInfiniteTransition1() {
    val infiniteTransition = rememberInfiniteTransition()
    val color by infiniteTransition.animateColor(
        initialValue = Color.Red,
        targetValue = Color.Green,
        animationSpec = infiniteRepeatable(
            animation = tween(1000, easing = LinearEasing),
            repeatMode = RepeatMode.Reverse
        )
    )

    Box(Modifier.fillMaxSize(1f), contentAlignment = Alignment.Center) {
        Box(
            Modifier
                .fillMaxSize(0.8f)
                .background(color),
            contentAlignment = Alignment.Center
        ) {
            Text(
                text = "公衆號：安安安安卓 原創，禁抄襲",
                style = TextStyle(color = Color.White, fontSize = 30.sp)
            )
        }
    }
}
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效果

TargetBasedAnimation

TargetBasedAnimation 能夠控制動畫的執行時間，還能夠延遲一段時間再開啓動畫。

代碼

@Composable
fun animTargetBasedAnimation() {
    var state by remember {
        mutableStateOf(0)
    }
    val anim = remember {
        TargetBasedAnimation(
            animationSpec = tween(2000),
            typeConverter = Float.VectorConverter,
            initialValue = 100f,
            targetValue = 300f
        )
    }
    var playTime by remember { mutableStateOf(0L) }
    var animationValue by remember {
        mutableStateOf(0)
    }

    LaunchedEffect(state) {
        val startTime = withFrameNanos { it }
        println("進入協程：")
        do {
            playTime = withFrameNanos { it } - startTime
            animationValue = anim.getValueFromNanos(playTime).toInt()
        } while (!anim.isFinishedFromNanos(playTime))

    }
    Box(modifier = Modifier.fillMaxSize(1f),contentAlignment = Alignment.Center) {
        Box(modifier = Modifier
            .size(animationValue.dp)
            .background(Color.Red,shape = RoundedCornerShape(animationValue/5))
            .clickable {
                state++
            },contentAlignment = Alignment.Center) {
            Text(text = animationValue.toString(),style = TextStyle(color = Color.White,fontSize = (animationValue/5).sp))
        }
    }
}

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效果

自定義動畫

AnimationSpec

AnimationSpec 能夠自定義動畫的行爲，效果相似於原生動畫中的估值器。

SpringSpec 彈簧效果

代碼

@Composable
fun animSpring() {
    val state = remember {
        mutableStateOf(true)
    }
    var value = animateIntAsState(
        targetValue = if (state.value) 300 else 100,
        animationSpec = spring(
            dampingRatio = Spring.DampingRatioHighBouncy,
            stiffness = Spring.StiffnessVeryLow
        )
    )

    Box(
        Modifier
            .fillMaxSize(1f)
            .padding(start = 30.dp), contentAlignment = Alignment.CenterStart
    ) {
        Box(
            Modifier
                .width(value.value.dp)
                .height(80.dp)
                .background(Color.Red, RoundedCornerShape(topEnd = 30.dp, bottomEnd = 30.dp))
                .clickable {
                    state.value = !state.value
                }, contentAlignment = Alignment.CenterStart
        ) {
            Text(text = "哈哈哈", style = TextStyle(color = Color.White, fontSize = 20.sp))
        }
    }
}
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效果

TweenSpec 動畫時間可控

代碼

@Composable
fun animTweenSpec() {
    val state = remember {
        mutableStateOf(true)
    }
    val value = animateIntAsState(
        targetValue = if (state.value) 300 else 100,
        animationSpec = tween(
            durationMillis = 1500,
            delayMillis = 200,
            easing = LinearEasing
        )
    )

    Box(
        Modifier
            .fillMaxSize(1f)
            .padding(start = 50.dp), contentAlignment = Alignment.CenterStart
    ) {
        Box(
            Modifier
                .width(value.value.dp)
                .height(100.dp)
                .background(Color.Red, RoundedCornerShape(topEnd = 30.dp, bottomEnd = 30.dp))
                .clickable {
                    state.value = !state.value
                }
        ) {

        }
    }

}
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效果

FrameSpec

代碼

@Composable
fun animkeyframesSpec() {
    var state by remember {
        mutableStateOf(true)
    }
    val value by animateIntAsState(
        targetValue = if (state) 300 else 100,
        animationSpec = keyframes {
            durationMillis = 2000
            0 at 700 with LinearOutSlowInEasing
            700 at 1400 with FastOutLinearInEasing
            1400 at 2000
        })

    Box(Modifier.fillMaxSize(1f), contentAlignment = Alignment.CenterStart) {
        Box(
            Modifier
                .width(value.dp)
                .height(100.dp)
                .background(Color.Red, RoundedCornerShape(topEnd = 30.dp, bottomEnd = 30.dp))
                .clickable {
                    state = !state
                }
        ) {

        }
    }
}

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效果

RepeatableSpec 實現有限次數的重複動畫

執行有限次數動畫後自動中止

代碼

@Composable
fun animrepeatableSpec() {
    var state by remember {
        mutableStateOf(true)
    }
    val value by animateIntAsState(
        targetValue = if (state) 300 else 100,
        animationSpec = repeatable(
            iterations = 5,//動畫重複執行的次數，設置多少就執行多少次
            animation = tween(durationMillis = 1000),
            repeatMode = RepeatMode.Reverse
        )
    )
    Box(
        Modifier
            .fillMaxSize(1f)
            .padding(start = 30.dp), contentAlignment = Alignment.CenterStart) {
        Box(
            Modifier
                .width(value.dp)
                .height(100.dp)
                .background(Color.Red, RoundedCornerShape(topEnd = 30.dp, bottomEnd = 30.dp))
                .clickable {
                    state = !state
                }
        ) {

        }
    }
}
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效果

代碼中設置了重複 5 次，因此反覆執行五次後動畫結束

InfiniteRepeatableSpec 無限次數執行動畫

動畫會無限次的執行下去，直到視圖被移除

代碼

@Composable
fun animinfiniteRepeatableSpec() {
    var state by remember {
        mutableStateOf(true)
    }
    val value by animateIntAsState(
        targetValue = if (state) 300 else 100,
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis = 1000),
            repeatMode = RepeatMode.Reverse
        )
    )
    Box(
        Modifier
            .fillMaxSize(1f)
            .padding(start = 30.dp), contentAlignment = Alignment.CenterStart) {
        Box(
            Modifier
                .width(value.dp)
                .height(100.dp)
                .background(Color.Red, RoundedCornerShape(topEnd = 30.dp, bottomEnd = 30.dp))
                .clickable {
                    state = !state
                }
        ) {
            Text(text = "公衆號：安安安安卓 原創，禁轉載")
        }
    }
}
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效果

Easing

Easing 相似於咱們原生動畫中的差值器

有如下幾種選擇：

FastOutSlowInEasing
LinearOutSlowInEasing
FastOutLinearInEasing
LinearEasing
CubicBezierEasing

這幾種實現的效果和 android 原生實現的動畫差值器差距很大，甚至看不出有啥效果，因此代碼我就不放了。有清楚緣由的讀者能夠聯繫我

實現效果：

AnimationVector

大多數 Compose 動畫 API 都支持將 Float、Color、Dp 以及其餘基本數據類型做爲開箱即用的動畫值，但有時咱們須要爲其餘數據類型（包括咱們的自定義類型）添加動畫效果

本例中實現顏色和大小的變換動畫

代碼中咱們定義了一個 AnimSize 類，類中的第一個參數是顏色數據，第二個參數是尺寸數據。動畫執行過程當中會同事改變顏色和控件尺寸效果。

代碼

@Composable
fun animAnimationVector() {
    var state by remember {
        mutableStateOf(true)
    }
    val value by animateValueAsState(
        targetValue = if (state) AnimSize(0xffff5500, 100f) else AnimSize(0xff00ff00, 300f),
        typeConverter = TwoWayConverter(
            convertToVector = {
//                AnimationVector2D(target.color.toFloat(), target.size)
                AnimationVector2D(it.color.toFloat(), it.size)
            },
            convertFromVector = {
                AnimSize(it.v1.toLong(), it.v2)
            }
        )
    )
    println("顏色:${value.color}")
    Box(modifier = Modifier.fillMaxSize(1f).padding(30.dp), contentAlignment = Alignment.Center) {
        Box(
            modifier = Modifier
                .size(value.size.dp)
//                .size(300.dp)
                .background(Color(value.color), RoundedCornerShape(30.dp))
                .clickable {
                    state = !state
                }
        ) {

        }
    }
}

data class AnimSize(val color: Long, val size: Float)
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效果

缺點是執行顏色變化過程當中有閃爍

高級動畫

高級動畫通常指封裝性較高的動畫，使用較爲簡單，主要有如下三種：

因高級動畫效果不明顯，gif 很難展示出效果，因此這裏不放代碼和效果圖了

AnimatedVisibility
animateContentSize
Crossfade

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