Compose 文字滚动动画

SizeTransform(clip = true)

为true得时候不会超出边界

 为false则可以超出

package com.example.prettynumber

import androidx.lifecycle.ViewModel
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.asFlow
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.flow.onEach

class MainViewModel : ViewModel() {
    val seconds = (0..100)
        .asSequence()
        .asFlow()
        .map {
            if (it in 0..9) "0$it" else "$it"
        }
        .onEach { delay(1000) }
}

package com.example.prettynumber

import android.util.Log
import androidx.compose.animation.*
import androidx.compose.animation.core.tween
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material.MaterialTheme
import androidx.compose.material.SnackbarDuration
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.style.TextAlign
import androidx.lifecycle.viewmodel.compose.viewModel

private const val TAG = "MainScreen"
@OptIn(ExperimentalAnimationApi::class)
@Composable
fun MainScreen(mainViewModel: MainViewModel = viewModel()) {
    val secodnds by mainViewModel.seconds.collectAsState(initial = "00")
    Column(
        modifier = Modifier.fillMaxSize(),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally
    ) {
        AnimatedContent(targetState = secodnds, transitionSpec = {
            addAnimation().using(SizeTransform(clip = true))
        }) { targetCount ->
            Log.e(TAG, "MainScreen:${targetCount} ", )
            Text(
                text = "$targetCount",
                style = TextStyle(fontSize = MaterialTheme.typography.h1.fontSize),
                textAlign = TextAlign.Center
            )

        }

    }

}

@ExperimentalAnimationApi
fun addAnimation(duration: Int = 800): ContentTransform {
    return slideInVertically(animationSpec = tween(durationMillis = duration)) { height -> height } + fadeIn(
        animationSpec = tween(durationMillis = duration)
    ) with slideOutVertically(animationSpec = tween(durationMillis = duration)) { height -> -height } + fadeOut(
        animationSpec = tween(durationMillis = duration)
    )
}