如何使用Jetpack Compose在TopAppBar中设置渐变背景

implementation 'androidx.compose.material:material:1.0.0'
implementation 'androidx.compose.ui:ui-tooling:1.0.0'

@Composable
fun GradientTopAppBar() {
    TopAppBar(
        title = { Text(text = "My App") },
        backgroundColor = Color.Transparent, // 设置背景颜色为透明
        elevation = 0.dp // 设置阴影为0
    )
}

@Composable
fun MyApp() {
    Scaffold(
        topBar = { GradientTopAppBar() },
        content = { /* 内容区域 */ }
    )
}

@Composable
fun GradientBackground() {
    Box(
        modifier = Modifier
            .fillMaxSize()
            .background(
                brush = Brush.verticalGradient(
                    colors = listOf(Color.Blue, Color.Green), // 渐变颜色列表
                    startY = 0f,
                    endY = Float.POSITIVE_INFINITY
                )
            )
    )
}

@Composable
fun MyApp() {
    Scaffold(
        topBar = { GradientTopAppBar() },
        content = { 
            GradientBackground()
            // 其他内容
        }
    )
}