如何使用composables在应用程序中动态切换明暗主题

import androidx.compose.foundation.isSystemInDarkTheme
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Surface
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.tooling.preview.Preview

@Composable
fun MyAppTheme(content: @Composable () -> Unit) {
    val isDarkTheme = remember { mutableStateOf(isSystemInDarkTheme()) }
    val colors = if (isDarkTheme.value) {
        DarkColorPalette
    } else {
        LightColorPalette
    }

    MaterialTheme(
        colors = colors,
        content = content
    )
}

object LightColorPalette {
    val primary = MaterialTheme.colors.primary
    val background = MaterialTheme.colors.background
    val surface = MaterialTheme.colors.surface
    val onPrimary = MaterialTheme.colors.onPrimary
    val onBackground = MaterialTheme.colors.onBackground
    val onSurface = MaterialTheme.colors.onSurface
}

object DarkColorPalette {
    val primary = MaterialTheme.colors.primaryVariant
    val background = MaterialTheme.colors.background
    val surface = MaterialTheme.colors.surfaceVariant
    val onPrimary = MaterialTheme.colors.onPrimaryVariant
    val onBackground = MaterialTheme.colors.onBackgroundVariant
    val onSurface = MaterialTheme.colors.onSurfaceVariant
}

@Composable
fun ThemeSwitcher(onThemeChange: (Boolean) -> Unit) {
    val isDarkTheme = remember { mutableStateOf(isSystemInDarkTheme()) }
    val toggleTheme = {
        isDarkTheme.value = !isDarkTheme.value
        onThemeChange(isDarkTheme.value)
    }

    // 这里可以添加一个按钮或其他 UI 元素来触发主题切换
    // 例如：Button(onClick = toggleTheme) { Text("Toggle Theme") }
}

@Preview(showBackground = true)
@Composable
fun DefaultPreview() {
    MyAppTheme {
        Surface(color = MaterialTheme.colors.background) {
            Text(text = "Hello, World!")
        }
    }
}