[英]how to launch a coroutine inside a composable in Android Jetpack Compose
[英]How to Improve performance with Jetpack Compose (when assembling something inside a @Composable function)
假設我的應用程序中有兩個可組合項:
@Composable
fun CoreKeyboard(keyboardKeys: List<List<KeyboardKey>>, ...) {
// ...
}
和
@Composable
fun NumberKeyboard(...) {
val keyboardKeys = listOf(
listOf(KeyboardKey("1"), KeyboardKey("2"), KeyboardKey("3")),
listOf(KeyboardKey("4"), KeyboardKey("5"), KeyboardKey("6")),
listOf(KeyboardKey("7"), KeyboardKey("8"), KeyboardKey("9")),
listOf(KeyboardKey("0"))
)
CoreKeyboard(keyboardKeys = keyboardKeys, ...)
}
如果我沒記錯的話,這種方法的性能不是很好,因為在每次重組中NumberKeyboard
中的keyboardKeys
鍵都會被重新組裝。
做這個的最好方式是什么?
我考慮過使用by remember { mutableStateOf(...) }
,但keyboardKeys
是不可變的。 它仍然是一個好方法嗎?
如果你有一些計算起來很昂貴的東西,並且你只想在你的可組合上計算它一次,只需用remember
包裝它
val keyboardKeys = remember {
listOf(
listOf(KeyboardKey("1"), KeyboardKey("2"), KeyboardKey("3")),
listOf(KeyboardKey("4"), KeyboardKey("5"), KeyboardKey("6")),
listOf(KeyboardKey("7"), KeyboardKey("8"), KeyboardKey("9")),
listOf(KeyboardKey("0"))
)
}
如果你想改變值以便觀察它,你只需要mutableStateOf
。
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