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[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)
假设我的应用程序中有两个可组合项:
@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, ...)
}
如果我没记错的话,这种方法的性能不是很好,因为在每次重组中NumberKeyboard
中的keyboardKeys
键都会被重新组装。
做这个的最好方式是什么?
我考虑过使用by remember { mutableStateOf(...) }
,但keyboardKeys
是不可变的。 它仍然是一个好方法吗?
如果你有一些计算起来很昂贵的东西,并且你只想在你的可组合上计算它一次,只需用remember
包装它
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"))
)
}
如果你想改变值以便观察它,你只需要mutableStateOf
。
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