Android Weekly Issue #462
How to parse JSON in Android using Kotlin
原來不用第三方庫解析JSON也挺容易的, 就用JSONTokener就行.
Android Vitals - Tap Response Time
Py對點(diǎn)擊響應(yīng)時(shí)間的研究.
Handling back presses in Jetpack Compose
關(guān)于Compose如何處理back.
首先介紹了導(dǎo)航庫的基本實(shí)現(xiàn).
一個(gè)簡單的單向數(shù)據(jù)流:
abstract class DetailViewModel : ViewModel() {
abstract val state: StateFlow<DetailState>
abstract fun onAction(action: Action)
}
如果我們想獲取back的action來進(jìn)行處理呢?
如果是覆寫Activity.onBackPressed()可能會有點(diǎn)丑. 不是很推薦, 見官方文檔.
Compose有這么一個(gè)BackHandler composable (added in Activity Compose in 1.3.0-alpha02):
源碼是這樣:
@Composable
public fun BackHandler(enabled: Boolean = true, onBack: () -> Unit) {
// Safely update the current `onBack` lambda when a new one is provided
val currentOnBack by rememberUpdatedState(onBack)
// Remember in Composition a back callback that calls the `onBack` lambda
val backCallback = remember {
object : OnBackPressedCallback(enabled) {
override fun handleOnBackPressed() {
currentOnBack()
}
}
}
// On every successful composition, update the callback with the `enabled` value
SideEffect {
backCallback.isEnabled = enabled
}
val backDispatcher = checkNotNull(LocalOnBackPressedDispatcherOwner.current) {
"No OnBackPressedDispatcherOwner was provided via LocalOnBackPressedDispatcherOwner"
}.onBackPressedDispatcher
val lifecycleOwner = LocalLifecycleOwner.current
DisposableEffect(lifecycleOwner, backDispatcher) {
// Add callback to the backDispatcher
backDispatcher.addCallback(lifecycleOwner, backCallback)
// When the effect leaves the Composition, remove the callback
onDispose {
backCallback.remove()
}
}
}
具體使用就很簡單了:
@Composable
fun Detail(
state: DetailState,
onBack: () -> Unit,
) {
BackHandler(onBack = onBack)
Scaffold(
topBar = { DetailTopAppBar(onBack) }
) {
// detail content
}
}
Animate as State and Animation Specs
關(guān)于Compose的動畫選擇和實(shí)現(xiàn).
Compose, Camera and Canvas
這人的第二周挑戰(zhàn)居然搞了一個(gè)番茄鐘.
Android Runtime — How Dalvik and ART work?
上期有一個(gè)視頻: https://www.youtube.com/watch?v=0J1bm585UCc
這應(yīng)該是配套文章.
Assign multiple styles to a single View in Android
給View疊加多個(gè)style.
貌似只適用于自定義View.
Using DataStore With Kotlin Serialization
DataStore + Kotlin serialization.
How to Pull Request..
關(guān)于PR的種種.
