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Flutter Hooks, sometimes Jetpack Compose
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Daichi Furiya (Wasabeef)
June 22, 2021
Programming
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1.8k
Flutter Hooks, sometimes Jetpack Compose
Flutter Hooks, sometimes Jetpack Compose
Daichi Furiya (Wasabeef)
June 22, 2021
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Transcript
Flutter 1 Flutter Hooksɺ ɹɹɹ࣌ʑ Jetpack Compose Daichi Furiya @wasabeef_jp
Target audience Hooks ΛΒͳ͍ਓ React Hook ͬͯΔਓ 2 ͜ΕΛظʹ Hooks
ʹ৮Εͯɺ Flutter Hooks/React Hook ͱ Jetpack Compose ͷεςʔ τཧΛཧղͷҰาΛਐΉ Flutter Hooks ͱ React Hook ɺ΄΅ಉ͡ͳͷͰม ͭͭ͠ Jetpack Compose ͷ εςʔτཧʹ৮ΕΔ Jetpack Compose ͱ Flutter Hooks/React Hooks Λม Ͱ͖ΔΑ͏ʹ͢Δ Jetpack Compose ͬͯΔਓ
Target audience Hooks ΛΒͳ͍ਓ React Hook ͬͯΔਓ 3 ͜ΕΛظʹ Hooks
ʹ৮Εͯɺ Flutter Hooks/React Hook ͱ Jetpack Compose ͷεςʔ τཧΛཧղͷҰาΛਐΉ Flutter Hooks ͱ React Hook ɺ΄΅ಉ͡ͳͷͰม ͭͭ͠ Jetpack Compose ͷ εςʔτཧʹ৮ΕΔ Jetpack Compose ͱ Flutter Hooks/React Hooks Λม Ͱ͖ΔΑ͏ʹ͢Δ Jetpack Compose ͬͯΔਓ
Target audience Hooks ΛΒͳ͍ਓ React Hook ͬͯΔਓ 4 ͜ΕΛظʹ Hooks
ʹ৮Εͯɺ Flutter Hooks/React Hook ͱ Jetpack Compose ͷεςʔ τཧΛཧղͷҰาΛਐΉ Flutter Hooks ͱ React Hook ɺ΄΅ಉ͡ͳͷͰม ͭͭ͠ Jetpack Compose ͷ εςʔτཧʹ৮ΕΔ Jetpack Compose ͱ Flutter Hooks/React Hooks Λม Ͱ͖ΔΑ͏ʹ͢Δ Jetpack Compose ͬͯΔਓ
Target audience Hooks ΛΒͳ͍ਓ React Hook ͬͯΔਓ 5 ͜ΕΛظʹ Hooks
ʹ৮Εͯɺ Flutter Hooks/React Hook ͱ Jetpack Compose ͷεςʔ τཧΛཧղͷҰาΛਐΉ Flutter Hooks ͱ React Hook ɺ΄΅ಉ͡ͳͷͰม ͭͭ͠ Jetpack Compose ͷ εςʔτཧʹ৮ΕΔ Jetpack Compose ͱ Flutter Hooks/React Hooks Λม Ͱ͖ΔΑ͏ʹ͢Δ Jetpack Compose ͬͯΔਓ
6 02 StatelessWidget, StatefulWidget 01 Flutter Hooks 03 useXXX 04
Use Cases 05 Conclusion
Flutter Hooks Flutter Hooks ͱʁ ϝϦοτ 7 React Hooks ͷ
Flutter ൛Ͱจ ๏͍ํ΄΅Ұॹɻ εςʔτͷॳظԽʢinitStateʣഁغ (dispose) ΛΟδΣοτͱ͕Ͱ͖Δɻ ୯७ʹΫϥεͷఆٛΛݮΒ͢γϯλοΫεγϡ ΨʔతͳԸܙ͋Δɻ
Flutter Hooks Flutter Hooks ͱʁ ϝϦοτ 8 React Hooks ͷ
Flutter ൛Ͱจ ๏͍ํ΄΅Ұॹɻ εςʔτͷॳظԽʢinitStateʣഁغ (dispose) ΛΟδΣοτͱ͕Ͱ͖Δɻ ୯७ʹΫϥεͷఆٛΛݮΒ͢γϯλοΫεγϡ ΨʔతͳԸܙ͋Δɻ
Flutter Hooks Flutter Hooks ͱʁ ϝϦοτ 9 React Hooks ͷ
Flutter ൛Ͱจ ๏͍ํ΄΅Ұॹɻ εςʔτͷॳظԽʢinitStateʣഁغ (dispose) ΛΟδΣοτͱ͕Ͱ͖Δɻ ୯७ʹΫϥεͷఆٛΛݮΒ͢γϯλοΫεγϡ ΨʔతͳԸܙ͋Δɻ
10 02 StatelessWidget, StatefulWidget 01 Flutter Hooks 03 useXXX 04
Use Cases 05 Conclusion
11 StatelessWidget, StatefulWidget StatelessWidget StatefulWidget ΦϒδΣΫτੜ࣌ʹ༩͑ΒΕͨ ใͱ BuildContext Ҏ֎ʹґଘ͠ͳ ͍ΟδΣοτͰ͢ɻIconɺ
IconButton Text ͳͲ͕ StatelessWidget ͷαϒΫϥεͰ͢ɻ γεςϜͷঢ়ଶͳͲʹΑͬͯಈతʹ มԽΛ͢Δখ͞ͳϥΠϑαΠΫϧΛ ͬͨΟδΣοτͰ͢ɻImageɺ TextFormField Hero ͳͲ͕ StatefulWidget ͷαϒΫϥεͰ͢ɻ
12 StatelessWidget, StatefulWidget StatelessWidget StatefulWidget ΦϒδΣΫτੜ࣌ʹ༩͑ΒΕͨ ใͱ BuildContext Ҏ֎ʹґଘ͠ͳ ͍ΟδΣοτͰ͢ɻIconɺ
IconButton Text ͳͲ͕ StatelessWidget ͷαϒΫϥεͰ͢ɻ γεςϜͷঢ়ଶͳͲʹΑͬͯಈతʹ มԽΛ͢Δখ͞ͳϥΠϑαΠΫϧΛ ͬͨΟδΣοτͰ͢ɻImageɺ TextFormField Hero ͳͲ͕ StatefulWidget ͷαϒΫϥεͰ͢ɻ
13 StatelessWidget, StatefulWidget StatelessWidget StatefulWidget ΦϒδΣΫτੜ࣌ʹ༩͑ΒΕͨ ใͱ BuildContext Ҏ֎ʹґଘ͠ͳ ͍ΟδΣοτͰ͢ɻIconɺ
IconButton Text ͳͲ͕ StatelessWidget ͷαϒΫϥεͰ͢ɻ γεςϜͷঢ়ଶͳͲʹΑͬͯಈతʹ มԽΛ͢Δখ͞ͳϥΠϑαΠΫϧΛ ͬͨΟδΣοτͰ͢ɻImageɺ TextFormField Hero ͳͲ͕ StatefulWidget ͷαϒΫϥεͰ͢ɻ
14 StatelessWidget, StatefulWidget class Counter extends StatefulWidget { @override State
createState() "=> _CountState(); } class _CountState extends State<CountPage> { int count = 0; void setCount(int value) { setState(() "=> count = value); } @override Widget build(BuildContext context) { return TextButton( child: Text("a is $count"), onPressed: () "=> setCount(count + 1), ); } } StatelessWidget class SimpleLabel extends StatelessWidget { const SimpleLabel({required this.label}); final String label; @override Widget build(BuildContext context) { return Text( label, style: const TextStyle( decoration: TextDecoration.underline, ), ); } } StatefulWidget ϘλϯΛԡ͢ຖʹ count ͕૿͑ɺςΩετ͕Մม͢ΔΟδΣοτˢ ↑ ༩͑ΒΕͨใͷΈͰෆมͳΟδΣοτ
15 StatelessWidget, StatefulWidget class Counter extends StatefulWidget { @override State
createState() "=> _CountState(); } class _CountState extends State<CountPage> { int count = 0; void setCount(int value) { setState(() "=> count = value); } @override Widget build(BuildContext context) { return TextButton( child: Text("a is $count"), onPressed: () "=> setCount(count + 1), ); } } StatelessWidget class SimpleLabel extends StatelessWidget { const SimpleLabel({required this.label}); final String label; @override Widget build(BuildContext context) { return Text( label, style: const TextStyle( decoration: TextDecoration.underline, ), ); } } StatefulWidget ϘλϯΛԡ͢ຖʹ count ͕૿͑ɺςΩετ͕Մม͢ΔΟδΣοτˢ ↑ ༩͑ΒΕͨใͷΈͰෆมͳΟδΣοτ
16 StatelessWidget, StatefulWidget class Counter extends StatefulWidget { @override State
createState() "=> _CountState(); } class _CountState extends State<CountPage> { int count = 0; void setCount(int value) { setState(() "=> count = value); } @override Widget build(BuildContext context) { return TextButton( child: Text("a is $count"), onPressed: () "=> setCount(count + 1), ); } } StatelessWidget class SimpleLabel extends StatelessWidget { const SimpleLabel({required this.label}); final String label; @override Widget build(BuildContext context) { return Text( label, style: const TextStyle( decoration: TextDecoration.underline, ), ); } } StatefulWidget ϘλϯΛԡ͢ຖʹ count ͕૿͑ɺςΩετ͕Մม͢ΔΟδΣοτˢ ↑ ༩͑ΒΕͨใͷΈͰෆมͳΟδΣοτ
17 class CountPage extends StatefulWidget { @override State createState() "=>
_CountState(); } class _CountState extends State<CountPage> { int count = 0; @override void initState() { ""/** ॳظԽ **/ } @override void dispose() { ""/** ഁغ **/ } void setCount(int value) "=> setState(() "=> count = value); @override Widget build(BuildContext context) { return TextButton( child: Text("Count is $count"), onPressed: () "=> setCount(count + 1), ); } } StatefulWidget Λ͏ʹجຊతʹೋͭ ͷΫϥεΛ࡞Δඞཁ͕͋Γ·͢ɻ StatefulWidget Λܧঝͨ͠ CountPage ͱ State<T extends StatefulWidget> Λܧঝ ͨ͠ _CountState Ͱ͢ɻ initState ͰॳظԽɺdispose Ͱഁغͷॲ ཧΛॻ͘͜ͱ͕Ͱ͖·͢ɻ ·ͨ setState ΛݺͿ͜ͱͰঢ়ଶ͕มԽ͠ ͨ͜ͱΛ௨ͯ͠ϦϏϧυ͕Γ·͢ɻ StatelessWidget, StatefulWidget
18 class CountPage extends HookWidget { @override Widget build(BuildContext context)
{ final count = useState(0); return TextButton( child: Text("Count: ${count.value}"), onPressed: () "=> count.value"++, ); } } StatelessWidget, StatefulWidget γϯϓϧʹ useState Λ͏ͱॻ͘ͱ͜Ε ͘Β͍Ͱલͷϖʔδͱಉ͡ίʔυͷಈ࡞ Λ࣮ݱ͢Δ͜ͱ͕Ͱ͖·͢ɻuseState ͷ ׂͳͲޙड़͍͖ͯ͠·͢ɻ
19 class HomePage extends HookWidget { const HomePage({Key? key}) :
super(key: key); @override Widget build(BuildContext context) { final enabled = useState(false); return Column( children: [ TextFormField( onChanged: (value) "=> enabled.value = value.isNotEmpty, ), ElevatedButton( onPressed: enabled.value ? () { ""/** Submit **/ } : null, child: Text('Submit'), ), ], ); } } StatelessWidget, StatefulWidget Flutter Hooks ͷॳΊͯͷαϯϓϧΛ୳͠ ͯΈΔͱઌ΄ͲΑ͏ʹΧϯλʔͷίʔ υΛΑ͘ݟ͔͚·͕͢ɺ࣮ࡍʹॳݟͰ ͦΕ͚ͩΈͯϐϯͱ͜ͳ͔ͬͨͷͰɺ ͜͜ͰϑΥʔϜʹ͕͋Δ͔Ͳ͏͔Ͱ Ϙλϯͷ༗ޮແޮΛΓସ͍͑ͯ·͢ɻ
20 02 StatelessWidget, StatefulWidget 01 Flutter Hooks 03 useXXX 04
Use Cases 05 Conclusion
Flutter Hooks ͷϝιου HookWidget Λܧঝͨ͠ build ͷதͰ ݺͳ͍ͱ͍͚ͳ͍ useContext BuildContext
ΛऔಘͰ͖Δ 21
@Composable fun SampleName() { val context = LocalContext.current Text( text
= "${context.getString(R.string.name)}" ) } 22 useContext class SampleName extends HookWidget { @override Widget build(BuildContext context) { final l10n = useL10n(); return Text(l10n.name); } } L10n useL10n() { final context = useContext(); return L10n.of(context)!; } Flutter Hooks Jetpack Compose HookWidget Λܧঝ͢Δඞཁ͕͋Δɻ Hooks Λͬͨϝιουʹৗʹ use Ͱ࢝·Δ͜ͱ ͕ϧʔϧͱͳ͍ͬͯΔɻ
@Composable fun SampleName() { val context = LocalContext.current Text( text
= "${context.getString(R.string.name)}" ) } 23 useContext class SampleName extends HookWidget { @override Widget build(BuildContext context) { final l10n = useL10n(); return Text(l10n.name); } } L10n useL10n() { final context = useContext(); return L10n.of(context)!; } Flutter Hooks Jetpack Compose HookWidget Λܧঝ͢Δඞཁ͕͋Δɻ Hooks Λͬͨϝιουʹৗʹ use Ͱ࢝·Δ͜ͱ ͕ϧʔϧͱͳ͍ͬͯΔɻ
@Composable fun SampleName() { val context = LocalContext.current Text( text
= "${context.getString(R.string.name)}" ) } 24 useContext class SampleName extends HookWidget { @override Widget build(BuildContext context) { final l10n = useL10n(); return Text(l10n.name); } } L10n useL10n() { final context = useContext(); return L10n.of(context)!; } Flutter Hooks Jetpack Compose HookWidget Λܧঝ͢Δඞཁ͕͋Δɻ Hooks Λͬͨϝιουʹৗʹ use Ͱ࢝·Δ͜ͱ ͕ϧʔϧͱͳ͍ͬͯΔɻ
StatelessWidget ͰԿ͔͠Βͷঢ়ଶ ཧ͕͍ͨ͠ͱࢥ͕ͬͨ࣌ useState Λ͏໘Ͱ͢ʢViewModel ૬Ͱ อ࣋͢Δ΄ͲͰͳ͍ͷͳͲʣ useState final count
= useState(0); count.value = 3; େମ֮͑Δͷ͜Ε͚ͩ StatefulWidget ΛΘͳ͍ ؆୯ 25
useState final count = useState(0); count.value = 3; େମ֮͑Δͷ͜Ε͚ͩ StatefulWidget
ΛΘͳ͍ ؆୯ 26 StatelessWidget ͰԿ͔͠Βͷঢ়ଶ ཧ͕͍ͨ͠ͱࢥ͕ͬͨ࣌ useState Λ͏໘Ͱ͢ʢViewModel ૬Ͱ อ࣋͢Δ΄ͲͰͳ͍ͷͳͲʣ
useState final count = useState(0); count.value = 3; େମ֮͑Δͷ͜Ε͚ͩ StatefulWidget
ΛΘͳ͍ ؆୯ 27 StatelessWidget ͰԿ͔͠Βͷঢ়ଶ ཧ͕͍ͨ͠ͱࢥ͕ͬͨ࣌ useState Λ͏໘Ͱ͢ʢViewModel ૬Ͱ อ࣋͢Δ΄ͲͰͳ͍ͷͳͲʣ
@Composable fun Count() { val count = remember { mutableStateOf(0)
} Button(onClick = { count.value"++ }) { Text("Count: ${count.value}") } } 28 useState class CountPage extends HookWidget { @override Widget build(BuildContext context) { final count = useState(0); return TextButton( onPressed: () { count.value"++; }, child: Text("Count: ${count.value}"), ); } } Flutter Hooks Jetpack Compose remember composable Λར༻ͯ͠ঢ়ଶͷอ ࣋Λߦ͏͜ͱ͕Ͱ͖Δ final state = useState(initialValue); state.value = newValue; ͜Ε͚ͩ
@Composable fun Count() { val count = remember { mutableStateOf(0)
} Button(onClick = { count.value"++ }) { Text("Count: ${count.value}") } } 29 useState class CountPage extends HookWidget { @override Widget build(BuildContext context) { final count = useState(0); return TextButton( onPressed: () { count.value"++; }, child: Text("Count: ${count.value}"), ); } } Flutter Hooks Jetpack Compose remember composable Λར༻ͯ͠ঢ়ଶͷอ ࣋Λߦ͏͜ͱ͕Ͱ͖Δ final state = useState(initialValue); state.value = newValue; ͜Ε͚ͩ
@Composable fun Count() { val (count, setCount) = remember {
mutableStateOf(0) } Button(onClick = { setCount(count + 1) }) { Text("Count: ${count}") } } 30 useState class CountPage extends HookWidget { @override Widget build(BuildContext context) { final count = useState(0); return TextButton( onPressed: () { count.value"++; }, child: Text("Count: ${count.value}"), ); } } Flutter Hooks Jetpack Compose Jetpack Compose value ͱ setter Λ࣋ͭ tuple Λੜ͢Δ͜ͱͰ͖·͢ʢReact Ά͍ʣ final state = useState(initialValue); state.value = newValue; ͜Ε͚ͩ
@Composable fun Count() { val (count, setCount) = remember {
mutableStateOf(0) } Button(onClick = { setCount(count + 1) }) { Text("Count: ${count}") } } 31 useState class CountPage extends HookWidget { @override Widget build(BuildContext context) { final count = useState(0); return TextButton( onPressed: () { count.value"++; }, child: Text("Count: ${count.value}"), ); } } Flutter Hooks Jetpack Compose remember composable Λར༻ͯ͠ঢ়ଶͷอ ࣋Λߦ͏͜ͱ͕Ͱ͖Δ final state = useState(initialValue); state.value = newValue; ͜Ε͚ͩ
؆୯ͳϥΠϑαΠΫϧॲཧ͕ඞཁ ͩͬͨ߹ʹ useEffect Λ͍· ͢ɻΟδΣοτੜ࣌ʹॳظԽ͠ ͍ͨ߹ͳͲɻ useEffect ॳظԽഁغͷॲཧ͕ඞཁͩͬͨΒ 32
DisposableEffect(id) { val subscription = source.subscribe(id) onDispose { "// ഁغ͞ΕΔ࣌ʹ࣮ߦ(ActivityഁغͳͲ)
subscription.unsubscribe(id) } } 33 useEffect useEffect(() "=> { final subscription = source.subscribe(id); return () "=> { "// ഁغ͞ΕΔ࣌ʹ࣮ߦ subscription.unsubscribe(id); }; }, [id]); Flutter Hooks Jetpack Compose
DisposableEffect(id) { val subscription = source.subscribe(id) onDispose { "// ഁغ͞ΕΔ࣌ʹ࣮ߦ(ActivityഁغͳͲ)
subscription.unsubscribe(id) } } 34 useEffect useEffect(() "=> { final subscription = source.subscribe(id); return () "=> { "// ഁغ͞ΕΔ࣌ʹ࣮ߦ subscription.unsubscribe(id); }; }, [id]); Flutter Hooks Jetpack Compose
DisposableEffect(id) { val subscription = source.subscribe(id) onDispose { "// ഁغ͞ΕΔ࣌ʹ࣮ߦ(ActivityഁغͳͲ)
subscription.unsubscribe(id) } } 35 useEffect useEffect(() "=> { final subscription = source.subscribe(id); return () "=> { "// ഁغ͞ΕΔ࣌ʹ࣮ߦ subscription.unsubscribe(id); }; }, [id]); Flutter Hooks Jetpack Compose
LaunchedEffect(id) { "// ID ͕มߋ͞ΕΔͨͼ } SideEffect { "// ຖճ
} LaunchedEffect(Unit) { "// ࠷ॳͷҰճ } 36 useEffect useEffect(() "=> { "// ID ͕มߋ͞ΕΔͨͼ }, [id]); useEffect(() "=> { "// ຖճ }); useEffect(() "=> { "// ࠷ॳͷҰճ }, []); Flutter Hooks Jetpack Compose
LaunchedEffect(id) { "// ID ͕มߋ͞ΕΔͨͼ } SideEffect { "// ຖճ
} LaunchedEffect(Unit) { "// ࠷ॳͷҰճ } 37 useEffect useEffect(() "=> { "// ID ͕มߋ͞ΕΔͨͼ }, [id]); useEffect(() "=> { "// ຖճ }); useEffect(() "=> { "// ࠷ॳͷҰճ }, []); Flutter Hooks Jetpack Compose
LaunchedEffect(id) { "// ID ͕มߋ͞ΕΔͨͼ } SideEffect { "// ຖճ
} LaunchedEffect(Unit) { "// ࠷ॳͷҰճ } 38 useEffect useEffect(() "=> { "// ID ͕มߋ͞ΕΔͨͼ }, [id]); useEffect(() "=> { "// ຖճ }); useEffect(() "=> { "// ࠷ॳͷҰճ }, const []); Flutter Hooks Jetpack Compose
39 useEffect Flutter Hooks @override Widget build(BuildContext context) { final
enabled = useState(false); useEffect(() { print("ॳճͷΈ"); }, const []); return Column( children: [ TextFormField( onChanged: (value) "=> enabled.value = value.isNotEmpty, ), ElevatedButton( onPressed: enabled.value ? () { ""/** Submit **/ } : null, child: Text('Submit'), ), ], ); } ςΩετ͕ೖྗ͞ΕͨΒϘλϯ͕༗ޮͱ ͳΔαϯϓϧͰ͕ͨ͠ɺ͜ͷ useEffect ͷ͍ํΛͨ͠߹ʹ࣮ߦ͞ΕΔͷ ࠷ॳͷҰճͱͳΓ·͢ɻ
State ͱ͍͍ͯͨ͠Θ͚Ͱͳ͘ຖ ճಉ͡σʔλΛऔಘ͢ΔͷͰͳ͘ Ωϟογϡ͓͖͍ͯͨ͠߹ͳͲʹ useMemoized ΛΩϟογϡ͍ͨ͠߹ 40
val now = remember(key) { LocalDateTime.now() } 41 useMemoized final
now = useMemoized(() { return DateTime.now(); }, [key]); Flutter Hooks Jetpack Compose remember ʹΩʔΛ͢͜ͱͰ͖ɺΩʔ͕ಉ͡ Ͱ͋ΕͦͷॲཧΩϟογϡ͞Ε·͢ useMemoized Λ͏͜ͱͰΩϟογϡ͕Ͱ ͖ɺΩʔ͕ಉ͡Ͱ͋ΕͦͷॲཧΩϟογϡ ͞Ε·͢
val now = remember(key) { LocalDateTime.now() } 42 useMemoized final
now = useMemoized(() { return DateTime.now(); }, [key]); Flutter Hooks Jetpack Compose remember ʹΩʔΛ͢͜ͱͰ͖ɺΩʔ͕ಉ͡ Ͱ͋ΕͦͷॲཧΩϟογϡ͞Ε·͢ useMemoized Λ͏͜ͱͰΩϟογϡ͕Ͱ ͖ɺΩʔ͕ಉ͡Ͱ͋ΕͦͷॲཧΩϟογϡ ͞Ε·͢
val now = remember(key) { LocalDateTime.now() } 43 useMemoized final
now = useMemoized(() { return DateTime.now(); }, [key]); Flutter Hooks Jetpack Compose remember ʹΩʔΛ͢͜ͱͰ͖ɺΩʔ͕ಉ͡ Ͱ͋ΕͦͷॲཧΩϟογϡ͞Ε·͢ useMemoized Λ͏͜ͱͰΩϟογϡ͕Ͱ ͖ɺΩʔ͕ಉ͡Ͱ͋ΕͦͷॲཧΩϟογϡ ͞Ε·͢
@Composable fun Greeting() { val (count, setCount) = remember {
mutableStateOf(0) } val now = remember(count) { LocalDateTime.now() } Column { Text(text = "Click Time: $now") Button(onClick = { setCount(count + 1) }) { Text("Count: ${count}") } } } 44 useMemoized @override Widget build(BuildContext context) { final count = useState(0); final now = useMemoized(() "=> DateTime.now(), [count.value]); return Column( children: [ Text("Click Time: $now"), TextButton( onPressed: () "=> count.value"++, child: Text("Count: ${count.value}"), ), ], ); } Flutter Hooks Jetpack Compose ͜ͷྫͰɺcount ͕૿͑ͨʢΫϦοΫͨ͠ʣλΠϛϯάͰݱࡏ࣌ؒ Λऔಘͯ͠Ωϟογϡ͍ͯ͠·͢
@Composable fun Greeting() { val (count, setCount) = remember {
mutableStateOf(0) } val now = remember(count) { LocalDateTime.now() } Column { Text(text = "Click Time: $now") Button(onClick = { setCount(count + 1) }) { Text("Count: ${count}") } } } 45 useMemoized @override Widget build(BuildContext context) { final count = useState(0); final now = useMemoized(() "=> DateTime.now(), [count.value]); return Column( children: [ Text("Click Time: $now"), TextButton( onPressed: () "=> count.value"++, child: Text("Count: ${count.value}"), ), ], ); } Flutter Hooks Jetpack Compose ͜ͷྫͰɺcount ͕૿͑ͨʢΫϦοΫͨ͠ʣλΠϛϯάͰݱࡏ࣌ؒ Λऔಘͯ͠Ωϟογϡ͍ͯ͠·͢
@Composable fun Greeting() { val (count, setCount) = remember {
mutableStateOf(0) } val now = remember(count) { LocalDateTime.now() } Column { Text(text = "Click Time: $now") Button(onClick = { setCount(count + 1) }) { Text("Count: ${count}") } } } 46 useMemoized @override Widget build(BuildContext context) { final count = useState(0); final now = useMemoized(() "=> DateTime.now(), [count.value]); return Column( children: [ Text("Click Time: $now"), TextButton( onPressed: () "=> count.value"++, child: Text("Count: ${count.value}"), ), ], ); } Flutter Hooks Jetpack Compose ͜ͷྫͰɺcount ͕૿͑ͨʢΫϦοΫͨ͠ʣλΠϛϯάͰݱࡏ࣌ؒ Λऔಘͯ͠Ωϟογϡ͍ͯ͠·͢
47 02 StatelessWidget, StatefulWidget 01 Flutter Hooks 03 useXXX 04
Use Cases 05 Conclusion
48 Use Cases VideoPlayerController useAssetVideoController({ required String asset, bool autoPlay
= false, bool looping = false, }) { final controller = useMemoized( () "=> VideoPlayerController.asset(asset), [asset], ); useEffect(() { controller "..initialize() "..setLooping(looping); if (autoPlay) { controller.play(); } return () "=> controller.dispose(); }, [asset, autoPlay, looping]); return controller; } Flutter Hooks class VideoPage extends HookWidget { @override Widget build(BuildContext context) { final videoController = useAssetVideoController( asset: Assets.videos.bigbuckbunny, autoPlay: true, looping: true, ); return Scaffold( appBar: AppBar(), body: Center( child: AspectRatio( aspectRatio: 16 / 9, child: VideoPlayer(videoController), ), ), ); } } video_player ΛͬͨྫɻVideoPlayerController ͷॳظԽɾഁغΛΟδΣοτͱ͓ͯ͘͜͠ͱͰɺผͷΟδΣοτͰ͍ճ͕͠Ͱ͖Δ
49 Use Cases @Composable public fun BackHandler(enabled: Boolean = true,
onBack: () "-> Unit) { val currentOnBack by rememberUpdatedState(onBack) val backCallback = remember { object : OnBackPressedCallback(enabled) { override fun handleOnBackPressed() { currentOnBack() } } } SideEffect { backCallback.isEnabled = enabled } val backDispatcher = checkNotNull(LocalOnBackPressedDispatcherOwner.current) { "No OnBackPressedDispatcherOwner" }.onBackPressedDispatcher val lifecycleOwner = LocalLifecycleOwner.current DisposableEffect(lifecycleOwner, backDispatcher) { backDispatcher.addCallback(lifecycleOwner, backCallback) onDispose { backCallback.remove() } } } Jetpack Compose class MainActivity : ComponentActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { MaterialTheme { Surface() { BackHandler(onBack = { "// Back pressed }) } } } } } Back key ͷϋϯυϦϯάΛ Composable Խͨ͠ྫɻ͜Εଞͷը໘Ͱ͍ճ͕͠Ͱ͖ΔΑ͏ʹͳΔ
50 02 StatelessWidget, StatefulWidget 01 Flutter Hooks 03 useXXX 04
Use Cases 05 Conclusion
Thank you! https://wasabeef.jp http://github.com/wasabeef https://twitter.com/wasabeef_jp Resources 51 Daichi Furiya @wasabeef_jp