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SavingUIStateSnippets.kt
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SavingUIStateSnippets.kt
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/*
* Copyright 2023 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
@file:Suppress("unused", "UNUSED_PARAMETER")
package com.example.compose.snippets.state
import androidx.compose.foundation.lazy.LazyListState
import androidx.compose.foundation.text.ClickableText
import androidx.compose.material.Text
import androidx.compose.material.TextField
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.runtime.setValue
import androidx.compose.ui.text.AnnotatedString
import androidx.compose.ui.text.input.TextFieldValue
import androidx.lifecycle.SavedStateHandle
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewmodel.compose.SavedStateHandleSaveableApi
import androidx.lifecycle.viewmodel.compose.saveable
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.MutableSharedFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.flow.onStart
private object SavingUIStateSnippets1 {
// [START android_compose_state_saving_rememberSaveable]
@Composable
fun ChatBubble(
message: Message
) {
var showDetails by rememberSaveable { mutableStateOf(false) }
ClickableText(
text = AnnotatedString(message.content),
onClick = { showDetails = !showDetails }
)
if (showDetails) {
Text(message.timestamp)
}
}
// [END android_compose_state_saving_rememberSaveable]
}
private object SavingUIStateSnippets2 {
// [START android_compose_state_with_saver]
@Composable
fun rememberLazyListState(
initialFirstVisibleItemIndex: Int = 0,
initialFirstVisibleItemScrollOffset: Int = 0
): LazyListState {
return rememberSaveable(saver = LazyListState.Saver) {
LazyListState(
initialFirstVisibleItemIndex, initialFirstVisibleItemScrollOffset
)
}
}
// [END android_compose_state_with_saver]
}
private object SavingUIStateSnippets3 {
@OptIn(SavedStateHandleSaveableApi::class)
// [START android_compose_state_apis_saveable]
class ConversationViewModel(
savedStateHandle: SavedStateHandle
) : ViewModel() {
var message by savedStateHandle.saveable(stateSaver = TextFieldValue.Saver) {
mutableStateOf(TextFieldValue(""))
}
private set
fun update(newMessage: TextFieldValue) {
message = newMessage
}
/*...*/
}
val viewModel = ConversationViewModel(SavedStateHandle())
@Composable
fun UserInput(/*...*/) {
TextField(
value = viewModel.message,
onValueChange = { viewModel.update(it) }
)
}
// [END android_compose_state_apis_saveable]
}
private object SavingUIStateSnippets4 {
class Channel
class ChannelsRepository {
fun getAll() = MutableSharedFlow<List<Channel>>()
}
fun filter(channels: List<Channel>, type: ChannelsFilterType) = listOf<Channel>()
// [START android_compose_state_apis_savedStateHandle]
private const val CHANNEL_FILTER_SAVED_STATE_KEY = "ChannelFilterKey"
class ChannelViewModel(
channelsRepository: ChannelsRepository,
private val savedStateHandle: SavedStateHandle
) : ViewModel() {
private val savedFilterType: StateFlow<ChannelsFilterType> = savedStateHandle.getStateFlow(
key = CHANNEL_FILTER_SAVED_STATE_KEY, initialValue = ChannelsFilterType.ALL_CHANNELS
)
private val filteredChannels: Flow<List<Channel>> =
combine(channelsRepository.getAll(), savedFilterType) { channels, type ->
filter(channels, type)
}.onStart { emit(emptyList()) }
fun setFiltering(requestType: ChannelsFilterType) {
savedStateHandle[CHANNEL_FILTER_SAVED_STATE_KEY] = requestType
}
/*...*/
}
enum class ChannelsFilterType {
ALL_CHANNELS, RECENT_CHANNELS, ARCHIVED_CHANNELS
}
// [END android_compose_state_apis_savedStateHandle]
}