| /* |
| * Copyright 2020 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 |
| * |
| * http://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. |
| */ |
| |
| package androidx.ui.core.demos |
| |
| import androidx.compose.Composable |
| import androidx.compose.getValue |
| import androidx.lifecycle.LiveData |
| import androidx.lifecycle.SavedStateHandle |
| import androidx.lifecycle.ViewModel |
| import androidx.ui.core.Alignment |
| import androidx.compose.foundation.Text |
| import androidx.compose.foundation.layout.Arrangement |
| import androidx.compose.foundation.layout.Column |
| import androidx.compose.runtime.livedata.observeAsState |
| import androidx.ui.material.Button |
| import androidx.ui.viewmodel.viewModel |
| |
| @Composable |
| fun ViewModelDemo() { |
| Column( |
| horizontalGravity = Alignment.CenterHorizontally, |
| verticalArrangement = Arrangement.SpaceEvenly |
| ) { |
| val countViewModel = viewModel<CountViewModel>() |
| val count by countViewModel.count.observeAsState() |
| Text("Count is $count") |
| Button(onClick = { countViewModel.increaseCount() }) { |
| Text("Increase") |
| } |
| } |
| } |
| |
| class CountViewModel(private val savedStateHandle: SavedStateHandle) : ViewModel() { |
| |
| private val CountKey = "${javaClass.simpleName}-count" |
| |
| val count: LiveData<Int> = |
| savedStateHandle.getLiveData(CountKey, 0) |
| |
| fun increaseCount() { |
| savedStateHandle[CountKey] = (count.value ?: 0) + 1 |
| } |
| } |