回答編集履歴

  `Settings.Designer.cs`を編集すれば可能です。

  が、`Settings.settings`のデザイナをいじったりすると消えやすいので、別に書いたほうが安全です（`partial`なので）

 

  `TaskList`が`MainWindowViewModel`経由になっている深い意味はありません。

 

  <Window

  x:Class="Questions288214.Views.MainWindow"

  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

  xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"

  xmlns:prism="http://prismlibrary.com/"

  xmlns:properties="clr-namespace:Questions288214.Properties"

  Width="{Binding Width, Mode=TwoWay, Source={x:Static properties:Settings.Default}}"

  Height="{Binding Height, Mode=TwoWay, Source={x:Static properties:Settings.Default}}"

  prism:ViewModelLocator.AutoWireViewModel="True"

  Left="{Binding Left, Mode=TwoWay, Source={x:Static properties:Settings.Default}}"

  Top="{Binding Top, Mode=TwoWay, Source={x:Static properties:Settings.Default}}">

  <Window.Resources>

  <BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />

  <Style TargetType="Label">

  <Setter Property="Margin" Value="5" />

  </Style>

  <Style TargetType="TextBox">

  <Setter Property="Margin" Value="5" />

  <Setter Property="VerticalAlignment" Value="Center" />

  <Setter Property="TextWrapping" Value="Wrap" />

  </Style>

  </Window.Resources>

  <i:Interaction.Triggers>

  <i:EventTrigger EventName="Closing">

  <prism:InvokeCommandAction Command="{Binding WindowClosingCommand}" />

  </i:EventTrigger>

  </i:Interaction.Triggers>

  <Grid>

  <Grid.ColumnDefinitions>

  <ColumnDefinition />

  <ColumnDefinition Width="2*" />

  </Grid.ColumnDefinitions>

  <Grid.RowDefinitions>

  <RowDefinition Height="Auto" />

  <RowDefinition />

  </Grid.RowDefinitions>

 

  <Grid>

  <Grid.ColumnDefinitions>

  <ColumnDefinition Width="Auto" />

  <ColumnDefinition />

  </Grid.ColumnDefinitions>

  <Label VerticalAlignment="Center" Content="表題" />

  <TextBox Grid.Column="1" Text="{Binding Txt_Title.Value, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />

  </Grid>

 

  <Grid Grid.Column="1">

  <Grid.ColumnDefinitions>

  <ColumnDefinition Width="Auto" />

  <ColumnDefinition />

  <ColumnDefinition Width="Auto" />

  </Grid.ColumnDefinitions>

  <Label VerticalAlignment="Center" Content="Memo" />

  <TextBox Grid.Column="1" Text="{Binding Txt_Memo.Value, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />

  <Button

  Grid.Column="2"

  MinWidth="56"

  Margin="5"

  Command="{Binding AddListCommand}"

  Content="追加" />

  </Grid>

 

  <ListBox

  x:Name="lst_Title"

  Grid.Row="1"

  Margin="5"

  DisplayMemberPath="Title"

  IsSynchronizedWithCurrentItem="True"

  ItemsSource="{Binding TaskList}"

  SelectionMode="Multiple">

  <ListBox.ItemContainerStyle>

  <Style TargetType="ListBoxItem">

  <Setter Property="IsSelected" Value="{Binding IsSelected.Value}" />

  </Style>

  </ListBox.ItemContainerStyle>

  </ListBox>

 

  <ListBox

  Grid.Row="1"

  Grid.Column="1"

  Margin="5"

  ItemsSource="{Binding TaskList}">

  <ListBox.ItemContainerStyle>

  <Style TargetType="ListBoxItem">

  <Setter Property="Visibility" Value="{Binding IsSelected.Value, Converter={StaticResource BooleanToVisibilityConverter}}" />

  </Style>

  </ListBox.ItemContainerStyle>

  <ListBox.ItemTemplate>

  <DataTemplate>

  <StackPanel>

  <TextBlock FontWeight="Bold" Text="{Binding Title}" />

  <TextBlock Text="{Binding Memo}" />

  </StackPanel>

  </DataTemplate>

  </ListBox.ItemTemplate>

  </ListBox>

  </Grid>

  </Window>

  ```

 

  using System.Collections.ObjectModel;

  using System.Reactive.Linq;

  using Prism.Mvvm;

  using Reactive.Bindings;

 

  namespace Questions288214.ViewModels

  {

  public class MainWindowViewModel : BindableBase

  {

  public ReactiveProperty<string> Txt_Title { get; set; } = new ReactiveProperty<string>();

  public ReactiveProperty<string> Txt_Memo { get; set; } = new ReactiveProperty<string>();

 

  public ObservableCollection<Task> TaskList

  {

  get => Properties.Settings.Default.TaskList;

  private set => Properties.Settings.Default.TaskList = value;

 

  public ReactiveCommand AddListCommand { get; }

  public ReactiveCommand WindowClosingCommand { get; } = new ReactiveCommand();

 

 

  public MainWindowViewModel()

  {

  if(TaskList == null) TaskList = new ObservableCollection<Task>();

 

  AddListCommand = Txt_Title

  .Select(x => !string.IsNullOrEmpty(x))

  .ToReactiveCommand();

 

  AddListCommand.Subscribe(() =>

  {

  TaskList.Add(new Task { Title = Txt_Title.Value, Memo = Txt_Memo.Value, });

  Txt_Title.Value = "";

  Txt_Memo.Value = "";

  });

 

  WindowClosingCommand.Subscribe(() => Properties.Settings.Default.Save());

 

  public class Task

  {

  public string Title { get; set; }

  public string Memo { get; set; }

  public ReactiveProperty<bool> IsSelected { get; set; } = new ReactiveProperty<bool>();

  }

 

  // 別ファイルに書けば安心

  namespace Questions288214.Properties

  {

  using Questions288214.ViewModels;

 

  internal sealed partial class Settings

  {

  [System.Configuration.UserScopedSetting()]

  [System.Diagnostics.DebuggerNonUserCode()]

  public ObservableCollection<Task> TaskList

  {

  get => (ObservableCollection<Task>)this[nameof(TaskList)];

  set => this[nameof(TaskList)] = value;

  }

  ```

 

  ウィンドウ位置保存用は普通にデザイナで入れたとする

  //------------------------------------------------------------------------------

  // <auto-generated>

  // このコードはツールによって生成されました。

  // ランタイム バージョン:4.0.30319.42000

  //

  // このファイルへの変更は、以下の状況下で不正な動作の原因になったり、

  // コードが再生成されるときに損失したりします。

  // </auto-generated>

  //------------------------------------------------------------------------------

 

  namespace Questions288214.Properties {

 

 

  [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]

  [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator", "16.7.0.0")]

  internal sealed partial class Settings : global::System.Configuration.ApplicationSettingsBase {

  private static Settings defaultInstance = ((Settings)(global::System.Configuration.ApplicationSettingsBase.Synchronized(new Settings())));

  public static Settings Default {

  return defaultInstance;

  [global::System.Configuration.DefaultSettingValueAttribute("NaN")]

  public double Top {

  return ((double)(this["Top"]));

  this["Top"] = value;

  [global::System.Configuration.DefaultSettingValueAttribute("NaN")]

  public double Left {

  return ((double)(this["Left"]));

  this["Left"] = value;

  [global::System.Configuration.DefaultSettingValueAttribute("525")]

  public double Width {

  return ((double)(this["Width"]));

  this["Width"] = value;

  [global::System.Configuration.DefaultSettingValueAttribute("350")]

  public double Height {

  return ((double)(this["Height"]));

  this["Height"] = value;

  }

  ```