C#のWPFでアイコン付きでファイルの一覧表示するリストビューを作る2。「コンバーターを使ってファイルサイズと更新日付を表示する」

using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;


namespace ListViewWithIcon.converter;

public class DateSizeConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        long length = (long)value;
        long x = System.Convert.ToInt64(Math.Ceiling((double)length/1024));
        return length < 0 ? "" : string.Format("{0:#,0} KB", x);
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;


namespace ListViewWithIcon.converter;

public class DateTimeConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        DateTime date = (DateTime)value;
        return date.ToString("yyyy/MM/dd HH:mm");
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

using System.Windows.Media.Imaging;

namespace ListViewWithIcon;

public class FileInfoEntity
{
    public BitmapSource Icon { get; set; } = new BitmapImage();
    public string Name { get; set; } = "";
    public DateTime LastModifed { get; set; } = new DateTime();
    public long Length { get; set; } = -1;
}

using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Windows.Media.Imaging;

public class IconManager
{
    static public BitmapImage GetIcon(string path)
    {
        string systemRoot = Environment.GetEnvironmentVariable("SystemRoot") ?? @"C:\Windows";
        string dllPath = Path.Join(systemRoot, @"System32\SHELL32.dll");

        BitmapImage bi = new();
        System.Drawing.Icon? icon;
        if (File.Exists(path))
        {
            icon = Icon.ExtractAssociatedIcon(path);
        }
        else
        {
            icon = Icon.ExtractIcon(dllPath, 3, 64);
        }
        if (icon is null) return bi;

        var ms = new MemoryStream();
        icon.ToBitmap().Save(ms, ImageFormat.Png);
        icon.Dispose();
        ms.Seek(0, SeekOrigin.Begin);

        bi.BeginInit();
        bi.StreamSource = ms;
        bi.CacheOption = BitmapCacheOption.OnLoad;
        bi.CreateOptions = BitmapCreateOptions.None;
        bi.EndInit();
        bi.Freeze();

        ms.SetLength(0);

        return bi;
    }
}

<Window x:Class="ListViewWithIcon.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:i="clr-namespace:Microsoft.Xaml.Behaviors;assembly=Microsoft.Xaml.Behaviors"
        xmlns:interactivity="clr-namespace:Reactive.Bindings.Interactivity;assembly=ReactiveProperty.WPF"
        xmlns:local="clr-namespace:ListViewWithIcon"
        xmlns:converter="clr-namespace:ListViewWithIcon.converter"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.DataContext>
        <local:MainWindowViewModel />
    </Window.DataContext>
    <Window.Resources>
        <converter:DateTimeConverter x:Key="DateTimeConverter"/>
        <converter:DateSizeConverter x:Key="DateSizeConverter"/>
    </Window.Resources>
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="Loaded">
            <interactivity:EventToReactiveCommand Command="{Binding WindowLoadedCommand}" />
        </i:EventTrigger>
        <i:EventTrigger EventName="Closed">
            <interactivity:EventToReactiveCommand Command="{Binding WindowClosedCommand}" />
        </i:EventTrigger>
    </i:Interaction.Triggers>
    <Grid>
        <ListView
            ItemsSource="{Binding FileInfos}">
            <ListView.Resources>
                <Style x:Key="listviewHeaderStyle" TargetType="GridViewColumnHeader">
                    <Setter Property="HorizontalContentAlignment" Value="Stretch" />
                </Style>
            </ListView.Resources>
            <ListView.View>
                <GridView ColumnHeaderContainerStyle="{StaticResource listviewHeaderStyle}">
                    <GridViewColumn Width="300" Header="名前">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <StackPanel Orientation="Horizontal">
                                    <Image Width="16" Height="16" Source="{Binding Icon}"></Image>
                                    <TextBlock Width="Auto" TextAlignment="Left" Text="{Binding Name}" />
                                </StackPanel>
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                    <GridViewColumn Width="Auto" Header="更新日時">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <TextBlock Width="100" TextAlignment="Right" Text="{Binding LastModified, Converter={StaticResource DateTimeConverter}}" />
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                    <GridViewColumn Width="Auto" Header="サイズ">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <TextBlock Width="100" TextAlignment="Right" Text="{Binding Length, Converter={StaticResource DateSizeConverter}}" />
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                </GridView>
            </ListView.View>
        </ListView>
    </Grid>
</Window>

using System.ComponentModel;
using Reactive.Bindings;
using System.Reactive.Disposables;

using System.IO;

namespace ListViewWithIcon;

public class MainWindowViewModel : INotifyPropertyChanged, IDisposable
{
    public event PropertyChangedEventHandler? PropertyChanged;
    protected virtual void OnPropertyChanged(string name)
        => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
    private CompositeDisposable Disposable { get; } = new ();
    public void Dispose() => Disposable.Dispose();
    public ReactiveCommand<EventArgs> WindowLoadedCommand { get; }
    public ReactiveCommand<EventArgs> WindowClosedCommand { get; }

    public ReactiveCollection<FileInfoEntity> FileInfos { get; set; } = [];
    public MainWindowViewModel()
    {
        WindowClosedCommand = new ReactiveCommand<EventArgs>()
            .WithSubscribe(e => Disposable.Dispose());
        WindowLoadedCommand = new ReactiveCommand<EventArgs>()
            .WithSubscribe(e =>
            {
                string targetDir = @"F:\csharp\dotnet8\wpf\ListViewWithIcon";
                foreach(var fullname in Directory.EnumerateFileSystemEntries(targetDir))
                {
                    if (fullname is null) continue;
                    var info = new FileInfo(fullname);
                    bool flag = ((info.Attributes & FileAttributes.Directory) == FileAttributes.Directory);
                    FileInfos.AddOnScheduler
                    (
                        new FileInfoEntity
                        {
                            Icon = IconManager.GetIcon(fullname),
                            Name = info.Name,
                            LastModified = info.LastWriteTime,
                            Length = flag ? -1 : info.Length,
                        }
                    );
                }                
            });
    }
}