C#でMemoryCacheクラスでWPFのBitmapSourceをキャッシュしてみる。

using System.Diagnostics;
using System.IO;
using System.IO.Compression;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Runtime.Caching;

namespace BitmapImageLoad01;

/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    MemoryCache _cache = MemoryCache.Default;
    CacheItemPolicy _policy = new ()
    {
        SlidingExpiration = new TimeSpan(0, 5, 0),  // 有効期限を5分にセット
        RemovedCallback = arg =>
        {
            Debug.Print("key:{0}が削除された。", arg.CacheItem.Key);
        },
    };
    static async Task<BitmapSource> LoadImageFormStream(Stream s)
    {
        const int dpi = 96;

        MemoryStream ms = new();
        await s.CopyToAsync(ms);
        ms.Seek(0, SeekOrigin.Begin);

        BitmapSource bs = await Task.Run(()=>
        {
            BitmapSource bs = BitmapFrame.Create(ms);

            int stride = (bs.PixelWidth * bs.Format.BitsPerPixel + 7) / 8;
            byte[] pixels = new byte[stride * bs.PixelHeight];
            bs.CopyPixels(pixels, stride, 0);

            bs = BitmapImage.Create(bs.PixelWidth, bs.PixelHeight, dpi, dpi, PixelFormats.Bgra32, null, pixels, stride);
            bs.Freeze();
            return bs;
        });
        
        ms.SetLength(0);
        ms.Close();

        return bs;
    }
    static public bool IsValidExtension(string path)
    {
        string pattern = @"\.(jpeg|jpg|bmp|tif|bmp|png|gif)$";
        return System.Text.RegularExpressions.Regex.IsMatch(path, pattern);
    }
    public async Task<BitmapSource?> LoadImage(string location, string name)
    {
        string key = System.IO.Path.Join(location, name);
        BitmapSource? bs = null;

        if (_cache.Contains(key))
        {
            bs = _cache[key] as BitmapSource;
            return bs;
        }

        string ext = System.IO.Path.GetExtension(location).ToUpper();
        
        if (ext == ".ZIP")
        {
            string zipFile = location;
            string entryName = name;
            ZipArchiveEntry? entry = ZipFile.OpenRead(zipFile).GetEntry(entryName);
            if (entry is null) return null;

            using Stream stream = entry.Open();
            bs = await LoadImageFormStream(stream);
        } else {
            string fullPath = key;
            FileStream fs = new (fullPath, FileMode.Open, FileAccess.Read);

            using Stream stream = fs;
            bs = await LoadImageFormStream(stream);
        }

        _cache.Set(key, bs, _policy);
        return bs;
    }

    public MainWindow()
    {
        InitializeComponent();

        Loaded += async (s, e) =>
        {

            string zipFile = @"F:\csharp\dotnet8\wpf\BitmapImageLoad01\sample.zip";

            ZipArchive zip = ZipFile.OpenRead(zipFile);

            if (zip.Entries.Any())
            {
                string location = zipFile;

                foreach (var entry in zip.Entries.Where(x=>IsValidExtension(x.FullName)))
                {
                    var _ = await LoadImage(location, entry.FullName);
                }

                string name = zip.Entries.Where(x=>IsValidExtension(x.FullName)).First().FullName;
                Image1.Source = await LoadImage(location, name);
            }
            Debug.Print("Loaded ID:{0}", Environment.CurrentManagedThreadId);
        };
        Closed += (s, e) =>
        {
            Debug.Print("Closed ID:{0}", Environment.CurrentManagedThreadId);
            _cache?.Dispose();
        };
    }
}

<Window x:Class="BitmapImageLoad01.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:local="clr-namespace:BitmapImageLoad01"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Image x:Name="Image1" />
    </Grid>
</Window>

Loaded ID:1
Closed ID:1
key:F:\csharp\dotnet8\wpf\BitmapImageLoad01\sample.zip\2024-09-08090028.pngが削除された。
key:F:\csharp\dotnet8\wpf\BitmapImageLoad01\sample.zip\2024-09-05193316.pngが削除された。
key:F:\csharp\dotnet8\wpf\BitmapImageLoad01\sample.zip\スクリーンショット 2024-09-08 090021.pngが削除された。
key:F:\csharp\dotnet8\wpf\BitmapImageLoad01\sample.zip\2024-09-08090058.pngが削除された。
key:F:\csharp\dotnet8\wpf\BitmapImageLoad01\sample.zip\スクリーンショット 2024-09-05 193312.pngが削除された。
key:F:\csharp\dotnet8\wpf\BitmapImageLoad01\sample.zip\スクリーンショット 2024-09-05 193305.pngが削除された。