WPF学習中「２枚の画像を左右に並べて表示 – その２」

mkdir プロジェクト名
cd プロジェクト名
dotnet new wpf
code .

<Window x:Class="Sample55CopyPixels2.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:Sample55CopyPixels2"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <StackPanel>
            <Canvas>
                <Image
                    Name="Image1"
                    Width="{Binding ActualWidth, RelativeSource={RelativeSource FindAncestor, AncestorType=StackPanel}}"
                    Height="{Binding ActualHeight, RelativeSource={RelativeSource FindAncestor, AncestorType=StackPanel}}"
                    Stretch="Uniform">
                </Image>
            </Canvas>
        </StackPanel>
    </Grid>
</Window>

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

namespace Sample55CopyPixels2;

/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    /// <summary>
    /// ビットマップソースの読み込み
    /// </summary>
    /// <param name="fs">ファイルストリーム</param>
    /// <returns>BitmapImageオブジェクト</returns>
    public static async Task<BitmapImage> LoadBitmapImageAsync(Stream fs)
    {
        using var ms = new MemoryStream();

        await fs.CopyToAsync(ms);

        BitmapImage bi = await Task.Run(()=>
        {
            BitmapImage bi = new();
            ms.Seek(0, SeekOrigin.Begin);

            bi.BeginInit();
            bi.CacheOption = BitmapCacheOption.OnLoad;
            bi.StreamSource = ms;
            bi.EndInit();
            bi.Freeze();

            return bi;
        });

        return bi;
    }
    /// <summary>
    /// ビットマップソースの読み込み
    /// </summary>
    /// <param name="file">画像ファイルのパス</param>
    /// <returns>BitmapImageオブジェクト</returns>
    public static async Task<BitmapImage> LoadBitmapImageAsync(string file)
    {
        using var fs = new FileStream(file, FileMode.Open, FileAccess.Read);
        return await LoadBitmapImageAsync(fs);
    }
    /// <summary>
    /// 2枚のBitmapImageを左右に連結
    /// </summary>
    /// <param name="lb"></param>
    /// <param name="rb"></param>
    /// <returns>WriteableBitmapオブジェクト</returns>
    public static async Task<WriteableBitmap> JoinBitmapImageAsync(BitmapImage lb, BitmapImage rb)
    {
        int lb_stride = (lb.PixelWidth * lb.Format.BitsPerPixel + 7) / 8;
        byte[] lb_datas = new byte[lb_stride * lb.PixelHeight];
        
        int rb_stride = (rb.PixelWidth * rb.Format.BitsPerPixel + 7) / 8;
        byte[] rb_datas = new byte[rb_stride * rb.PixelHeight];

        Task lcopy = Task.Run(()=>
        {
            // 左側画像をbyte配列にコピー
            lb.CopyPixels(
                new Int32Rect(0, 0, lb.PixelWidth, lb.PixelHeight), lb_datas, lb_stride, 0);
        });

        Task rcopy = Task.Run(()=>
        {
            // 右側画像をbyte配列へコピー
            rb.CopyPixels(
                new Int32Rect(0, 0, rb.PixelWidth, rb.PixelHeight), rb_datas, rb_stride, 0);
        });

        await lcopy;
        await rcopy;

        WriteableBitmap wb = await Task.Run(()=>
        {
            // 表示画像の作成
            int height = (lb.PixelHeight > rb.PixelHeight) ? lb.PixelHeight : rb.PixelHeight;
            int width = lb.PixelWidth + rb.PixelWidth;
            WriteableBitmap wb = new (width, height, lb.DpiX, lb.DpiY, lb.Format, null);

            // 左右のbyte配列をWriteableBitmapへコピー
            wb.WritePixels(
                new Int32Rect(0, 0, lb.PixelWidth, lb.PixelHeight), lb_datas, lb_stride, 0);
            wb.WritePixels(
                new Int32Rect(lb.PixelWidth, 0, rb.PixelWidth, rb.PixelHeight), rb_datas, rb_stride, 0);

            wb.Freeze();
            return wb;
        });


        // 画像をコピー
        return wb;
    }

    async void init()
    {
        // 左側画像の読み込み
        string leftPath = @"F:\csharp\dotnet8\wpf\Sample55CopyPixels2\sample1.png";
        var lb = await LoadBitmapImageAsync(leftPath);

        // 右側画像の読み込み
        string rightPath = @"F:\csharp\dotnet8\wpf\Sample55CopyPixels2\sample2.png";
        var rb = await LoadBitmapImageAsync(rightPath);

        // 左右の画像を結合        
        WriteableBitmap wb = await JoinBitmapImageAsync(lb, rb);

        // イメージコントロールのソースにビットマップイメージを割り当て
        Image1.Source = wb;
    }
    /// <summary>
    /// コンストラクタ
    /// </summary>
    public MainWindow()
    {
        InitializeComponent();

        init();
    }
}