如何获得四舍五入的图像源或位图图像，以便在UWP中裁剪椭圆形状的图像

// 加载原始图像
BitmapImage originalImage = new BitmapImage(new Uri("path_to_original_image"));

// 创建图像处理流程
using (var stream = await originalImage.OpenReadAsync())
{
    var decoder = await BitmapDecoder.CreateAsync(stream);
    var transform = new BitmapTransform();

    // 设置图像四舍五入
    transform.ScaledWidth = (uint)Math.Round(decoder.PixelWidth);
    transform.ScaledHeight = (uint)Math.Round(decoder.PixelHeight);

    var pixelData = await decoder.GetPixelDataAsync(
        BitmapPixelFormat.Bgra8, 
        BitmapAlphaMode.Ignore,
        transform,
        ExifOrientationMode.IgnoreExifOrientation,
        ColorManagementMode.DoNotColorManage);

    // 创建新的位图图像
    var roundedImage = new SoftwareBitmap(
        BitmapPixelFormat.Bgra8, 
        (int)transform.ScaledWidth, 
        (int)transform.ScaledHeight, 
        BitmapAlphaMode.Premultiplied);

    roundedImage.CopyFromBuffer(pixelData.DetachPixelData());

    // 裁剪为椭圆形状
    using (var canvas = new CanvasRenderTarget(CanvasDevice.GetSharedDevice(), (int)transform.ScaledWidth, (int)transform.ScaledHeight, 96))
    using (var ds = canvas.CreateDrawingSession())
    using (var ellipse = CanvasPathBuilder.CreateEllipse(ds, new Rect(0, 0, transform.ScaledWidth, transform.ScaledHeight)))
    {
        ds.Clear(Colors.Transparent);
        ds.DrawImage(roundedImage);

        ds.ClipGeometry = CanvasGeometry.CreatePath(ellipse);
        ds.FillCircle(transform.ScaledWidth / 2, transform.ScaledHeight / 2, transform.ScaledWidth / 2, Colors.Transparent);
    }

    // 将最终图像显示在UI上
    var roundedBitmapImage = new BitmapImage();
    using (var roundedStream = new InMemoryRandomAccessStream())
    {
        await CanvasBitmap.SaveAsync(canvas, roundedStream, CanvasBitmapFileFormat.Png);
        roundedStream.Seek(0);
        await roundedBitmapImage.SetSourceAsync(roundedStream);
    }
}