Load a WPF BitmapImage from a System.Drawing.Bitmap

Question

How about loading it from MemoryStream?

using(MemoryStream memory = new MemoryStream())
{
    bitmap.Save(memory, ImageFormat.Png);
    memory.Position = 0;
    BitmapImage bitmapImage = new BitmapImage();
    bitmapImage.BeginInit();
    bitmapImage.StreamSource = memory;
    bitmapImage.CacheOption = BitmapCacheOption.OnLoad;
    bitmapImage.EndInit();
}

Thanks to Hallgrim, here is the code I ended up with:

ScreenCapture = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
   bmp.GetHbitmap(), 
   IntPtr.Zero, 
   System.Windows.Int32Rect.Empty, 
   BitmapSizeOptions.FromWidthAndHeight(width, height));

I also ended up binding to a BitmapSource instead of a BitmapImage as in my original question

I know this has been answered, but here are a couple of extension methods (for .NET 3.0+) that do the conversion. :)

        /// <summary>
    /// Converts a <see cref="System.Drawing.Image"/> into a WPF <see cref="BitmapSource"/>.
    /// </summary>
    /// <param name="source">The source image.</param>
    /// <returns>A BitmapSource</returns>
    public static BitmapSource ToBitmapSource(this System.Drawing.Image source)
    {
        System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(source);

        var bitSrc = bitmap.ToBitmapSource();

        bitmap.Dispose();
        bitmap = null;

        return bitSrc;
    }

    /// <summary>
    /// Converts a <see cref="System.Drawing.Bitmap"/> into a WPF <see cref="BitmapSource"/>.
    /// </summary>
    /// <remarks>Uses GDI to do the conversion. Hence the call to the marshalled DeleteObject.
    /// </remarks>
    /// <param name="source">The source bitmap.</param>
    /// <returns>A BitmapSource</returns>
    public static BitmapSource ToBitmapSource(this System.Drawing.Bitmap source)
    {
        BitmapSource bitSrc = null;

        var hBitmap = source.GetHbitmap();

        try
        {
            bitSrc = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
                hBitmap,
                IntPtr.Zero,
                Int32Rect.Empty,
                BitmapSizeOptions.FromEmptyOptions());
        }
        catch (Win32Exception)
        {
            bitSrc = null;
        }
        finally
        {
            NativeMethods.DeleteObject(hBitmap);
        }

        return bitSrc;
    }

and the NativeMethods class (to appease FxCop)

    /// <summary>
/// FxCop requires all Marshalled functions to be in a class called NativeMethods.
/// </summary>
internal static class NativeMethods
{
    [DllImport("gdi32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static extern bool DeleteObject(IntPtr hObject);
}

It took me some time to get the conversion working both ways, so here are the two extension methods I came up with:

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

public static class BitmapConversion {

    public static Bitmap ToWinFormsBitmap(this BitmapSource bitmapsource) {
        using (MemoryStream stream = new MemoryStream()) {
            BitmapEncoder enc = new BmpBitmapEncoder();
            enc.Frames.Add(BitmapFrame.Create(bitmapsource));
            enc.Save(stream);

            using (var tempBitmap = new Bitmap(stream)) {
                // According to MSDN, one "must keep the stream open for the lifetime of the Bitmap."
                // So we return a copy of the new bitmap, allowing us to dispose both the bitmap and the stream.
                return new Bitmap(tempBitmap);
            }
        }
    }

    public static BitmapSource ToWpfBitmap(this Bitmap bitmap) {
        using (MemoryStream stream = new MemoryStream()) {
            bitmap.Save(stream, ImageFormat.Bmp);

            stream.Position = 0;
            BitmapImage result = new BitmapImage();
            result.BeginInit();
            // According to MSDN, "The default OnDemand cache option retains access to the stream until the image is needed."
            // Force the bitmap to load right now so we can dispose the stream.
            result.CacheOption = BitmapCacheOption.OnLoad;
            result.StreamSource = stream;
            result.EndInit();
            result.Freeze();
            return result;
        }
    }
}