IDataObject implementation that can handle CFSTR_FILEDESCRIPTOR based drag-and-drop. Now compatible with .NET 10.

OutlookDataObject.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Reflection;
using System.IO;
using System.Windows;

// You may need to uncomment the following line to use C# 8.0 or later.
// #nullable disable

namespace Helpers
{
    /// <summary>
    /// Provides a format-independant machanism for transfering data with support for outlook messages and attachments.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Although the class name and the above summary suggest that
    /// this class does something specific to Outlook, it doesn't.
    /// In fact, this class adds support for <c>CFSTR_FILEDESCRIPTOR</c> based file transfer
    /// to the standard <see cref="DataObject"/>.
    /// </para>
    /// <para>
    /// To use this class to receive files through drag-and-drop operation,
    /// you first create its instance
    /// by passing an <see cref="System.Windows.IDataObject"/> instance
    /// received from the <see cref="UIElement.Drop"/> event.
    /// Then, you can use it as just an ordinary <c>IDataObject</c>
    /// except for <c>"FileContents"</c> and <c>"FileGroupDescriptorW"</c>
    /// (as well as "FileGroupDescriptor" if you ever need an ANSI version.)
    /// This class expands the functionality of the standard <c>IDataObject</c> implementation
    /// to support the <c>CFSTR_FILEDESCRIPTOR</c> based file transfer.
    /// </para>
    /// <para>
    /// When you call <see cref="GetData(string)"/> of this class with <c>"FileGroupDescriptorW"</c>,
    /// it returns an array of strings (<c>string[]</c>) containing the list of file names to be transferred.
    /// When you call <see cref="GetData(string)"/> of this class with <c>"FileContents"</c>,
    /// it returns an array of <see cref="MemoryStream"/>s containing the content bytes of files to be transferred.
    /// You can match a file name with its content by the index number.
    /// </para>
    /// <para>
    /// You can also use <see cref="GetData(string, int)"/>
    /// by passing "FileContents" in <c>format</c> and an index number in <c>index</c>
    /// to get a single <see cref="MemoryStream"/> object for a single file content.
    /// It works with lower memory footprint if you process dropped files one-by-one,
    /// in exchange for a risk that the clipboard content changes before handling the last file.
    /// </para>
    /// <example>
    /// async void MyDragEventHandler(object sender, DragEventArgs e)
    /// {
    ///     OutlookDataObject data = new OutlookDataObject(e.Data);
    ///     if (data.GetDataPresent("FileGroupDescriptorW"))
    ///     {
    ///         string[] names = (string[])data.GetData("FileGroupDescriptorW");
    ///         for (int i = 0; i &lt; names.Length; i++)
    ///         {
    ///             using (Stream outstream = File.Create(names[i]))
    ///             {
    ///                 MemoryStream content = data.GetData("FileContents", i);
    ///                 await content.CopyToAsync(outstream);
    ///             }
    ///         }
    ///     }
    /// }
    /// </example>
    /// <para>
    /// Note the following C++ macro to string mapping when using this class:
    /// <list type="bullet">
    /// <term><c>CFSTR_FILEDESCEIPTORA</c></term><item><c>"FileGroupDescriptor"</c></item>
    /// <term><c>CFSTR_FILEDESCEIPTORW</c></term><item><c>"FileGroupDescriptorW"</c></item>
    /// <term><c>CFSTR_FILECONTENTS</c></term><item><c>"FileContents"</c></item>
    /// </list>
    /// </para>
    /// </remarks>
    public class OutlookDataObject : System.Windows.IDataObject
    {
        #region NativeMethods

        private class NativeMethods
        {
            [DllImport("kernel32.dll")]
            public static extern IntPtr GlobalLock(IntPtr hMem);

            [DllImport("kernel32.dll")]
            public static extern IntPtr GlobalSize(IntPtr hMem);

            [DllImport("kernel32.dll")]
            public static extern int GlobalUnlock(IntPtr hMem);

            [DllImport("OLE32.DLL")]
            public static extern void ReleaseStgMedium(ref STGMEDIUM lpSTGMEDIUM);

            [DllImport("ole32.dll", PreserveSig = false)]
            public static extern ILockBytes CreateILockBytesOnHGlobal(IntPtr hGlobal, bool fDeleteOnRelease);

            [DllImport("OLE32.DLL", CharSet = CharSet.Auto, PreserveSig = false)]
            public static extern IntPtr GetHGlobalFromILockBytes(ILockBytes pLockBytes);

            [DllImport("OLE32.DLL", CharSet = CharSet.Unicode, PreserveSig = false)]
            public static extern IStorage StgCreateDocfileOnILockBytes(ILockBytes plkbyt, uint grfMode, uint reserved);

            [ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("0000000B-0000-0000-C000-000000000046")]
            public interface IStorage
            {
                [return: MarshalAs(UnmanagedType.Interface)]
                IStream CreateStream([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved1, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
                [return: MarshalAs(UnmanagedType.Interface)]
                IStream OpenStream([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, IntPtr reserved1, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
                [return: MarshalAs(UnmanagedType.Interface)]
                IStorage CreateStorage([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved1, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
                [return: MarshalAs(UnmanagedType.Interface)]
                IStorage OpenStorage([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, IntPtr pstgPriority, [In, MarshalAs(UnmanagedType.U4)] int grfMode, IntPtr snbExclude, [In, MarshalAs(UnmanagedType.U4)] int reserved);
                void CopyTo(int ciidExclude, [In, MarshalAs(UnmanagedType.LPArray)] Guid[] pIIDExclude, IntPtr snbExclude, [In, MarshalAs(UnmanagedType.Interface)] IStorage stgDest);
                void MoveElementTo([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.Interface)] IStorage stgDest, [In, MarshalAs(UnmanagedType.BStr)] string pwcsNewName, [In, MarshalAs(UnmanagedType.U4)] int grfFlags);
                void Commit(int grfCommitFlags);
                void Revert();
                void EnumElements([In, MarshalAs(UnmanagedType.U4)] int reserved1, IntPtr reserved2, [In, MarshalAs(UnmanagedType.U4)] int reserved3, [MarshalAs(UnmanagedType.Interface)] out object ppVal);
                void DestroyElement([In, MarshalAs(UnmanagedType.BStr)] string pwcsName);
                void RenameElement([In, MarshalAs(UnmanagedType.BStr)] string pwcsOldName, [In, MarshalAs(UnmanagedType.BStr)] string pwcsNewName);
                void SetElementTimes([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In] System.Runtime.InteropServices.ComTypes.FILETIME pctime, [In] System.Runtime.InteropServices.ComTypes.FILETIME patime, [In] System.Runtime.InteropServices.ComTypes.FILETIME pmtime);
                void SetClass([In] ref Guid clsid);
                void SetStateBits(int grfStateBits, int grfMask);
                void Stat([Out]out System.Runtime.InteropServices.ComTypes.STATSTG pStatStg, int grfStatFlag);
            }

            [ComImport, Guid("0000000A-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
            public interface ILockBytes
            {
                void ReadAt([In, MarshalAs(UnmanagedType.U8)] long ulOffset, [Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] byte[] pv, [In, MarshalAs(UnmanagedType.U4)] int cb, [Out, MarshalAs(UnmanagedType.LPArray)] int[] pcbRead);
                void WriteAt([In, MarshalAs(UnmanagedType.U8)] long ulOffset, IntPtr pv, [In, MarshalAs(UnmanagedType.U4)] int cb, [Out, MarshalAs(UnmanagedType.LPArray)] int[] pcbWritten);
                void Flush();
                void SetSize([In, MarshalAs(UnmanagedType.U8)] long cb);
                void LockRegion([In, MarshalAs(UnmanagedType.U8)] long libOffset, [In, MarshalAs(UnmanagedType.U8)] long cb, [In, MarshalAs(UnmanagedType.U4)] int dwLockType);
                void UnlockRegion([In, MarshalAs(UnmanagedType.U8)] long libOffset, [In, MarshalAs(UnmanagedType.U8)] long cb, [In, MarshalAs(UnmanagedType.U4)] int dwLockType);
                void Stat([Out]out System.Runtime.InteropServices.ComTypes.STATSTG pstatstg, [In, MarshalAs(UnmanagedType.U4)] int grfStatFlag);
            }

            [StructLayout(LayoutKind.Sequential)]
            public sealed class POINTL
            {
                public int x;
                public int y;
            }

            [StructLayout(LayoutKind.Sequential)]
            public sealed class SIZEL
            {
                public int cx;
                public int cy;
            }

            [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
            public sealed class FILEGROUPDESCRIPTORA
            {
                public uint cItems;
                public FILEDESCRIPTORA fgd;
            }

            [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
            public sealed class FILEDESCRIPTORA
            {
                public uint dwFlags;
                public Guid clsid;
                public SIZEL sizel;
                public POINTL pointl;
                public uint dwFileAttributes;
                public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
                public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
                public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
                public uint nFileSizeHigh;
                public uint nFileSizeLow;
                [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
                public string cFileName;
            }

            [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
            public sealed class FILEGROUPDESCRIPTORW
            {
                public uint cItems;
                public FILEDESCRIPTORW fgd;
            }

            [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
            public sealed class FILEDESCRIPTORW
            {
                public uint dwFlags;
                public Guid clsid;
                public SIZEL sizel;
                public POINTL pointl;
                public uint dwFileAttributes;
                public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
                public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
                public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
                public uint nFileSizeHigh;
                public uint nFileSizeLow;
                [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
                public string cFileName;
            }
        }

        #endregion

        #region Property(s)

        /// <summary>
        /// Holds the <see cref="System.Windows.IDataObject"/> that this class is wrapping
        /// </summary>
        private System.Windows.IDataObject underlyingDataObject;

        /// <summary>
        /// Holds the <see cref="System.Runtime.InteropServices.ComTypes.IDataObject"/> interface to the <see cref="System.Windows.IDataObject"/> that this class is wrapping.
        /// </summary>
        private System.Runtime.InteropServices.ComTypes.IDataObject comUnderlyingDataObject;

        #endregion

        #region Constructor(s)

        /// <summary>
        /// Initializes a new instance of the <see cref="OutlookDataObject"/> class.
        /// </summary>
        /// <param name="underlyingDataObject">The underlying data object to wrap.</param>
        public OutlookDataObject(System.Windows.IDataObject underlyingDataObject)
        {
            //get the underlying dataobject and its ComType IDataObject interface to it
            this.underlyingDataObject = underlyingDataObject;
            this.comUnderlyingDataObject = (System.Runtime.InteropServices.ComTypes.IDataObject)this.underlyingDataObject;
        }

        #endregion

        #region IDataObject Members

        /// <summary>
        /// Retrieves the data associated with the specified class type format.
        /// </summary>
        /// <param name="format">A <see cref="T:System.Type"></see> representing the format of the data to retrieve. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <returns>
        /// The data associated with the specified format, or null.
        /// </returns>
        public object GetData(Type format)
        {
            return this.GetData(format.FullName);
        }

        /// <summary>
        /// Retrieves the data associated with the specified data format.
        /// </summary>
        /// <param name="format">The format of the data to retrieve. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <returns>
        /// The data associated with the specified format, or null.
        /// </returns>
        public object GetData(string format)
        {
            return this.GetData(format, true);
        }

        /// <summary>
        /// Retrieves the data associated with the specified data format, using a Boolean to determine whether to convert the data to the format.
        /// </summary>
        /// <param name="format">The format of the data to retrieve. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <param name="autoConvert">true to convert the data to the specified format; otherwise, false.</param>
        /// <returns>
        /// The data associated with the specified format, or null.
        /// </returns>
        public object GetData(string format, bool autoConvert)
        {
            //handle the "FileGroupDescriptor" and "FileContents" format request in this class otherwise pass through to underlying IDataObject
            switch (format)
            {
                case "FileGroupDescriptor":
                    //override the default handling of FileGroupDescriptor which returns a
                    //MemoryStream and instead return a string array of file names
                    IntPtr fileGroupDescriptorAPointer = IntPtr.Zero;
                    try
                    {
                        //use the underlying IDataObject to get the FileGroupDescriptor as a MemoryStream
                        MemoryStream fileGroupDescriptorStream = (MemoryStream)this.underlyingDataObject.GetData("FileGroupDescriptor", autoConvert);
                        byte[] fileGroupDescriptorBytes = new byte[fileGroupDescriptorStream.Length];
                        fileGroupDescriptorStream.Read(fileGroupDescriptorBytes, 0, fileGroupDescriptorBytes.Length);
                        fileGroupDescriptorStream.Close();

                        //copy the file group descriptor into unmanaged memory
                        fileGroupDescriptorAPointer = Marshal.AllocHGlobal(fileGroupDescriptorBytes.Length);
                        Marshal.Copy(fileGroupDescriptorBytes, 0, fileGroupDescriptorAPointer, fileGroupDescriptorBytes.Length);

                        ////marshal the unmanaged memory to to FILEGROUPDESCRIPTORA struct
                        //FIX FROM - https://stackoverflow.com/questions/27173844/accessviolationexception-after-copying-a-file-from-inside-a-zip-archive-to-the-c
                        int ITEMCOUNT = Marshal.ReadInt32(fileGroupDescriptorAPointer);

                        //create a new array to store file names in of the number of items in the file group descriptor
                        string[] fileNames = new string[ITEMCOUNT];

                        //get the pointer to the first file descriptor
                        IntPtr fileDescriptorPointer = (IntPtr)((long)fileGroupDescriptorAPointer + Marshal.SizeOf(ITEMCOUNT));

                        //loop for the number of files acording to the file group descriptor
                        for (int fileDescriptorIndex = 0; fileDescriptorIndex < ITEMCOUNT; fileDescriptorIndex++)
                        {
                            //marshal the pointer top the file descriptor as a FILEDESCRIPTORA struct and get the file name
                            NativeMethods.FILEDESCRIPTORA fileDescriptor = (NativeMethods.FILEDESCRIPTORA)Marshal.PtrToStructure(fileDescriptorPointer, typeof(NativeMethods.FILEDESCRIPTORA));
                            fileNames[fileDescriptorIndex] = fileDescriptor.cFileName;

                            //move the file descriptor pointer to the next file descriptor
                            fileDescriptorPointer = (IntPtr)((long)fileDescriptorPointer + Marshal.SizeOf(fileDescriptor));
                        }

                        //return the array of filenames
                        return fileNames;
                    }
                    finally
                    {
                        //free unmanaged memory pointer
                        Marshal.FreeHGlobal(fileGroupDescriptorAPointer);
                    }

                case "FileGroupDescriptorW":
                    //override the default handling of FileGroupDescriptorW which returns a
                    //MemoryStream and instead return a string array of file names
                    IntPtr fileGroupDescriptorWPointer = IntPtr.Zero;
                    try
                    {
                        //use the underlying IDataObject to get the FileGroupDescriptorW as a MemoryStream
                        MemoryStream fileGroupDescriptorStream = (MemoryStream)this.underlyingDataObject.GetData("FileGroupDescriptorW");
                        byte[] fileGroupDescriptorBytes = new byte[fileGroupDescriptorStream.Length];
                        fileGroupDescriptorStream.Read(fileGroupDescriptorBytes, 0, fileGroupDescriptorBytes.Length);
                        fileGroupDescriptorStream.Close();

                        //copy the file group descriptor into unmanaged memory
                        fileGroupDescriptorWPointer = Marshal.AllocHGlobal(fileGroupDescriptorBytes.Length);
                        Marshal.Copy(fileGroupDescriptorBytes, 0, fileGroupDescriptorWPointer, fileGroupDescriptorBytes.Length);

                        //marshal the unmanaged memory to to FILEGROUPDESCRIPTORW struct
                        //FIX FROM - https://stackoverflow.com/questions/27173844/accessviolationexception-after-copying-a-file-from-inside-a-zip-archive-to-the-c
                        int ITEMCOUNT = Marshal.ReadInt32(fileGroupDescriptorWPointer);

                        //create a new array to store file names in of the number of items in the file group descriptor
                        string[] fileNames = new string[ITEMCOUNT];

                        //get the pointer to the first file descriptor
                        IntPtr fileDescriptorPointer = (IntPtr)((long)fileGroupDescriptorWPointer + Marshal.SizeOf(ITEMCOUNT));

                        //loop for the number of files acording to the file group descriptor
                        for (int fileDescriptorIndex = 0; fileDescriptorIndex < ITEMCOUNT; fileDescriptorIndex++)
                        {
                            //marshal the pointer top the file descriptor as a FILEDESCRIPTORW struct and get the file name
                            NativeMethods.FILEDESCRIPTORW fileDescriptor = (NativeMethods.FILEDESCRIPTORW)Marshal.PtrToStructure(fileDescriptorPointer, typeof(NativeMethods.FILEDESCRIPTORW));
                            fileNames[fileDescriptorIndex] = fileDescriptor.cFileName;

                            //move the file descriptor pointer to the next file descriptor
                            fileDescriptorPointer = (IntPtr)((long)fileDescriptorPointer + Marshal.SizeOf(fileDescriptor));
                        }

                        //return the array of filenames
                        return fileNames;
                    }
                    finally
                    {
                        //free unmanaged memory pointer
                        Marshal.FreeHGlobal(fileGroupDescriptorWPointer);
                    }

                case "FileContents":
                    //override the default handling of FileContents which returns the
                    //contents of the first file as a memory stream and instead return
                    //a array of MemoryStreams containing the data to each file dropped
                    //
                    // FILECONTENTS requires a companion FILEGROUPDESCRIPTOR to be
                    // available so we bail out if we don't find one in the data object.

                    string fgdFormatName;
                    if (GetDataPresent("FileGroupDescriptorW"))
                        fgdFormatName = "FileGroupDescriptorW";
                    else if (GetDataPresent("FileGroupDescriptor"))
                        fgdFormatName = "FileGroupDescriptor";
                    else
                        return null;
                    //get the array of filenames which lets us know how many file contents exist
                    string[] fileContentNames = (string[])this.GetData(fgdFormatName);

                    //create a MemoryStream array to store the file contents
                    MemoryStream[] fileContents = new MemoryStream[fileContentNames.Length];

                    //loop for the number of files acording to the file names
                    for (int fileIndex = 0; fileIndex < fileContentNames.Length; fileIndex++)
                    {
                        //get the data at the file index and store in array
                        fileContents[fileIndex] = this.GetData(format, fileIndex);
                    }

                    //return array of MemoryStreams containing file contents
                    return fileContents;
            }

            //use underlying IDataObject to handle getting of data
            return this.underlyingDataObject.GetData(format, autoConvert);
        }

        /// <summary>
        /// Retrieves the data associated with the specified data format at the specified index.
        /// </summary>
        /// <param name="format">The format of the data to retrieve. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <param name="index">The index of the data to retrieve.</param>
        /// <returns>
        /// A <see cref="MemoryStream"/> containing the raw data for the specified data format at the specified index.
        /// </returns>
        public MemoryStream GetData(string format, int index)
        {
            //create a FORMATETC struct to request the data with
            FORMATETC formatetc = new FORMATETC();
            formatetc.cfFormat = (short)DataFormats.GetDataFormat(format).Id;
            formatetc.dwAspect = DVASPECT.DVASPECT_CONTENT;
            formatetc.lindex = index;
            formatetc.ptd = new IntPtr(0);
            formatetc.tymed = TYMED.TYMED_ISTREAM | TYMED.TYMED_ISTORAGE | TYMED.TYMED_HGLOBAL;

            //create STGMEDIUM to output request results into
            STGMEDIUM medium = new STGMEDIUM();

            //using the Com IDataObject interface get the data using the defined FORMATETC
            this.comUnderlyingDataObject.GetData(ref formatetc, out medium);

            //retrieve the data depending on the returned store type
            switch (medium.tymed)
            {
                case TYMED.TYMED_ISTORAGE:
                    //to handle a IStorage it needs to be written into a second unmanaged
                    //memory mapped storage and then the data can be read from memory into
                    //a managed byte and returned as a MemoryStream

                    NativeMethods.IStorage iStorage = null;
                    NativeMethods.IStorage iStorage2 = null;
                    NativeMethods.ILockBytes iLockBytes = null;
                    System.Runtime.InteropServices.ComTypes.STATSTG iLockBytesStat;
                    try
                    {
                        //marshal the returned pointer to a IStorage object
                        iStorage = (NativeMethods.IStorage)Marshal.GetObjectForIUnknown(medium.unionmember);
                        Marshal.Release(medium.unionmember);

                        //create a ILockBytes (unmanaged byte array) and then create a IStorage using the byte array as a backing store
                        iLockBytes = NativeMethods.CreateILockBytesOnHGlobal(IntPtr.Zero, true);
                        iStorage2 = NativeMethods.StgCreateDocfileOnILockBytes(iLockBytes, 0x00001012, 0);

                        //copy the returned IStorage into the new IStorage
                        iStorage.CopyTo(0, null, IntPtr.Zero, iStorage2);
                        iLockBytes.Flush();
                        iStorage2.Commit(0);

                        //get the STATSTG of the ILockBytes to determine how many bytes were written to it
                        iLockBytesStat = new System.Runtime.InteropServices.ComTypes.STATSTG();
                        iLockBytes.Stat(out iLockBytesStat, 1);
                        int iLockBytesSize = (int)iLockBytesStat.cbSize;

                        //read the data from the ILockBytes (unmanaged byte array) into a managed byte array
                        byte[] iLockBytesContent = new byte[iLockBytesSize];
                        iLockBytes.ReadAt(0, iLockBytesContent, iLockBytesContent.Length, null);

                        //wrapped the managed byte array into a memory stream and return it
                        return new MemoryStream(iLockBytesContent);
                    }
                    finally
                    {
                        //release all unmanaged objects
                        Marshal.ReleaseComObject(iStorage2);
                        Marshal.ReleaseComObject(iLockBytes);
                        Marshal.ReleaseComObject(iStorage);
                    }

                case TYMED.TYMED_ISTREAM:
                    //to handle a IStream it needs to be read into a managed byte and
                    //returned as a MemoryStream

                    IStream iStream = null;
                    System.Runtime.InteropServices.ComTypes.STATSTG iStreamStat;
                    try
                    {
                        //marshal the returned pointer to a IStream object
                        iStream = (IStream)Marshal.GetObjectForIUnknown(medium.unionmember);
                        Marshal.Release(medium.unionmember);

                        //get the STATSTG of the IStream to determine how many bytes are in it
                        iStreamStat = new System.Runtime.InteropServices.ComTypes.STATSTG();
                        iStream.Stat(out iStreamStat, 0);
                        int iStreamSize = (int)iStreamStat.cbSize;

                        //read the data from the IStream into a managed byte array
                        byte[] iStreamContent = new byte[iStreamSize];
                        iStream.Read(iStreamContent, iStreamContent.Length, IntPtr.Zero);

                        //wrapped the managed byte array into a memory stream and return it
                        return new MemoryStream(iStreamContent);
                    }
                    finally
                    {
                        //release all unmanaged objects
                        Marshal.ReleaseComObject(iStream);
                    }

                case TYMED.TYMED_HGLOBAL:
                    // To handle an HGlobal,
                    // we can simply copy the unmanaged memory content to a managed array
                    // and return it as a MemoryStream.

                    // Lock the global memory.
                    IntPtr lpData = NativeMethods.GlobalLock(medium.unionmember);
                    if (lpData == IntPtr.Zero) return null;

                    try
                    {
                        // Get the size of the global memory.
                        IntPtr szData = NativeMethods.GlobalSize(medium.unionmember);

                        // The size of the global memory is a 64 bit value in 64 bit Windows,
                        // which could be longer than Int32.MaxValue or Array.MaxLength.
                        // If it happened, either ToInt32 (if > Int32.MaxValue) or
                        // the new operator (if > Array.MaxLength) throws an exception.
                        // (However, Windows SDK documentation says TYMED_HGLOBAL is
                        // for transfer of small data,
                        // so I hope nobody would use it for several GB...)

                        // Copy the content data to the managed array.
                        byte[] content = new byte[szData.ToInt32()];
                        Marshal.Copy(lpData, content, 0, szData.ToInt32());

                        // Wrap the array in a memory stream and return it.
                        return new MemoryStream(content);
                    }
                    catch (Exception)
                    {
                        // Likely a too long data.
                        return null;
                    }
                    finally
                    {
                        // Don't forget to unlock the global memory.
                        NativeMethods.GlobalUnlock(medium.unionmember);

                        // Then, we should call the ReleaseStgMedium
                        // to free the global memory, rather than GlobalFree.
                        // That's what Windows SDK documentation says:
                        // https://learn.microsoft.com/windows/win32/shell/dataobject#extracting-a-global-memory-object-from-a-data-object
                        NativeMethods.ReleaseStgMedium(ref medium);

                        // Note: Although I have a strong feeling
                        // we should call ReleaseStgMedium for
                        // TYMED_ISTREAM and TYMED_ISTORAGE too,
                        // the original code by Matty Boy doesn't.
                        // I don't know why.
                        // For now, I leave it as it is.
                        // -- Alissa.
                    }
            }

            return null;
        }

        /// <summary>
        /// Determines whether data stored in this instance is associated with, or can be converted to, the specified format.
        /// </summary>
        /// <param name="format">A <see cref="T:System.Type"></see> representing the format for which to check. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <returns>
        /// true if data stored in this instance is associated with, or can be converted to, the specified format; otherwise, false.
        /// </returns>
        public bool GetDataPresent(Type format)
        {
            return this.underlyingDataObject.GetDataPresent(format);
        }

        /// <summary>
        /// Determines whether data stored in this instance is associated with, or can be converted to, the specified format.
        /// </summary>
        /// <param name="format">The format for which to check. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <returns>
        /// true if data stored in this instance is associated with, or can be converted to, the specified format; otherwise false.
        /// </returns>
        public bool GetDataPresent(string format)
        {
            return this.underlyingDataObject.GetDataPresent(format);
        }

        /// <summary>
        /// Determines whether data stored in this instance is associated with the specified format, using a Boolean value to determine whether to convert the data to the format.
        /// </summary>
        /// <param name="format">The format for which to check. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <param name="autoConvert">true to determine whether data stored in this instance can be converted to the specified format; false to check whether the data is in the specified format.</param>
        /// <returns>
        /// true if the data is in, or can be converted to, the specified format; otherwise, false.
        /// </returns>
        public bool GetDataPresent(string format, bool autoConvert)
        {
            return this.underlyingDataObject.GetDataPresent(format, autoConvert);
        }

        /// <summary>
        /// Returns a list of all formats that data stored in this instance is associated with or can be converted to.
        /// </summary>
        /// <returns>
        /// An array of the names that represents a list of all formats that are supported by the data stored in this object.
        /// </returns>
        public string[] GetFormats()
        {
            return this.underlyingDataObject.GetFormats();
        }

        /// <summary>
        /// Gets a list of all formats that data stored in this instance is associated with or can be converted to, using a Boolean value to determine whether to retrieve all formats that the data can be converted to or only native data formats.
        /// </summary>
        /// <param name="autoConvert">true to retrieve all formats that data stored in this instance is associated with or can be converted to; false to retrieve only native data formats.</param>
        /// <returns>
        /// An array of the names that represents a list of all formats that are supported by the data stored in this object.
        /// </returns>
        public string[] GetFormats(bool autoConvert)
        {
            return this.underlyingDataObject.GetFormats(autoConvert);
        }

        /// <summary>
        /// Stores the specified data in this instance, using the class of the data for the format.
        /// </summary>
        /// <param name="data">The data to store.</param>
        public void SetData(object data)
        {
            this.underlyingDataObject.SetData(data);
        }

        /// <summary>
        /// Stores the specified data and its associated class type in this instance.
        /// </summary>
        /// <param name="format">A <see cref="T:System.Type"></see> representing the format associated with the data. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <param name="data">The data to store.</param>
        public void SetData(Type format, object data)
        {
            this.underlyingDataObject.SetData(format, data);
        }

        /// <summary>
        /// Stores the specified data and its associated format in this instance.
        /// </summary>
        /// <param name="format">The format associated with the data. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <param name="data">The data to store.</param>
        public void SetData(string format, object data)
        {
            this.underlyingDataObject.SetData(format, data);
        }

        /// <summary>
        /// Stores the specified data and its associated format in this instance, using a Boolean value to specify whether the data can be converted to another format.
        /// </summary>
        /// <param name="format">The format associated with the data. See <see cref="T:System.Windows.DataFormats"></see> for predefined formats.</param>
        /// <param name="autoConvert">true to allow the data to be converted to another format; otherwise, false.</param>
        /// <param name="data">The data to store.</param>
        public void SetData(string format, object data, bool autoConvert)
        {
            this.underlyingDataObject.SetData(format, data, autoConvert);
        }

        #endregion
    }
}