File: System\Windows\Forms\OLE\DataObject.Composition.NativeToWinFormsAdapter.cs
Web Access
Project: src\src\System.Windows.Forms\src\System.Windows.Forms.csproj (System.Windows.Forms)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Drawing;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Text;
using Com = Windows.Win32.System.Com;
 
namespace System.Windows.Forms;
 
public unsafe partial class DataObject
{
    internal unsafe partial class Composition
    {
        /// <summary>
        ///  Maps native pointer <see cref="Com.IDataObject"/> to <see cref="IDataObject"/>.
        /// </summary>
        private unsafe class NativeToWinFormsAdapter : IDataObject, Com.IDataObject.Interface
        {
            private readonly AgileComPointer<Com.IDataObject> _nativeDataObject;
 
            public NativeToWinFormsAdapter(Com.IDataObject* dataObject)
            {
#if DEBUG
                _nativeDataObject = new(dataObject, takeOwnership: true, trackDisposal: false);
#else
                _nativeDataObject = new(dataObject, takeOwnership: true);
#endif
            }
 
            #region Com.IDataObject.Interface
 
            HRESULT Com.IDataObject.Interface.DAdvise(Com.FORMATETC* pformatetc, uint advf, Com.IAdviseSink* pAdvSink, uint* pdwConnection)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->DAdvise(pformatetc, advf, pAdvSink, pdwConnection);
            }
 
            HRESULT Com.IDataObject.Interface.DUnadvise(uint dwConnection)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->DUnadvise(dwConnection);
            }
 
            HRESULT Com.IDataObject.Interface.EnumDAdvise(Com.IEnumSTATDATA** ppenumAdvise)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->EnumDAdvise(ppenumAdvise);
            }
 
            HRESULT Com.IDataObject.Interface.EnumFormatEtc(uint dwDirection, Com.IEnumFORMATETC** ppenumFormatEtc)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->EnumFormatEtc(dwDirection, ppenumFormatEtc);
            }
 
            HRESULT Com.IDataObject.Interface.GetData(Com.FORMATETC* pformatetcIn, Com.STGMEDIUM* pmedium)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->GetData(pformatetcIn, pmedium);
            }
 
            HRESULT Com.IDataObject.Interface.GetDataHere(Com.FORMATETC* pformatetc, Com.STGMEDIUM* pmedium)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->GetDataHere(pformatetc, pmedium);
            }
 
            HRESULT Com.IDataObject.Interface.QueryGetData(Com.FORMATETC* pformatetc)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->QueryGetData(pformatetc);
            }
 
            HRESULT Com.IDataObject.Interface.GetCanonicalFormatEtc(Com.FORMATETC* pformatectIn, Com.FORMATETC* pformatetcOut)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->GetCanonicalFormatEtc(pformatectIn, pformatetcOut);
            }
 
            HRESULT Com.IDataObject.Interface.SetData(Com.FORMATETC* pformatetc, Com.STGMEDIUM* pmedium, BOOL fRelease)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                return nativeDataObject.Value->SetData(pformatetc, pmedium, fRelease);
            }
 
            #endregion
 
            /// <summary>
            ///  Retrieves the specified format from the specified <paramref name="hglobal"/>.
            /// </summary>
            private static object? GetDataFromHGLOBAL(HGLOBAL hglobal, string format)
            {
                if (hglobal == 0)
                {
                    return null;
                }
 
                return format switch
                {
                    DataFormats.TextConstant or DataFormats.RtfConstant or DataFormats.OemTextConstant
                        => ReadStringFromHGLOBAL(hglobal, unicode: false),
                    DataFormats.HtmlConstant => ReadUtf8StringFromHGLOBAL(hglobal),
                    DataFormats.UnicodeTextConstant => ReadStringFromHGLOBAL(hglobal, unicode: true),
                    DataFormats.FileDropConstant => ReadFileListFromHDROP((HDROP)(nint)hglobal),
                    CF_DEPRECATED_FILENAME => new string[] { ReadStringFromHGLOBAL(hglobal, unicode: false) },
                    CF_DEPRECATED_FILENAMEW => new string[] { ReadStringFromHGLOBAL(hglobal, unicode: true) },
                    _ => ReadObjectFromHGLOBAL(hglobal, RestrictDeserializationToSafeTypes(format))
                };
 
                static object ReadObjectFromHGLOBAL(HGLOBAL hglobal, bool restrictDeserialization)
                {
                    MemoryStream stream = ReadByteStreamFromHGLOBAL(hglobal, out bool isSerializedObject);
                    return !isSerializedObject ? stream : BinaryFormatUtilities.ReadObjectFromStream(stream, restrictDeserialization);
                }
            }
 
            private static unsafe MemoryStream ReadByteStreamFromHGLOBAL(HGLOBAL hglobal, out bool isSerializedObject)
            {
                void* buffer = PInvokeCore.GlobalLock(hglobal);
                if (buffer is null)
                {
                    throw new ExternalException(SR.ExternalException, (int)HRESULT.E_OUTOFMEMORY);
                }
 
                try
                {
                    int size = (int)PInvokeCore.GlobalSize(hglobal);
                    byte[] bytes = new byte[size];
                    Marshal.Copy((nint)buffer, bytes, 0, size);
                    int index = 0;
 
                    // The object here can either be a stream or a serialized object. We identify a serialized object
                    // by writing the bytes for the guid serializedObjectID at the front of the stream.
 
                    if (isSerializedObject = bytes.AsSpan().StartsWith(s_serializedObjectID))
                    {
                        index = s_serializedObjectID.Length;
                    }
 
                    return new MemoryStream(bytes, index, bytes.Length - index);
                }
                finally
                {
                    PInvokeCore.GlobalUnlock(hglobal);
                }
            }
 
            private static unsafe string ReadStringFromHGLOBAL(HGLOBAL hglobal, bool unicode)
            {
                string? stringData = null;
 
                void* buffer = PInvokeCore.GlobalLock(hglobal);
                try
                {
                    stringData = unicode ? new string((char*)buffer) : new string((sbyte*)buffer);
                }
                finally
                {
                    PInvokeCore.GlobalUnlock(hglobal);
                }
 
                return stringData;
            }
 
            private static unsafe string ReadUtf8StringFromHGLOBAL(HGLOBAL hglobal)
            {
                void* buffer = PInvokeCore.GlobalLock(hglobal);
                try
                {
                    int size = (int)PInvokeCore.GlobalSize(hglobal);
                    return Encoding.UTF8.GetString((byte*)buffer, size - 1);
                }
                finally
                {
                    PInvokeCore.GlobalUnlock(hglobal);
                }
            }
 
            private static unsafe string[]? ReadFileListFromHDROP(HDROP hdrop)
            {
                uint count = PInvoke.DragQueryFile(hdrop, iFile: 0xFFFFFFFF, lpszFile: null, cch: 0);
                if (count == 0)
                {
                    return null;
                }
 
                Span<char> fileName = stackalloc char[(int)PInvokeCore.MAX_PATH + 1];
                string[] files = new string[count];
 
                fixed (char* buffer = fileName)
                {
                    for (uint i = 0; i < count; i++)
                    {
                        uint charactersCopied = PInvoke.DragQueryFile(hdrop, i, buffer, (uint)fileName.Length);
                        if (charactersCopied == 0)
                        {
                            continue;
                        }
 
                        string s = fileName[..(int)charactersCopied].ToString();
                        files[i] = s;
                    }
                }
 
                return files;
            }
 
            /// <summary>
            ///  Extracts a managed object from <see cref="Com.IDataObject"/> of the specified format.
            /// </summary>
            /// <param name="doNotContinue">
            ///  A restricted type was encountered, do not continue trying to deserialize.
            /// </param>
            private static object? GetObjectFromDataObject(Com.IDataObject* dataObject, string format, out bool doNotContinue)
            {
                object? data = null;
                doNotContinue = false;
                try
                {
                    // Try to get the data as a bitmap first.
                    data = TryGetBitmapData(dataObject, format);
 
                    // Check for one of our standard data types.
                    data ??= TryGetHGLOBALData(dataObject, format, out doNotContinue);
 
                    if (data is null && !doNotContinue)
                    {
                        // Lastly check to see if the data is an IStream.
                        data = TryGetIStreamData(dataObject, format);
                    }
                }
                catch (Exception e)
                {
                    Debug.Fail(e.ToString());
                }
 
                return data;
 
                static object? TryGetHGLOBALData(Com.IDataObject* dataObject, string format, out bool doNotContinue)
                {
                    doNotContinue = false;
 
                    Com.FORMATETC formatetc = new()
                    {
                        cfFormat = (ushort)DataFormats.GetFormat(format).Id,
                        dwAspect = (uint)Com.DVASPECT.DVASPECT_CONTENT,
                        lindex = -1,
                        tymed = (uint)Com.TYMED.TYMED_HGLOBAL
                    };
 
                    if (dataObject->QueryGetData(formatetc).Failed)
                    {
                        return null;
                    }
 
                    object? data = null;
                    HRESULT hr = dataObject->GetData(formatetc, out Com.STGMEDIUM medium);
 
                    // One of the ways this can happen is when we attempt to put binary formatted data onto the
                    // clipboard, which will succeed as Windows ignores all errors when putting data on the clipboard.
                    // The data state, however, is not good, and this error will be returned by Windows when asking to
                    // get the data out.
                    Debug.WriteLineIf(hr == HRESULT.CLIPBRD_E_BAD_DATA, "CLIPBRD_E_BAD_DATA returned when trying to get clipboard data.");
                    Debug.WriteLineIf(hr == HRESULT.DV_E_TYMED, "DV_E_TYMED returned when trying to get clipboard data.");
 
                    try
                    {
                        if (medium.tymed == Com.TYMED.TYMED_HGLOBAL && !medium.hGlobal.IsNull)
                        {
                            data = GetDataFromHGLOBAL(medium.hGlobal, format);
                        }
                    }
                    catch (RestrictedTypeDeserializationException)
                    {
                        doNotContinue = true;
                    }
                    catch
                    {
                    }
                    finally
                    {
                        PInvoke.ReleaseStgMedium(ref medium);
                    }
 
                    return data;
                }
 
                static unsafe object? TryGetIStreamData(Com.IDataObject* dataObject, string format)
                {
                    Com.FORMATETC formatEtc = new()
                    {
                        cfFormat = (ushort)DataFormats.GetFormat(format).Id,
                        dwAspect = (uint)Com.DVASPECT.DVASPECT_CONTENT,
                        lindex = -1,
                        tymed = (uint)Com.TYMED.TYMED_ISTREAM
                    };
 
                    // Limit the # of exceptions we may throw below.
                    if (dataObject->QueryGetData(formatEtc).Failed
                        || dataObject->GetData(formatEtc, out Com.STGMEDIUM medium).Failed)
                    {
                        return null;
                    }
 
                    HGLOBAL hglobal = default;
                    try
                    {
                        if (medium.tymed != Com.TYMED.TYMED_ISTREAM || medium.hGlobal.IsNull)
                        {
                            return null;
                        }
 
                        using ComScope<Com.IStream> pStream = new((Com.IStream*)medium.hGlobal);
                        pStream.Value->Stat(out Com.STATSTG sstg, (uint)Com.STATFLAG.STATFLAG_DEFAULT);
 
                        hglobal = PInvokeCore.GlobalAlloc(GLOBAL_ALLOC_FLAGS.GMEM_MOVEABLE | GLOBAL_ALLOC_FLAGS.GMEM_ZEROINIT, (uint)sstg.cbSize);
 
                        // Not throwing here because the other out of memory condition on GlobalAlloc
                        // happens inside innerData.GetData and gets turned into a null return value.
                        if (hglobal.IsNull)
                        {
                            return null;
                        }
 
                        void* ptr = PInvokeCore.GlobalLock(hglobal);
                        pStream.Value->Read((byte*)ptr, (uint)sstg.cbSize, null);
                        PInvokeCore.GlobalUnlock(hglobal);
 
                        return GetDataFromHGLOBAL(hglobal, format);
                    }
                    finally
                    {
                        if (!hglobal.IsNull)
                        {
                            PInvokeCore.GlobalFree(hglobal);
                        }
 
                        PInvoke.ReleaseStgMedium(ref medium);
                    }
                }
            }
 
            private static Image? TryGetBitmapData(Com.IDataObject* dataObject, string format)
            {
                if (format != DataFormats.BitmapConstant)
                {
                    return null;
                }
 
                Com.FORMATETC formatEtc = new()
                {
                    cfFormat = (ushort)DataFormats.GetFormat(format).Id,
                    dwAspect = (uint)Com.DVASPECT.DVASPECT_CONTENT,
                    lindex = -1,
                    tymed = (uint)Com.TYMED.TYMED_GDI
                };
 
                Com.STGMEDIUM medium = default;
 
                if (dataObject->QueryGetData(formatEtc).Succeeded)
                {
                    HRESULT hr = dataObject->GetData(formatEtc, out medium);
                    // One of the ways this can happen is when we attempt to put binary formatted data onto the
                    // clipboard, which will succeed as Windows ignores all errors when putting data on the clipboard.
                    // The data state, however, is not good, and this error will be returned by Windows when asking to
                    // get the data out.
                    Debug.WriteLineIf(hr == HRESULT.CLIPBRD_E_BAD_DATA, "CLIPBRD_E_BAD_DATA returned when trying to get clipboard data.");
                }
 
                Image? data = null;
 
                try
                {
                    // GDI+ doesn't own this HBITMAP, but we can't delete it while the object is still around. So we
                    // have to do the really expensive thing of cloning the image so we can release the HBITMAP.
                    if ((uint)medium.tymed == (uint)TYMED.TYMED_GDI
                        && !medium.hGlobal.IsNull
                        && Image.FromHbitmap(medium.hGlobal) is Image clipboardImage)
                    {
                        data = (Image)clipboardImage.Clone();
                        clipboardImage.Dispose();
                    }
                }
                finally
                {
                    PInvoke.ReleaseStgMedium(ref medium);
                }
 
                return data;
            }
 
            #region IDataObject
 
            object? IDataObject.GetData(string format, bool autoConvert)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                object? data = GetObjectFromDataObject(nativeDataObject, format, out bool doNotContinue);
 
                if (doNotContinue
                    || !autoConvert
                    || (data is not null && data is not MemoryStream)
                    || GetMappedFormats(format) is not { } mappedFormats)
                {
                    return data;
                }
 
                object? originalData = data;
 
                // Try to find a mapped format that works better.
                foreach (string mappedFormat in mappedFormats)
                {
                    if (!format.Equals(mappedFormat))
                    {
                        data = GetObjectFromDataObject(nativeDataObject, mappedFormat, out doNotContinue);
                        if (doNotContinue)
                        {
                            break;
                        }
 
                        if (data is not null and not MemoryStream)
                        {
                            return data;
                        }
                    }
                }
 
                return originalData ?? data;
            }
 
            object? IDataObject.GetData(string format) => ((IDataObject)this).GetData(format, autoConvert: true);
 
            object? IDataObject.GetData(Type format) => ((IDataObject)this).GetData(format.FullName!);
 
            bool IDataObject.GetDataPresent(Type format) => GetDataPresent(format.FullName!);
 
            public bool GetDataPresent(string format, bool autoConvert)
            {
                bool dataPresent = GetDataPresentInner(format);
 
                if (dataPresent || !autoConvert || GetMappedFormats(format) is not { } mappedFormats)
                {
                    return dataPresent;
                }
 
                foreach (string mappedFormat in mappedFormats)
                {
                    if (!format.Equals(mappedFormat) && (dataPresent = GetDataPresentInner(mappedFormat)))
                    {
                        break;
                    }
                }
 
                return dataPresent;
            }
 
            public bool GetDataPresent(string format) => GetDataPresent(format, autoConvert: true);
 
            public string[] GetFormats(bool autoConvert)
            {
                using var nativeDataObject = _nativeDataObject.GetInterface();
                Debug.Assert(!nativeDataObject.IsNull, "You must have an innerData on all DataObjects");
 
                using ComScope<Com.IEnumFORMATETC> enumFORMATETC = new(null);
                nativeDataObject.Value->EnumFormatEtc((uint)DATADIR.DATADIR_GET, enumFORMATETC).AssertSuccess();
 
                if (enumFORMATETC.IsNull)
                {
                    return [];
                }
 
                // Since we are only adding elements to the HashSet, the order will be preserved.
                HashSet<string> distinctFormats = [];
 
                enumFORMATETC.Value->Reset();
 
                Com.FORMATETC formatEtc = default;
 
                while (enumFORMATETC.Value->Next(1, &formatEtc) == HRESULT.S_OK)
                {
                    string name = DataFormats.GetFormat(formatEtc.cfFormat).Name;
                    if (autoConvert)
                    {
                        string[] mappedFormats = GetMappedFormats(name)!;
                        for (int i = 0; i < mappedFormats.Length; i++)
                        {
                            distinctFormats.Add(mappedFormats[i]);
                        }
                    }
                    else
                    {
                        distinctFormats.Add(name);
                    }
 
                    formatEtc = default;
                }
 
                return [.. distinctFormats];
            }
 
            public string[] GetFormats() => GetFormats(autoConvert: true);
 
            void IDataObject.SetData(string format, bool autoConvert, object? data) { }
            void IDataObject.SetData(string format, object? data) { }
            void IDataObject.SetData(Type format, object? data) { }
            void IDataObject.SetData(object? data) { }
 
            #endregion
 
            private bool GetDataPresentInner(string format)
            {
                Com.FORMATETC formatEtc = new()
                {
                    cfFormat = (ushort)(DataFormats.GetFormat(format).Id),
                    dwAspect = (uint)Com.DVASPECT.DVASPECT_CONTENT,
                    lindex = -1,
                    tymed = (uint)AllowedTymeds
                };
 
                using var nativeDataObject = _nativeDataObject.GetInterface();
                HRESULT hr = nativeDataObject.Value->QueryGetData(formatEtc);
 
                // APIs will return S_FALSE, which is "success"
                return hr == HRESULT.S_OK;
            }
        }
    }
}