Tweak OLE code to allow metafile handling in WPF (dotnet#13045)

Few minor tweaks to handle metafile scenarios in WPF.

Expand comments on IOleServices.

Author: JeremyKuhne

src/System.Private.Windows.Core/src/System/Private/Windows/Ole/Composition.NativeToManagedAdapter.cs

@@ -258,9 +258,8 @@ private static bool TryGetObjectFromDataObject<T>(
 
             try
             {
-                // Try to get the data as a bitmap first.
-                if (request.Format == DataFormatNames.Bitmap
-                    && TOleServices.TryGetBitmapFromDataObject(dataObject, out data))
+                // Try to get platform specific data first.
+                if (TOleServices.TryGetObjectFromDataObject(dataObject, request.Format, out data))
                 {
                     return true;
                 }

src/System.Private.Windows.Core/src/System/Private/Windows/Ole/DataFormatNames.cs

@@ -34,6 +34,7 @@ internal static partial class DataFormatNames
     internal const string FileNameAnsi = PInvokeCore.CFSTR_FILENAMEA;
     internal const string FileNameUnicode = PInvokeCore.CFSTR_FILENAME;
     internal const string BinaryFormatBitmap = "System.Drawing.Bitmap";
+    internal const string BinaryFormatMetafile = "System.Drawing.Imaging.Metafile";
 
     /// <summary>
     ///  A format used internally by the drag image manager.
@@ -109,6 +110,12 @@ internal static void AddMappedFormats<T>(string format, T formats)
             case BinaryFormatBitmap:
                 formats.Add(Bitmap);
                 break;
+            case Emf:
+                formats.Add(BinaryFormatMetafile);
+                break;
+            case BinaryFormatMetafile:
+                formats.Add(Emf);
+                break;
         }
     }
 

src/System.Private.Windows.Core/src/System/Private/Windows/Ole/DataStore.cs

@@ -94,12 +94,17 @@ public void SetData(Type format, object? data)
         SetData(format.FullName.OrThrowIfNull(), data);
     }
 
+    /// <inheritdoc cref="IDataObjectInternal.SetData(object?)"/>
+    /// <remarks>
+    ///  <para>
+    ///   This is the only method that has special behavior for <see cref="ISerializable"/> objects.
+    ///  </para>
+    /// </remarks>
     public void SetData(object? data)
     {
         ArgumentNullException.ThrowIfNull(data);
 
-        if (data is ISerializable
-            && !_mappedData.ContainsKey(DataFormatNames.Serializable))
+        if (data is ISerializable && !_mappedData.ContainsKey(DataFormatNames.Serializable))
         {
             SetData(DataFormatNames.Serializable, data);
         }
@@ -120,20 +125,18 @@ public bool GetDataPresent(string format, bool autoConvert)
         {
             return _mappedData.ContainsKey(format);
         }
-        else
-        {
-            string[] formats = GetFormats(autoConvert);
 
-            for (int i = 0; i < formats.Length; i++)
+        string[] formats = GetFormats(autoConvert);
+
+        for (int i = 0; i < formats.Length; i++)
+        {
+            if (format.Equals(formats[i]))
             {
-                if (format.Equals(formats[i]))
-                {
-                    return true;
-                }
+                return true;
             }
-
-            return false;
         }
+
+        return false;
     }
 
     public bool GetDataPresent(string format) => GetDataPresent(format, autoConvert: true);

src/System.Private.Windows.Core/src/System/Private/Windows/Ole/FormatEnumerator.cs

@@ -43,7 +43,9 @@ public FormatEnumerator(IDataObjectInternal dataObject, Func<string, int> getFor
                 dwAspect = ComTypes.DVASPECT.DVASPECT_CONTENT,
                 ptd = 0,
                 lindex = -1,
-                tymed = format.Equals(DataFormatNames.Bitmap) ? ComTypes.TYMED.TYMED_GDI : ComTypes.TYMED.TYMED_HGLOBAL
+                tymed = format == DataFormatNames.Bitmap
+                    ? ComTypes.TYMED.TYMED_GDI
+                    : format == DataFormatNames.Emf ? ComTypes.TYMED.TYMED_ENHMF : ComTypes.TYMED.TYMED_HGLOBAL
             };
 
             _formats.Add(temp);

src/System.Private.Windows.Core/src/System/Private/Windows/Ole/IOleServices.cs

@@ -5,6 +5,9 @@
 
 namespace System.Private.Windows.Ole;
 
+/// <summary>
+///  Platform specific OLE services.
+/// </summary>
 internal unsafe interface IOleServices
 {
     /// <summary>
@@ -17,15 +20,29 @@ internal unsafe interface IOleServices
     /// <summary>
     ///  Called after unsuccessfully performing clipboard <see cref="TYMED.TYMED_HGLOBAL"/> serialization.
     /// </summary>
+    /// <remarks>
+    ///  <para>
+    ///   <paramref name="pformatetc"/> and <paramref name="pmedium"/> are checked for validity before this call.
+    ///  </para>
+    /// </remarks>
+    /// <param name="format">The data format that is being serialized.</param>
+    /// <inheritdoc cref="IDataObject.GetDataHere(FORMATETC*, STGMEDIUM*)"/>
     static abstract HRESULT GetDataHere(string format, object data, FORMATETC* pformatetc, STGMEDIUM* pmedium);
 
     /// <summary>
-    ///  If the <typeparamref name="T"/> is a bitmap this method will attempt to extract it
+    ///  If the <typeparamref name="T"/> is a the requested format this method will attempt to extract it
     ///  from the <paramref name="dataObject"/>.
     /// </summary>
+    /// <param name="format">The data format that is being requested.</param>
+    /// <remarks>
+    ///  <para>
+    ///   This is intended for platform specific logic, notably for bitmaps and metafiles.
+    ///  </para>
+    /// </remarks>
     /// <returns><see langword="true"/> if a bitmap was extracted.</returns>
-    static abstract bool TryGetBitmapFromDataObject<T>(
+    static abstract bool TryGetObjectFromDataObject<T>(
         IDataObject* dataObject,
+        string format,
         [NotNullWhen(true)] out T data);
 
     /// <summary>
@@ -46,6 +63,11 @@ static abstract bool TryGetBitmapFromDataObject<T>(
     /// <summary>
     ///  Allows custom validation or adapting of <see cref="DataStore{TOleServices}"/> data and formats.
     /// </summary>
+    /// <param name="format">
+    ///  The format to be checked against <paramref name="data"/>, can be modified to another format name if
+    ///  <paramref name="autoConvert"/> is true.
+    /// </param>
+    /// <param name="data">The data to be checked against <paramref name="data"/>.</param>
     static abstract void ValidateDataStoreData(ref string format, bool autoConvert, object? data);
 
     /// <summary>

src/System.Private.Windows.Core/tests/System.Private.Windows.Core.Tests/System/Private/Windows/Ole/ClipboardCoreTests.cs

@@ -42,7 +42,7 @@ private class InvalidThreadOleServices() : IOleServices
         static HRESULT IOleServices.OleFlushClipboard() => throw new NotImplementedException();
         static unsafe HRESULT IOleServices.OleGetClipboard(IDataObject** dataObject) => throw new NotImplementedException();
         static unsafe HRESULT IOleServices.OleSetClipboard(IDataObject* dataObject) => throw new NotImplementedException();
-        static unsafe bool IOleServices.TryGetBitmapFromDataObject<T>(IDataObject* dataObject, [NotNullWhen(true)] out T data) => throw new NotImplementedException();
+        static unsafe bool IOleServices.TryGetObjectFromDataObject<T>(IDataObject* dataObject, string requestedFormat, [NotNullWhen(true)] out T data) => throw new NotImplementedException();
         static void IOleServices.ValidateDataStoreData(ref string format, bool autoConvert, object? data) => throw new NotImplementedException();
     }
 

src/System.Private.Windows.Core/tests/System.Private.Windows.Core.Tests/System/Private/Windows/Ole/MockOleServices.cs

@@ -21,7 +21,7 @@ static void IOleServices.EnsureThreadState() { }
     static bool IOleServices.IsValidTypeForFormat(Type type, string format) => true;
     static void IOleServices.ValidateDataStoreData(ref string format, bool autoConvert, object? data) { }
 
-    static unsafe bool IOleServices.TryGetBitmapFromDataObject<T>(IDataObject* dataObject, [NotNullWhen(true)] out T data)
+    static unsafe bool IOleServices.TryGetObjectFromDataObject<T>(IDataObject* dataObject, string requestedFormat, [NotNullWhen(true)] out T data)
     {
         data = default!;
         return false;

src/System.Windows.Forms/src/System/Windows/Forms/OLE/WinFormsOleServices.cs

@@ -57,9 +57,13 @@ static unsafe HRESULT IOleServices.GetDataHere(string format, object data, FORMA
         return HRESULT.DV_E_TYMED;
     }
 
-    static unsafe bool IOleServices.TryGetBitmapFromDataObject<T>(Com.IDataObject* dataObject, [NotNullWhen(true)] out T data)
+    static unsafe bool IOleServices.TryGetObjectFromDataObject<T>(
+        Com.IDataObject* dataObject,
+        string requestedFormat,
+        [NotNullWhen(true)] out T data)
     {
-        if ((typeof(Bitmap) == typeof(T) || typeof(Image) == typeof(T))
+        if (requestedFormat == DataFormatNames.Bitmap
+            && (typeof(Bitmap) == typeof(T) || typeof(Image) == typeof(T))
             && TryGetBitmapData(dataObject, out Bitmap? bitmap))
         {
             data = (T)(object)bitmap!;

src/System.Windows.Forms/tests/TestUtilities/Data/DataObjectTestHelpers.cs

@@ -42,7 +42,6 @@ public static TheoryData<string> UndefinedRestrictedFormat() =>
         DataFormats.Tiff,
         DataFormats.WaveAudio,
         DataFormats.SymbolicLink,
-        DataFormats.EnhancedMetafile,
         DataFormats.MetafilePict,
         DataFormats.Palette
     ];