Avoid serialization with in-process Clipboard use

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

@@ -115,6 +115,26 @@ internal static void AddMappedFormats<T>(string format, T formats)
                 break;
             case BinaryFormatMetafile:
                 formats.Add(Emf);
+                break;
+            default:
+                // The formats aren't case sensitive, notably when they are looked up via the OLE IDataObject
+                // proxy. We're most likely to see "TEXT", so we'll handle text cases.
+                if (string.Equals(format, Text, StringComparison.OrdinalIgnoreCase))
+                {
+                    formats.Add(String);
+                    formats.Add(UnicodeText);
+                }
+                else if (string.Equals(format, UnicodeText, StringComparison.OrdinalIgnoreCase))
+                {
+                    formats.Add(String);
+                    formats.Add(Text);
+                }
+                else if (string.Equals(format, String, StringComparison.OrdinalIgnoreCase))
+                {
+                    formats.Add(Text);
+                    formats.Add(UnicodeText);
+                }
+
                 break;
         }
     }

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

@@ -130,7 +130,7 @@ public bool GetDataPresent(string format, bool autoConvert)
 
         for (int i = 0; i < formats.Length; i++)
         {
-            if (format.Equals(formats[i]))
+            if (format.Equals(formats[i], StringComparison.OrdinalIgnoreCase))
             {
                 return true;
             }

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

@@ -130,7 +130,7 @@ public void RoundTrip_Text()
     }
 
     [Fact]
-    public void Clipboard_DerivedDataObject_DataPresent()
+    public void DerivedDataObject_DataPresent()
     {
         // https://github.com/dotnet/winforms/issues/12789
         SomeDataObject data = new();
@@ -152,4 +152,31 @@ internal class SomeDataObject : DataObject
         public override bool GetDataPresent(string format, bool autoConvert)
             => format == Format || base.GetDataPresent(format, autoConvert);
     }
+
+    [Fact]
+    public void SerializableObject_InProcess_DoesNotUseBinaryFormatter()
+    {
+        // This test ensures that the SerializableObject does not use BinaryFormatter when running in process.
+        using ClipboardScope scope = new();
+
+        DataObject dataObject = new();
+        SerializablePerson person = new() { Name = "John Doe", Age = 30 };
+        dataObject.SetData(person);
+        HRESULT result = ClipboardCore.SetData(dataObject, copy: false, retryTimes: 1, retryDelay: 0);
+        result.Should().Be(HRESULT.S_OK);
+
+        result = ClipboardCore.GetDataObject<DataObject, ITestDataObject>(out var data, retryTimes: 1, retryDelay: 0);
+        result.Should().Be(HRESULT.S_OK);
+        data.Should().NotBeNull();
+        data!.GetDataPresent(typeof(SerializablePerson).FullName!).Should().BeTrue();
+
+        data.GetData(typeof(SerializablePerson).FullName!).Should().BeSameAs(person);
+    }
+
+    [Serializable]
+    internal class SerializablePerson
+    {
+        public string Name { get; set; } = "DefaultName";
+        public int Age { get; set; }
+    }
 }

src/System.Windows.Forms/PublicAPI.Unshipped.txt

@@ -0,0 +1 @@
+static System.Windows.Forms.Clipboard.TryGetData<T>(out T data) -> bool

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

@@ -352,6 +352,10 @@ public static bool ContainsText(TextDataFormat format)
         return dataObject.TryGetData(format, out data);
     }
 
+    /// <inheritdoc cref="TryGetData{T}(string, out T)"/>
+    public static bool TryGetData<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] T>(
+        [NotNullWhen(true), MaybeNullWhen(false)] out T data) => TryGetData(typeof(T).FullName!, out data);
+
     /// <summary>
     ///  Retrieves a collection of file names from the <see cref="Clipboard"/>.
     /// </summary>

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

@@ -14,7 +14,6 @@ public WrappingDataObject(object data) : base(data)
     {
         // Don't wrap existing DataObject instances.
         Debug.Assert(data is not DataObject);
-
         _originalIsIDataObject = data is IDataObject;
     }
 
@@ -26,7 +25,25 @@ internal override bool TryUnwrapUserDataObject([NotNullWhen(true)] out IDataObje
             return base.TryUnwrapUserDataObject(out dataObject);
         }
 
-        dataObject = null;
-        return false;
+        // When we hand back our wrapper we're emulating what would happen via the native IDataObject proxy.
+        // As the native interface has no concept of "autoConvert", we need to always consider it "true"
+        // as our native IDataObject implementation would.
+        dataObject = this;
+        return true;
     }
+
+    public override string[] GetFormats(bool autoConvert)
+        // Always auto convert to emulate native IDataObject behavior.
+        => base.GetFormats(autoConvert: true);
+
+    public override bool GetDataPresent(string format, bool autoConvert)
+        // Always auto convert to emulate native IDataObject behavior.
+        => base.GetDataPresent(format, autoConvert: true);
+
+#pragma warning disable WFDEV005 // Type or member is obsolete
+    [Obsolete]
+    public override object? GetData(string format, bool autoConvert)
+        // Always auto convert to emulate native IDataObject behavior.
+        => base.GetData(format, autoConvert: true);
+#pragma warning restore WFDEV005 // Type or member is obsolete
 }

src/test/unit/System.Windows.Forms/System/Windows/Forms/ClipboardTests.cs

@@ -276,7 +276,7 @@ public void SetDataObject_InvokeObjectNotIComDataObject_GetReturnsExpected(objec
     {
         Clipboard.SetDataObject(data);
 
-        DataObject dataObject = Clipboard.GetDataObject().Should().BeOfType<DataObject>().Subject;
+        DataObject dataObject = Clipboard.GetDataObject().Should().BeAssignableTo<DataObject>().Subject;
         dataObject.GetData(data.GetType()).Should().Be(data);
         Clipboard.ContainsData(data.GetType().FullName).Should().BeTrue();
     }
@@ -303,7 +303,7 @@ public void SetDataObject_InvokeObjectBoolNotIComDataObject_GetReturnsExpected(o
     {
         Clipboard.SetDataObject(data, copy);
 
-        DataObject dataObject = Clipboard.GetDataObject().Should().BeOfType<DataObject>().Subject;
+        DataObject dataObject = Clipboard.GetDataObject().Should().BeAssignableTo<DataObject>().Subject;
         dataObject.GetData(data.GetType()).Should().Be(data);
         Clipboard.ContainsData(data.GetType().FullName).Should().BeTrue();
     }
@@ -332,7 +332,7 @@ public void SetDataObject_InvokeObjectBoolIntIntNotIComDataObject_GetReturnsExpe
     {
         Clipboard.SetDataObject(data, copy, retryTimes, retryDelay);
 
-        DataObject dataObject = Clipboard.GetDataObject().Should().BeOfType<DataObject>().Subject;
+        DataObject dataObject = Clipboard.GetDataObject().Should().BeAssignableTo<DataObject>().Subject;
         dataObject.GetData(data.GetType()).Should().Be(data);
         Clipboard.ContainsData(data.GetType().FullName).Should().BeTrue();
     }
@@ -1193,7 +1193,7 @@ public void SetData_Text_Format_AllUpper()
         formats.Should().BeEquivalentTo(["System.String", "UnicodeText", "Text"]);
 
         formats = dataObject.GetFormats(autoConvert: false);
-        formats.Should().BeEquivalentTo(["Text"]);
+        formats.Should().BeEquivalentTo(["System.String", "UnicodeText", "Text"]);
 
         // CLIPBRD_E_BAD_DATA returned when trying to get clipboard data.
         Clipboard.GetText().Should().BeEmpty();
@@ -1256,10 +1256,8 @@ public void SetDataObject_Text()
 
         Clipboard.GetData("System.String").Should().Be(expected);
 
-        // Case sensitivity matters so we end up reading stream/object from HGLOBAL instead of string.
-        MemoryStream stream = Clipboard.GetData("TEXT").Should().BeOfType<MemoryStream>().Subject;
-        byte[] array = stream.ToArray();
-        array.Should().BeEquivalentTo("Hello, World!\0"u8.ToArray());
+        string result = Clipboard.GetData("TEXT").Should().BeOfType<string>().Subject;
+        result.Should().Be(expected);
     }
 
     [WinFormsFact]
@@ -1324,18 +1322,19 @@ public void RoundTrip_Object_SupportsTypedInterface(bool copy)
         string format = typeof(SerializableTestData).FullName!;
 
         // Opt-in into access to the binary formatted stream.
-        using BinaryFormatterInClipboardDragDropScope clipboardScope = new(enable: true);
+        using BinaryFormatterInClipboardDragDropScope clipboardScope = new(enable: copy);
+
         // We need the BinaryFormatter to flush the data from the managed object to the HGLOBAL
         // and to write data to HGLOBAL as a binary formatted stream now if it hadn't been flushed.
-        using BinaryFormatterScope scope = new(enable: true);
+        using BinaryFormatterScope scope = new(enable: copy);
 
         Clipboard.SetDataObject(data, copy);
 
-        DataObject received = Clipboard.GetDataObject().Should().BeOfType<DataObject>().Subject;
+        DataObject received = Clipboard.GetDataObject().Should().BeAssignableTo<DataObject>().Subject;
 
         received.TryGetData(
             format,
-            (TypeName name) => name.FullName == typeof(SerializableTestData).FullName ? typeof(SerializableTestData) : null,
+            name => name.FullName == typeof(SerializableTestData).FullName ? typeof(SerializableTestData) : null,
             autoConvert: false,
             out SerializableTestData? result).Should().BeTrue();
 
@@ -1450,4 +1449,27 @@ public unsafe void OleGetClipboard_ProxyBehavior()
         using ComScope<IUnknown> wrapperUnknown = wrapper.Query<IUnknown>();
         ((nint)wrapperUnknown.Value).Should().Be((nint)originalUnknown.Value);
     }
+
+    [WinFormsFact]
+    public void SetDataObject_SerializableObject_CopyFalse_DoesNotUseBinaryFormatter()
+    {
+        // This test ensures that the SerializableObject does not use BinaryFormatter when running in process.
+        // This only works when copy is not set to true as that is the only case where we are able to extract
+        // the original DataObject we created for the user data.
+
+        SerializablePerson person = new() { Name = "John Doe", Age = 30 };
+        Clipboard.SetDataObject(person);
+
+        bool result = Clipboard.TryGetData(out SerializablePerson? data);
+        result.Should().BeTrue();
+        data.Should().NotBeNull();
+        data.Should().BeSameAs(person);
+    }
+
+    [Serializable]
+    internal class SerializablePerson
+    {
+        public string Name { get; set; } = "DefaultName";
+        public int Age { get; set; }
+    }
 }