Add information about how the clipboard/dataobject changes in .NET 10 #2129
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…mation and the desire to upgrade clipboard code
| { | ||
| public class BinaryFormatterSupport | ||
| { | ||
| public class Person |
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BinaryFormatter serialization requires [Serializable].
| // Explicit allow-list of permitted types—add only what you need | ||
| var allowedTypes = new Dictionary<string, Type> | ||
| { | ||
| ["MyApp.Person"] = typeof(Person), |
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These type names don't match the real type names.
| namespace ClipboardExamples | ||
| { | ||
| // <ITypedDataObjectImplementation> | ||
| public class TypedDataObject : DataObject, ITypedDataObject |
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DataObject implements ITypedDataObject so this isn't a good example. I don't think writing samples for ITypedDataObject is worth pre-emptively doing.
| public static void ModernTryGetDataExample() | ||
| { | ||
| // Use this - type-safe approach with TryGetData<T>() | ||
| if (Clipboard.TryGetData("MyApp.Person", out Person person)) |
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This code isn't particularly helpful without the set/get loop. The true modern way would be to SetDataAsJson then TryGetData.
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| public static void BrokenCustomTypeExample() | ||
| { | ||
| // This worked in .NET 8 and earlier but silently fails starting with .NET 9 |
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You should see a first chance exception under the debugger. The failure happens when OLE tries to make a copy of the data because of the default is copy = true on SetData. If it is set to false it will just work in process as we don't actually have to serialize the type.
| // Later retrieval with type safety | ||
| if (Clipboard.TryGetData("MyInt", out int value)) | ||
| { | ||
| ProcessInteger(value); |
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Maybe having the Console.WriteLine inline would be clearer?
| Clipboard.SetData("MyTimeSpan", TimeSpan.FromMinutes(30)); | ||
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| // Later retrieval with type safety | ||
| if (Clipboard.TryGetData("MyInt", out int value)) |
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This won't work. The clipboard only has a single item, which would be "MyTimeSpan" in this case.
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| `BinaryFormatter` was removed from the runtime in .NET 9 because of security vulnerabilities. This change broke clipboard and drag-and-drop operations with custom objects. .NET 10 introduces new APIs that use JSON serialization and type-safe methods to restore this functionality, improve security, and provide better error handling and cross-process compatibility. | ||
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| One significant change is that <xref:System.Windows.Clipboard.SetData(System.String,System.Object)?displayProperty=nameWithType> no longer works with custom types. It silently fails without storing data on the clipboard. <xref:System.Windows.Forms.Clipboard.GetData(System.String)?displayProperty=nameWithType> is obsolete in .NET 10 and shouldn't be used, even for built-in types. Use the new <xref:System.Windows.Forms.Clipboard.TryGetData*?displayProperty=nameWithType> and <xref:System.Windows.Forms.Clipboard.SetDataAsJson``1(System.String,``0)?displayProperty=nameWithType> methods for type-safe operations and JSON serialization of custom objects. |
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No longer works "by default".
To see the failure, you have to catch first chance exceptions under the debugger to see it fail on OLE trying to retrieve a copy of the data (which happens when you set if copy == true, the default, otherwise on get).
| :::code language="json" source="./snippets/how-to-enable-binaryformatter-clipboard-support/csharp/runtimeconfig.json"::: | ||
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| > [!IMPORTANT] | ||
| > Without this specific runtime switch, clipboard operations won't fall back to `BinaryFormatter` even if general serialization support is enabled. This switch is required specifically for Windows Forms clipboard functionality. |
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The same procedures and switch are used for WPF. If you happen to have both WPF and WinForms in the same project, both Clipboard classes will be enabled.
Summary
Fixes #2113
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