Restoring autoConvert behavior in Clipboard APIs - #11837
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Pull request overview
This PR restores the pre-.NET 10 Clipboard retrieval behavior by ensuring autoConvert is only enabled for formats that historically relied on it (FileDrop and Bitmap), preventing unintended text format conversion that can result in mojibake.
Changes:
- Update
Clipboard.GetTypedDataIfAvailable<T>to useIsDataFormatAutoConvert(format)instead of always enablingautoConvert. - Add a unit test asserting
Clipboard.GetText(...)does not auto-convert betweenTextandUnicodeText.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/Microsoft.DotNet.Wpf/tests/UnitTests/PresentationCore.Tests/System/Windows/ClipboardTests.cs | Adds coverage to verify GetText does not auto-convert between auto-convertible text formats. |
| src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/clipboard.cs | Fixes the regression by applying the existing IsDataFormatAutoConvert policy to typed clipboard retrieval APIs. |
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JeremyKuhne
approved these changes
Aug 12, 2026
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Fixes one issue in dotnet/winforms#14322
Description
Till .NET 9.0,
autoConvertwas set to true only forFileDropandBitmapscenarios. However, since .NET 10, it is being set to true forGetAudioStream,GetFileDropList,GetImage, andGetTextAPIs inside the private methodGetTypedDataIfAvailable. This causes issues with GetText API with mojibake characters as described in bug dotnet/winforms#14322Customer Impact
There is no way for the app to know whether the clipboard contents were corrupted or if there is any problem with the API as it didn't get the desired data.
Regression
Yes - from .NET 9.0
Testing
Created a WPF app to write unicode data on the clipboard and another app to read it. Before the changes, the reader app returned several hits for mojibake characters. After fix, there were none.
Risk
This should be a very low risk change as this behavior was working fine in 9.0 and previous versions.
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