Add JSON Serialization Support for OLE

[lonitra]

Related: #11368

This is a start to support JSON serialization in OLE scenarios.
JsonData: This is our wrapper class that holds the JSON serialized data along with the original type information. Note that the data that is being JSON serialized uses default JsonSerializer behavior. Users can follow the remarks of the public APIs if custom JSON serialization behavior is needed.

Public APIs:

• DataObject.SetDataAsJson() - Allows users to add data to DataObject that will be JSON serialized. This is how we support JSON serialization for drag/drop scenario.
• Clipboard.SetDataAsJson() - Allows users to conveniently JSON serialize a type onto the clipboard, but note that this does not accept DataObject being passed in. If users want to place a DataObject on the clipboard, users should ensure data they want to be JSON serialized is already in the DataObject by utilizing DataObject.SetDataAsJson and then use Clipboard.SetDataObject().
• Control.DoDragDropAsJson() - Allows users to conveniently JSON serialize a type for drag operation, but note that this does not accept DataObject being passed in. If users wants to start a drag operation with a DataObject, user should ensure data they want to be JSON serialized is already in the DataObject by utilizing DataObject.SetDataAsJson and then use Control.DoDragDrop()

Tests:

• Unit tests added for new APIs, some of the same tests also added in ComDisabledTests to ensure same behavior if built in com support is turned off.
• Manually tested cross process scenario -- drag/drop and copy/paste from 2 WinForms apps and confirmed able to retrieve the original data without exposing JsonData<T>. If using legacy GetData APIs, user should change to use TryGetData APIs, otherwise follow recommendations to manually deserialize the data.
• Manually tested copying data onto clipboard from app running on main branch and pasting into .NET 8 app for informational purposes. This scenario does not work as one may expect likely due to JsonData not existing in .NET 8. In order to properly deserialize, users will need to follow recommendations to manually deserialize the stream.
• Test behavior in trimmed app: JsonSerializer uses reflection to serialize by default, which will not be available when trimming is turned on. In the future, we will need to either use source generator APIs to support trimming or configure JsonSerializerOptions.TypeInfoResolver
  to support trim scenarios.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Attention: Patch coverage is 90.61224% with 69 lines in your changes missing coverage. Please review.

Project coverage is 76.03659%. Comparing base (a5281d9) to head (3d32e84).
Report is 2 commits behind head on main.

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  Lines         354561      639600      +285039     
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[JeremyKuhne]

Generally looks good, some minor comments.

[elachlan]

@willibrandon you might be interested in the clipboard work here.

[willibrandon]

Thanks for working on these new APIs 🤤 I plan on testing your branch this evening, and will post any feedback that I have here.

[willibrandon]

Looks good! I am able to drag and drop JSON cats now 😸

var data = new DataObject();
var cat = new NyanCat()
{
    Ascii = _nyanCatAscii
};

data.SetDataAsJson(nameof(_nyanCatAscii), cat);
toolStripItem.DoDragDrop(
    data: data,
    allowedEffects: DragDropEffects.All,
    dragImage: _nyanCatAscii301Bmp,
    cursorOffset: new Point(0, 111),
    useDefaultDragImage: false);

[Tanya-Solyanik]

Consider replacing with TheoryData time permitting

[Tanya-Solyanik]

We would need the same change in Clipboard.GetData, or alternatively we could block this in the BinaryFormatUtilities reader code. This is the case of legacyMode == true and we can test if the stream contains BD-ed JsonData struct

[lonitra]

Clipboard.GetData will call to DataObject.GetData so I don't think JsonData will still not be exposed in that scenario, but I'll also write a test for this

[Tanya-Solyanik]

You are right, but still user applications that have no access to JsonData type will throw a first chance SerializationException from BInaryFormatter. If this scenario is blocked before the binary formatter, then there is no exception.

[lonitra]

Wouldn't the exception be a good indicator for user the data has been JSON serialized and binary formatted - if they want to deserialize this with BinaryFormatter to retrieve the data, they need to follow recommended steps? Otherwise, user will just get null and that gives very little information to user what went wrong. We also cannot avoid this exception from happening if user is trying to retrieve data in older .NET versions. We check and return null here because this is for in proc scenarios where users doing SetDataAsJson should use TryGetData instead of GetData.

[Tanya-Solyanik]

I agree with argument about exception stirring the user in the right direction. But are you sure that result is IJsonData can happen outside an internalsvisible to assembly?

[lonitra]

Yes, I had tested this in our scratch project which does not have InternalsVisibleTo and this is the following results:

        TestData testData = new() { x = 1 };
        DataObject dataObject = new DataObject();
        dataObject.SetDataAsJson("test", testData);

        // This is null.
        var test1 = dataObject.GetData("test");


        Clipboard.SetDataObject(dataObject, copy: false);
        // This is null.
        var test2 = Clipboard.GetData("test");

        Clipboard.SetDataObject(dataObject, copy: true);
        // Empty memory stream. If first chance exception on, throws SerializationException when path to use BinaryFormatter enabled
        var test3 = Clipboard.GetData("test");

[Tanya-Solyanik]

But are you hitting a breakpoint on line 243 with result not null?

[elachlan]

Congratulations on getting this merged!