If the variant contains a string or image, try to encode the QString or QImage, respectively, according to the specified mime type. If it's neither, or if the mime type is not supported by known encoders, then generate a warning. To make the code unit-testable, move the QQuickDragAttachedPrivate into a private header that we can include in a new test case. Verify that data that matches the mime type results in correctly populated QMimeData, and that mismatches produce runtime warnings. [ChangeLog][Qt Quick][Drag] The attaching type Drag supports more mime types in the mimeData property, which is now of type 'variantlist' instead of 'stringlist'. Qt Quick Drag validates the type of the data against supported mime types, and generates warnings in case of a mismatch. If the type of the data is ArrayBuffer (i.e. a QByteArray), then the data is accepted without any validation. Task-number: QTBUG-71922 Change-Id: I82789086fed9c7bc399183e76ffb83b819df440f Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>