IDataObject

IDataObject is an interface in Microsoft’s Component Object Model (COM) and .NET Framework that defines a standard way for objects to support drag-and-drop operations and clipboard data exchange. It serves as a bridge between applications by enabling the transfer of formatted data, such as text, images, files, or custom data types, during cut, copy, paste, or drag-and-drop actions.

The interface originates from the Windows API and was later adapted into .NET through the `System.Runtime.InteropServices` namespace. It requires implementing methods like `GetData`, `GetDataHere`, `QueryGetData`, and `SetData` to handle data retrieval and modification. Additionally, it supports enumerating available data formats via the `EnumFormatEtc` method, allowing applications to determine which data types are supported before transfer.

IDataObject is commonly used in scenarios where interoperability between COM-based and .NET applications is necessary. For example, it enables drag-and-drop functionality between a WinForms application and an Office document, or between a custom COM component and a .NET client. The interface also plays a role in clipboard operations, ensuring consistent behavior across different applications.

While modern frameworks like WPF and UWP have introduced more advanced drag-and-drop mechanisms, IDataObject remains relevant for legacy systems and scenarios requiring direct COM interoperability. Developers often use it indirectly through higher-level abstractions, such as `DataObject` in .NET, which wraps IDataObject functionality for easier use.