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Signed-off-by: Peter Siegmund <mars3142@noreply.mars3142.dev>

libs/wxWidgets-3.3.1/docs/doxygen/overviews/dataobject.h

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+/////////////////////////////////////////////////////////////////////////////
+// Name:        dataobject.h
+// Purpose:     topic overview
+// Author:      wxWidgets team
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+/**
+
+@page overview_dataobject wxDataObject Overview
+
+@tableofcontents
+
+This overview discusses data transfer through clipboard or drag and drop. In
+wxWidgets, these two ways to transfer data (either between different
+applications or inside one and the same) are very similar which allows to
+implement both of them using almost the same code - or, in other words, if you
+implement drag and drop support for your application, you get clipboard support
+for free and vice versa.
+
+At the heart of both clipboard and drag and drop operations lies the
+wxDataObject class. The objects of this class (or, to be precise, classes
+derived from it) represent the data which is being carried by the mouse during
+drag and drop operation or copied to or pasted from the clipboard. wxDataObject
+is a "smart" piece of data because it knows which formats it supports (see
+GetFormatCount and GetAllFormats) and knows how to render itself in any of them
+(see GetDataHere). It can also receive its value from the outside in a format
+it supports if it implements the SetData method. Please see the documentation
+of this class for more details.
+
+Both clipboard and drag and drop operations have two sides: the source and
+target, the data provider and the data receiver. These which may be in the same
+application and even the same window when, for example, you drag some text from
+one position to another in a word processor. Let us describe what each of them
+should do.
+
+@see @ref overview_dnd, @ref group_class_dnd, @ref page_samples_dnd
+
+
+
+@section overview_dataobject_source The Data Provider (Source)
+
+The data provider is responsible for creating a wxDataObject containing the
+data to be transferred. Then it should either pass it to the clipboard using
+wxClipboard::SetData function or to wxDropSource and call
+wxDropSource::DoDragDrop function.
+
+The only (but important) difference is that the object for the clipboard
+transfer must always be created on the heap (i.e. using @c new) and it will be
+freed by the clipboard when it is no longer needed (indeed, it is not known in
+advance when, if ever, the data will be pasted from the clipboard). On the
+other hand, the object for drag and drop operation must only exist while
+wxDropSource::DoDragDrop executes and may be safely deleted afterwards and so
+can be created either on heap or on stack (i.e. as a local variable).
+
+Another small difference is that in the case of clipboard operation, the
+application usually knows in advance whether it copies or cuts (i.e. copies and
+deletes) data - in fact, this usually depends on which menu item the user
+chose. But for drag and drop it can only know it after wxDropSource::DoDragDrop
+returns (from its return value).
+
+
+
+@section overview_dataobject_target The Data Receiver (Target)
+
+To receive (paste in usual terminology) data from the clipboard, you should
+create a wxDataObject derived class which supports the data formats you need
+and pass it as argument to wxClipboard::GetData. If it returns @false,
+no data in (any of) the supported format(s) is available. If it returns @true,
+the data has been successfully transferred to wxDataObject.
+
+For drag and drop case, the wxDropTarget::OnData virtual function will be
+called when a data object is dropped, from which the data itself may be
+requested by calling wxDropTarget::GetData method which fills the data object.
+
+*/