NAME

       wxDataObject - Functions for wxDataObject class

DESCRIPTION

       A  wxDataObject  represents data that can be copied to or from the clipboard, or dragged and dropped. The
       important thing about wxDataObject is that this is a 'smart' piece of data unlike 'dumb' data  containers
       such  as  memory  buffers or files. Being 'smart' here means that the data object itself should know what
       data formats it supports and how to render itself in each of its supported formats.

       A supported format, incidentally, is exactly the format in which the data can be requested  from  a  data
       object  or  from  which  the data object may be set. In the general case, an object may support different
       formats on 'input' and 'output', i.e. it may be able to render itself  in  a  given  format  but  not  be
       created  from  data  on  this format or vice versa. wxDataObject defines the wxDataObject::Direction (not
       implemented in wx) enumeration type which distinguishes between them.

       See wxDataFormat (not implemented in wx) documentation for more about formats.

       Not surprisingly, being 'smart' comes at a  price  of  added  complexity.  This  is  reasonable  for  the
       situations  when  you really need to support multiple formats, but may be annoying if you only want to do
       something simple like cut and paste text.

       To provide  a  solution  for  both  cases,  wxWidgets  has  two  predefined  classes  which  derive  from
       wxDataObject:  wxDataObjectSimple  (not  implemented in wx) and wxDataObjectComposite (not implemented in
       wx). wxDataObjectSimple (not implemented in wx) is the simplest wxDataObject possible and only holds data
       in  a  single  format  (such  as  HTML  or text) and wxDataObjectComposite (not implemented in wx) is the
       simplest way to implement a wxDataObject that does support multiple formats because it achieves  this  by
       simply holding several wxDataObjectSimple (not implemented in wx) objects.

       So,  you  have several solutions when you need a wxDataObject class (and you need one as soon as you want
       to transfer data via the clipboard or drag and drop):

       Please note that the easiest way to use drag and drop and the clipboard with multiple formats is by using
       wxDataObjectComposite  (not  implemented  in  wx),  but  it  is  not  the  most  efficient  one  as  each
       wxDataObjectSimple (not implemented in wx) would contain the whole data in its  respective  formats.  Now
       imagine  that you want to paste 200 pages of text in your proprietary format, as well as Word, RTF, HTML,
       Unicode and plain text to the clipboard and even today's computers are in trouble.  For  this  case,  you
       will  have to derive from wxDataObject directly and make it enumerate its formats and provide the data in
       the requested format on demand.

       Note that neither the GTK+ data transfer mechanisms for  clipboard  and  drag  and  drop,  nor  OLE  data
       transfer,  copies  any  data until another application actually requests the data. This is in contrast to
       the 'feel' offered to the user of a program who would  normally  think  that  the  data  resides  in  the
       clipboard after having pressed 'Copy' - in reality it is only declared to be available.

       You  may  also  derive  your  own data object classes from wxCustomDataObject (not implemented in wx) for
       user-defined types. The format of user-defined data is given as  a  mime-type  string  literal,  such  as
       "application/word"  or  "image/png".  These strings are used as they are under Unix (so far only GTK+) to
       identify a format and are translated into their Windows equivalent under Win32 (using the OLE IDataObject
       for  data  exchange  to  and  from  the  clipboard  and  for  drag and drop). Note that the format string
       translation under Windows is not yet finished.

       Each class derived directly from wxDataObject must override and implement all of its functions which  are
       pure  virtual  in the base class. The data objects which only render their data or only set it (i.e. work
       in only one direction), should return 0 from GetFormatCount() (not implemented in wx).

       See: Overview dnd, Examples, wxFileDataObject, wxTextDataObject,  wxBitmapDataObject,  wxCustomDataObject
       (not  implemented  in  wx),  wxDropTarget  (not implemented in wx), wxDropSource (not implemented in wx),
       wxTextDropTarget (not implemented in wx), wxFileDropTarget (not implemented in wx)

       wxWidgets docs: wxDataObject

DATA TYPES

       wxDataObject() = wx:wx_object()