Version: 3.1.1
wxDataObjectComposite Class Reference

#include <wx/dataobj.h>

+ Inheritance diagram for wxDataObjectComposite:

Detailed Description

wxDataObjectComposite is the simplest wxDataObject derivation which may be used to support multiple formats.

It contains several wxDataObjectSimple objects and supports any format supported by at least one of them. Only one of these data objects is preferred (the first one if not explicitly changed by using the second parameter of Add()) and its format determines the preferred format of the composite data object as well.

See wxDataObject documentation for the reasons why you might prefer to use wxDataObject directly instead of wxDataObjectComposite for efficiency reasons.

This example shows how a composite data object capable of storing either bitmaps or file names (presumably of bitmap files) can be initialized and used:

dataobj->Add(new wxBitmapDataObject(), true);
dataobj->Add(new wxFileDataObject());
wxDragResult MyDropTarget::OnData(wxCoord x, wxCoord y,
wxDragResult defaultDragResult)
if ( !GetData() )
return wxDragNone;
dataobjComp = static_cast<wxDataObjectComposite *>(GetDataObject());
wxDataFormat format = dataobjComp->GetReceivedFormat();
wxDataObject *dataobj = dataobjComp->GetObject(format);
switch ( format.GetType() )
dataobjBitmap = static_cast<wxBitmapDataObject *>(dataobj);
... use dataobj->GetBitmap() ...
dataobjFile = static_cast<wxFileDataObject *>(dataobj);
... use dataobj->GetFilenames() ...
wxFAIL_MSG( "unexpected data object format" );
return defaultDragResult;

Library:  wxCore
Category:  Clipboard and Drag & Drop
See also
Drag and Drop Overview, wxDataObject, wxDataObjectSimple, wxFileDataObject, wxTextDataObject, wxBitmapDataObject

Public Member Functions

 wxDataObjectComposite ()
 The default constructor. More...
void Add (wxDataObjectSimple *dataObject, bool preferred=false)
 Adds the dataObject to the list of supported objects and it becomes the preferred object if preferred is true. More...
wxDataFormat GetReceivedFormat () const
 Report the format passed to the SetData() method. More...
wxDataObjectSimpleGetObject (const wxDataFormat &format, wxDataObject::Direction dir=wxDataObject::Get) const
 Returns the pointer to the object which supports the passed format for the specified direction. More...
- Public Member Functions inherited from wxDataObject
 wxDataObject ()
 Constructor. More...
virtual ~wxDataObject ()
 Destructor. More...
virtual void GetAllFormats (wxDataFormat *formats, Direction dir=Get) const =0
 Copies all formats supported in the given direction dir to the array pointed to by formats. More...
virtual bool GetDataHere (const wxDataFormat &format, void *buf) const =0
 The method will write the data of the format format to the buffer buf. More...
virtual size_t GetDataSize (const wxDataFormat &format) const =0
 Returns the data size of the given format format. More...
virtual size_t GetFormatCount (Direction dir=Get) const =0
 Returns the number of available formats for rendering or setting the data. More...
virtual wxDataFormat GetPreferredFormat (Direction dir=Get) const =0
 Returns the preferred format for either rendering the data (if dir is Get, its default value) or for setting it. More...
virtual bool SetData (const wxDataFormat &format, size_t len, const void *buf)
 Set the data in the format format of the length len provided in the buffer buf. More...
bool IsSupported (const wxDataFormat &format, Direction dir=Get) const
 Returns true if this format is supported. More...

Additional Inherited Members

- Public Types inherited from wxDataObject
enum  Direction {
  Get = 0x01,
  Set = 0x02,
  Both = 0x03

Constructor & Destructor Documentation

wxDataObjectComposite::wxDataObjectComposite ( )

The default constructor.

Member Function Documentation

void wxDataObjectComposite::Add ( wxDataObjectSimple dataObject,
bool  preferred = false 

Adds the dataObject to the list of supported objects and it becomes the preferred object if preferred is true.

wxDataObjectSimple* wxDataObjectComposite::GetObject ( const wxDataFormat format,
wxDataObject::Direction  dir = wxDataObject::Get 
) const

Returns the pointer to the object which supports the passed format for the specified direction.

NULL is returned if the specified format is not supported for this direction dir. The returned pointer is owned by wxDataObjectComposite itself and shouldn't be deleted by caller.

wxDataFormat wxDataObjectComposite::GetReceivedFormat ( ) const

Report the format passed to the SetData() method.

This should be the format of the data object within the composite that received data from the clipboard or the DnD operation. You can use this method to find out what kind of data object was received.