A wxDataFormat is an encapsulation of a platform-specific format handle which is used by the system for the clipboard and drag and drop operations. The applications are usually only interested in, for example, pasting data from the clipboard only if the data is in a format the program understands and a data format is something which uniquely identifies this format.
On the system level, a data format is usually just a number (CLIPFORMAT under Windows or Atom under X11, for example) and the standard formats are, indeed, just numbers which can be implicitly converted to wxDataFormat. The standard formats are:
| wxDF_INVALID | An invalid format - used as default argument for functions taking a wxDataFormat argument sometimes |
| wxDF_TEXT | Text format (wxString) |
| wxDF_BITMAP | A bitmap (wxBitmap) |
| wxDF_METAFILE | A metafile (wxMetafile, Windows only) |
| wxDF_FILENAME | A list of filenames |
| wxDF_HTML | An HTML string. This is only valid when passed to wxSetClipboardData when compiled with Visual C++ in non-Unicode mode |
As mentioned above, these standard formats may be passed to any function taking wxDataFormat argument because wxDataFormat has an implicit conversion from them (or, to be precise from the type wxDataFormat::NativeFormat which is the type used by the underlying platform for data formats).
Aside the standard formats, the application may also use custom formats which are identified by their names (strings) and not numeric identifiers. Although internally custom format must be created (or registered) first, you shouldn't care about it because it is done automatically the first time the wxDataFormat object corresponding to a given format name is created. The only implication of this is that you should avoid having global wxDataFormat objects with non-default constructor because their constructors are executed before the program has time to perform all necessary initialisations and so an attempt to do clipboard format registration at this time will usually lead to a crash!
Virtual functions to override
None
Derived from
None
See also
Clipboard and drag and drop overview, DnD sample, wxDataObject
Include files
<wx/dataobj.h>
Members
wxDataFormat::wxDataFormat
wxDataFormat::wxDataFormat
wxDataFormat::operator ==
wxDataFormat::operator !=
wxDataFormat::GetId
wxDataFormat::GetType
wxDataFormat::SetId
wxDataFormat::SetType
wxDataFormat(NativeFormat format = wxDF_INVALID)
Constructs a data format object for one of the standard data formats or an empty data object (use SetType or SetId later in this case)
wxDataFormat(const wxChar *format)
Constructs a data format object for a custom format identified by its name format.
bool operator ==(const wxDataFormat& format) const
Returns true if the formats are equal.
bool operator !=(const wxDataFormat& format) const
Returns true if the formats are different.
wxString GetId() const
Returns the name of a custom format (this function will fail for a standard format).
NativeFormat GetType() const
Returns the platform-specific number identifying the format.
void SetId(const wxChar *format)
Sets the format to be the custom format identified by the given name.
void SetType(NativeFormat format)
Sets the format to the given value, which should be one of wxDF_XXX constants.