1 /////////////////////////////////////////////////////////////////////////////
3 // Purpose: interface of wx*DataObject
4 // Author: wxWidgets team
6 // Licence: wxWindows license
7 /////////////////////////////////////////////////////////////////////////////
10 @class wxCustomDataObject
13 wxCustomDataObject is a specialization of wxDataObjectSimple for some
14 application-specific data in arbitrary (either custom or one of the
15 standard ones). The only restriction is that it is supposed that this data
16 can be copied bitwise (i.e. with @c memcpy()), so it would be a bad idea to
17 make it contain a C++ object (though C struct is fine).
19 By default, wxCustomDataObject stores the data inside in a buffer. To put
20 the data into the buffer you may use either SetData() or TakeData()
21 depending on whether you want the object to make a copy of data or not.
23 This class may be used as is, but if you don't want store the data inside
24 the object but provide it on demand instead, you should override GetSize(),
25 GetData() and SetData() (or may be only the first two or only the last one
26 if you only allow reading/writing the data).
33 class wxCustomDataObject
: public wxDataObjectSimple
37 The constructor accepts a @a format argument which specifies the
38 (single) format supported by this object. If it isn't set here,
39 wxDataObjectSimple::SetFormat() should be used.
41 wxCustomDataObject(const wxDataFormat
& format
= wxFormatInvalid
);
44 The destructor will free the data held by the object. Notice that
45 although it calls the virtual Free() function, the base class version
46 will always be called (C++ doesn't allow calling virtual functions from
47 constructors or destructors), so if you override Free(), you should
48 override the destructor in your class as well (which would probably
49 just call the derived class' version of Free()).
51 virtual ~wxCustomDataObject();
54 This function is called to allocate @a size bytes of memory from
55 SetData(). The default version just uses the operator new.
57 virtual void* Alloc(size_t size
);
60 This function is called when the data is freed, you may override it to
61 anything you want (or may be nothing at all). The default version calls
62 operator delete[] on the data.
67 Returns a pointer to the data.
69 virtual void* GetData() const;
72 Returns the data size in bytes.
74 virtual size_t GetSize() const;
77 Set the data. The data object will make an internal copy.
80 This method expects a string in wxPython. You can pass nearly any
81 object by pickling it first.
84 virtual void SetData(size_t size
, const void data
);
87 Like SetData(), but doesn't copy the data - instead the object takes
88 ownership of the pointer.
91 This method expects a string in wxPython. You can pass nearly any
92 object by pickling it first.
95 virtual void TakeData(size_t size
, const void data
);
101 @class wxDataObjectComposite
104 wxDataObjectComposite is the simplest wxDataObject derivation which may be
105 used to support multiple formats. It contains several wxDataObjectSimple
106 objects and supports any format supported by at least one of them. Only one
107 of these data objects is @e preferred (the first one if not explicitly
108 changed by using the second parameter of Add()) and its format determines
109 the preferred format of the composite data object as well.
111 See wxDataObject documentation for the reasons why you might prefer to use
112 wxDataObject directly instead of wxDataObjectComposite for efficiency
118 @see @ref overview_dnd, wxDataObject, wxDataObjectSimple, wxFileDataObject,
119 wxTextDataObject, wxBitmapDataObject
121 class wxDataObjectComposite
: public wxDataObject
125 The default constructor.
127 wxDataObjectComposite();
130 Adds the @a dataObject to the list of supported objects and it becomes
131 the preferred object if @a preferred is @true.
133 void Add(wxDataObjectSimple dataObject
, bool preferred
= false);
136 Report the format passed to the SetData() method. This should be the
137 format of the data object within the composite that recieved data from
138 the clipboard or the DnD operation. You can use this method to find
139 out what kind of data object was recieved.
141 wxDataFormat
GetReceivedFormat() const;
147 @class wxDataObjectSimple
150 This is the simplest possible implementation of the wxDataObject class. The
151 data object of (a class derived from) this class only supports one format,
152 so the number of virtual functions to be implemented is reduced.
154 Notice that this is still an abstract base class and cannot be used
155 directly, it must be derived. The objects supporting rendering the data
156 must override GetDataSize() and GetDataHere() while the objects which may
157 be set must override SetData(). Of course, the objects supporting both
158 operations must override all three methods.
161 If you wish to create a derived wxDataObjectSimple class in wxPython you
162 should derive the class from wxPyDataObjectSimple in order to get
163 Python-aware capabilities for the various virtual methods.
167 In wxPerl, you need to derive your data object class from
168 Wx::PlDataObjectSimple.
174 @see @ref overview_dnd, @ref page_samples_dnd, wxFileDataObject,
175 wxTextDataObject, wxBitmapDataObject
177 class wxDataObjectSimple
: public wxDataObject
181 Constructor accepts the supported format (none by default) which may
182 also be set later with SetFormat().
184 wxDataObjectSimple(const wxDataFormat
& format
= wxFormatInvalid
);
187 Copy the data to the buffer, return @true on success. Must be
188 implemented in the derived class if the object supports rendering its
192 When implementing this method in wxPython, no additional parameters are
193 required and the data should be returned from the method as a string.
196 virtual bool GetDataHere(void buf
) const;
199 Gets the size of our data. Must be implemented in the derived class if
200 the object supports rendering its data.
202 virtual size_t GetDataSize() const;
205 Returns the (one and only one) format supported by this object. It is
206 assumed that the format is supported in both directions.
208 const wxDataFormat
GetFormat() const;
211 Copy the data from the buffer, return @true on success. Must be
212 implemented in the derived class if the object supports setting its
216 When implementing this method in wxPython, the data comes as a single
217 string parameter rather than the two shown here.
220 virtual bool SetData(size_t len
, const void buf
);
223 Sets the supported format.
225 void SetFormat(const wxDataFormat
& format
);
231 @class wxBitmapDataObject
234 wxBitmapDataObject is a specialization of wxDataObject for bitmap data. It
235 can be used without change to paste data into the wxClipboard or a
236 wxDropSource. A user may wish to derive a new class from this class for
237 providing a bitmap on-demand in order to minimize memory consumption when
238 offering data in several formats, such as a bitmap and GIF.
240 This class may be used as is, but GetBitmap() may be overridden to increase
244 If you wish to create a derived wxBitmapDataObject class in wxPython you
245 should derive the class from wxPyBitmapDataObject in order to get
246 Python-aware capabilities for the various virtual methods.
252 @see @ref overview_dnd, wxDataObject, wxDataObjectSimple, wxFileDataObject,
253 wxTextDataObject, wxDataObject
255 class wxBitmapDataObject
: public wxDataObjectSimple
259 Constructor, optionally passing a bitmap (otherwise use SetBitmap()
262 wxBitmapDataObject(const wxBitmap
& bitmap
= wxNullBitmap
);
265 Returns the bitmap associated with the data object. You may wish to
266 override this method when offering data on-demand, but this is not
267 required by wxWidgets' internals. Use this method to get data in bitmap
268 form from the wxClipboard.
270 virtual wxBitmap
GetBitmap() const;
273 Sets the bitmap associated with the data object. This method is called
274 when the data object receives data. Usually there will be no reason to
275 override this function.
277 virtual void SetBitmap(const wxBitmap
& bitmap
);
286 A wxDataFormat is an encapsulation of a platform-specific format handle
287 which is used by the system for the clipboard and drag and drop operations.
288 The applications are usually only interested in, for example, pasting data
289 from the clipboard only if the data is in a format the program understands
290 and a data format is something which uniquely identifies this format.
292 On the system level, a data format is usually just a number (@c CLIPFORMAT
293 under Windows or @c Atom under X11, for example) and the standard formats
294 are, indeed, just numbers which can be implicitly converted to wxDataFormat.
295 The standard formats are:
298 @itemdef{wxDF_INVALID,
299 An invalid format - used as default argument for functions taking
300 a wxDataFormat argument sometimes.}
302 Text format (wxString).}
303 @itemdef{wxDF_BITMAP,
304 A bitmap (wxBitmap).}
305 @itemdef{wxDF_METAFILE,
306 A metafile (wxMetafile, Windows only).}
307 @itemdef{wxDF_FILENAME,
308 A list of filenames.}
310 An HTML string. This is only valid when passed to
311 wxSetClipboardData when compiled with Visual C++ in non-Unicode
315 As mentioned above, these standard formats may be passed to any function
316 taking wxDataFormat argument because wxDataFormat has an implicit
317 conversion from them (or, to be precise from the type
318 @c wxDataFormat::NativeFormat which is the type used by the underlying
319 platform for data formats).
321 Aside the standard formats, the application may also use custom formats
322 which are identified by their names (strings) and not numeric identifiers.
323 Although internally custom format must be created (or @e registered) first,
324 you shouldn't care about it because it is done automatically the first time
325 the wxDataFormat object corresponding to a given format name is created.
326 The only implication of this is that you should avoid having global
327 wxDataFormat objects with non-default constructor because their
328 constructors are executed before the program has time to perform all
329 necessary initialisations and so an attempt to do clipboard format
330 registration at this time will usually lead to a crash!
335 @see @ref overview_dnd, @ref page_samples_dnd, wxDataObject
341 Constructs a data format object for one of the standard data formats or
342 an empty data object (use SetType() or SetId() later in this case).
344 wxDataFormat(NativeFormat format
= wxDF_INVALID
);
346 Constructs a data format object for a custom format identified by its
349 wxDataFormat(const wxChar format
);
352 Returns the name of a custom format (this function will fail for a
355 wxString
GetId() const;
358 Returns the platform-specific number identifying the format.
360 NativeFormat
GetType() const;
363 Sets the format to be the custom format identified by the given name.
365 void SetId(const wxChar format
);
368 Sets the format to the given value, which should be one of wxDF_XXX
371 void SetType(NativeFormat format
);
374 Returns @true if the formats are different.
376 bool operator !=(const wxDataFormat
& format
) const;
379 Returns @true if the formats are equal.
381 bool operator ==(const wxDataFormat
& format
) const;
387 @class wxURLDataObject
390 wxURLDataObject is a wxDataObject containing an URL and can be used e.g.
391 when you need to put an URL on or retrieve it from the clipboard:
394 wxTheClipboard->SetData(new wxURLDataObject(url));
397 @note This class is derived from wxDataObjectComposite on Windows rather
398 than wxTextDataObject on all other platforms.
403 @see @ref overview_dnd, wxDataObject
405 class wxURLDataObject
: public wxTextDataObject
409 Constructor, may be used to initialize the URL. If @a url is empty,
410 SetURL() can be used later.
412 wxURLDataObject(const wxString
& url
= wxEmptyString
);
415 Returns the URL stored by this object, as a string.
417 wxString
GetURL() const;
420 Sets the URL stored by this object.
422 void SetURL(const wxString
& url
);
431 A wxDataObject represents data that can be copied to or from the clipboard,
432 or dragged and dropped. The important thing about wxDataObject is that this
433 is a 'smart' piece of data unlike 'dumb' data containers such as memory
434 buffers or files. Being 'smart' here means that the data object itself
435 should know what data formats it supports and how to render itself in each
436 of its supported formats.
438 A supported format, incidentally, is exactly the format in which the data
439 can be requested from a data object or from which the data object may be
440 set. In the general case, an object may support different formats on
441 'input' and 'output', i.e. it may be able to render itself in a given
442 format but not be created from data on this format or vice versa.
443 wxDataObject defines an enumeration type which distinguishes between them:
448 Get = 0x01, // format is supported by GetDataHere()
449 Set = 0x02 // format is supported by SetData()
453 See wxDataFormat documentation for more about formats.
455 Not surprisingly, being 'smart' comes at a price of added complexity. This
456 is reasonable for the situations when you really need to support multiple
457 formats, but may be annoying if you only want to do something simple like
460 To provide a solution for both cases, wxWidgets has two predefined classes
461 which derive from wxDataObject: wxDataObjectSimple and
462 wxDataObjectComposite. wxDataObjectSimple is the simplest wxDataObject
463 possible and only holds data in a single format (such as HTML or text) and
464 wxDataObjectComposite is the simplest way to implement a wxDataObject that
465 does support multiple formats because it achieves this by simply holding
466 several wxDataObjectSimple objects.
468 So, you have several solutions when you need a wxDataObject class (and you
469 need one as soon as you want to transfer data via the clipboard or drag and
472 -# Use one of the built-in classes.
473 - You may use wxTextDataObject, wxBitmapDataObject or wxFileDataObject
474 in the simplest cases when you only need to support one format and
475 your data is either text, bitmap or list of files.
476 -# Use wxDataObjectSimple
477 - Deriving from wxDataObjectSimple is the simplest solution for custom
478 data - you will only support one format and so probably won't be able
479 to communicate with other programs, but data transfer will work in
480 your program (or between different copies of it).
481 -# Use wxDataObjectComposite
482 - This is a simple but powerful solution which allows you to support
483 any number of formats (either standard or custom if you combine it
484 with the previous solution).
485 -# Use wxDataObject Directly
486 - This is the solution for maximal flexibility and efficiency, but it
487 is also the most difficult to implement.
489 Please note that the easiest way to use drag and drop and the clipboard
490 with multiple formats is by using wxDataObjectComposite, but it is not the
491 most efficient one as each wxDataObjectSimple would contain the whole data
492 in its respective formats. Now imagine that you want to paste 200 pages of
493 text in your proprietary format, as well as Word, RTF, HTML, Unicode and
494 plain text to the clipboard and even today's computers are in trouble. For
495 this case, you will have to derive from wxDataObject directly and make it
496 enumerate its formats and provide the data in the requested format on
499 Note that neither the GTK+ data transfer mechanisms for clipboard and drag
500 and drop, nor OLE data transfer, copy any data until another application
501 actually requests the data. This is in contrast to the 'feel' offered to
502 the user of a program who would normally think that the data resides in the
503 clipboard after having pressed 'Copy' - in reality it is only declared to
506 There are several predefined data object classes derived from
507 wxDataObjectSimple: wxFileDataObject, wxTextDataObject, wxBitmapDataObject
508 and wxURLDataObject which can be used without change.
510 You may also derive your own data object classes from wxCustomDataObject
511 for user-defined types. The format of user-defined data is given as a
512 mime-type string literal, such as "application/word" or "image/png". These
513 strings are used as they are under Unix (so far only GTK+) to identify a
514 format and are translated into their Windows equivalent under Win32 (using
515 the OLE IDataObject for data exchange to and from the clipboard and for
516 drag and drop). Note that the format string translation under Windows is
519 Each class derived directly from wxDataObject must override and implement
520 all of its functions which are pure virtual in the base class. The data
521 objects which only render their data or only set it (i.e. work in only one
522 direction), should return 0 from GetFormatCount().
525 At this time this class is not directly usable from wxPython. Derive a
526 class from wxPyDataObjectSimple() instead.
530 This class is not currently usable from wxPerl; you may use
531 Wx::PlDataObjectSimple instead.
537 @see @ref overview_dnd, @ref page_samples_dnd, wxFileDataObject,
538 wxTextDataObject, wxBitmapDataObject, wxCustomDataObject,
539 wxDropTarget, wxDropSource, wxTextDropTarget, wxFileDropTarget
555 Copy all supported formats in the given direction to the array pointed
556 to by @a formats. There is enough space for GetFormatCount(dir) formats
559 virtual void GetAllFormats(wxDataFormat
* formats
,
560 Direction dir
= Get
) const;
563 The method will write the data of the format @a format in the buffer
564 @a buf and return @true on success, @false on failure.
566 virtual bool GetDataHere(const wxDataFormat
& format
, void buf
) const;
569 Returns the data size of the given format @a format.
571 virtual size_t GetDataSize(const wxDataFormat
& format
) const;
574 Returns the number of available formats for rendering or setting the
577 virtual size_t GetFormatCount(Direction dir
= Get
) const;
580 Returns the preferred format for either rendering the data (if @a dir
581 is @c Get, its default value) or for setting it. Usually this will be
582 the native format of the wxDataObject.
584 virtual wxDataFormat
GetPreferredFormat(Direction dir
= Get
) const;
587 Set the data in the format @a format of the length @a len provided in
590 @return @true on success, @false on failure.
592 virtual bool SetData(const wxDataFormat
& format
, size_t len
,
599 @class wxTextDataObject
602 wxTextDataObject is a specialization of wxDataObject for text data. It can
603 be used without change to paste data into the wxClipboard or a
604 wxDropSource. A user may wish to derive a new class from this class for
605 providing text on-demand in order to minimize memory consumption when
606 offering data in several formats, such as plain text and RTF because by
607 default the text is stored in a string in this class, but it might as well
608 be generated when requested. For this, GetTextLength() and GetText() will
609 have to be overridden.
611 Note that if you already have the text inside a string, you will not
612 achieve any efficiency gain by overriding these functions because copying
613 wxStrings is already a very efficient operation (data is not actually
614 copied because wxStrings are reference counted).
617 If you wish to create a derived wxTextDataObject class in wxPython you
618 should derive the class from wxPyTextDataObject in order to get
619 Python-aware capabilities for the various virtual methods.
625 @see @ref overview_dnd, wxDataObject, wxDataObjectSimple, wxFileDataObject,
628 class wxTextDataObject
: public wxDataObjectSimple
632 Constructor, may be used to initialise the text (otherwise SetText()
633 should be used later).
635 wxTextDataObject(const wxString
& text
= wxEmptyString
);
638 Returns the text associated with the data object. You may wish to
639 override this method when offering data on-demand, but this is not
640 required by wxWidgets' internals. Use this method to get data in text
641 form from the wxClipboard.
643 virtual wxString
GetText() const;
646 Returns the data size. By default, returns the size of the text data
647 set in the constructor or using SetText(). This can be overridden to
648 provide text size data on-demand. It is recommended to return the text
649 length plus 1 for a trailing zero, but this is not strictly required.
651 virtual size_t GetTextLength() const;
654 Sets the text associated with the data object. This method is called
655 when the data object receives the data and, by default, copies the text
656 into the member variable. If you want to process the text on the fly
657 you may wish to override this function.
659 virtual void SetText(const wxString
& strText
);
665 @class wxFileDataObject
668 wxFileDataObject is a specialization of wxDataObject for file names. The
669 program works with it just as if it were a list of absolute file names, but
670 internally it uses the same format as Explorer and other compatible
671 programs under Windows or GNOME/KDE filemanager under Unix which makes it
672 possible to receive files from them using this class.
674 @warning Under all non-Windows platforms this class is currently
675 "input-only", i.e. you can receive the files from another
676 application, but copying (or dragging) file(s) from a wxWidgets
677 application is not currently supported. PS: GTK2 should work as
683 @see wxDataObject, wxDataObjectSimple, wxTextDataObject,
684 wxBitmapDataObject, wxDataObject
686 class wxFileDataObject
: public wxDataObjectSimple
695 Adds a file to the file list represented by this data object (Windows
698 virtual void AddFile(const wxString
& file
);
701 Returns the array of file names.
703 const wxArrayString
GetFilenames() const;