1 /////////////////////////////////////////////////////////////////////////////
3 // Purpose: interface of wxCustomDataObject
4 // Author: wxWidgets team
6 // Licence: wxWindows license
7 /////////////////////////////////////////////////////////////////////////////
10 @class wxCustomDataObject
13 wxCustomDataObject is a specialization of
14 wxDataObjectSimple for some
15 application-specific data in arbitrary (either custom or one of the standard
16 ones). The only restriction is that it is supposed that this data can be
17 copied bitwise (i.e. with @c memcpy()), so it would be a bad idea to make
18 it contain a C++ object (though C struct is fine).
20 By default, wxCustomDataObject stores the data inside in a buffer. To put the
21 data into the buffer you may use either
22 wxCustomDataObject::SetData or
23 wxCustomDataObject::TakeData depending on whether you want
24 the object to make a copy of data or not.
26 If you already store the data in another place, it may be more convenient and
27 efficient to provide the data on-demand which is possible too if you override
28 the virtual functions mentioned below.
35 class wxCustomDataObject
: public wxDataObjectSimple
39 The constructor accepts a @a format argument which specifies the (single)
40 format supported by this object. If it isn't set here,
41 wxDataObjectSimple::SetFormat should be used.
43 wxCustomDataObject(const wxDataFormat
& format
= wxFormatInvalid
);
46 The destructor will free the data hold by the object. Notice that although it
47 calls a virtual Free() function, the base
48 class version will always be called (C++ doesn't allow calling virtual
49 functions from constructors or destructors), so if you override @c Free(), you
50 should override the destructor in your class as well (which would probably
51 just call the derived class' version of @c Free()).
53 ~wxCustomDataObject();
56 This function is called to allocate @a size bytes of memory from SetData().
57 The default version just uses the operator new.
59 virtual void* Alloc(size_t size
);
62 This function is called when the data is freed, you may override it to anything
63 you want (or may be nothing at all). The default version calls operator
69 Returns a pointer to the data.
71 virtual void* GetData() const;
74 Returns the data size in bytes.
76 virtual size_t GetSize() const;
79 Set the data. The data object will make an internal copy.
81 virtual void SetData(size_t size
, const void data
);
84 Like SetData(), but doesn't copy the data -
85 instead the object takes ownership of the pointer.
86 @b wxPython note: This method expects a string in wxPython. You can pass
87 nearly any object by pickling it first.
89 virtual void TakeData(size_t size
, const void data
);
95 @class wxDataObjectComposite
98 wxDataObjectComposite is the simplest
99 wxDataObject derivation which may be used to support
100 multiple formats. It contains several
101 wxDataObjectSimple objects and supports any
102 format supported by at least one of them. Only one of these data objects is
103 @e preferred (the first one if not explicitly changed by using the second
104 parameter of wxDataObjectComposite::Add) and its format determines
105 the preferred format of the composite data object as well.
107 See wxDataObject documentation for the reasons why you
108 might prefer to use wxDataObject directly instead of wxDataObjectComposite for
114 @see @ref overview_wxdndoverview "Clipboard and drag and drop overview",
115 wxDataObject, wxDataObjectSimple, wxFileDataObject, wxTextDataObject, wxBitmapDataObject
117 class wxDataObjectComposite
: public wxDataObject
121 The default constructor.
123 wxDataObjectComposite();
126 Adds the @a dataObject to the list of supported objects and it becomes the
127 preferred object if @a preferred is @true.
129 void Add(wxDataObjectSimple dataObject
, bool preferred
= false);
132 Report the format passed to the SetData method. This should be the
133 format of the data object within the composite that recieved data from
134 the clipboard or the DnD operation. You can use this method to find
135 out what kind of data object was recieved.
137 wxDataFormat
GetReceivedFormat() const;
143 @class wxDataObjectSimple
146 This is the simplest possible implementation of the
147 wxDataObject class. The data object of (a class derived
148 from) this class only supports one format, so the number of virtual functions
149 to be implemented is reduced.
151 Notice that this is still an abstract base class and cannot be used but should
154 @b wxPython note: If you wish to create a derived wxDataObjectSimple class in
155 wxPython you should derive the class from wxPyDataObjectSimple
156 in order to get Python-aware capabilities for the various virtual
159 @b wxPerl note: In wxPerl, you need to derive your data object class
160 from Wx::PlDataObjectSimple.
165 @see @ref overview_wxdndoverview "Clipboard and drag and drop overview", @ref
166 overview_samplednd "DnD sample", wxFileDataObject, wxTextDataObject, wxBitmapDataObject
168 class wxDataObjectSimple
: public wxDataObject
172 Constructor accepts the supported format (none by default) which may also be
173 set later with SetFormat().
175 wxDataObjectSimple(const wxDataFormat
& format
= wxFormatInvalid
);
178 Copy the data to the buffer, return @true on success. Must be implemented in the
179 derived class if the object supports rendering its data.
181 virtual bool GetDataHere(void buf
) const;
184 Gets the size of our data. Must be implemented in the derived class if the
185 object supports rendering its data.
187 virtual size_t GetDataSize() const;
190 Returns the (one and only one) format supported by this object. It is supposed
191 that the format is supported in both directions.
193 const wxDataFormat
GetFormat() const;
196 Copy the data from the buffer, return @true on success. Must be implemented in
197 the derived class if the object supports setting its data.
198 @b wxPython note: When implementing this method in wxPython, the data comes
199 as a single string parameter rather than the two shown here.
201 virtual bool SetData(size_t len
, const void buf
);
204 Sets the supported format.
206 void SetFormat(const wxDataFormat
& format
);
212 @class wxBitmapDataObject
215 wxBitmapDataObject is a specialization of wxDataObject for bitmap data. It can
216 be used without change to paste data into the
217 wxClipboard or a wxDropSource. A
218 user may wish to derive a new class from this class for providing a bitmap
219 on-demand in order to minimize memory consumption when offering data in several
220 formats, such as a bitmap and GIF.
222 @b wxPython note: If you wish to create a derived wxBitmapDataObject class in
223 wxPython you should derive the class from wxPyBitmapDataObject
224 in order to get Python-aware capabilities for the various virtual
230 @see @ref overview_wxdndoverview "Clipboard and drag and drop overview",
231 wxDataObject, wxDataObjectSimple, wxFileDataObject, wxTextDataObject, wxDataObject
233 class wxBitmapDataObject
: public wxDataObjectSimple
237 Constructor, optionally passing a bitmap (otherwise use
240 wxBitmapDataObject(const wxBitmap
& bitmap
= wxNullBitmap
);
243 Returns the bitmap associated with the data object. You may wish to override
244 this method when offering data on-demand, but this is not required by
245 wxWidgets' internals. Use this method to get data in bitmap form from
248 virtual wxBitmap
GetBitmap() const;
251 Sets the bitmap associated with the data object. This method is called when the
252 data object receives data. Usually there will be no reason to override this
255 virtual void SetBitmap(const wxBitmap
& bitmap
);
264 A wxDataFormat is an encapsulation of a platform-specific format handle which
265 is used by the system for the clipboard and drag and drop operations. The
266 applications are usually only interested in, for example, pasting data from the
267 clipboard only if the data is in a format the program understands and a data
268 format is something which uniquely identifies this format.
270 On the system level, a data format is usually just a number (@c CLIPFORMAT
271 under Windows or @c Atom under X11, for example) and the standard formats
272 are, indeed, just numbers which can be implicitly converted to wxDataFormat.
273 The standard formats are:
280 An invalid format - used as default argument for
281 functions taking a wxDataFormat argument sometimes
287 Text format (wxString)
299 A metafile (wxMetafile, Windows only)
311 An HTML string. This is only valid when passed to wxSetClipboardData
312 when compiled with Visual C++ in non-Unicode mode
316 As mentioned above, these standard formats may be passed to any function taking
317 wxDataFormat argument because wxDataFormat has an implicit conversion from
318 them (or, to be precise from the type @c wxDataFormat::NativeFormat which is
319 the type used by the underlying platform for data formats).
321 Aside the standard formats, the application may also use custom formats which
322 are identified by their names (strings) and not numeric identifiers. Although
323 internally custom format must be created (or @e registered) first, you
324 shouldn't care about it because it is done automatically the first time the
325 wxDataFormat object corresponding to a given format name is created. The only
326 implication of this is that you should avoid having global wxDataFormat objects
327 with non-default constructor because their constructors are executed before the
328 program has time to perform all necessary initialisations and so an attempt to
329 do clipboard format registration at this time will usually lead to a crash!
334 @see @ref overview_wxdndoverview "Clipboard and drag and drop overview", @ref
335 overview_samplednd "DnD sample", wxDataObject
341 Constructs a data format object for a custom format identified by its name
344 wxDataFormat(const wxChar format
);
347 Returns the name of a custom format (this function will fail for a standard
350 wxString
GetId() const;
353 Returns the platform-specific number identifying the format.
355 NativeFormat
GetType() const;
358 Sets the format to be the custom format identified by the given name.
360 void SetId(const wxChar format
);
363 Sets the format to the given value, which should be one of wxDF_XXX constants.
365 void SetType(NativeFormat format
);
368 Returns @true if the formats are different.
370 bool operator !=(const wxDataFormat
& format
) const;
373 Returns @true if the formats are equal.
375 bool operator ==(const wxDataFormat
& format
) const;
381 @class wxURLDataObject
384 wxURLDataObject is a wxDataObject containing an URL
385 and can be used e.g. when you need to put an URL on or retrieve it from the
389 wxTheClipboard-SetData(new wxURLDataObject(url));
395 @see @ref overview_wxdndoverview "Clipboard and drag and drop overview",
398 class wxURLDataObject
402 Constructor, may be used to initialize the URL. If @a url is empty,
403 SetURL() can be used later.
405 wxURLDataObject(const wxString
& url
= wxEmptyString
);
408 Returns the URL stored by this object, as a string.
410 wxString
GetURL() const;
413 Sets the URL stored by this object.
415 void SetURL(const wxString
& url
);
424 A wxDataObject represents data that can be copied to or from the clipboard, or
425 dragged and dropped. The important thing about wxDataObject is that this is a
426 'smart' piece of data unlike 'dumb' data containers such as memory
427 buffers or files. Being 'smart' here means that the data object itself should
428 know what data formats it supports and how to render itself in each of
429 its supported formats.
431 A supported format, incidentally, is exactly the format in which the data can
432 be requested from a data object or from which the data object may be set. In
433 the general case, an object may support different formats on 'input' and
434 'output', i.e. it may be able to render itself in a given format but not be
435 created from data on this format or vice versa. wxDataObject defines an
441 Get = 0x01, // format is supported by GetDataHere()
442 Set = 0x02 // format is supported by SetData()
446 which distinguishes between them. See
447 wxDataFormat documentation for more about formats.
449 Not surprisingly, being 'smart' comes at a price of added complexity. This is
450 reasonable for the situations when you really need to support multiple formats,
451 but may be annoying if you only want to do something simple like cut and paste
454 To provide a solution for both cases, wxWidgets has two predefined classes
455 which derive from wxDataObject: wxDataObjectSimple and
456 wxDataObjectComposite.
457 wxDataObjectSimple is
458 the simplest wxDataObject possible and only holds data in a single format (such
459 as HTML or text) and wxDataObjectComposite is
460 the simplest way to implement a wxDataObject that does support multiple formats
461 because it achieves this by simply holding several wxDataObjectSimple objects.
463 So, you have several solutions when you need a wxDataObject class (and you need
464 one as soon as you want to transfer data via the clipboard or drag and drop):
468 @b 1. Use one of the built-in classes
471 You may use wxTextDataObject,
472 wxBitmapDataObject or wxFileDataObject in the simplest cases when you only need
473 to support one format and your data is either text, bitmap or list of files.
476 @b 2. Use wxDataObjectSimple
479 Deriving from wxDataObjectSimple is the simplest
480 solution for custom data - you will only support one format and so probably
481 won't be able to communicate with other programs, but data transfer will work
482 in your program (or between different copies of it).
485 @b 3. Use wxDataObjectComposite
488 This is a simple but powerful
489 solution which allows you to support any number of formats (either
490 standard or custom if you combine it with the previous solution).
493 @b 4. Use wxDataObject directly
496 This is the solution for
497 maximal flexibility and efficiency, but it is also the most difficult to
502 Please note that the easiest way to use drag and drop and the clipboard with
503 multiple formats is by using wxDataObjectComposite, but it is not the most
504 efficient one as each wxDataObjectSimple would contain the whole data in its
505 respective formats. Now imagine that you want to paste 200 pages of text in
506 your proprietary format, as well as Word, RTF, HTML, Unicode and plain text to
507 the clipboard and even today's computers are in trouble. For this case, you
508 will have to derive from wxDataObject directly and make it enumerate its
509 formats and provide the data in the requested format on demand.
511 Note that neither the GTK+ data transfer mechanisms for clipboard and
512 drag and drop, nor OLE data transfer, copy any data until another application
513 actually requests the data. This is in contrast to the 'feel' offered to the
514 user of a program who would normally think that the data resides in the
515 clipboard after having pressed 'Copy' - in reality it is only declared to be
518 There are several predefined data object classes derived from
519 wxDataObjectSimple: wxFileDataObject,
521 wxBitmapDataObject and
523 which can be used without change.
525 You may also derive your own data object classes from
526 wxCustomDataObject for user-defined types. The
527 format of user-defined data is given as a mime-type string literal, such as
528 "application/word" or "image/png". These strings are used as they are under
529 Unix (so far only GTK+) to identify a format and are translated into their
530 Windows equivalent under Win32 (using the OLE IDataObject for data exchange to
531 and from the clipboard and for drag and drop). Note that the format string
532 translation under Windows is not yet finished.
534 @b wxPython note: At this time this class is not directly usable from wxPython.
535 Derive a class from wxPyDataObjectSimple()
538 @b wxPerl note: This class is not currently usable from wxPerl; you may
539 use Wx::PlDataObjectSimple instead.
544 @see @ref overview_wxdndoverview "Clipboard and drag and drop overview", @ref
545 overview_samplednd "DnD sample", wxFileDataObject, wxTextDataObject, wxBitmapDataObject, wxCustomDataObject, wxDropTarget, wxDropSource, wxTextDropTarget, wxFileDropTarget
561 Copy all supported formats in the given direction to the array pointed to by
562 @e formats. There is enough space for GetFormatCount(dir) formats in it.
564 virtual void GetAllFormats(wxDataFormat
* formats
,
565 Direction dir
= Get
) const;
568 The method will write the data of the format @a format in the buffer @a buf and
569 return @true on success, @false on failure.
571 virtual bool GetDataHere(const wxDataFormat
& format
, void buf
) const;
574 Returns the data size of the given format @e format.
576 virtual size_t GetDataSize(const wxDataFormat
& format
) const;
579 Returns the number of available formats for rendering or setting the data.
581 virtual size_t GetFormatCount(Direction dir
= Get
) const;
584 Returns the preferred format for either rendering the data (if @a dir is @c Get,
585 its default value) or for setting it. Usually this will be the
586 native format of the wxDataObject.
588 virtual wxDataFormat
GetPreferredFormat(Direction dir
= Get
) const;
591 Set the data in the format @a format of the length @a len provided in the
593 Returns @true on success, @false on failure.
595 virtual bool SetData(const wxDataFormat
& format
, size_t len
,
602 @class wxTextDataObject
605 wxTextDataObject is a specialization of wxDataObject for text data. It can be
606 used without change to paste data into the wxClipboard
607 or a wxDropSource. A user may wish to derive a new
608 class from this class for providing text on-demand in order to minimize memory
609 consumption when offering data in several formats, such as plain text and RTF
610 because by default the text is stored in a string in this class, but it might
611 as well be generated when requested. For this,
612 wxTextDataObject::GetTextLength and
613 wxTextDataObject::GetText will have to be overridden.
615 Note that if you already have the text inside a string, you will not achieve
616 any efficiency gain by overriding these functions because copying wxStrings is
617 already a very efficient operation (data is not actually copied because
618 wxStrings are reference counted).
620 @b wxPython note: If you wish to create a derived wxTextDataObject class in
621 wxPython you should derive the class from wxPyTextDataObject
622 in order to get Python-aware capabilities for the various virtual
628 @see @ref overview_wxdndoverview "Clipboard and drag and drop overview",
629 wxDataObject, wxDataObjectSimple, wxFileDataObject, wxBitmapDataObject
631 class wxTextDataObject
: public wxDataObjectSimple
635 Constructor, may be used to initialise the text (otherwise
636 SetText() should be used later).
638 wxTextDataObject(const wxString
& text
= wxEmptyString
);
641 Returns the text associated with the data object. You may wish to override
642 this method when offering data on-demand, but this is not required by
643 wxWidgets' internals. Use this method to get data in text form from
646 virtual wxString
GetText() const;
649 Returns the data size. By default, returns the size of the text data
650 set in the constructor or using SetText().
651 This can be overridden to provide text size data on-demand. It is recommended
652 to return the text length plus 1 for a trailing zero, but this is not
655 virtual size_t GetTextLength() const;
658 Sets the text associated with the data object. This method is called
659 when the data object receives the data and, by default, copies the text into
660 the member variable. If you want to process the text on the fly you may wish to
661 override this function.
663 virtual void SetText(const wxString
& strText
);
669 @class wxFileDataObject
672 wxFileDataObject is a specialization of wxDataObject
673 for file names. The program works with it just as if it were a list of absolute
675 names, but internally it uses the same format as
676 Explorer and other compatible programs under Windows or GNOME/KDE filemanager
677 under Unix which makes it possible to receive files from them using this
680 @b Warning: Under all non-Windows platforms this class is currently
681 "input-only", i.e. you can receive the files from another application, but
682 copying (or dragging) file(s) from a wxWidgets application is not currently
683 supported. PS: GTK2 should work as well.
688 @see wxDataObject, wxDataObjectSimple, wxTextDataObject, wxBitmapDataObject,
691 class wxFileDataObject
: public wxDataObjectSimple
700 @b MSW only: adds a file to the file list represented by this data object.
702 virtual void AddFile(const wxString
& file
);
705 Returns the array() of file names.
707 const wxArrayString
GetFilenames() const;