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move wxDataFormat and wxDataObject docs at the beginning of the file, before the derived classes' docs.

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Many small improvements.
Document wxTextDataObject::GetFormatCount, GetAllFormats(), GetFormat() functions as the wxDataObjectSimple docs for those functions result misleading for wxTextDataObject (closes #10431)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@59390 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Francesco Montorsi
2009-03-06 22:36:03 +00:00
parent caa4f8ff5c
commit 98b04f2112
1 changed files with 323 additions and 299 deletions
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622
interface/wx/dataobj.h
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@@ -6,6 +6,288 @@
// Licence: wxWindows license // Licence: wxWindows license
///////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////
/**
@class wxDataFormat
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 (@c CLIPFORMAT
under Windows or @c Atom under X11, for example) and the standard formats
are, indeed, just numbers which can be implicitly converted to wxDataFormat.
The standard formats are:
@beginDefList
@itemdef{wxDF_INVALID,
An invalid format - used as default argument for functions taking
a wxDataFormat argument sometimes.}
@itemdef{wxDF_TEXT,
Text format (wxString).}
@itemdef{wxDF_BITMAP,
A bitmap (wxBitmap).}
@itemdef{wxDF_METAFILE,
A metafile (wxMetafile, Windows only).}
@itemdef{wxDF_FILENAME,
A list of filenames.}
@itemdef{wxDF_HTML,
An HTML string. This is only valid when passed to
wxSetClipboardData when compiled with Visual C++ in non-Unicode
mode.}
@endDefList
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
@c 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 @e 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!
@library{wxbase}
@category{dnd}
@see @ref overview_dnd, @ref page_samples_dnd, wxDataObject
*/
class wxDataFormat
{
public:
/**
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(wxDataFormatId format = wxDF_INVALID);
/**
Constructs a data format object for a custom format identified by its
name @a format.
*/
wxDataFormat(const wxString& format);
/**
Returns the name of a custom format (this function will fail for a
standard format).
*/
wxString GetId() const;
/**
Returns the platform-specific number identifying the format.
*/
wxDataFormatId GetType() const;
/**
Sets the format to be the custom format identified by the given name.
*/
void SetId(const wxString& format);
/**
Sets the format to the given value, which should be one of wxDF_XXX
constants.
*/
void SetType(wxDataFormatId type);
/**
Returns @true if the formats are different.
*/
bool operator !=(wxDataFormatId format) const;
/**
Returns @true if the formats are equal.
*/
bool operator ==(wxDataFormatId format) const;
};
/**
@class wxDataObject
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 enumeration type which
distinguishes between them.
See wxDataFormat 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 and
wxDataObjectComposite. wxDataObjectSimple is the simplest wxDataObject
possible and only holds data in a single format (such as HTML or text) and
wxDataObjectComposite is the simplest way to implement a wxDataObject that
does support multiple formats because it achieves this by simply holding
several wxDataObjectSimple 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):
-# Use one of the built-in classes.
- You may use wxTextDataObject, wxBitmapDataObject wxFileDataObject,
wxURLDataObject in the simplest cases when you only need to support
one format and your data is either text, bitmap or list of files.
-# Use wxDataObjectSimple
- Deriving from wxDataObjectSimple is the simplest solution for custom
data - you will only support one format and so probably won't be able
to communicate with other programs, but data transfer will work in
your program (or between different instances of it).
-# Use wxDataObjectComposite
- This is a simple but powerful solution which allows you to support
any number of formats (either standard or custom if you combine it
with the previous solution).
-# Use wxDataObject directly
- This is the solution for maximum flexibility and efficiency, but it
is also the most difficult to implement.
Please note that the easiest way to use drag and drop and the clipboard
with multiple formats is by using wxDataObjectComposite, but it is not the
most efficient one as each wxDataObjectSimple 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, @e 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 @e available.
You may also derive your own data object classes from wxCustomDataObject
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().
@beginWxPythonOnly
At this time this class is not directly usable from wxPython. Derive a
class from wxPyDataObjectSimple() instead.
@endWxPythonOnly
@beginWxPerlOnly
This class is not currently usable from wxPerl; you may use
Wx::PlDataObjectSimple instead.
@endWxPerlOnly
@library{wxcore}
@category{dnd}
@see @ref overview_dnd, @ref page_samples_dnd, wxFileDataObject,
wxTextDataObject, wxBitmapDataObject, wxCustomDataObject,
wxDropTarget, wxDropSource, wxTextDropTarget, wxFileDropTarget
*/
class wxDataObject
{
public:
enum Direction
{
/** Format is supported by GetDataHere() */
Get = 0x01,
/** Format is supported by SetData() */
Set = 0x02,
/**
Format is supported by both GetDataHere() and SetData()
(unused currently)
*/
Both = 0x03
};
/**
Constructor.
*/
wxDataObject();
/**
Destructor.
*/
virtual ~wxDataObject();
/**
Copies all formats supported in the given direction @a dir to the array
pointed to by @a formats.
There must be enough space for GetFormatCount(dir) formats in it.
*/
virtual void GetAllFormats(wxDataFormat* formats,
Direction dir = Get) const = 0;
/**
The method will write the data of the format @a format in the buffer
@a buf and return @true on success, @false on failure.
*/
virtual bool GetDataHere(const wxDataFormat& format, void* buf) const = 0;
/**
Returns the data size of the given format @a format.
*/
virtual size_t GetDataSize(const wxDataFormat& format) const = 0;
/**
Returns the number of available formats for rendering or setting the
data.
*/
virtual size_t GetFormatCount(Direction dir = Get) const = 0;
/**
Returns the preferred format for either rendering the data (if @a dir
is @c Get, its default value) or for setting it. Usually this will be
the native format of the wxDataObject.
*/
virtual wxDataFormat GetPreferredFormat(Direction dir = Get) const = 0;
/**
Set the data in the format @a format of the length @a len provided in
the buffer @a buf.
@return @true on success, @false on failure.
*/
virtual bool SetData(const wxDataFormat& format, size_t len, const void* buf);
/**
Returns true if this format is supported.
*/
bool IsSupported(const wxDataFormat& format, Direction dir = Get) const;
};
/** /**
@class wxCustomDataObject @class wxCustomDataObject
@@ -144,9 +426,10 @@ public:
/** /**
@class wxDataObjectSimple @class wxDataObjectSimple
This is the simplest possible implementation of the wxDataObject class. The This is the simplest possible implementation of the wxDataObject class.
data object of (a class derived from) this class only supports one format, The data object of (a class derived from) this class only supports
so the number of virtual functions to be implemented is reduced. <strong>one format</strong>, so the number of virtual functions to
be implemented is reduced.
Notice that this is still an abstract base class and cannot be used Notice that this is still an abstract base class and cannot be used
directly, it must be derived. The objects supporting rendering the data directly, it must be derived. The objects supporting rendering the data
@@ -181,9 +464,9 @@ public:
wxDataObjectSimple(const wxDataFormat& format = wxFormatInvalid); wxDataObjectSimple(const wxDataFormat& format = wxFormatInvalid);
/** /**
Copy the data to the buffer, return @true on success. Must be Copy the data to the buffer, return @true on success.
implemented in the derived class if the object supports rendering its Must be implemented in the derived class if the object supports rendering
data. its data.
@beginWxPythonOnly @beginWxPythonOnly
When implementing this method in wxPython, no additional parameters are When implementing this method in wxPython, no additional parameters are
@@ -199,15 +482,15 @@ public:
virtual size_t GetDataSize() const; virtual size_t GetDataSize() const;
/** /**
Returns the (one and only one) format supported by this object. It is Returns the (one and only one) format supported by this object.
assumed that the format is supported in both directions. It is assumed that the format is supported in both directions.
*/ */
const wxDataFormat& GetFormat() const; const wxDataFormat& GetFormat() const;
/** /**
Copy the data from the buffer, return @true on success. Must be Copy the data from the buffer, return @true on success.
implemented in the derived class if the object supports setting its Must be implemented in the derived class if the object supports setting
data. its data.
@beginWxPythonOnly @beginWxPythonOnly
When implementing this method in wxPython, the data comes as a single When implementing this method in wxPython, the data comes as a single
@@ -317,8 +600,8 @@ public:
/** /**
@class wxTextDataObject @class wxTextDataObject
wxTextDataObject is a specialization of wxDataObject for text data. It can wxTextDataObject is a specialization of wxDataObjectSimple for text data.
be used without change to paste data into the wxClipboard or a It can be used without change to paste data into the wxClipboard or a
wxDropSource. A user may wish to derive a new class from this class for wxDropSource. A user may wish to derive a new class from this class for
providing text on-demand in order to minimize memory consumption when providing text on-demand in order to minimize memory consumption when
offering data in several formats, such as plain text and RTF because by offering data in several formats, such as plain text and RTF because by
@@ -368,6 +651,33 @@ public:
*/ */
virtual size_t GetTextLength() const; virtual size_t GetTextLength() const;
/**
Returns 2 under wxMac and wxGTK, where text data coming from the
clipboard may be provided as ANSI (@c wxDF_TEXT) or as Unicode text
(@c wxDF_UNICODETEXT, but only when @c wxUSE_UNICODE==1).
Returns 1 under other platforms (e.g. wxMSW) or when building in ANSI mode
(@c wxUSE_UNICODE==0).
*/
virtual size_t GetFormatCount(Direction dir = Get);
/**
Returns the preferred format supported by this object.
This is @c wxDF_TEXT or @c wxDF_UNICODETEXT depending on the platform
and from the build mode (i.e. from @c wxUSE_UNICODE).
*/
const wxDataFormat& GetFormat() const;
/**
Returns all the formats supported by wxTextDataObject.
Under wxMac and wxGTK they are @c wxDF_TEXT and @c wxDF_UNICODETEXT,
under other ports returns only one of the two, depending on the build mode.
*/
virtual void GetAllFormats(wxDataFormat* formats,
Direction dir = Get) const = 0;
/** /**
Sets the text associated with the data object. This method is called Sets the text associated with the data object. This method is called
when the data object receives the data and, by default, copies the text when the data object receives the data and, by default, copies the text
@@ -420,289 +730,3 @@ public:
}; };
/**
@class wxDataFormat
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 (@c CLIPFORMAT
under Windows or @c Atom under X11, for example) and the standard formats
are, indeed, just numbers which can be implicitly converted to wxDataFormat.
The standard formats are:
@beginDefList
@itemdef{wxDF_INVALID,
An invalid format - used as default argument for functions taking
a wxDataFormat argument sometimes.}
@itemdef{wxDF_TEXT,
Text format (wxString).}
@itemdef{wxDF_BITMAP,
A bitmap (wxBitmap).}
@itemdef{wxDF_METAFILE,
A metafile (wxMetafile, Windows only).}
@itemdef{wxDF_FILENAME,
A list of filenames.}
@itemdef{wxDF_HTML,
An HTML string. This is only valid when passed to
wxSetClipboardData when compiled with Visual C++ in non-Unicode
mode.}
@endDefList
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
@c 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 @e 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!
@library{wxbase}
@category{dnd}
@see @ref overview_dnd, @ref page_samples_dnd, wxDataObject
*/
class wxDataFormat
{
public:
/**
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(wxDataFormatId format = wxDF_INVALID);
/**
Constructs a data format object for a custom format identified by its
name @a format.
*/
wxDataFormat(const wxString& format);
/**
Returns the name of a custom format (this function will fail for a
standard format).
*/
wxString GetId() const;
/**
Returns the platform-specific number identifying the format.
*/
wxDataFormatId GetType() const;
/**
Sets the format to be the custom format identified by the given name.
*/
void SetId(const wxString& format);
/**
Sets the format to the given value, which should be one of wxDF_XXX
constants.
*/
void SetType(wxDataFormatId type);
/**
Returns @true if the formats are different.
*/
bool operator !=(wxDataFormatId format) const;
/**
Returns @true if the formats are equal.
*/
bool operator ==(wxDataFormatId format) const;
};
/**
@class wxDataObject
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 an enumeration type which distinguishes between them:
@code
enum Direction
{
Get = 0x01, // format is supported by GetDataHere()
Set = 0x02 // format is supported by SetData()
Both = 0x03 // format is supported by both (unused currently)
};
@endcode
See wxDataFormat 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 and
wxDataObjectComposite. wxDataObjectSimple is the simplest wxDataObject
possible and only holds data in a single format (such as HTML or text) and
wxDataObjectComposite is the simplest way to implement a wxDataObject that
does support multiple formats because it achieves this by simply holding
several wxDataObjectSimple 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):
-# Use one of the built-in classes.
- You may use wxTextDataObject, wxBitmapDataObject or wxFileDataObject
in the simplest cases when you only need to support one format and
your data is either text, bitmap or list of files.
-# Use wxDataObjectSimple
- Deriving from wxDataObjectSimple is the simplest solution for custom
data - you will only support one format and so probably won't be able
to communicate with other programs, but data transfer will work in
your program (or between different copies of it).
-# Use wxDataObjectComposite
- This is a simple but powerful solution which allows you to support
any number of formats (either standard or custom if you combine it
with the previous solution).
-# Use wxDataObject Directly
- This is the solution for maximal flexibility and efficiency, but it
is also the most difficult to implement.
Please note that the easiest way to use drag and drop and the clipboard
with multiple formats is by using wxDataObjectComposite, but it is not the
most efficient one as each wxDataObjectSimple 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, copy 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.
There are several predefined data object classes derived from
wxDataObjectSimple: wxFileDataObject, wxTextDataObject, wxBitmapDataObject
and wxURLDataObject which can be used without change.
You may also derive your own data object classes from wxCustomDataObject
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().
@beginWxPythonOnly
At this time this class is not directly usable from wxPython. Derive a
class from wxPyDataObjectSimple() instead.
@endWxPythonOnly
@beginWxPerlOnly
This class is not currently usable from wxPerl; you may use
Wx::PlDataObjectSimple instead.
@endWxPerlOnly
@library{wxcore}
@category{dnd}
@see @ref overview_dnd, @ref page_samples_dnd, wxFileDataObject,
wxTextDataObject, wxBitmapDataObject, wxCustomDataObject,
wxDropTarget, wxDropSource, wxTextDropTarget, wxFileDropTarget
*/
class wxDataObject
{
public:
enum Direction
{
/** Format is supported by GetDataHere() */
Get = 0x01,
/** Format is supported by SetData() */
Set = 0x02,
};
/**
Constructor.
*/
wxDataObject();
/**
Destructor.
*/
virtual ~wxDataObject();
/**
Copy all supported formats in the given direction to the array pointed
to by @a formats. There is enough space for GetFormatCount(dir) formats
in it.
*/
virtual void GetAllFormats(wxDataFormat* formats,
Direction dir = Get) const = 0;
/**
The method will write the data of the format @a format in the buffer
@a buf and return @true on success, @false on failure.
*/
virtual bool GetDataHere(const wxDataFormat& format, void* buf) const = 0;
/**
Returns the data size of the given format @a format.
*/
virtual size_t GetDataSize(const wxDataFormat& format) const = 0;
/**
Returns the number of available formats for rendering or setting the
data.
*/
virtual size_t GetFormatCount(Direction dir = Get) const = 0;
/**
Returns the preferred format for either rendering the data (if @a dir
is @c Get, its default value) or for setting it. Usually this will be
the native format of the wxDataObject.
*/
virtual wxDataFormat GetPreferredFormat(Direction dir = Get) const = 0;
/**
Set the data in the format @a format of the length @a len provided in
the buffer @a buf.
@return @true on success, @false on failure.
*/
virtual bool SetData(const wxDataFormat& format, size_t len, const void* buf);
/**
Returns true if this format is supported.
*/
bool IsSupported(const wxDataFormat& format, Direction dir = Get) const;
};