Detailed Description

This class implements a Unicode to/from multibyte converter capable of automatically recognizing the encoding of the multibyte text on input.

The logic used is very simple: the class uses the BOM (byte order mark) if it's present and tries to interpret the input as UTF-8 otherwise. If this fails, the input is interpreted as being in the default multibyte encoding which can be specified in the constructor of a wxConvAuto instance and, in turn, defaults to the value of GetFallbackEncoding() if not explicitly given.

For the conversion from Unicode to multibyte, the same encoding as was previously used for multibyte to Unicode conversion is reused. If there had been no previous multibyte to Unicode conversion, UTF-8 is used by default. Notice that once the multibyte encoding is automatically detected, it doesn't change any more, i.e. it is entirely determined by the first use of wxConvAuto object in the multibyte-to-Unicode direction. However creating a copy of wxConvAuto object, either via the usual copy constructor or assignment operator, or using wxMBConv::Clone(), resets the automatically detected encoding so that the new copy will try to detect the encoding of the input on first use.

This class is used by default in wxWidgets classes and functions reading text from files such as wxFile, wxFFile, wxTextFile, wxFileConfig and various stream classes so the encoding set with its SetFallbackEncoding() method will affect how these classes treat input files. In particular, use this method to change the fall-back multibyte encoding used to interpret the contents of the files whose contents isn't valid UTF-8 or to disallow it completely.

Library: wxBase

Category: Data Structures

See Also: wxMBConv Overview

Public Member Functions
	wxConvAuto (wxFontEncoding enc=wxFONTENCODING_DEFAULT)
	Constructs a new wxConvAuto instance.

wxBOM	GetBOM () const
	Return the detected BOM type.

const char *	GetBOMChars (wxBOM bom, size_t *count)
	Return a pointer to the characters that makes up this BOM.

Public Member Functions inherited from wxMBConv
	wxMBConv ()
	Trivial default constructor.

virtual wxMBConv *	Clone () const =0
	This pure virtual function is overridden in each of the derived classes to return a new copy of the object it is called on.

virtual size_t	GetMBNulLen () const
	This function returns 1 for most of the multibyte encodings in which the string is terminated by a single `NUL`, 2 for UTF-16 and 4 for UTF-32 for which the string is terminated with 2 and 4 `NUL` characters respectively.

virtual size_t	ToWChar (wchar_t dst, size_t dstLen, const char src, size_t srcLen=wxNO_LEN) const
	Convert multibyte string to a wide character one.

virtual size_t	FromWChar (char dst, size_t dstLen, const wchar_t src, size_t srcLen=wxNO_LEN) const
	Converts wide character string to multibyte.

const wxWCharBuffer	cMB2WC (const char in, size_t inLen, size_t outLen) const
	Converts from multibyte encoding to Unicode by calling ToWChar() and allocating a temporary wxWCharBuffer to hold the result.

const wxWCharBuffer	cMB2WC (const wxCharBuffer &buf) const
	Converts a char buffer to wide char one.

const wxCharBuffer	cWC2MB (const wchar_t in, size_t inLen, size_t outLen) const
	Converts from Unicode to multibyte encoding by calling FromWChar() and allocating a temporary wxCharBuffer to hold the result.

const wxCharBuffer	cWC2MB (const wxWCharBuffer &buf) const
	Converts a wide char buffer to char one.

virtual size_t	MB2WC (wchar_t out, const char in, size_t outLen) const

virtual size_t	WC2MB (char buf, const wchar_t psz, size_t n) const

const char *	cMB2WX (const char *psz) const
	Converts from multibyte encoding to the current wxChar type (which depends on whether wxUSE_UNICODE is set to 1).

const wxWCharBuffer	cMB2WX (const char *psz) const
	Converts from multibyte encoding to the current wxChar type (which depends on whether wxUSE_UNICODE is set to 1).

const wchar_t *	cWC2WX (const wchar_t *psz) const
	Converts from Unicode to the current wxChar type.

const wxCharBuffer	cWC2WX (const wchar_t *psz) const
	Converts from Unicode to the current wxChar type.

const char *	cWX2MB (const wxChar *psz) const
	Converts from the current wxChar type to multibyte encoding.

const wxCharBuffer	cWX2MB (const wxChar *psz) const
	Converts from the current wxChar type to multibyte encoding.

const wchar_t *	cWX2WC (const wxChar *psz) const
	Converts from the current wxChar type to Unicode.

const wxWCharBuffer	cWX2WC (const wxChar *psz) const
	Converts from the current wxChar type to Unicode.

Static Public Member Functions
static void	DisableFallbackEncoding ()
	Disable the use of the fall back encoding: if the input doesn't have a BOM and is not valid UTF-8, the conversion will fail.

static wxFontEncoding	GetFallbackEncoding ()
	Returns the encoding used by default by wxConvAuto if no other encoding is explicitly specified in constructor.

static void	SetFallbackEncoding (wxFontEncoding enc)
	Changes the encoding used by default by wxConvAuto if no other encoding is explicitly specified in constructor.

static wxBOM	DetectBOM (const char *src, size_t srcLen)
	Return the BOM type of this buffer.

Static Public Member Functions inherited from wxMBConv
static size_t	GetMaxMBNulLen ()
	Returns the maximal value which can be returned by GetMBNulLen() for any conversion object.

Constructor & Destructor Documentation

wxConvAuto::wxConvAuto ( wxFontEncoding enc = wxFONTENCODING_DEFAULT )

Constructs a new wxConvAuto instance.

The object will try to detect the input of the multibyte text given to its wxMBConv::ToWChar() method automatically but if the automatic detection of Unicode encodings fails, the fall-back encoding enc will be used to interpret it as multibyte text.

The default value of enc, wxFONTENCODING_DEFAULT, means that the global default value (which can be set using SetFallbackEncoding()) should be used. As with that method, passing wxFONTENCODING_MAX inhibits using this encoding completely so the input multibyte text will always be interpreted as UTF-8 in the absence of BOM and the conversion will fail if the input doesn't form valid UTF-8 sequence.

Another special value is wxFONTENCODING_SYSTEM which means to use the encoding currently used on the user system, i.e. the encoding returned by wxLocale::GetSystemEncoding(). Any other encoding will be used as is, e.g. passing wxFONTENCODING_ISO8859_1 ensures that non-UTF-8 input will be treated as latin1.

Member Function Documentation

static wxBOM wxConvAuto::DetectBOM	(	const char *	src,
		size_t	srcLen
	)

static

Return the BOM type of this buffer.

This is a helper function which is normally only used internally by wxConvAuto but provided for convenience of the code that wants to detect the encoding of a stream by checking it for BOM presence on its own.

Since: 2.9.3

static void wxConvAuto::DisableFallbackEncoding ( )

static

Disable the use of the fall back encoding: if the input doesn't have a BOM and is not valid UTF-8, the conversion will fail.

wxBOM wxConvAuto::GetBOM ( ) const

Return the detected BOM type.

The BOM type is detected after sufficiently many initial bytes have passed through this conversion object so it will always return wxBOM_Unknown immediately after the object creation but may return a different value later.

Since: 2.9.3

const char* wxConvAuto::GetBOMChars	(	wxBOM	bom,
		size_t *	count
	)

Return a pointer to the characters that makes up this BOM.

The returned character count is 2, 3 or 4, or undefined if the return value is NULL.

Parameters

bom	A valid BOM type, i.e. not wxBOM_Unknown or wxBOM_None.
count	A non-NULL pointer receiving the number of characters in this BOM.

Returns: Pointer to characters composing the BOM or NULL if BOM is unknown or invalid. Notice that the returned string is not NUL-terminated and may contain embedded NULs so count must be used to handle it correctly.

Since: 2.9.3

static wxFontEncoding wxConvAuto::GetFallbackEncoding ( )

static

Returns the encoding used by default by wxConvAuto if no other encoding is explicitly specified in constructor.

By default, returns wxFONTENCODING_ISO8859_1 but can be changed using SetFallbackEncoding().

static void wxConvAuto::SetFallbackEncoding ( wxFontEncoding enc )

static

Changes the encoding used by default by wxConvAuto if no other encoding is explicitly specified in constructor.

The default value, which can be retrieved using GetFallbackEncoding(), is wxFONTENCODING_ISO8859_1.

Special values of wxFONTENCODING_SYSTEM or wxFONTENCODING_MAX can be used for the enc parameter to use the encoding of the current user locale as fall back or not use any encoding for fall back at all, respectively (just as with the similar constructor parameter). However, wxFONTENCODING_DEFAULT can't be used here.

Detailed Description

Public Member Functions

Static Public Member Functions

Constructor & Destructor Documentation

Member Function Documentation