wxWidgets/interface/convauto.h

/////////////////////////////////////////////////////////////////////////////
// Name:        convauto.h
// Purpose:     documentation for wxConvAuto class
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**
    @class wxConvAuto
    @wxheader{convauto.h}
    
    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 @ref wxConvAuto::getdefaultmbencoding 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 method, 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 
    @ref wxConvAuto::setdefaultmbencoding 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{FIXME}
    
    @seealso
    @ref overview_mbconvclasses "wxMBConv classes overview"
*/
class wxConvAuto : public wxMBConv
{
public:
    /**
        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 @e enc will be used to interpret it as multibyte text.
        The default value of this parameter, @c wxFONTENCODING_DEFAULT means
        that the global default value which can be set using
        @ref setdefaultmbencoding() SetFallbackEncoding method should be
        used. As with that method, passing @c 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
        @c 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 @c wxFONTENCODING_ISO8859_1 
        ensures that non-UTF-8 input will be treated as latin1.
    */
    wxConvAuto(wxFontEncoding enc = wxFONTENCODING_DEFAULT);

    /**
        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 void DisableFallbackEncoding();

    /**
        Returns the encoding used by default by wxConvAuto if no other encoding is
        explicitly specified in constructor. By default, returns 
        @c wxFONTENCODING_ISO8859_1 but can be changed using 
        @ref setdefaultmbencoding() SetFallbackEncoding method.
    */
    static wxFontEncoding GetFallbackEncoding();

    /**
        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 @ref getdefaultmbencoding() GetFallbackEncoding, is 
        @c wxFONTENCODING_ISO8859_1.
        
        Special values of @c wxFONTENCODING_SYSTEM or 
        @c wxFONTENCODING_MAX can be used for @e 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 @c wxFONTENCODING_DEFAULT value cannot be used here.
    */
    static void SetFallbackEncoding(wxFontEncoding enc);
};