why constructor cannot be virtual Post: 302130103

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qimageformattype

QImageFormatType(3qt)													     QImageFormatType(3qt)

NAME

       QImageFormatType - Factory that makes QImageFormat objects

SYNOPSIS

       #include <qasyncimageio.h>

   Public Members
       virtual ~QImageFormatType ()
       virtual QImageFormat * decoderFor ( const uchar * buffer, int length ) = 0
       virtual const char * formatName () const = 0

   Protected Members
       QImageFormatType ()

DESCRIPTION

       The QImageFormatType class is a factory that makes QImageFormat objects.

       Whereas the QImageIO class allows for complete loading of images, QImageFormatType allows for incremental loading of images.

       New image file formats are installed by creating objects of derived classes of QImageFormatType. They must implement decoderFor() and
       formatName().

       QImageFormatType is a very simple class. Its only task is to recognize image data in some format and make a new object, subclassed from
       QImageFormat, which can decode that format.

       The factories for formats built into Qt are automatically defined before any other factory is initialized. If two factories would recognize
       an image format, the factory created last will override the earlier one; you can thus override current and future built-in formats.

       See also Graphics Classes, Image Processing Classes, and Multimedia Classes.

MEMBER FUNCTION DOCUMENTATION

QImageFormatType::QImageFormatType () [protected]
       Constructs a factory. It automatically registers itself with QImageDecoder.

QImageFormatType::~QImageFormatType () [virtual]
       Destroys a factory. It automatically unregisters itself from QImageDecoder.

QImageFormat * QImageFormatType::decoderFor ( const uchar * buffer, int length ) [pure virtual]
       Returns a decoder for decoding an image that starts with the bytes in buffer. The length of the data is given in length. This function
       should only return a decoder if it is certain that the decoder applies to data with the given header. Returns 0 if there is insufficient
       data in the header to make a positive identification or if the data is not recognized.

const char * QImageFormatType::formatName () const [pure virtual]
       Returns the name of the format supported by decoders from this factory. The string is statically allocated.

SEE ALSO

       http://doc.trolltech.com/qimageformattype.html http://www.trolltech.com/faq/tech.html

COPYRIGHT

       Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the license file included in the distribution for a complete license
       statement.

AUTHOR

       Generated automatically from the source code.

BUGS

       If you find a bug in Qt, please report it as described in http://doc.trolltech.com/bughowto.html.  Good bug reports help us to help you.
       Thank you.

       The definitive Qt documentation is provided in HTML format; it is located at $QTDIR/doc/html and can be read using Qt Assistant or with a
       web browser. This man page is provided as a convenience for those users who prefer man pages, although this format is not officially
       supported by Trolltech.

       If you find errors in this manual page, please report them to qt-bugs@trolltech.com.  Please include the name of the manual page
       (qimageformattype.3qt) and the Qt version (3.1.1).

Trolltech AS							  9 December 2002					     QImageFormatType(3qt)