QImageDecoder(3qt)QImageDecoder(3qt)NAME
QImageDecoder - Incremental image decoder for all supported image
formats
SYNOPSIS
#include <qasyncimageio.h>
Public Members
QImageDecoder ( QImageConsumer * c )
~QImageDecoder ()
const QImage & image ()
int decode ( const uchar * buffer, int length )
Static Public Members
const char * formatName ( const uchar * buffer, int length )
QImageFormatType * format ( const char * name )
QStrList inputFormats ()
void registerDecoderFactory ( QImageFormatType * f )
void unregisterDecoderFactory ( QImageFormatType * f )
DESCRIPTION
The QImageDecoder class is an incremental image decoder for all
supported image formats.
New formats are installed by creating objects of class
QImageFormatType; the QMovie class can be used for all installed
incremental image formats. QImageDecoder is only useful for creating
new ways of feeding data to an QImageConsumer.
A QImageDecoder is a machine that decodes images. It takes encoded
image data via its decode() method and expresses its decoding by
supplying information to a QImageConsumer. It implements its decoding
by using a QImageFormat created by one of the currently-existing
QImageFormatType factory objects.
QImageFormatType and QImageFormat are the classes that you might need
to implement support for additional image formats.
Qt supports GIF reading if it is configured that way during
installation (see qgif.h). If it is, we are required to state that" The
Graphics Interchange Format(c) is the Copyright property of CompuServe
Incorporated. GIF(sm) is a Service Mark property of CompuServe
Incorporated."
Warning: If you are in a country that recognizes software patents and
in which Unisys holds a patent on LZW compression and/or decompression
and you want to use GIF, Unisys may require you to license that
technology. Such countries include Canada, Japan, the USA, France,
Germany, Italy and the UK.
GIF support may be removed completely in a future version of Qt. We
recommend using the MNG or PNG format.
See also Graphics Classes, Image Processing Classes, and Multimedia
Classes.
MEMBER FUNCTION DOCUMENTATIONQImageDecoder::QImageDecoder ( QImageConsumer * c )
Constructs a QImageDecoder that will send change information to the
QImageConsumer c.
QImageDecoder::~QImageDecoder ()
Destroys a QImageDecoder. The image it built is destroyed. The decoder
built by the factory for the file format is destroyed. The consumer for
which it decoded the image is not destroyed.
int QImageDecoder::decode ( const uchar * buffer, int length )
Call this function to decode some data into image changes. The data in
buffer will be decoded, sending change information to the
QImageConsumer of this QImageDecoder until one of the change functions
of the consumer returns FALSE. The length of the data is given in
length.
Returns the number of bytes consumed: 0 if consumption is complete, and
-1 if decoding fails due to invalid data.
QImageFormatType * QImageDecoder::format ( const char * name ) [static]
Returns a QImageFormatType by name. This might be used when the user
needs to force data to be interpreted as being in a certain format.
name is one of the formats listed by QImageDecoder::inputFormats().
Note that you will still need to supply decodable data to
result->decoderFor() before you can begin decoding the data.
const char * QImageDecoder::formatName ( const uchar * buffer, int length )
[static]
Call this function to find the name of the format of the given header.
The returned string is statically allocated. The function will look at
the first length characters in the buffer.
Returns 0 if the format is not recognized.
const QImage & QImageDecoder::image ()
Returns the image currently being decoded.
QStrList QImageDecoder::inputFormats () [static]
Returns a sorted list of formats for which asynchronous loading is
supported.
void QImageDecoder::registerDecoderFactory ( QImageFormatType * f ) [static]
Registers the new QImageFormatType f. This is not needed in application
code because factories call this themselves.
void QImageDecoder::unregisterDecoderFactory ( QImageFormatType * f ) [static]
Unregisters the QImageFormatType f. This is not needed in application
code because factories call this themselves.
SEE ALSO
http://doc.trolltech.com/qimagedecoder.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2007 Trolltech ASA, 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
(qimagedecoder.3qt) and the Qt version (3.3.8).
Trolltech AS 2 February 2007 QImageDecoder(3qt)