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RedHat 9 (Linux i386) - man page for qimageio (redhat section 3qt)

QImageIO(3qt)									    QImageIO(3qt)

NAME
       QImageIO - Parameters for loading and saving images

SYNOPSIS
       #include <qimage.h>

   Public Members
       QImageIO ()
       QImageIO ( QIODevice * ioDevice, const char * format )
       QImageIO ( const QString & fileName, const char * format )
       ~QImageIO ()
       const QImage & image () const
       int status () const
       const char * format () const
       QIODevice * ioDevice () const
       QString fileName () const
       int quality () const
       QString description () const
       const char * parameters () const
       float gamma () const
       void setImage ( const QImage & image )
       void setStatus ( int status )
       void setFormat ( const char * format )
       void setIODevice ( QIODevice * ioDevice )
       void setFileName ( const QString & fileName )
       void setQuality ( int q )
       void setDescription ( const QString & description )
       void setParameters ( const char * parameters )
       void setGamma ( float gamma )
       bool read ()
       bool write ()

   Static Public Members
       const char * imageFormat ( const QString & fileName )
       const char * imageFormat ( QIODevice * d )
       QStrList inputFormats ()
       QStrList outputFormats ()
       void defineIOHandler ( const char * format, const char * header, const char * flags,
	   image_io_handler readImage, image_io_handler writeImage )

DESCRIPTION
       The QImageIO class contains parameters for loading and saving images.

       QImageIO contains a QIODevice object that is used for image data I/O. The programmer can
       install new image file formats in addition to those that Qt provides.

       Qt currently supports the following image file formats: PNG, BMP, XBM, XPM and PNM. It may
       also support JPEG, MNG and GIF, if specially configured during compilation. The different
       PNM formats are: PBM (P1 or P4), PGM (P2 or P5), and PPM (P3 or P6).

       You don't normally need to use this class; QPixmap::load(), QPixmap::save(), and QImage
       contain sufficient functionality.

       For image files that contain sequences of images, only the first is read. See QMovie for
       loading multiple images.

       PBM, PGM, and PPM format output is always in the more condensed raw format. PPM and PGM
       files with more than 256 levels of intensity are scaled down when reading.

       Warning: If you are in a country which 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 the 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
       PNG format.

       See also QImage, QPixmap, QFile, QMovie, Graphics Classes, Image Processing Classes, and
       Input/Output and Networking.

MEMBER FUNCTION DOCUMENTATION
QImageIO::QImageIO ()
       Constructs a QImageIO object with all parameters set to zero.

QImageIO::QImageIO ( QIODevice * ioDevice, const char * format )
       Constructs a QImageIO object with the I/O device ioDevice and a format tag.

QImageIO::QImageIO ( const QString & fileName, const char * format )
       Constructs a QImageIO object with the file name fileName and a format tag.

QImageIO::~QImageIO ()
       Destroys the object and all related data.

void QImageIO::defineIOHandler ( const char * format, const char * header, const char * flags,
       image_io_handler readImage, image_io_handler writeImage ) [static]
       Defines an image I/O handler for the image format called format, which is recognized using
       the regular expression header, read using readImage and written using writeImage.

       flags is a string of single-character flags for this format. The only flag defined
       currently is T (upper case), so the only legal value for flags are "T" and the empty
       string. The "T" flag means that the image file is a text file, and Qt should treat all
       newline conventions as equivalent. (XPM files and some PPM files are text files for
       example.)

       format is used to select a handler to write a QImage; header is used to select a handler
       to read an image file.

       If readImage is a null pointer, the QImageIO will not be able to read images in format. If
       writeImage is a null pointer, the QImageIO will not be able to write images in format. If
       both are null, the QImageIO object is valid but useless.

       Example:

	       void readGIF( QImageIO *image )
	       {
	       // read the image using the image->ioDevice()
	       }
	       void writeGIF( QImageIO *image )
	       {
	       // write the image using the image->ioDevice()
	       }
	       // add the GIF image handler
	       QImageIO::defineIOHandler( "GIF",
					  "^GIF[0-9][0-9][a-z]",
					  0,
					  readGIF,
					  writeGIF );

       Before the regex test, all the 0 bytes in the file header are converted to 1 bytes. This
       is done because when Qt was ASCII-based, QRegExp could not handle 0 bytes in strings.

       (Note that if one handlerIO supports writing a format and another supports reading it, Qt
       supports both reading and writing. If two handlers support the same operation, Qt chooses
       one arbitrarily.)

QString QImageIO::description () const
       Returns the image description string.

       See also setDescription().

QString QImageIO::fileName () const
       Returns the file name currently set.

       See also setFileName().

const char * QImageIO::format () const
       Returns the image format string or 0 if no format has been explicitly set.

float QImageIO::gamma () const
       Returns the gamma value at which the image will be viewed.

       See also setGamma().

const QImage &; QImageIO::image () const
       Returns the image currently set.

       See also setImage().

const char * QImageIO::imageFormat ( const QString & fileName ) [static]
       Returns a string that specifies the image format of the file fileName, or null if the file
       cannot be read or if the format is not recognized.

const char * QImageIO::imageFormat ( QIODevice * d ) [static]
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns a string that specifies the image format of the image read from IO device d, or 0
       if the device cannot be read or if the format is not recognized.

       Make sure that d is at the right position in the device (for example, at the beginning of
       the file).

       See also QIODevice::at().

QStrList QImageIO::inputFormats () [static]
       Returns a sorted list of image formats that are supported for image input.

QIODevice * QImageIO::ioDevice () const
       Returns the IO device currently set.

       See also setIODevice().

QStrList QImageIO::outputFormats () [static]
       Returns a sorted list of image formats that are supported for image output.

       Example: scribble/scribble.cpp.

const char * QImageIO::parameters () const
       Returns the image's parameters string.

       See also setParameters().

int QImageIO::quality () const
       Returns the quality of the written image, related to the compression ratio.

       See also setQuality() and QImage::save().

bool QImageIO::read ()
       Reads an image into memory and returns TRUE if the image was successfully read; otherwise
       returns FALSE.

       Before reading an image you must set an IO device or a file name. If both an IO device and
       a file name have been set, the IO device will be used.

       Setting the image file format string is optional.

       Note that this function does not set the format used to read the image. If you need that
       information, use the imageFormat() static functions.

       Example:

	       QImageIO iio;
	       QPixmap	pixmap;
	       iio.setFileName( "vegeburger.bmp" );
	       if ( image.read() )	  // ok
		   pixmap = iio.image();  // convert to pixmap

       See also setIODevice(), setFileName(), setFormat(), write(), and QPixmap::load().

void QImageIO::setDescription ( const QString & description )
       Sets the image description string for image handlers that support image descriptions to
       description.

       Currently, no image format supported by Qt uses the description string.

void QImageIO::setFileName ( const QString & fileName )
       Sets the name of the file to read or write an image from to fileName.

       See also setIODevice().

void QImageIO::setFormat ( const char * format )
       Sets the image format to format for the image to be read or written.

       It is necessary to specify a format before writing an image, but it is not necessary to
       specify a format before reading an image.

       If no format has been set, Qt guesses the image format before reading it. If a format is
       set the image will only be read if it has that format.

       See also read(), write(), and format().

void QImageIO::setGamma ( float gamma )
       Sets the gamma value at which the image will be viewed to gamma. If the image format
       stores a gamma value for which the image is intended to be used, then this setting will be
       used to modify the image. Setting to 0.0 will disable gamma correction (i.e. any
       specification in the file will be ignored).

       The default value is 0.0.

       See also gamma().

void QImageIO::setIODevice ( QIODevice * ioDevice )
       Sets the IO device to be used for reading or writing an image.

       Setting the IO device allows images to be read/written to any block-oriented QIODevice.

       If ioDevice is not null, this IO device will override file name settings.

       See also setFileName().

void QImageIO::setImage ( const QImage & image )
       Sets the image to image.

       See also image().

void QImageIO::setParameters ( const char * parameters )
       Sets the image's parameter string to parameters. This is for image handlers that require
       special parameters.

       Although the current image formats supported by Qt ignore the parameters string, it may be
       used in future extensions or by contributions (for example, JPEG).

       See also parameters().

void QImageIO::setQuality ( int q )
       Sets the quality of the written image to q, related to the compression ratio.

       q must be in the range -1..100. Specify 0 to obtain small compressed files, 100 for large
       uncompressed files. (-1 signifies the default compression.)

       See also quality() and QImage::save().

void QImageIO::setStatus ( int status )
       Sets the image IO status to status. A non-zero value indicates an error, whereas 0 means
       that the IO operation was successful.

       See also status().

int QImageIO::status () const
       Returns the image's IO status. A non-zero value indicates an error, whereas 0 means that
       the IO operation was successful.

       See also setStatus().

bool QImageIO::write ()
       Writes an image to an IO device and returns TRUE if the image was successfully written;
       otherwise returns FALSE.

       Before writing an image you must set an IO device or a file name. If both an IO device and
       a file name have been set, the IO device will be used.

       The image will be written using the specified image format.

       Example:

	       QImageIO iio;
	       QImage	im;
	       im = pixmap; // convert to image
	       iio.setImage( im );
	       iio.setFileName( "vegeburger.bmp" );
	       iio.setFormat( "BMP" );
	       if ( iio.write() )
		   // returned TRUE if written successfully

       See also setIODevice(), setFileName(), setFormat(), read(), and QPixmap::save().

SEE ALSO
       http://doc.trolltech.com/qimageio.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 (qimageio.3qt) and the Qt version (3.1.1).

Trolltech AS				 9 December 2002			    QImageIO(3qt)


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