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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta name="robots" content="noindex,noarchive">
<title>Qt Toolkit - QImageIO Class</title><style type="text/css"><!--
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<h1 align=center>QImageIO Class Reference</h1><br clear="all">
<p>
The QImageIO class contains parameters for loading and saving images.
<a href="#details">More...</a>
<p>
<code>#include <<a href="qimage-h.html">qimage.h</a>></code>
<p><a href="qimageio-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li><span class="fn"><a href="qimageio.html#a0"><strong>QImageIO</strong></a>()</span>
<li><span class="fn"><a href="qimageio.html#a1"><strong>QImageIO</strong></a>(QIODevice*ioDevice, constchar*format)</span>
<li><span class="fn"><a href="qimageio.html#a2"><strong>QImageIO</strong></a>(constchar*fileName, constchar*format)</span>
<li><span class="fn"><a href="qimageio.html#a3"><strong>~QImageIO</strong></a>()</span>
<li><span class="fn">constQImage&<a href="qimageio.html#a4"><strong>image</strong></a>()const</span>
<li><span class="fn">int<a href="qimageio.html#a5"><strong>status</strong></a>()const</span>
<li><span class="fn">constchar*<a href="qimageio.html#a6"><strong>format</strong></a>()const</span>
<li><span class="fn">QIODevice*<a href="qimageio.html#a7"><strong>ioDevice</strong></a>()const</span>
<li><span class="fn">constchar*<a href="qimageio.html#a8"><strong>fileName</strong></a>()const</span>
<li><span class="fn">constchar*<a href="qimageio.html#a9"><strong>parameters</strong></a>()const</span>
<li><span class="fn">constchar*<a href="qimageio.html#b0"><strong>description</strong></a>()const</span>
<li><span class="fn">void<a href="qimageio.html#b1"><strong>setImage</strong></a>(constQImage&)</span>
<li><span class="fn">void<a href="qimageio.html#b2"><strong>setStatus</strong></a>(int)</span>
<li><span class="fn">void<a href="qimageio.html#b3"><strong>setFormat</strong></a>(constchar*)</span>
<li><span class="fn">void<a href="qimageio.html#b4"><strong>setIODevice</strong></a>(QIODevice*)</span>
<li><span class="fn">void<a href="qimageio.html#b5"><strong>setFileName</strong></a>(constchar*)</span>
<li><span class="fn">void<a href="qimageio.html#b6"><strong>setParameters</strong></a>(constchar*)</span>
<li><span class="fn">void<a href="qimageio.html#b7"><strong>setDescription</strong></a>(constchar*)</span>
<li><span class="fn">bool<a href="qimageio.html#b8"><strong>read</strong></a>()</span>
<li><span class="fn">bool<a href="qimageio.html#b9"><strong>write</strong></a>()</span>
</ul>
<h2>Static Public Members</h2>
<ul>
<li><span class="fn">constchar*<a href="qimageio.html#c6"><strong>imageFormat</strong></a>(constchar*fileName)</span>
<li><span class="fn">constchar*<a href="qimageio.html#c7"><strong>imageFormat</strong></a>(QIODevice*)</span>
<li><span class="fn">QStrList<a href="qimageio.html#c8"><strong>inputFormats</strong></a>()</span>
<li><span class="fn">QStrList<a href="qimageio.html#c9"><strong>outputFormats</strong></a>()</span>
<li><span class="fn">void<a href="qimageio.html#c5"><strong>defineIOHandler</strong></a>(constchar*format, constchar*header, constchar*flags, image_io_handlerread_image, image_io_handlerwrite_image)</span>
</ul>
<hr><h2><a name="details"></a>Detailed Description</h2>
The QImageIO class contains parameters for loading and saving images.
<p>
QImageIO contains a <a href="qiodevice.html">QIODevice</a> object that is used for image data I/O.
The programmer can install new image file formats in addition to those
that Qt implements.
<p>Qt currently supports the following image file formats: GIF (reading
only), BMP, XBM, XPM and PNM. The different PNM formats are: PBM
(P1), PGM (P2), PPM (P3), PBMRAW (P4), PGMRAW (P5) and PPMRAW (P6).
<p>Additional formats are available with the
<a href="imageio.html">Qt Image IO Extension</a> package.
<p>You will normally not need to use this class, <a href="qpixmap.html#d4">QPixmap::load</a>(),
<a href="qpixmap.html#d8">QPixmap::save</a>() and <a href="qimage.html">QImage</a> contain most of the needed functionality.
<p>For image files which contain sequences of images, only the first is
read. See the <a href="qmovie.html">QMovie</a> for loading multiple images.
<p>PBM, PGM, and PPM format output is only supported in PPMRAW format.<p><strong>Warning:</strong> Unisys has changed its position regarding GIF. If you are
in a country where Unisys holds a patent on LZW compression and/or
decompression, Unisys may require you to license that technology.
These countries include Canada, Japan, the USA, France, Germany,
Italy and the UK. There is more information on Unisys web site: <a
href="http://corp2.unisys.com/LeadStory/lzwfaq.html">Overview of
Unisys' position.</a> GIF support may be removed in a future version
of Qt. We recommend using the PNG format, which is available in the
<a href="imageio.html">Qt Image IO Extension</a> package.
<p>See also: <a href="qimage.html">QImage</a>, <a href="qpixmap.html">QPixmap</a>, <a href="qfile.html">QFile</a> and <a href="qmovie.html">QMovie</a>.
<hr><h2>Member Function Documentation</h2>
<h3 class="fn"><a name="a0"></a>QImageIO::QImageIO()</h3>
<p>Constructs a QImageIO object with all parameters set to zero.
<h3 class="fn"><a name="a1"></a>QImageIO::QImageIO(<a href="qiodevice.html">QIODevice</a>*ioDevice, constchar*format)</h3>
<p>Constructs a QImageIO object with an I/O device and a format tag.
<h3 class="fn"><a name="a2"></a>QImageIO::QImageIO(constchar*fileName, constchar*format)</h3>
<p>Constructs a QImageIO object with a file name and a format tag.
<h3 class="fn"><a name="a3"></a>QImageIO::~QImageIO()</h3>
<p>Destroys the object an all related data.
<h3 class="fn">void<a name="c5"></a>QImageIO::defineIOHandler(constchar*format, constchar*header, constchar*flags, image_io_handlerread_image, image_io_handlerwrite_image) <code>[static]</code></h3>
<p>Defines a image IO handler for a specified image format.
An image IO handler is responsible for reading and writing images.
<p>Arguments:
<ul>
<li><em>format</em> is the name of the format.
<li><em>header</em> is a regular expression that recognizes the image header.
<li><em>flags</em> is "T" for text formats like PBM; generally you will
want to use 0.
<li><em>read_image</em> is a function to read an image of this format.
<li><em>write_image</em> is a function to write an image of this format.
</ul>
Both read_image and write_image are of type image_io_handler, which is
a function pointer.
<p>Example:
<pre> void readGIF( <a href="qimageio.html">QImageIO</a> *image )
{
// read the image, using the image-><a href="qimageio.html#a7">ioDevice</a>()
}
void writeGIF( <a href="qimageio.html">QImageIO</a> *image )
{
// write the image, using the image-><a href="qimageio.html#a7">ioDevice</a>()
}
// add the GIF image handler
<a href="qimageio.html#c5">QImageIO::defineIOHandler</a>( "GIF",
"^GIF[0-9][0-9][a-z]",
0,
readGIF,
writeGIF );
</pre>
<p>Prior to comparison with the regular expression, the file header is
converted to change all 0 bytes into 1 bytes. This is done because 0
is such a common header byte yet regular expressions cannot match it.
<p>For image formats supporting incremental display, such as sequences
of animated frames, see the <a href="qimageformattype.html">QImageFormatType</a> class.
<h3 class="fn">constchar*<a name="b0"></a>QImageIO::description()const</h3>
<p>Returns the image description string.
<p>See also: <a href="qimageio.html#b7">setDescription</a>().
<h3 class="fn">constchar*<a name="a8"></a>QImageIO::fileName()const</h3>
<p>Returns the file name currently set.
<p>See also: <a href="qimageio.html#b5">setFileName</a>().
<h3 class="fn">constchar*<a name="a6"></a>QImageIO::format()const</h3>
<p>Returns the image format string, or 0 if no format has been explicitly set.
<h3 class="fn">const<a href="qimage.html">QImage</a>&<a name="a4"></a>QImageIO::image()const</h3>
<p>Returns the image currently set.
<p>See also: <a href="qimageio.html#b1">setImage</a>().
<h3 class="fn">constchar*<a name="c7"></a>QImageIO::imageFormat(<a href="qiodevice.html">QIODevice</a>*d) <code>[static]</code></h3>
<p>Returns a string that specifies the image format of the image read from
<em>d,</em> or null if the file cannot be read or if the format is not recognized.
<h3 class="fn">constchar*<a name="c6"></a>QImageIO::imageFormat(constchar*fileName) <code>[static]</code></h3>
<p>Returns a string that specifies the image format of the file <em>fileName,</em>
or null if the file cannot not be read or if the format is not recognized.
<h3 class="fn"><a href="qstrlist.html">QStrList</a><a name="c8"></a>QImageIO::inputFormats() <code>[static]</code></h3>
<p>Returns a sorted list of image formats which are supported for image input.
<h3 class="fn"><a href="qiodevice.html">QIODevice</a>*<a name="a7"></a>QImageIO::ioDevice()const</h3>
<p>Returns the IO device currently set.
<p>See also: <a href="qimageio.html#b4">setIODevice</a>().
<h3 class="fn"><a href="qstrlist.html">QStrList</a><a name="c9"></a>QImageIO::outputFormats() <code>[static]</code></h3>
<p>Returns a sorted list of image formats which are supported for image output.
<h3 class="fn">constchar*<a name="a9"></a>QImageIO::parameters()const</h3>
<p>Returns image parameters string.
<p>See also: <a href="qimageio.html#b6">setParameters</a>().
<h3 class="fn">bool<a name="b8"></a>QImageIO::read()</h3>
<p>Reads an image into memory and returns TRUE if the image was successfully
read.
<p>Before reading an image, you must set an IO device or a file name.
If both an IO device and a file name has been set, then the IO device will
be used.
<p>Setting the image file format string is optional.
<p>Note that this function does <em>not</em> set the <a href="qimageio.html#a6">format</a>
used to read the image. If you need that information, use the <a href="qimageio.html#c6">imageFormat</a>()
static functions.
<p>Example:
<p><pre> <a href="qimageio.html">QImageIO</a> iio;
<a href="qpixmap.html">QPixmap</a> pixmap;
iio.<a href="qimageio.html#b5">setFileName</a>( "burger.bmp" );
if ( image.read() ) // ok
pixmap = iio.<a href="qimageio.html#a4">image</a>(); // convert to pixmap
</pre>
<p>See also: <a href="qimageio.html#b4">setIODevice</a>(), <a href="qimageio.html#b5">setFileName</a>(), <a href="qimageio.html#b3">setFormat</a>(), <a href="qimageio.html#b9">write</a>() and <a href="qpixmap.html#d4">QPixmap::load</a>().
<h3 class="fn">void<a name="b7"></a>QImageIO::setDescription(constchar*description)</h3>
<p>Sets the image description string for image handlers that support image
descriptions.
<p>Currently, no image format supported by Qt use the description string.
<h3 class="fn">void<a name="b5"></a>QImageIO::setFileName(constchar*fileName)</h3>
<p>Sets the name of the file to read or write an image.
<p>See also: <a href="qimageio.html#b4">setIODevice</a>().
<h3 class="fn">void<a name="b3"></a>QImageIO::setFormat(constchar*format)</h3>
<p>Sets the image format name of the image about to be read or written.
<p>It is necessary to specify a format before writing an image.
<p>It is not necessary to specify a format before reading an image.
If not format has been set, Qt guesses the image format before reading
it. If a format is set, but the image has another (valid) format,
the image will not be read.
<p>See also: <a href="qimageio.html#b8">read</a>(), <a href="qimageio.html#b9">write</a>() and <a href="qimageio.html#a6">format</a>().
<h3 class="fn">void<a name="b4"></a>QImageIO::setIODevice(<a href="qiodevice.html">QIODevice</a>*ioDevice)</h3>
<p>Sets the IO device to be used for reading or writing an image.
<p>Setting the IO device allows images to be read/written to any
block-oriented <a href="qiodevice.html">QIODevice</a>.
<p>If <em>ioDevice</em> is not null, this IO device will override file name
settings.
<p>See also: <a href="qimageio.html#b5">setFileName</a>().
<h3 class="fn">void<a name="b1"></a>QImageIO::setImage(const<a href="qimage.html">QImage</a>&image)</h3>
<p>Sets the image.
<p>See also: <a href="qimageio.html#a4">image</a>().
<h3 class="fn">void<a name="b6"></a>QImageIO::setParameters(constchar*parameters)</h3>
<p>Sets the image parameters string for image handlers that require
special parameters.
<p>Although all image formats supported by Qt ignore the parameters string,
it will be useful for future extentions or contributions (like JPEG).
<h3 class="fn">void<a name="b2"></a>QImageIO::setStatus(intstatus)</h3>
<p>Sets the image IO status. A non-zero value indicates an error, while 0 means
that the IO operation was successful.
<p>See also: <a href="qimageio.html#a5">status</a>().
<h3 class="fn">int<a name="a5"></a>QImageIO::status()const</h3>
<p>Returns the image IO status. A non-zero value indicates an error, while 0
means that the IO operation was successful.
<p>See also: <a href="qimageio.html#b2">setStatus</a>().
<h3 class="fn">bool<a name="b9"></a>QImageIO::write()</h3>
<p>Writes an image to an IO device and returns TRUE if the image was
successfully written.
<p>Before writing an image, you must set an IO device or a file name.
If both an IO device and a file name has been set, then the IO
device will be used.
<p>The image will be written using the specified image format.
<p>Example:
<pre> <a href="qimageio.html">QImageIO</a> iio;
<a href="qimage.html">QImage</a> im;
im = pixmap; // convert to image
iio.<a href="qimageio.html#b1">setImage</a>( im );
iio.<a href="qimageio.html#b5">setFileName</a>( "burger.bmp" );
iio.<a href="qimageio.html#b3">setFormat</a>( "BMP" );
iio.<a href="qimageio.html#b9">write</a>(); // TRUE if ok
</pre>
<p>See also: <a href="qimageio.html#b4">setIODevice</a>(), <a href="qimageio.html#b5">setFileName</a>(), <a href="qimageio.html#b3">setFormat</a>(), <a href="qimageio.html#b8">read</a>() and <a href="qpixmap.html#d8">QPixmap::save</a>().
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