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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<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><div class="fn"><a href="#afc47b"><b>QImageIO</b></a>()</div>
<li><div class="fn"><a href="#ff7b34"><b>QImageIO</b></a>(QIODevice*ioDevice, constchar*format)</div>
<li><div class="fn"><a href="#a49478"><b>QImageIO</b></a>(constQString&fileName, constchar*format)</div>
<li><div class="fn"><a href="#b8d6a8"><b>~QImageIO</b></a>()</div>
<li><div class="fn">constQImage&<a href="#3bed6d"><b>image</b></a>()const</div>
<li><div class="fn">int<a href="#cef10f"><b>status</b></a>()const</div>
<li><div class="fn">constchar*<a href="#11648f"><b>format</b></a>()const</div>
<li><div class="fn">QIODevice*<a href="#5437be"><b>ioDevice</b></a>()const</div>
<li><div class="fn">QString<a href="#8aad19"><b>fileName</b></a>()const</div>
<li><div class="fn">constchar*<a href="#bbfc9f"><b>parameters</b></a>()const</div>
<li><div class="fn">QString<a href="#a4d516"><b>description</b></a>()const</div>
<li><div class="fn">void<a href="#1f6590"><b>setImage</b></a>(constQImage&)</div>
<li><div class="fn">void<a href="#7d6c7e"><b>setStatus</b></a>(int)</div>
<li><div class="fn">void<a href="#ca413e"><b>setFormat</b></a>(constchar*)</div>
<li><div class="fn">void<a href="#d05dce"><b>setIODevice</b></a>(QIODevice*)</div>
<li><div class="fn">void<a href="#55b14c"><b>setFileName</b></a>(constQString&)</div>
<li><div class="fn">void<a href="#c30e03"><b>setParameters</b></a>(constchar*)</div>
<li><div class="fn">void<a href="#03ae95"><b>setDescription</b></a>(constQString&)</div>
<li><div class="fn">bool<a href="#be99e5"><b>read</b></a>()</div>
<li><div class="fn">bool<a href="#ee15db"><b>write</b></a>()</div>
</ul>
<h2>Static Public Members</h2>
<ul>
<li><div class="fn">constchar*<a href="#05c737"><b>imageFormat</b></a>(constQString&fileName)</div>
<li><div class="fn">constchar*<a href="#91d640"><b>imageFormat</b></a>(QIODevice*)</div>
<li><div class="fn">QStrList<a href="#9824aa"><b>inputFormats</b></a>()</div>
<li><div class="fn">QStrList<a href="#040fd9"><b>outputFormats</b></a>()</div>
<li><div class="fn">void<a href="#4d20fa"><b>defineIOHandler</b></a>(constchar*format, constchar*header, constchar*flags, image_io_handlerread_image, image_io_handlerwrite_image)</div>
</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: 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), PPM (P3 or P6).
<p>You will normally not need to use this class, <a href="qpixmap.html#a728cf">QPixmap::load</a>(),
<a href="qpixmap.html#a38b1c">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 <em>output</em> is always in the more condensed
raw format. PPM and PGM files with more than 256 levels of intensity
are scaled down when reading.<p><b>Warning:</b> Unisys has changed its position regarding GIF. If you are
in a country where Unisys holds a patent on LZW compression and/or
decompression and you want to use GIF, Unisys may require you to
license that technology. These countries include Canada, Japan, the
USA, France, Germany, Italy and the UK.
<p>GIF support may be removed completely in a future version of Qt. We
recommend using the PNG format.
<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="afc47b"></a>QImageIO::QImageIO()</h3>
<p>Constructs a QImageIO object with all parameters set to zero.
<h3 class="fn"><a name="ff7b34"></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="a49478"></a>QImageIO::QImageIO(const<a href="qstring.html">QString</a>&fileName, constchar*format)</h3>
<p>Constructs a QImageIO object with a file name and a format tag.
<h3 class="fn"><a name="b8d6a8"></a>QImageIO::~QImageIO()</h3>
<p>Destructs the object and all related data.
<h3 class="fn">void<a name="4d20fa"></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="#5437be">ioDevice</a>()
}
void writeGIF( <a href="qimageio.html">QImageIO</a> *image )
{
// write the image, using the image-><a href="#5437be">ioDevice</a>()
}
// add the GIF image handler
<a href="#4d20fa">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"><a href="qstring.html">QString</a><a name="a4d516"></a>QImageIO::description()const</h3>
<p>Returns the image description string.
<p>See also <a href="#03ae95">setDescription</a>().
<h3 class="fn"><a href="qstring.html">QString</a><a name="8aad19"></a>QImageIO::fileName()const</h3>
<p>Returns the file name currently set.
<p>See also <a href="#55b14c">setFileName</a>().
<h3 class="fn">constchar*<a name="11648f"></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="3bed6d"></a>QImageIO::image()const</h3>
<p>Returns the image currently set.
<p>See also <a href="#1f6590">setImage</a>().
<h3 class="fn">constchar*<a name="91d640"></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="05c737"></a>QImageIO::imageFormat(const<a href="qstring.html">QString</a>&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="9824aa"></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="5437be"></a>QImageIO::ioDevice()const</h3>
<p>Returns the IO device currently set.
<p>See also <a href="#d05dce">setIODevice</a>().
<h3 class="fn"><a href="qstrlist.html">QStrList</a><a name="040fd9"></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="bbfc9f"></a>QImageIO::parameters()const</h3>
<p>Returns image parameters string.
<p>See also <a href="#c30e03">setParameters</a>().
<h3 class="fn">bool<a name="be99e5"></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="#11648f">format</a>
used to read the image. If you need that information, use the <a href="#05c737">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="#55b14c">setFileName</a>( "burger.bmp" );
if ( image.read() ) // ok
pixmap = iio.<a href="#3bed6d">image</a>(); // convert to pixmap
</pre>
<p>See also <a href="#d05dce">setIODevice</a>(), <a href="#55b14c">setFileName</a>(), <a href="#ca413e">setFormat</a>(), <a href="#ee15db">write</a>() and <a href="qpixmap.html#a728cf">QPixmap::load</a>().
<h3 class="fn">void<a name="03ae95"></a>QImageIO::setDescription(const<a href="qstring.html">QString</a>&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="55b14c"></a>QImageIO::setFileName(const<a href="qstring.html">QString</a>&fileName)</h3>
<p>Sets the name of the file to read or write an image.
<p>See also <a href="#d05dce">setIODevice</a>().
<h3 class="fn">void<a name="ca413e"></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="#be99e5">read</a>(), <a href="#ee15db">write</a>() and <a href="#11648f">format</a>().
<h3 class="fn">void<a name="d05dce"></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="#55b14c">setFileName</a>().
<h3 class="fn">void<a name="1f6590"></a>QImageIO::setImage(const<a href="qimage.html">QImage</a>&image)</h3>
<p>Sets the image.
<p>See also <a href="#3bed6d">image</a>().
<h3 class="fn">void<a name="c30e03"></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 extensions or contributions (like JPEG).
<h3 class="fn">void<a name="7d6c7e"></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="#cef10f">status</a>().
<h3 class="fn">int<a name="cef10f"></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="#7d6c7e">setStatus</a>().
<h3 class="fn">bool<a name="ee15db"></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="#1f6590">setImage</a>( im );
iio.<a href="#55b14c">setFileName</a>( "burger.bmp" );
iio.<a href="#ca413e">setFormat</a>( "BMP" );
iio.<a href="#ee15db">write</a>(); // TRUE if ok
</pre>
<p>See also <a href="#d05dce">setIODevice</a>(), <a href="#55b14c">setFileName</a>(), <a href="#ca413e">setFormat</a>(), <a href="#be99e5">read</a>() and <a href="qpixmap.html#a38b1c">QPixmap::save</a>().
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