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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<a href="#gdk-pixbuf-refcounting.description" class="shortcut">Description</a>
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<div class="refentry" title="Reference Counting and Memory Mangement">
<a name="gdk-pixbuf-refcounting"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
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<h2><span class="refentrytitle"><a name="gdk-pixbuf-refcounting.top_of_page"></a>Reference Counting and Memory Mangement</span></h2>
<p>Reference Counting and Memory Mangement — Functions for reference counting and memory management on pixbufs.</p>
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<td valign="top" align="right"></td>
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<div class="refsynopsisdiv" title="Synopsis">
<a name="gdk-pixbuf-refcounting.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">
#include <gdk-pixbuf/gdk-pixbuf.h>
<a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="returnvalue">GdkPixbuf</span></a> * <a class="link" href="gdk-pixbuf-refcounting.html#gdk-pixbuf-ref" title="gdk_pixbuf_ref ()">gdk_pixbuf_ref</a> (<em class="parameter"><code><a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> *pixbuf</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gdk-pixbuf-refcounting.html#gdk-pixbuf-unref" title="gdk_pixbuf_unref ()">gdk_pixbuf_unref</a> (<em class="parameter"><code><a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> *pixbuf</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gdk-pixbuf-refcounting.html#GdkPixbufDestroyNotify" title="GdkPixbufDestroyNotify ()">*GdkPixbufDestroyNotify</a>) (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar"><span class="type">guchar</span></a> *pixels</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> data</code></em>);
</pre>
</div>
<div class="refsect1" title="Description">
<a name="gdk-pixbuf-refcounting.description"></a><h2>Description</h2>
<p>
<a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> structures are reference counted. This means that an
application can share a single pixbuf among many parts of the
code. When a piece of the program needs to keep a pointer to a
pixbuf, it should add a reference to it by calling <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-ref"><code class="function">g_object_ref()</code></a>.
When it no longer needs the pixbuf, it should subtract a reference
by calling <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-unref"><code class="function">g_object_unref()</code></a>. The pixbuf will be destroyed when
its reference count drops to zero. Newly-created <a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a>
structures start with a reference count of one.
</p>
<div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
As <a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> is derived from <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject"><span class="type">GObject</span></a> now, <a class="link" href="gdk-pixbuf-refcounting.html#gdk-pixbuf-ref" title="gdk_pixbuf_ref ()"><code class="function">gdk_pixbuf_ref()</code></a> and
<a class="link" href="gdk-pixbuf-refcounting.html#gdk-pixbuf-unref" title="gdk_pixbuf_unref ()"><code class="function">gdk_pixbuf_unref()</code></a> are deprecated in favour of <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-ref"><code class="function">g_object_ref()</code></a>
and <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-unref"><code class="function">g_object_unref()</code></a> resp.
</p>
</div>
<p>
<span class="emphasis"><em>Finalizing</em></span> a pixbuf means to free its pixel
data and to free the <a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> structure itself. Most of the
library functions that create <a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> structures create the
pixel data by themselves and define the way it should be freed;
you do not need to worry about those. The only function that lets
you specify how to free the pixel data is
<a class="link" href="gdk-pixbuf-creating.html#gdk-pixbuf-new-from-data" title="gdk_pixbuf_new_from_data ()"><code class="function">gdk_pixbuf_new_from_data()</code></a>. Since you pass it a pre-allocated
pixel buffer, you must also specify a way to free that data. This
is done with a function of type <a class="link" href="gdk-pixbuf-refcounting.html#GdkPixbufDestroyNotify" title="GdkPixbufDestroyNotify ()"><span class="type">GdkPixbufDestroyNotify</span></a>. When a
pixbuf created with <a class="link" href="gdk-pixbuf-creating.html#gdk-pixbuf-new-from-data" title="gdk_pixbuf_new_from_data ()"><code class="function">gdk_pixbuf_new_from_data()</code></a> is finalized, your
destroy notification function will be called, and it is its
responsibility to free the pixel array.
</p>
</div>
<div class="refsect1" title="Details">
<a name="gdk-pixbuf-refcounting.details"></a><h2>Details</h2>
<div class="refsect2" title="gdk_pixbuf_ref ()">
<a name="gdk-pixbuf-ref"></a><h3>gdk_pixbuf_ref ()</h3>
<pre class="programlisting"><a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="returnvalue">GdkPixbuf</span></a> * gdk_pixbuf_ref (<em class="parameter"><code><a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> *pixbuf</code></em>);</pre>
<div class="warning" title="Warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Warning</h3>
<p><code class="literal">gdk_pixbuf_ref</code> has been deprecated since version 2.0 and should not be used in newly-written code. Use <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-ref"><code class="function">g_object_ref()</code></a>.</p>
</div>
<p>
Adds a reference to a pixbuf.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>pixbuf</code></em> :</span></p></td>
<td>A pixbuf.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The same as the <em class="parameter"><code>pixbuf</code></em> argument.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="gdk_pixbuf_unref ()">
<a name="gdk-pixbuf-unref"></a><h3>gdk_pixbuf_unref ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gdk_pixbuf_unref (<em class="parameter"><code><a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> *pixbuf</code></em>);</pre>
<div class="warning" title="Warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Warning</h3>
<p><code class="literal">gdk_pixbuf_unref</code> has been deprecated since version 2.0 and should not be used in newly-written code. Use <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-unref"><code class="function">g_object_unref()</code></a>.</p>
</div>
<p>
Removes a reference from a pixbuf.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>pixbuf</code></em> :</span></p></td>
<td>A pixbuf.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GdkPixbufDestroyNotify ()">
<a name="GdkPixbufDestroyNotify"></a><h3>GdkPixbufDestroyNotify ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GdkPixbufDestroyNotify) (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar"><span class="type">guchar</span></a> *pixels</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> data</code></em>);</pre>
<p>
A function of this type is responsible for freeing the pixel array
of a pixbuf. The <a class="link" href="gdk-pixbuf-creating.html#gdk-pixbuf-new-from-data" title="gdk_pixbuf_new_from_data ()"><code class="function">gdk_pixbuf_new_from_data()</code></a> function lets you
pass in a pre-allocated pixel array so that a pixbuf can be
created from it; in this case you will need to pass in a function
of <a class="link" href="gdk-pixbuf-refcounting.html#GdkPixbufDestroyNotify" title="GdkPixbufDestroyNotify ()"><span class="type">GdkPixbufDestroyNotify</span></a> so that the pixel data can be freed
when the pixbuf is finalized.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>pixels</code></em> :</span></p></td>
<td>The pixel array of the pixbuf that is being finalized.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>data</code></em> :</span></p></td>
<td>User closure data.
</td>
</tr>
</tbody>
</table></div>
</div>
</div>
<div class="refsect1" title="See Also">
<a name="gdk-pixbuf-refcounting.see-also"></a><h2>See Also</h2>
<p>
<a class="link" href="gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a>, <a class="link" href="gdk-pixbuf-creating.html#gdk-pixbuf-new-from-data" title="gdk_pixbuf_new_from_data ()"><code class="function">gdk_pixbuf_new_from_data()</code></a>.
</p>
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