gtkobject.html

最新gtk中文资料集

<p>
<a class="link" href="GtkObject.html" title="GtkObject"><span class="type">GtkObject</span></a>s are created with a "floating" reference count.
This means that the initial reference is not owned by anyone. 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> on a newly-created <a class="link" href="GtkObject.html" title="GtkObject"><span class="type">GtkObject</span></a> is incorrect, the floating
reference has to be removed first. This can be done by anyone at any time, 
by calling <a
href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-ref-sink"
><code class="function">g_object_ref_sink()</code></a> to convert the floating reference into a
regular reference. <a
href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#g-object-ref-sink"
><code class="function">g_object_ref_sink()</code></a> returns a new reference if an object 
is already sunk (has no floating reference). 
</p>
<p>
When you add a widget to its parent container, the parent container
will do this:
</p>
<div class="informalexample"><pre class="programlisting">
  g_object_ref_sink (G_OBJECT (child_widget));
</pre></div>
<p>
This means that the container now owns a reference to the child widget
and the child widget has no floating reference.
</p>
<p>
The purpose of the floating reference is to keep the child widget alive 
until you add it to a parent container:
</p>
<div class="informalexample"><pre class="programlisting">
   button = gtk_button_new ();
   /* button has one floating reference to keep it alive */
   gtk_container_add (GTK_CONTAINER (container), button);
   /* button has one non-floating reference owned by the container */
</pre></div>
<p>
</p>
<p>
<a class="link" href="GtkWindow.html" title="GtkWindow"><span class="type">GtkWindow</span></a> is a special case, because GTK+ itself will ref/sink it on creation. 
That is, after calling <a class="link" href="GtkWindow.html#gtk-window-new"><code class="function">gtk_window_new()</code></a>, the <a class="link" href="GtkWindow.html" title="GtkWindow"><span class="type">GtkWindow</span></a> will have one 
reference which is owned by GTK+, and no floating references.
</p>
<p>
One more factor comes into play: the "destroy" signal, emitted by the
<a class="link" href="GtkObject.html#gtk-object-destroy"><code class="function">gtk_object_destroy()</code></a> method. The "destroy" signal asks all code owning a
reference to an object to release said reference. So, for example, if you call
<a class="link" href="GtkObject.html#gtk-object-destroy"><code class="function">gtk_object_destroy()</code></a> on a <a class="link" href="GtkWindow.html" title="GtkWindow"><span class="type">GtkWindow</span></a>, GTK+ will release the reference count that
it owns; if you call <a class="link" href="GtkObject.html#gtk-object-destroy"><code class="function">gtk_object_destroy()</code></a> on a <a class="link" href="GtkButton.html" title="GtkButton"><span class="type">GtkButton</span></a>, then the button will
be removed from its parent container and the parent container will release its
reference to the button.  Because these references are released, calling
<a class="link" href="GtkObject.html#gtk-object-destroy"><code class="function">gtk_object_destroy()</code></a> should result in freeing all memory associated with an
object, unless some buggy code fails to release its references in response to
the "destroy" signal. Freeing memory (referred to as
<em class="firstterm">finalization</em> only happens if the reference count reaches
zero.
</p>
<p>
Some simple rules for handling <span class="type">""</span>
</p>
<div class="itemizedlist"><ul type="disc">
<li><p>
Never call <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> unless you have previously called <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>, 
even if you created the <a class="link" href="GtkObject.html" title="GtkObject"><span class="type">GtkObject</span></a>. (Note: this is <span class="emphasis"><em>not</em></span>
true for <a
href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject"
><span class="type">GObject</span></a>; for <a
href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject"
><span class="type">GObject</span></a>, the creator of the object owns a reference.)
</p></li>
<li><p>
Call <a class="link" href="GtkObject.html#gtk-object-destroy"><code class="function">gtk_object_destroy()</code></a> to get rid of most objects in most cases. 
In particular, widgets are almost always destroyed in this way.
</p></li>
<li><p> Because of the floating reference count, you don't need to
worry about reference counting for widgets and toplevel windows, unless you
explicitly call <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> yourself.</p></li>
</ul></div>
<p>
</p>
</div>
</div>
<div class="refsect1" lang="en">
<a name="id4277846"></a><h2>Details</h2>
<div class="refsect2" lang="en">
<a name="id4277856"></a><h3>
<a name="GtkObject-struct"></a>GtkObject</h3>
<a class="indexterm" name="id4277869"></a><pre class="programlisting">typedef struct _GtkObject GtkObject;</pre>
<p>
The object itself.  You should never use these members directly -
 use the accessing macros instead.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id4277886"></a><h3>
<a name="GTK-OBJECT-TYPE:CAPS"></a>GTK_OBJECT_TYPE()</h3>
<a class="indexterm" name="id4277900"></a><pre class="programlisting">#define GTK_OBJECT_TYPE(object)		  (G_TYPE_FROM_INSTANCE (object))
</pre>
<p>
Gets the type of an object.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>object</code></em>&#160;:</span></p></td>
<td>a <a class="link" href="GtkObject.html" title="GtkObject"><span class="type">GtkObject</span></a>.


</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id4277942"></a><h3>
<a name="GTK-OBJECT-TYPE-NAME:CAPS"></a>GTK_OBJECT_TYPE_NAME()</h3>
<a class="indexterm" name="id4277955"></a><pre class="programlisting">#define GTK_OBJECT_TYPE_NAME(object)	  (g_type_name (GTK_OBJECT_TYPE (object)))
</pre>
<p>
Gets the name of an objects type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>object</code></em>&#160;:</span></p></td>
<td>a <a class="link" href="GtkObject.html" title="GtkObject"><span class="type">GtkObject</span></a>.


</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id4277998"></a><h3>
<a name="GtkObjectFlags"></a>enum GtkObjectFlags</h3>
<a class="indexterm" name="id4278011"></a><pre class="programlisting">typedef enum
{
  GTK_IN_DESTRUCTION	= 1 &lt;&lt; 0, /* Used internally during dispose */
#if !defined (GTK_DISABLE_DEPRECATED) || defined (GTK_COMPILATION)
  GTK_FLOATING		= 1 &lt;&lt; 1,
#endif
  GTK_RESERVED_1	= 1 &lt;&lt; 2,
  GTK_RESERVED_2	= 1 &lt;&lt; 3
} GtkObjectFlags;
</pre>
<p>
Tells about the state of the object.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><a name="GTK-IN-DESTRUCTION:CAPS"></a><code class="literal">GTK_IN_DESTRUCTION</code></span></p></td>
<td>the object is currently being destroyed. This is used 
  internally by GTK+ to prevent reinvokations during destruction.
</td>
</tr>
<tr>
<td><p><span class="term"><a name="GTK-FLOATING:CAPS"></a><code class="literal">GTK_FLOATING</code></span></p></td>
<td>
</td>
</tr>
<tr>
<td><p><span class="term"><a name="GTK-RESERVED-1:CAPS"></a><code class="literal">GTK_RESERVED_1</code></span></p></td>
<td>
</td>
</tr>
<tr>
<td><p><span class="term"><a name="GTK-RESERVED-2:CAPS"></a><code class="literal">GTK_RESERVED_2</code></span></p></td>
<td>reserved for future use

</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id4278128"></a><h3>
<a name="GTK-OBJECT-FLAGS:CAPS"></a>GTK_OBJECT_FLAGS()</h3>
<a class="indexterm" name="id4278141"></a><pre class="programlisting">#define GTK_OBJECT_FLAGS(obj)		  (GTK_OBJECT (obj)-&gt;flags)
</pre>
<p>
Gets the <a class="link" href="GtkObject.html#GtkObjectFlags"><span class="type">GtkObjectFlags</span></a> for an object without directly
accessing its members.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>obj</code></em>&#160;:</span></p></td>
<td>the object whose flags are returned.


</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id4278186"></a><h3>
<a name="GTK-OBJECT-FLOATING:CAPS"></a>GTK_OBJECT_FLOATING()</h3>
<a class="indexterm" name="id4278201"></a><pre class="programlisting">#define GTK_OBJECT_FLOATING(obj)	  (g_object_is_floating (obj))
</pre>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Warning</h3>
<p><code class="literal">GTK_OBJECT_FLOATING</code> is deprecated and should not be used in newly-written code.</p>
</div>
<p>
Evaluates to <a
href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#TRUE:CAPS"
><code class="literal">TRUE</code></a> if the object still has its floating reference count.
See the overview documentation for <a class="link" href="GtkObject.html" title="GtkObject"><span class="type">GtkObject</span></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>obj</code></em>&#160;:</span></p></td>
<td>the object to examine.


</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id4278267"></a><h3>
<a name="GtkArgFlags"></a>enum GtkArgFlags</h3>
<a class="indexterm" name="id4278283"></a><pre class="programlisting">typedef enum
{
  GTK_ARG_READABLE	 = G_PARAM_READABLE,
  GTK_ARG_WRITABLE	 = G_PARAM_WRITABLE,
  GTK_ARG_CONSTRUCT	 = G_PARAM_CONSTRUCT,
  GTK_ARG_CONSTRUCT_ONLY = G_PARAM_CONSTRUCT_ONLY,
  GTK_ARG_CHILD_ARG	 = 1 &lt;&lt; 4
} GtkArgFlags;
</pre>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Warning</h3>
<p><code class="literal">GtkArgFlags</code> is deprecated and should not be used in newly-written code. Use corresponding <a
href="/usr/share/gtk-doc/html/gobject/gobject-GParamSpec.html#GParamSpec"
><span class="type">GParamSpec</span></a> features instead</p>
</div>
<p>
Possible flags indicating how an argument should be treated.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><a name="GTK-ARG-READABLE:CAPS"></a><code class="literal">GTK_ARG_READABLE</code></span></p></td>
<td>the argument is readable. (i.e. can be queried)
</td>
</tr>
<tr>
<td><p><span class="term"><a name="GTK-ARG-WRITABLE:CAPS"></a><code class="literal">GTK_ARG_WRITABLE</code></span></p></td>
<td>the argument is writable. (i.e. settable)
</td>