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<div class="refentry" lang="en">
<a name="gst-plugins-base-libs-gstxoverlay"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2>
<a name="id2623126"></a><span class="refentrytitle">gstxoverlay</span>
</h2>
<p>gstxoverlay — Interface for setting/getting a Window on elements
supporting it</p>
</td>
<td valign="top" align="right"></td>
</tr></table></div>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<a name="GstXOverlay"></a><pre class="synopsis">
#include <gst/interfaces/xoverlay.h>
<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay-struct">GstXOverlay</a>;
void <a href="gst-plugins-base-libs-gstxoverlay.html#gst-x-overlay-set-xwindow-id">gst_x_overlay_set_xwindow_id</a> (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay,
gulong xwindow_id);
void <a href="gst-plugins-base-libs-gstxoverlay.html#gst-x-overlay-got-xwindow-id">gst_x_overlay_got_xwindow_id</a> (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay,
gulong xwindow_id);
void <a href="gst-plugins-base-libs-gstxoverlay.html#gst-x-overlay-prepare-xwindow-id">gst_x_overlay_prepare_xwindow_id</a> (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay);
void <a href="gst-plugins-base-libs-gstxoverlay.html#gst-x-overlay-expose">gst_x_overlay_expose</a> (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay);
void <a href="gst-plugins-base-libs-gstxoverlay.html#gst-x-overlay-handle-events">gst_x_overlay_handle_events</a> (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay,
gboolean handle_events);
</pre>
</div>
<div class="refsect1" lang="en">
<a name="id2623293"></a><h2>Object Hierarchy</h2>
<pre class="synopsis">
GInterface
+----GstXOverlay
</pre>
</div>
<div class="refsect1" lang="en">
<a name="id2623318"></a><h2>Prerequisites</h2>
<p>
GstXOverlay requires
GstObject, GstImplementsInterface and GstElement.</p>
</div>
<div class="refsect1" lang="en">
<a name="id2623354"></a><h2>Description</h2>
<p>
</p>
<div class="refsect2" lang="en">
<a name="id2623367"></a><p>
The XOverlay interface is used for 2 main purposes :
</p>
<div class="itemizedlist"><ul type="disc">
<li><p>
To get a grab on the Window where the video sink element is going to render.
This is achieved by either being informed about the Window identifier that
the video sink element generated, or by forcing the video sink element to use
a specific Window identifier for rendering.
</p></li>
<li><p>
To force a redrawing of the latest video frame the video sink element
displayed on the Window. Indeed if the <span class="type">GstPipeline</span> is in <span class="type">GST_STATE_PAUSED</span>
state, moving the Window around will damage its content. Application
developers will want to handle the Expose events themselves and force the
video sink element to refresh the Window's content.
</p></li>
</ul></div>
<p>
</p>
<p>
Using the Window created by the video sink is probably the simplest scenario,
in some cases, though, it might not be flexible enough for application
developers if they need to catch events such as mouse moves and button
clicks.
</p>
<p>
Setting a specific Window identifier on the video sink element is the most
flexible solution but it has some issues. Indeed the application needs to set
its Window identifier at the right time to avoid internal Window creation
from the video sink element. To solve this issue a <span class="type">GstMessage</span> is posted on
the bus to inform the application that it should set the Window identifier
immediately. Here is an example on how to do that correctly:
</p>
<pre class="programlisting">
static GstBusSyncReply
create_window (GstBus * bus, GstMessage * message, GstPipeline * pipeline)
{
// ignore anything but 'prepare-xwindow-id' element messages
if (GST_MESSAGE_TYPE (message) != GST_MESSAGE_ELEMENT)
return GST_BUS_PASS;
if (!gst_structure_has_name (message->structure, "prepare-xwindow-id"))
return GST_BUS_PASS;
win = XCreateSimpleWindow (disp, root, 0, 0, 320, 240, 0, 0, 0);
XSetWindowBackgroundPixmap (disp, win, None);
XMapRaised (disp, win);
XSync (disp, FALSE);
gst_x_overlay_set_xwindow_id (GST_X_OVERLAY (GST_MESSAGE_SRC (message)),
win);
gst_message_unref (message);
return GST_BUS_DROP;
}
...
int
main (int argc, char **argv)
{
...
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
gst_bus_set_sync_handler (bus, (GstBusSyncHandler) create_window, pipeline);
...
}
</pre>
<p>
</p>
</div>
<p>
</p>
</div>
<div class="refsect1" lang="en">
<a name="id2623500"></a><h2>Details</h2>
<div class="refsect2" lang="en">
<a name="id2623511"></a><h3>
<a name="GstXOverlay-struct"></a>GstXOverlay</h3>
<a class="indexterm" name="id2623523"></a><pre class="programlisting">typedef struct _GstXOverlay GstXOverlay;</pre>
<p>
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2623537"></a><h3>
<a name="gst-x-overlay-set-xwindow-id"></a>gst_x_overlay_set_xwindow_id ()</h3>
<a class="indexterm" name="id2623551"></a><pre class="programlisting">void gst_x_overlay_set_xwindow_id (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay,
gulong xwindow_id);</pre>
<p>
This will call the video overlay's set_xwindow_id method. You should
use this method to tell to a XOverlay to display video output to a
specific XWindow. Passing 0 as the xwindow_id will tell the overlay to
stop using that window and create an internal one.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><span class="term"><em class="parameter"><code>overlay</code></em> :</span></td>
<td> a <a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay"><span class="type">GstXOverlay</span></a> to set the XWindow on.
</td>
</tr>
<tr>
<td><span class="term"><em class="parameter"><code>xwindow_id</code></em> :</span></td>
<td> a <span class="type">XID</span> referencing the XWindow.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2623644"></a><h3>
<a name="gst-x-overlay-got-xwindow-id"></a>gst_x_overlay_got_xwindow_id ()</h3>
<a class="indexterm" name="id2623657"></a><pre class="programlisting">void gst_x_overlay_got_xwindow_id (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay,
gulong xwindow_id);</pre>
<p>
This will post a "have-xwindow-id" element message on the bus.
</p>
<p>
This function should only be used by video overlay plugin developers.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><span class="term"><em class="parameter"><code>overlay</code></em> :</span></td>
<td> a <a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay"><span class="type">GstXOverlay</span></a> which got a XWindow.
</td>
</tr>
<tr>
<td><span class="term"><em class="parameter"><code>xwindow_id</code></em> :</span></td>
<td> a <span class="type">XID</span> referencing the XWindow.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2623751"></a><h3>
<a name="gst-x-overlay-prepare-xwindow-id"></a>gst_x_overlay_prepare_xwindow_id ()</h3>
<a class="indexterm" name="id2623764"></a><pre class="programlisting">void gst_x_overlay_prepare_xwindow_id (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay);</pre>
<p>
This will post a "prepare-xwindow-id" element message on the bus
to give applications an opportunity to call
<a href="gst-plugins-base-libs-gstxoverlay.html#gst-x-overlay-set-xwindow-id"><code class="function">gst_x_overlay_set_xwindow_id()</code></a> before a plugin creates its own
window.
</p>
<p>
This function should only be used by video overlay plugin developers.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><span class="term"><em class="parameter"><code>overlay</code></em> :</span></td>
<td> a <a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay"><span class="type">GstXOverlay</span></a> which does not yet have an XWindow.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2623840"></a><h3>
<a name="gst-x-overlay-expose"></a>gst_x_overlay_expose ()</h3>
<a class="indexterm" name="id2623853"></a><pre class="programlisting">void gst_x_overlay_expose (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay);</pre>
<p>
Tell an overlay that it has been exposed. This will redraw the current frame
in the drawable even if the pipeline is PAUSED.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><span class="term"><em class="parameter"><code>overlay</code></em> :</span></td>
<td> a <a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay"><span class="type">GstXOverlay</span></a> to expose.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2623913"></a><h3>
<a name="gst-x-overlay-handle-events"></a>gst_x_overlay_handle_events ()</h3>
<a class="indexterm" name="id2623927"></a><pre class="programlisting">void gst_x_overlay_handle_events (<a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay">GstXOverlay</a> *overlay,
gboolean handle_events);</pre>
<p>
Tell an overlay that it should handle events from the window system. These
events are forwared upstream as navigation events. In some window system,
events are not propagated in the window hierarchy if a client is listening
for them. This method allows you to disable events handling completely
from the XOverlay.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><span class="term"><em class="parameter"><code>overlay</code></em> :</span></td>
<td> a <a href="gst-plugins-base-libs-gstxoverlay.html#GstXOverlay"><span class="type">GstXOverlay</span></a> to expose.
</td>
</tr>
<tr>
<td><span class="term"><em class="parameter"><code>handle_events</code></em> :</span></td>
<td> a <span class="type">gboolean</span> indicating if events should be handled or not.
</td>
</tr>
</tbody>
</table></div>
</div>
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