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<title>Qt 4.8: Restoring a Window's Geometry</title>
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<a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
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<li>Restoring a Window's Geometry</li>
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<h1 class="title">Restoring a Window's Geometry</h1>
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<p>This document describes how to save and restore a <a href="application-windows.html#window-geometry">window's geometry</a> using the geometry properties. On Windows, this is basically storing the result of <a href="qwidget.html#geometry-prop">QWidget::geometry</a>() and calling <a href="qwidget.html#geometry-prop">QWidget::setGeometry</a>() in the next session before calling <a href="qwidget.html#show">show()</a>.</p>
<p>On X11, this might not work because an invisible window does not have a frame yet. The window manager will decorate the window later. When this happens, the window shifts towards the bottom/right corner of the screen depending on the size of the decoration frame. Although X provides a way to avoid this shift, some window managers fail to implement this feature.</p>
<p>Since version 4.2, Qt provides functions that saves and restores a window's geometry and state for you. <a href="qwidget.html#saveGeometry">QWidget::saveGeometry</a>() saves the window geometry and maximized/fullscreen state, while <a href="qwidget.html#restoreGeometry">QWidget::restoreGeometry</a>() restores it. The restore function also checks if the restored geometry is outside the available screen geometry, and modifies it as appropriate if it is:</p>
<pre class="cpp"> <span class="type">void</span> MyMainWindow<span class="operator">::</span>closeEvent(<span class="type"><a href="qcloseevent.html">QCloseEvent</a></span> <span class="operator">*</span>event)
{
<span class="type"><a href="qsettings.html">QSettings</a></span> settings(<span class="string">"MyCompany"</span><span class="operator">,</span> <span class="string">"MyApp"</span>);
settings<span class="operator">.</span>setValue(<span class="string">"geometry"</span><span class="operator">,</span> saveGeometry());
settings<span class="operator">.</span>setValue(<span class="string">"windowState"</span><span class="operator">,</span> saveState());
<span class="type"><a href="qmainwindow.html">QMainWindow</a></span><span class="operator">::</span>closeEvent(event);
}
<span class="type">void</span> MainWindow<span class="operator">::</span>readSettings()
{
<span class="type"><a href="qsettings.html">QSettings</a></span> settings(<span class="string">"MyCompany"</span><span class="operator">,</span> <span class="string">"MyApp"</span>);
restoreGeometry(settings<span class="operator">.</span>value(<span class="string">"myWidget/geometry"</span>)<span class="operator">.</span>toByteArray());
restoreState(settings<span class="operator">.</span>value(<span class="string">"myWidget/windowState"</span>)<span class="operator">.</span>toByteArray());
}</pre>
<p>If those functions are not available or cannot be used, then a workaround is to call <a href="qwidget.html#geometry-prop">setGeometry()</a> after <a href="qwidget.html#show">show()</a>. This has the two disadvantages that the widget appears at a wrong place for a millisecond (results in flashing) and that currently only every second window manager gets it right. A safer solution is to store both <a href="qwidget.html#pos-prop">pos()</a> and <a href="qwidget.html#size-prop">size()</a> and to restore the geometry using <a href="qwidget.html#size-prop">QWidget::resize</a>() and <a href="qwidget.html#pos-prop">move()</a> before calling <a href="qwidget.html#show">show()</a>, as demonstrated in the <a href="mainwindows-application.html">Application</a> example.</p>
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