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6<title>QDesktopWidget Class</title>
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32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QDesktopWidget Class Reference</h1>
33
34<p>The QDesktopWidget class provides access to screen information on multi-head systems.
35<a href="#details">More...</a>
36<p><tt>#include &lt;<a href="qdesktopwidget-h.html">qdesktopwidget.h</a>&gt;</tt>
37<p>Inherits <a href="qwidget.html">QWidget</a>.
38<p><a href="qdesktopwidget-members.html">List of all member functions.</a>
39<h2>Public Members</h2>
40<ul>
41<li class=fn><a href="#QDesktopWidget"><b>QDesktopWidget</b></a> ()</li>
42<li class=fn><a href="#~QDesktopWidget"><b>~QDesktopWidget</b></a> ()</li>
43<li class=fn>bool <a href="#isVirtualDesktop"><b>isVirtualDesktop</b></a> () const</li>
44<li class=fn>int <a href="#numScreens"><b>numScreens</b></a> () const</li>
45<li class=fn>int <a href="#primaryScreen"><b>primaryScreen</b></a> () const</li>
46<li class=fn>int <a href="#screenNumber"><b>screenNumber</b></a> ( QWidget&nbsp;*&nbsp;widget = 0 ) const</li>
47<li class=fn>int <a href="#screenNumber-2"><b>screenNumber</b></a> ( const&nbsp;QPoint&nbsp;&amp;&nbsp;point ) const</li>
48<li class=fn>QWidget * <a href="#screen"><b>screen</b></a> ( int&nbsp;screen = -1 )</li>
49<li class=fn>const QRect &amp; <a href="#screenGeometry"><b>screenGeometry</b></a> ( int&nbsp;screen = -1 ) const</li>
50<li class=fn>const QRect &amp; <a href="#screenGeometry-2"><b>screenGeometry</b></a> ( QWidget&nbsp;*&nbsp;widget ) const</li>
51<li class=fn>const QRect &amp; <a href="#screenGeometry-3"><b>screenGeometry</b></a> ( const&nbsp;QPoint&nbsp;&amp;&nbsp;p ) const</li>
52<li class=fn>const QRect &amp; <a href="#availableGeometry"><b>availableGeometry</b></a> ( int&nbsp;screen = -1 ) const</li>
53<li class=fn>const QRect &amp; <a href="#availableGeometry-2"><b>availableGeometry</b></a> ( QWidget&nbsp;*&nbsp;widget ) const</li>
54<li class=fn>const QRect &amp; <a href="#availableGeometry-3"><b>availableGeometry</b></a> ( const&nbsp;QPoint&nbsp;&amp;&nbsp;p ) const</li>
55</ul>
56<h2>Signals</h2>
57<ul>
58<li class=fn>void <a href="#resized"><b>resized</b></a> ( int&nbsp;screen )</li>
59</ul>
60<hr><a name="details"></a><h2>Detailed Description</h2>
61
62
63The QDesktopWidget class provides access to screen information on multi-head systems.
64<p>
65
66<p> Systems with more than one graphics card and monitor can manage the
67physical screen space available either as multiple desktops, or as a
68large virtual desktop, which usually has the size of the bounding
69rectangle of all the screens (see <a href="#isVirtualDesktop">isVirtualDesktop</a>()). For an
70application, one of the available screens is the primary screen, i.e.
71the screen where the main widget resides (see <a href="#primaryScreen">primaryScreen</a>()). All
72windows opened in the context of the application must be
73constrained to the boundaries of the primary screen; for example,
74it would be inconvenient if a dialog box popped up on a different
75screen, or split over two screens.
76<p> The QDesktopWidget provides information about the geometry of the
77available screens with <a href="#screenGeometry">screenGeometry</a>(). The number of screens
78available is returned by <a href="#numScreens">numScreens</a>(). The screen number that a
79particular point or widget is located in is returned by
80<a href="#screenNumber">screenNumber</a>().
81<p> Widgets provided by Qt use this class, for example, to place
82tooltips, menus and dialog boxes according to the parent or
83application widget.
84<p> Applications can use this class to save window positions, or to place
85child widgets on one screen.
86<p> <center><img src="qdesktopwidget.png" alt="Managing Multiple Screens"></center>
87<p> In the illustration above, Application One's primary screen is
88screen 0, and App Two's primary screen is screen 1.
89<p> <p>See also <a href="advanced.html">Advanced Widgets</a> and <a href="environment.html">Environment Classes</a>.
90
91<hr><h2>Member Function Documentation</h2>
92<h3 class=fn><a name="QDesktopWidget"></a>QDesktopWidget::QDesktopWidget ()
93</h3>
94Creates the desktop widget.
95<p> If the system supports a virtual desktop, this widget will have
96the size of the virtual desktop; otherwise this widget will have
97the size of the primary screen.
98<p> Instead of using QDesktopWidget directly, use
99<a href="qapplication.html#desktop">QApplication::desktop</a>().
100
101<h3 class=fn><a name="~QDesktopWidget"></a>QDesktopWidget::~QDesktopWidget ()
102</h3>
103Destroy the object and free allocated resources.
104
105<h3 class=fn>const&nbsp;<a href="qrect.html">QRect</a>&nbsp;&amp; <a name="availableGeometry"></a>QDesktopWidget::availableGeometry ( int&nbsp;screen = -1 ) const
106</h3>
107Returns the available geometry of the screen with index <em>screen</em>. What
108is available will be subrect of <a href="#screenGeometry">screenGeometry</a>() based on what the
109platform decides is available (for example excludes the Dock and Menubar
110on Mac OS X, or the taskbar on Windows).
111<p> <p>See also <a href="#screenNumber">screenNumber</a>() and <a href="#screenGeometry">screenGeometry</a>().
112
113<h3 class=fn>const&nbsp;<a href="qrect.html">QRect</a>&nbsp;&amp; <a name="availableGeometry-2"></a>QDesktopWidget::availableGeometry ( <a href="qwidget.html">QWidget</a>&nbsp;*&nbsp;widget ) const
114</h3>
115This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
116<p> Returns the available geometry of the screen which contains <em>widget</em>.
117<p> <p>See also <a href="#screenGeometry">screenGeometry</a>().
118
119<h3 class=fn>const&nbsp;<a href="qrect.html">QRect</a>&nbsp;&amp; <a name="availableGeometry-3"></a>QDesktopWidget::availableGeometry ( const&nbsp;<a href="qpoint.html">QPoint</a>&nbsp;&amp;&nbsp;p ) const
120</h3>
121This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
122<p> Returns the available geometry of the screen which contains <em>p</em>.
123<p> <p>See also <a href="#screenGeometry">screenGeometry</a>().
124
125<h3 class=fn>bool <a name="isVirtualDesktop"></a>QDesktopWidget::isVirtualDesktop () const
126</h3>
127Returns TRUE if the system manages the available screens in a
128virtual desktop; otherwise returns FALSE.
129<p> For virtual desktops, <a href="#screen">screen</a>() will always return the same widget.
130The size of the virtual desktop is the size of this desktop
131widget.
132
133<h3 class=fn>int <a name="numScreens"></a>QDesktopWidget::numScreens () const
134</h3>
135Returns the number of available screens.
136<p> <p>See also <a href="#primaryScreen">primaryScreen</a>().
137
138<h3 class=fn>int <a name="primaryScreen"></a>QDesktopWidget::primaryScreen () const
139</h3>
140Returns the index of the primary screen.
141<p> <p>See also <a href="#numScreens">numScreens</a>().
142
143<h3 class=fn>void <a name="resized"></a>QDesktopWidget::resized ( int&nbsp;screen )<tt> [signal]</tt>
144</h3>
145This signal is emitted when the size of <em>screen</em> changes.
146
147<h3 class=fn><a href="qwidget.html">QWidget</a>&nbsp;* <a name="screen"></a>QDesktopWidget::screen ( int&nbsp;screen = -1 )
148</h3>
149Returns a widget that represents the screen with index <em>screen</em>.
150This widget can be used to draw directly on the desktop, using an
151unclipped painter like this:
152<p> <pre>
153 <a href="qpainter.html">QPainter</a> paint( QApplication::<a href="qapplication.html#desktop">desktop</a>()-&gt;screen( 0 ), TRUE );
154 paint.draw...
155 ...
156 paint.<a href="qpainter.html#end">end</a>();
157 </pre>
158
159<p> If the system uses a virtual desktop, the returned widget will
160have the geometry of the entire virtual desktop i.e. bounding
161every <em>screen</em>.
162<p> <p>See also <a href="#primaryScreen">primaryScreen</a>(), <a href="#numScreens">numScreens</a>(), and <a href="#isVirtualDesktop">isVirtualDesktop</a>().
163
164<h3 class=fn>const&nbsp;<a href="qrect.html">QRect</a>&nbsp;&amp; <a name="screenGeometry"></a>QDesktopWidget::screenGeometry ( int&nbsp;screen = -1 ) const
165</h3>
166Returns the geometry of the screen with index <em>screen</em>.
167<p> <p>See also <a href="#screenNumber">screenNumber</a>().
168
169<h3 class=fn>const&nbsp;<a href="qrect.html">QRect</a>&nbsp;&amp; <a name="screenGeometry-2"></a>QDesktopWidget::screenGeometry ( <a href="qwidget.html">QWidget</a>&nbsp;*&nbsp;widget ) const
170</h3>
171This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
172<p> Returns the geometry of the screen which contains <em>widget</em>.
173
174<h3 class=fn>const&nbsp;<a href="qrect.html">QRect</a>&nbsp;&amp; <a name="screenGeometry-3"></a>QDesktopWidget::screenGeometry ( const&nbsp;<a href="qpoint.html">QPoint</a>&nbsp;&amp;&nbsp;p ) const
175</h3>
176This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
177<p> Returns the geometry of the screen which contains <em>p</em>.
178
179<h3 class=fn>int <a name="screenNumber"></a>QDesktopWidget::screenNumber ( <a href="qwidget.html">QWidget</a>&nbsp;*&nbsp;widget = 0 ) const
180</h3>
181Returns the index of the screen that contains the largest
182part of <em>widget</em>, or -1 if the widget not on a screen.
183<p> <p>See also <a href="#primaryScreen">primaryScreen</a>().
184
185<h3 class=fn>int <a name="screenNumber-2"></a>QDesktopWidget::screenNumber ( const&nbsp;<a href="qpoint.html">QPoint</a>&nbsp;&amp;&nbsp;point ) const
186</h3>
187This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
188<p> Returns the index of the screen that contains <em>point</em>, or -1 if
189no screen contains the point.
190<p> <p>See also <a href="#primaryScreen">primaryScreen</a>().
191
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