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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta name="robots" content="noindex,noarchive">
<title>Qt Toolkit - QGLWidget Class</title><style type="text/css"><!--
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<a href=index.html><img width=122 height=65 src=qtlogo.jpg alt="Qt logo" align=left border=0></a>
<center><img src=dochead.gif width=472 height=27></center>
<br clear=all>
<h1 align=center>QGLWidget Class Reference</h1><br clear="all">
<p>
The QGLWidget class is a widget for rendering OpenGL graphics.
This class is part of the <b>Qt OpenGL Extension.</b>
<a href="#details">More...</a>
<p>
<code>#include <<a href="qgl-h.html">qgl.h</a>></code>
<p>
Inherits <a href="qwidget.html">QWidget</a> and QGL.
<p><a href="qglwidget-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li><span class="fn"><a href="qglwidget.html#a0"><strong>QGLWidget</strong></a>(QWidget*parent=0, constchar*name=0, constQGLWidget*shareWidget=0, WFlagsf=0)</span>
<li><span class="fn"><a href="qglwidget.html#a1"><strong>QGLWidget</strong></a>(constQGLFormat&format, QWidget*parent=0, constchar*name=0, constQGLWidget*shareWidget=0, WFlagsf=0)</span>
<li><span class="fn"><a href="qglwidget.html#a2"><strong>~QGLWidget</strong></a>()</span>
<li><span class="fn">bool<a href="qglwidget.html#a3"><strong>isValid</strong></a>()const</span>
<li><span class="fn">bool<a href="qglwidget.html#a4"><strong>isSharing</strong></a>()const</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#a5"><strong>makeCurrent</strong></a>()</span>
<li><span class="fn">bool<a href="qglwidget.html#a6"><strong>doubleBuffer</strong></a>()const</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#a7"><strong>swapBuffers</strong></a>()</span>
<li><span class="fn">QGLFormat<a href="qglwidget.html#a8"><strong>format</strong></a>()const</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#a9"><strong>setFormat</strong></a>(constQGLFormat&format)</span>
<li><span class="fn">constQGLContext*<a href="qglwidget.html#b0"><strong>context</strong></a>()const</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#b1"><strong>setContext</strong></a>(QGLContext*context, constQGLContext*shareContext=0, booldeleteOldContext=TRUE)</span>
<li><span class="fn">virtualQPixmap<a href="qglwidget.html#b2"><strong>renderPixmap</strong></a>(intw=0, inth=0, booluseContext=FALSE)</span>
</ul>
<h2>Public Slots</h2>
<ul>
<li><span class="fn">virtualvoid<a href="qglwidget.html#b3"><strong>updateGL</strong></a>()</span>
</ul>
<h2>Protected Members</h2>
<ul>
<li><span class="fn">virtualvoid<a href="qglwidget.html#b4"><strong>initializeGL</strong></a>()</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#b5"><strong>paintGL</strong></a>()</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#b6"><strong>resizeGL</strong></a>(intw, inth)</span>
<li><span class="fn">void<a href="qglwidget.html#b7"><strong>setAutoBufferSwap</strong></a>(boolon)</span>
<li><span class="fn">bool<a href="qglwidget.html#b8"><strong>autoBufferSwap</strong></a>()const</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#b9"><strong>paintEvent</strong></a>(QPaintEvent*)</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#c0"><strong>resizeEvent</strong></a>(QResizeEvent*)</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#c1"><strong>glInit</strong></a>()</span>
<li><span class="fn">virtualvoid<a href="qglwidget.html#c2"><strong>glDraw</strong></a>()</span>
</ul>
<hr><h2><a name="details"></a>Detailed Description</h2>
This class is defined in the <b>Qt OpenGL Extension</b>, which can be found in the <tt>qt/extensions</tt> directory.
It is not included in the main Qt API.
<p>
The QGLWidget class is a widget for rendering OpenGL graphics.
<p>
QGLWidget provides functionality for displaying OpenGL graphics
integrated in a Qt application. It is very simple to use: you
inherit from it and use the subclass like any other <a href="qwidget.html">QWidget</a>, only
that instead of drawing the widget's contents using <a href="qpainter.html">QPainter</a> & al.,
you use the standard OpenGL rendering commands.
<p>QGLWidget provides three convenient virtual functions that you can
reimplement in your subclass to perform the typical OpenGL tasks:
<p><ul>
<li> <a href="qglwidget.html#b5">paintGL</a>() - Render the OpenGL scene. Gets called whenever the widget
needs to be updated.
<li> <a href="qglwidget.html#b6">resizeGL</a>() - Set up OpenGL viewport, projection etc. Gets called
whenever the the widget has been resized (and also when it shown
for the first time, since all newly created widgets get a resize
event automatically).
<li> <a href="qglwidget.html#b4">initializeGL</a>() - Set up the OpenGL rendering context, define display
lists etc. Gets called once before the first time resizeGL() or
paintGL() is called.
</ul>
<p>Here is a rough outline of how your QGLWidget subclass may look:
<p><pre> class MyGLDrawer : public QGLWidget
{
Q_OBJECT // must include this if you use Qt signals/slots
public:
MyGLDrawer( <a href="qwidget.html">QWidget</a> *parent, const char *name )
: <a href="qglwidget.html">QGLWidget</a>(parent,name) {}
protected:
void initializeGL()
{
// Set up the rendering context, define display lists etc.:
...
glClearColor( 0.0, 0.0, 0.0, 0.0 );
glEnable(GL_DEPTH_TEST);
...
}
void resizeGL( int w, int h )
{
// setup viewport, projection etc.:
glViewport( 0, 0, (GLint)w, (GLint)h );
...
glFrustum( ... );
...
}
void paintGL()
{
// draw the scene:
...
glRotatef( ... );
glMaterialfv( ... );
glBegin( GL_QUADS );
glVertex3f( ... );
glVertex3f( ... );
...
glEnd();
...
}
};
</pre>
<p>If you need to trigger a repaint from other places than paintGL() (a
typical example is when using <a href="qtimer.html">timers</a> to animate
scenes), you should call the widget's <a href="qglwidget.html#b3">updateGL</a>() function.
<p>When paintGL(), resizeGL() or initializeGL() is called, your
widget's OpenGL rendering context has been made current. If you
need to call the standard OpenGL API functions from other places
(e.g. in your widget's constructor), you must call <a href="qglwidget.html#a5">makeCurrent</a>()
first.
<p>QGLWidget provides advanced functions for requesting a new display
<a href="qglformat.html">format</a>, and you can even set a new rendering
<a href="qglcontext.html">context</a>.
<p>You can achieve sharing of OpenGL display lists between QGLWidgets,
see the documentation of the QGLWidget constructors for details.
<hr><h2>Member Function Documentation</h2>
<h3 class="fn"><a name="a0"></a>QGLWidget::QGLWidget(<a href="qwidget.html">QWidget</a>*parent=0, constchar*name=0, constQGLWidget*shareWidget=0, WFlagsf=0)</h3>
<p>Constructs an OpenGL widget with a <em>parent</em> widget and a <em>name.</em>
<p>The <a href="qglformat.html#c7">default format</a> is
used. The widget will be <a href="qglwidget.html#a3">invalid</a> if the
system has no <a href="qglformat.html#c6">OpenGL support</a>.
<p>The <em>parent, name</em> and <em>f</em> arguments are passed to the <a href="qwidget.html">QWidget</a>
constructor.
<p>If the <em>shareWidget</em> parameter points to a valid QGLWidget, this
widget will share OpenGL display lists with <em>shareWidget.</em> Note: If
this widget and <em>shareWidget</em> has different <a href="qglwidget.html#a8">formats</a>, display list sharing may fail. You can check
whether display list sharing succeeded by using the <a href="qglwidget.html#a4">isSharing</a>()
method.
<p>Note: Initialization of OpenGL rendering state etc. should be done
by overriding the <a href="qglwidget.html#b4">initializeGL</a>() function, not in the constructor of
your QGLWidget subclass.
<p>See also: <a href="qglformat.html#c7">QGLFormat::defaultFormat</a>().
<h3 class="fn"><a name="a1"></a>QGLWidget::QGLWidget(const<a href="qglformat.html">QGLFormat</a>&format, <a href="qwidget.html">QWidget</a>*parent=0, constchar*name=0, constQGLWidget*shareWidget=0, WFlagsf=0)</h3>
<p>Constructs an OpenGL widget with a <em>parent</em> widget and a <em>name.</em>
<p>The <em>format</em> argument specifies the desired <a href="qglformat.html">rendering options</a>. If the underlying OpenGL/Window system
cannot satisfy all the features requested in <em>format,</em> the nearest
subset of features will be used. After creation, the <a href="qglwidget.html#a8">format</a>() method
will return the actual format obtained.
<p>The widget will be <a href="qglwidget.html#a3">invalid</a> if the
system has no <a href="qglformat.html#c6">OpenGL support</a>.
<p>The <em>parent, name</em> and <em>f</em> arguments are passed to the <a href="qwidget.html">QWidget</a>
constructor.
<p>If the <em>shareWidget</em> parameter points to a valid QGLWidget, this
widget will share OpenGL display lists with <em>shareWidget.</em> Note: If
this widget and <em>shareWidget</em> has different <a href="qglwidget.html#a8">formats</a>, display list sharing may fail. You can check
whether display list sharing succeeded by using the <a href="qglwidget.html#a4">isSharing</a>()
method.
<p>Note: Initialization of OpenGL rendering state etc. should be done
by overriding the <a href="qglwidget.html#b4">initializeGL</a>() function, not in the constructor of
your QGLWidget subclass.
<p>See also: <a href="qglformat.html#c7">QGLFormat::defaultFormat</a>() and <a href="qglwidget.html#a3">isValid</a>().
<h3 class="fn"><a name="a2"></a>QGLWidget::~QGLWidget()</h3>
<p>Destroys the widget.
<h3 class="fn">bool<a name="b8"></a>QGLWidget::autoBufferSwap()const <code>[protected]</code></h3>
<p>Returns TRUE if the widget is doing automatic GL buffer swapping.
<p>See also: <a href="qglwidget.html#b7">setAutoBufferSwap</a>().
<h3 class="fn">const<a href="qglcontext.html">QGLContext</a>*<a name="b0"></a>QGLWidget::context()const</h3>
<p>Returns the current context.
<p>See also: <a href="qglwidget.html#b1">setContext</a>().
<h3 class="fn">bool<a name="a6"></a>QGLWidget::doubleBuffer()const</h3>
<p>Returns TRUE if the contained GL rendering context has double buffering.
<p>See also: <a href="qglformat.html#a3">QGLFormat::doubleBuffer</a>().
<h3 class="fn"><a href="qglformat.html">QGLFormat</a><a name="a8"></a>QGLWidget::format()const</h3>
<p>Returns the format of the contained GL rendering context.
<p>See also: <a href="qglwidget.html#a9">setFormat</a>().
<h3 class="fn">void<a name="c2"></a>QGLWidget::glDraw() <code>[virtualprotected]</code></h3>
<p>Executes the virtual function <a href="qglwidget.html#b5">paintGL</a>(), initializing first as necessary.
<h3 class="fn">void<a name="c1"></a>QGLWidget::glInit() <code>[virtualprotected]</code></h3>
<p>Initializes OpenGL for this widget's context. Calls the virtual
function <a href="qglwidget.html#b4">initializeGL</a>().
<h3 class="fn">void<a name="b4"></a>QGLWidget::initializeGL() <code>[virtualprotected]</code></h3>
<p>This virtual function is called one time before the first call to
<a href="qglwidget.html#b5">paintGL</a>() or <a href="qglwidget.html#b6">resizeGL</a>(), and then one time whenever the widget has
been assigned a new <a href="qglcontext.html">QGLContext</a>. Reimplement it in a subclass.
<p>This function should take care of setting any required OpenGL
context rendering flags, defining display lists, etc.
<p>There is no need to call <a href="qglwidget.html#a5">makeCurrent</a>() because this has already been
done when this function is called.
<h3 class="fn">bool<a name="a4"></a>QGLWidget::isSharing()const</h3>
<p>Returns TRUE if display list sharing with another QGLWidget was
requested in the constructor, and the GL system was able to provide
it. The GL system may fail to provide display list sharing if the
two QGLWidgets use different formats.
<p>See also: <a href="qglwidget.html#a8">format</a>().
<h3 class="fn">bool<a name="a3"></a>QGLWidget::isValid()const</h3>
<p>Returns TRUE if the widget has a valid GL rendering context. A
widget will be invalid if the system has no <a href="qglformat.html#c6">OpenGL support</a>
<h3 class="fn">void<a name="a5"></a>QGLWidget::makeCurrent() <code>[virtual]</code></h3>
<p>Makes this widget the current widget for OpenGL
operations. I.e. makes this widget's rendering context the current
OpenGL rendering context.
<h3 class="fn">void<a name="b9"></a>QGLWidget::paintEvent(<a href="qpaintevent.html">QPaintEvent</a>*) <code>[virtualprotected]</code></h3>
<p>Handles paint events. Will cause the virtual <a href="qglwidget.html#b5">paintGL</a>() fucntion to
be called, initializing first as necessary.
<p>Reimplemented from <a href="qwidget.html#o4">QWidget.</a>
<h3 class="fn">void<a name="b5"></a>QGLWidget::paintGL() <code>[virtualprotected]</code></h3>
<p>This virtual function is called whenever the widget needs to be painted.
Reimplement it in a subclass.
<p>There is no need to call <a href="qglwidget.html#a5">makeCurrent</a>() because this has already been
done when this function is called.
<h3 class="fn"><a href="qpixmap.html">QPixmap</a><a name="b2"></a>QGLWidget::renderPixmap(intw=0, inth=0, booluseContext=FALSE) <code>[virtual]</code></h3>
<p>Renders the current scene on a pixmap and returns it.
<p>You may use this method on both visible and invisible QGLWidgets.
<p>This method will create a pixmap and a temporary <a href="qglcontext.html">QGLContext</a> to
render on it. Then, <a href="qglwidget.html#b4">initializeGL</a>(), <a href="qglwidget.html#b6">resizeGL</a>(), and <a href="qglwidget.html#b5">paintGL</a>() are
called on this context. Finally, the widget's original GL context is
restored.
<p>The size of the pixmap will be width <em>w</em> and height <em>h.</em> If any of
those are 0 (the default), the pixmap will have the same size as the
widget.
<p>If <em>useContext</em> is TRUE, this method will try to be more efficient
by using the existing GL context to render the pixmap. The default
is FALSE. Use only if you know what you are doing.
<p>Bugs and limitations:
<ul>
<li>May give unexpected results if the depth of the GL rendering
context is different from the depth of the desktop.
</ul>
<h3 class="fn">void<a name="c0"></a>QGLWidget::resizeEvent(<a href="qresizeevent.html">QResizeEvent</a>*) <code>[virtualprotected]</code></h3>
<p>Handles resize events. Calls the virtual function <a href="qglwidget.html#b6">resizeGL</a>().
<p>Reimplemented from <a href="qwidget.html#o6">QWidget.</a>
<h3 class="fn">void<a name="b6"></a>QGLWidget::resizeGL(intwidth, intheight) <code>[virtualprotected]</code></h3>
<p>This virtual function is called whenever the widget has been resized.
Reimplement it in a subclass.
<p>There is no need to call <a href="qglwidget.html#a5">makeCurrent</a>() because this has already been
done when this function is called.
<h3 class="fn">void<a name="b7"></a>QGLWidget::setAutoBufferSwap(boolon) <code>[protected]</code></h3>
<p>Turns on or off the automatic GL buffer swapping. If on, and the
widget is using a double-buffered format, the background and
foreground GL buffers will automatically be swapped after each time
the <a href="qglwidget.html#b5">paintGL</a>() function has been called.
<p>The buffer auto-swapping is on by default.
<p>See also: <a href="qglwidget.html#b8">autoBufferSwap</a>(), <a href="qglwidget.html#a6">doubleBuffer</a>() and <a href="qglwidget.html#a7">swapBuffers</a>().
<h3 class="fn">void<a name="b1"></a>QGLWidget::setContext(<a href="qglcontext.html">QGLContext</a>*context, const<a href="qglcontext.html">QGLContext</a>*shareContext=0, booldeleteOldContext=TRUE) <code>[virtual]</code></h3>
<p>Sets a new context for this widget. The <a href="qglcontext.html">QGLContext</a> <em>context</em> must
be created using <em>new.</em> QGLWidget will delete <em>context</em> when
another context is set or when the widget is destroyed.
<p>If <em>context</em> is invalid, <a href="qglcontext.html#a2">QGLContext::create</a>() is performed on
it. The <a href="qglwidget.html#b4">initializeGL</a>() function will then be executed for the new
context before the first <a href="qglwidget.html#b6">resizeGL</a>() or <a href="qglwidget.html#b5">paintGL</a>().
<p>If <em>context</em> is invalid, this method will try to keep any existing
display list sharing with other QGLWidgets this widget currently
has, or (if <em>shareContext</em> points to a valid context) start display
list sharing with that context, but it may fail. Use <a href="qglwidget.html#a4">isSharing</a>() to
test.
<p>If <em>deleteOldContext</em> is TRUE (the default), the existing context
will be deleted. You may use FALSE here if you have kept a pointer
to the old context (as returned by <a href="qglwidget.html#b0">context</a>()), and want to restore
that context later.
<p>See also: <a href="qglwidget.html#b0">context</a>(), <a href="qglwidget.html#a9">setFormat</a>() and <a href="qglwidget.html#a4">isSharing</a>().
<h3 class="fn">void<a name="a9"></a>QGLWidget::setFormat(const<a href="qglformat.html">QGLFormat</a>&format) <code>[virtual]</code></h3>
<p>Sets a new format for this widget.
<p>If the underlying OpenGL/Window system cannot satisfy all the
features requested in <em>format,</em> the nearest subset of features will
be used. After creation, the <a href="qglwidget.html#a8">format</a>() method will return the actual
rendering context format obtained.
<p>The widget will be assigned a new <a href="qglcontext.html">QGLContext</a>, and the <a href="qglwidget.html#b4">initializeGL</a>()
function will be executed for this new context before the first
<a href="qglwidget.html#b6">resizeGL</a>() or <a href="qglwidget.html#b5">paintGL</a>().
<p>This method will try to keep any existing display list sharing with
other QGLWidgets, but it may fail. Use <a href="qglwidget.html#a4">isSharing</a>() to test.
<p>See also: <a href="qglwidget.html#a8">format</a>(), <a href="qglwidget.html#b1">setContext</a>(), <a href="qglwidget.html#a4">isSharing</a>() and <a href="qglwidget.html#a3">isValid</a>().
<h3 class="fn">void<a name="a7"></a>QGLWidget::swapBuffers() <code>[virtual]</code></h3>
<p>Swaps the screen contents with an off-screen buffer. Works only if
the widget's format specifies double buffer mode.
<p>Normally, there is no need to explicitly call this function, because
it is done automatically after each widget repaint, i.e. after each
time <a href="qglwidget.html#b5">paintGL</a>() has been executed.
<p>See also: <a href="qglwidget.html#a6">doubleBuffer</a>(), <a href="qglwidget.html#b7">setAutoBufferSwap</a>() and <a href="qglformat.html#a4">QGLFormat::setDoubleBuffer</a>().
<h3 class="fn">void<a name="b3"></a>QGLWidget::updateGL() <code>[virtualslot]</code></h3>
<p>Updates the widget by calling <a href="qglwidget.html#c2">glDraw</a>().
<hr><p>
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