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QGLWidget(3qt)							QGLWidget(3qt)

NAME
       QGLWidget - Widget for rendering OpenGL graphics

SYNOPSIS
       #include <qgl.h>

       Inherits QWidget and QGL.

   Public Members
       QGLWidget ( QWidget * parent = 0, const char * name = 0, const
	   QGLWidget * shareWidget = 0, WFlags f = 0 )
       QGLWidget ( QGLContext * context, QWidget * parent, const char * name =
	   0, const QGLWidget * shareWidget = 0, WFlags f = 0 )
       QGLWidget ( const QGLFormat & format, QWidget * parent = 0, const char
	   * name = 0, const QGLWidget * shareWidget = 0, WFlags f = 0 )
       ~QGLWidget ()
       void qglColor ( const QColor & c ) const
       void qglClearColor ( const QColor & c ) const
       bool isValid () const
       bool isSharing () const
       virtual void makeCurrent ()
       void doneCurrent ()
       bool doubleBuffer () const
       virtual void swapBuffers ()
       QGLFormat format () const
       const QGLContext * context () const
       virtual QPixmap renderPixmap ( int w = 0, int h = 0, bool useContext =
	   FALSE )
       virtual QImage grabFrameBuffer ( bool withAlpha = FALSE )
       virtual void makeOverlayCurrent ()
       const QGLContext * overlayContext () const
       const QGLColormap & colormap () const
       void setColormap ( const QGLColormap & cmap )
       void renderText ( int x, int y, const QString & str, const QFont & fnt
	   = QFont ( ), int listBase = 2000 )
       void renderText ( double x, double y, double z, const QString & str,
	   const QFont & fnt = QFont ( ), int listBase = 2000 )

   Public Slots
       virtual void updateGL ()
       virtual void updateOverlayGL ()

   Static Public Members
       QImage convertToGLFormat ( const QImage & img )

   Protected Members
       virtual void initializeGL ()
       virtual void resizeGL ( int width, int height )
       virtual void paintGL ()
       virtual void initializeOverlayGL ()
       virtual void resizeOverlayGL ( int width, int height )
       virtual void paintOverlayGL ()
       void setAutoBufferSwap ( bool on )
       bool autoBufferSwap () const
       virtual void paintEvent ( QPaintEvent * )
       virtual void resizeEvent ( QResizeEvent * )
       virtual void glInit ()
       virtual void glDraw ()

DESCRIPTION
       The QGLWidget class is a widget for rendering OpenGL graphics.

       QGLWidget provides functionality for displaying OpenGL<sup>*</sup>
       graphics integrated into a Qt application. It is very simple to use.
       You inherit from it and use the subclass like any other QWidget, except
       that instead of drawing the widget's contents using QPainter etc. you
       use the standard OpenGL rendering commands.

       QGLWidget provides three convenient virtual functions that you can
       reimplement in your subclass to perform the typical OpenGL tasks:

       paintGL() - Renders the OpenGL scene. Gets called whenever the widget
       needs to be updated.

       resizeGL() - Sets up the OpenGL viewport, projection, etc. Gets called
       whenever the the widget has been resized (and also when it is shown for
       the first time because all newly created widgets get a resize event
       automatically).

       initializeGL() - Sets up the OpenGL rendering context, defines display
       lists, etc. Gets called once before the first time resizeGL() or
       paintGL() is called.

       Here is a rough outline of how a QGLWidget subclass might look:

	   class MyGLDrawer : public QGLWidget
	   {
	       Q_OBJECT	       // must include this if you use Qt signals/slots
	   public:
	       MyGLDrawer( QWidget *parent, const char *name )
		   : QGLWidget(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();
		   ...
	       }
	   };

       If you need to trigger a repaint from places other than paintGL() (a
       typical example is when using timers to animate scenes), you should
       call the widget's updateGL() function.

       Your widget's OpenGL rendering context is made current when paintGL(),
       resizeGL(), or initializeGL() is called. If you need to call the
       standard OpenGL API functions from other places (e.g. in your widget's
       constructor or in your own paint functions), you must call
       makeCurrent() first.

       QGLWidget provides functions for requesting a new display format and
       you can also create widgets with customized rendering contexts.

       You can also share OpenGL display lists between QGLWidgets (see the
       documentation of the QGLWidget constructors for details).

Overlays
       The QGLWidget creates a GL overlay context in addition to the normal
       context if overlays are supported by the underlying system.

       If you want to use overlays, you specify it in the format. (Note:
       Overlay must be requested in the format passed to the QGLWidget
       constructor.) Your GL widget should also implement some or all of these
       virtual methods:

       paintOverlayGL()

       resizeOverlayGL()

       initializeOverlayGL()

       These methods work in the same way as the normal paintGL() etc.
       functions, except that they will be called when the overlay context is
       made current. You can explicitly make the overlay context current by
       using makeOverlayCurrent(), and you can access the overlay context
       directly (e.g. to ask for its transparent color) by calling
       overlayContext().

       On X servers in which the default visual is in an overlay plane, non-GL
       Qt windows can also be used for overlays. See the
       examples/opengl/overlay_x11 example program for details.

       <sup>*</sup> OpenGL is a trademark of Silicon Graphics, Inc. in the
       United States and other countries.

       See also Graphics Classes and Image Processing Classes.

MEMBER FUNCTION DOCUMENTATION
QGLWidget::QGLWidget ( QWidget * parent = 0, const char * name = 0, const
       QGLWidget * shareWidget = 0, WFlags f = 0 )
       Constructs an OpenGL widget with a parent widget and a name.

       The default format is used. The widget will be invalid if the system
       has no OpenGL support.

       The parent, name and widget flag, f, arguments are passed to the
       QWidget constructor.

       If the shareWidget parameter points to a valid QGLWidget, this widget
       will share OpenGL display lists with shareWidget. If this widget and
       shareWidget have different formats, display list sharing may fail. You
       can check whether display list sharing succeeded by calling
       isSharing().

       The initialization of OpenGL rendering state, etc. should be done by
       overriding the initializeGL() function, rather than in the constructor
       of your QGLWidget subclass.

       See also QGLFormat::defaultFormat().

QGLWidget::QGLWidget ( QGLContext * context, QWidget * parent, const char *
       name = 0, const QGLWidget * shareWidget = 0, WFlags f = 0 )
       Constructs an OpenGL widget with parent parent, called name.

       The context argument is a pointer to the QGLContext that you wish to be
       bound to this widget. This allows you to pass in your own QGLContext
       sub-classes.

       The widget will be invalid if the system has no OpenGL support.

       The parent, name and widget flag, f, arguments are passed to the
       QWidget constructor.

       If the shareWidget parameter points to a valid QGLWidget, this widget
       will share OpenGL display lists with shareWidget. If this widget and
       shareWidget have different formats, display list sharing may fail. You
       can check whether display list sharing succeeded by calling
       isSharing().

       The initialization of OpenGL rendering state, etc. should be done by
       overriding the initializeGL() function, rather than in the constructor
       of your QGLWidget subclass.

       See also QGLFormat::defaultFormat() and isValid().

QGLWidget::QGLWidget ( const QGLFormat & format, QWidget * parent = 0, const
       char * name = 0, const QGLWidget * shareWidget = 0, WFlags f = 0 )
       Constructs an OpenGL widget with parent parent, called name.

       The format argument specifies the desired rendering options. If the
       underlying OpenGL/Window system cannot satisfy all the features
       requested in format, the nearest subset of features will be used. After
       creation, the format() method will return the actual format obtained.

       The widget will be invalid if the system has no OpenGL support.

       The parent, name and widget flag, f, arguments are passed to the
       QWidget constructor.

       If the shareWidget parameter points to a valid QGLWidget, this widget
       will share OpenGL display lists with shareWidget. If this widget and
       shareWidget have different formats, display list sharing may fail. You
       can check whether display list sharing succeeded by calling
       isSharing().

       The initialization of OpenGL rendering state, etc. should be done by
       overriding the initializeGL() function, rather than in the constructor
       of your QGLWidget subclass.

       See also QGLFormat::defaultFormat() and isValid().

QGLWidget::~QGLWidget ()
       Destroys the widget.

bool QGLWidget::autoBufferSwap () const [protected]
       Returns TRUE if the widget is doing automatic GL buffer swapping;
       otherwise returns FALSE.

       See also setAutoBufferSwap().

const QGLColormap & QGLWidget::colormap () const
       Returns the colormap for this widget.

       Usually it is only top-level widgets that can have different colormaps
       installed. Asking for the colormap of a child widget will return the
       colormap for the child's top-level widget.

       If no colormap has been set for this widget, the QColormap returned
       will be empty.

       See also setColormap().

const QGLContext * QGLWidget::context () const
       Returns the context of this widget.

       It is possible that the context is not valid (see isValid()), for
       example, if the underlying hardware does not support the format
       attributes that were requested.

QImage QGLWidget::convertToGLFormat ( const QImage & img ) [static]
       Converts the image img into the unnamed format expected by OpenGL
       functions such as glTexImage2D(). The returned image is not usable as a
       QImage, but QImage::width(), QImage::height() and QImage::bits() may be
       used with OpenGL. The following few lines are from the texture example.
       Most of the code is irrelevant, so we just quote the relevant bits:

	       QImage tex1, tex2, buf;
	       if ( !buf.load( "gllogo.bmp" ) ) {  // Load first image from file

       We create tex1 (and another variable) for OpenGL, and load a real image
       into buf.

	       tex1 = QGLWidget::convertToGLFormat( buf );  // flipped 32bit RGBA

       A few lines later, we convert buf into OpenGL format and store it in
       tex1.

	       glTexImage2D( GL_TEXTURE_2D, 0, 3, tex1.width(), tex1.height(), 0,
			     GL_RGBA, GL_UNSIGNED_BYTE, tex1.bits() );

       Note the dimension restrictions for texture images as described in the
       glTexImage2D() documentation. The width must be 2^m + 2*border and the
       height 2^n + 2*border where m and n are integers and border is either 0
       or 1.

       Another function in the same example uses tex1 with OpenGL.

       Example: opengl/texture/gltexobj.cpp.

void QGLWidget::doneCurrent ()
       Makes no GL context the current context. Normally, you do not need to
       call this function; QGLContext calls it as necessary. However, it may
       be useful in multithreaded environments.

bool QGLWidget::doubleBuffer () const
       Returns TRUE if the contained GL rendering context has double
       buffering; otherwise returns FALSE.

       See also QGLFormat::doubleBuffer().

QGLFormat QGLWidget::format () const
       Returns the format of the contained GL rendering context.

void QGLWidget::glDraw () [virtual protected]
       Executes the virtual function paintGL().

       The widget's rendering context will become the current context and
       initializeGL() will be called if it hasn't already been called.

void QGLWidget::glInit () [virtual protected]
       Initializes OpenGL for this widget's context. Calls the virtual
       function initializeGL().

QImage QGLWidget::grabFrameBuffer ( bool withAlpha = FALSE ) [virtual]
       Returns an image of the frame buffer. If withAlpha is TRUE the alpha
       channel is included.

       Depending on your hardware, you can explicitly select which color
       buffer to grab with a glReadBuffer() call before calling this function.

void QGLWidget::initializeGL () [virtual protected]
       This virtual function is called once before the first call to paintGL()
       or resizeGL(), and then once whenever the widget has been assigned a
       new QGLContext. Reimplement it in a subclass.

       This function should set up any required OpenGL context rendering
       flags, defining display lists, etc.

       There is no need to call makeCurrent() because this has already been
       done when this function is called.

void QGLWidget::initializeOverlayGL () [virtual protected]
       This virtual function is used in the same manner as initializeGL()
       except that it operates on the widget's overlay context instead of the
       widget's main context. This means that initializeOverlayGL() is called
       once before the first call to paintOverlayGL() or resizeOverlayGL().
       Reimplement it in a subclass.

       This function should set up any required OpenGL context rendering
       flags, defining display lists, etc. for the overlay context.

       There is no need to call makeOverlayCurrent() because this has already
       been done when this function is called.

bool QGLWidget::isSharing () const
       Returns TRUE if display list sharing with another QGLWidget was
       requested in the constructor, and the GL system was able to provide it;
       otherwise returns FALSE. The GL system may fail to provide display list
       sharing if the two QGLWidgets use different formats.

       See also format().

bool QGLWidget::isValid () const
       Returns TRUE if the widget has a valid GL rendering context; otherwise
       returns FALSE. A widget will be invalid if the system has no OpenGL
       support.

void QGLWidget::makeCurrent () [virtual]
       Makes this widget the current widget for OpenGL operations, i.e. makes
       the widget's rendering context the current OpenGL rendering context.

void QGLWidget::makeOverlayCurrent () [virtual]
       Makes the overlay context of this widget current. Use this if you need
       to issue OpenGL commands to the overlay context outside of
       initializeOverlayGL(), resizeOverlayGL(), and paintOverlayGL().

       Does nothing if this widget has no overlay.

       See also makeCurrent().

const QGLContext * QGLWidget::overlayContext () const
       Returns the overlay context of this widget, or 0 if this widget has no
       overlay.

       See also context().

void QGLWidget::paintEvent ( QPaintEvent * ) [virtual protected]
       Handles paint events. Will cause the virtual paintGL() function to be
       called.

       The widget's rendering context will become the current context and
       initializeGL() will be called if it hasn't already been called.

       Reimplemented from QWidget.

void QGLWidget::paintGL () [virtual protected]
       This virtual function is called whenever the widget needs to be
       painted. Reimplement it in a subclass.

       There is no need to call makeCurrent() because this has already been
       done when this function is called.

void QGLWidget::paintOverlayGL () [virtual protected]
       This virtual function is used in the same manner as paintGL() except
       that it operates on the widget's overlay context instead of the
       widget's main context. This means that paintOverlayGL() is called
       whenever the widget's overlay needs to be painted. Reimplement it in a
       subclass.

       There is no need to call makeOverlayCurrent() because this has already
       been done when this function is called.

void QGLWidget::qglClearColor ( const QColor & c ) const
       Convenience function for specifying the clearing color to OpenGL. Calls
       glClearColor (in RGBA mode) or glClearIndex (in color-index mode) with
       the color c. Applies to the current GL context.

       See also qglColor(), QGLContext::currentContext(), and QColor.

void QGLWidget::qglColor ( const QColor & c ) const
       Convenience function for specifying a drawing color to OpenGL. Calls
       glColor3 (in RGBA mode) or glIndex (in color-index mode) with the color
       c. Applies to the current GL context.

       See also qglClearColor(), QGLContext::currentContext(), and QColor.

QPixmap QGLWidget::renderPixmap ( int w = 0, int h = 0, bool useContext =
       FALSE ) [virtual]
       Renders the current scene on a pixmap and returns the pixmap.

       You can use this method on both visible and invisible QGLWidgets.

       This method will create a pixmap and a temporary QGLContext to render
       on the pixmap. It will then call initializeGL(), resizeGL(), and
       paintGL() on this context. Finally, the widget's original GL context is
       restored.

       The size of the pixmap will be w pixels wide and h pixels high unless
       one of these parameters is 0 (the default), in which case the pixmap
       will have the same size as the widget.

       If useContext is TRUE, this method will try to be more efficient by
       using the existing GL context to render the pixmap. The default is
       FALSE. Only use TRUE if you understand the risks.

       Overlays are not rendered onto the pixmap.

       If the GL rendering context and the desktop have different bit depths,
       the result will most likely look surprising.

       Note that the creation of display lists, modifications of the view
       frustum etc. should be done from within initializeGL(). If this is not
       done, the temporary QGLContext will not be initialized properly, and
       the rendered pixmap may be incomplete/corrupted.

void QGLWidget::renderText ( int x, int y, const QString & str, const QFont &
       fnt = QFont ( ), int listBase = 2000 )
       Renders the string str into the GL context of this widget.

       x and y are specified in window coordinates, with the origin in the
       upper left-hand corner of the window. If fnt is not specified, the
       currently set application font will be used to render the string. To
       change the color of the rendered text you can use the glColor() call
       (or the qglColor() convenience function), just before the renderText()
       call. Note that if you have GL_LIGHTING enabled, the string will not
       appear in the color you want. You should therefore switch lighting off
       before using renderText().

       listBase specifies the index of the first display list that is
       generated by this function. The default value is 2000. 256 display
       lists will be generated, one for each of the first 256 characters in
       the font that is used to render the string. If several fonts are used
       in the same widget, the display lists for these fonts will follow the
       last generated list. You would normally not have to change this value
       unless you are using lists in the same range. The lists are deleted
       when the widget is destroyed.

       Note: This function only works reliably with ASCII strings.

void QGLWidget::renderText ( double x, double y, double z, const QString &
       str, const QFont & fnt = QFont ( ), int listBase = 2000 )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       x, y and z are specified in scene or object coordinates relative to the
       currently set projection and model matrices. This can be useful if you
       want to annotate models with text labels and have the labels move with
       the model as it is rotated etc.

void QGLWidget::resizeEvent ( QResizeEvent * ) [virtual protected]
       Handles resize events. Calls the virtual function resizeGL().

       Reimplemented from QWidget.

void QGLWidget::resizeGL ( int width, int height ) [virtual protected]
       This virtual function is called whenever the widget has been resized.
       The new size is passed in width and height. Reimplement it in a
       subclass.

       There is no need to call makeCurrent() because this has already been
       done when this function is called.

void QGLWidget::resizeOverlayGL ( int width, int height ) [virtual protected]
       This virtual function is used in the same manner as paintGL() except
       that it operates on the widget's overlay context instead of the
       widget's main context. This means that resizeOverlayGL() is called
       whenever the widget has been resized. The new size is passed in width
       and height. Reimplement it in a subclass.

       There is no need to call makeOverlayCurrent() because this has already
       been done when this function is called.

void QGLWidget::setAutoBufferSwap ( bool on ) [protected]
       If on is TRUE automatic GL buffer swapping is switched on; otherwise it
       is switched off.

       If on is TRUE and the widget is using a double-buffered format, the
       background and foreground GL buffers will automatically be swapped
       after each paintGL() call.

       The buffer auto-swapping is on by default.

       See also autoBufferSwap(), doubleBuffer(), and swapBuffers().

void QGLWidget::setColormap ( const QGLColormap & cmap )
       Set the colormap for this widget to cmap. Usually it is only top-level
       widgets that can have colormaps installed.

       See also colormap().

void QGLWidget::swapBuffers () [virtual]
       Swaps the screen contents with an off-screen buffer. This only works if
       the widget's format specifies double buffer mode.

       Normally, there is no need to explicitly call this function because it
       is done automatically after each widget repaint, i.e. each time after
       paintGL() has been executed.

       See also doubleBuffer(), setAutoBufferSwap(), and
       QGLFormat::setDoubleBuffer().

void QGLWidget::updateGL () [virtual slot]
       Updates the widget by calling glDraw().

void QGLWidget::updateOverlayGL () [virtual slot]
       Updates the widget's overlay (if any). Will cause the virtual function
       paintOverlayGL() to be executed.

       The widget's rendering context will become the current context and
       initializeGL() will be called if it hasn't already been called.

SEE ALSO
       http://doc.trolltech.com/qglwidget.html
       http://www.trolltech.com/faq/tech.html

COPYRIGHT
       Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com.  See the
       license file included in the distribution for a complete license
       statement.

AUTHOR
       Generated automatically from the source code.

BUGS
       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to
       help you. Thank you.

       The definitive Qt documentation is provided in HTML format; it is
       located at $QTDIR/doc/html and can be read using Qt Assistant or with a
       web browser. This man page is provided as a convenience for those users
       who prefer man pages, although this format is not officially supported
       by Trolltech.

       If you find errors in this manual page, please report them to qt-
       bugs@trolltech.com.  Please include the name of the manual page
       (qglwidget.3qt) and the Qt version (3.3.8).

Trolltech AS			2 February 2007			QGLWidget(3qt)
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