QGLWidget Class Reference

The QGLWidget class is a widget for rendering OpenGL graphics. This class is part of the Qt OpenGL Extension. More...

#include <qgl.h>

Inherits QWidget.

List of all member functions.

Public Members

• QGLWidget ( QWidget * parent=0, 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 () 
• bool isValid () const
• void makeCurrent () 
• bool doubleBuffer () const
• void swapBuffers () 
• const QGLFormat& format () const
• void setFormat ( const QGLFormat & format ) 
• const QGLContext* context () const
• void setContext ( QGLContext * context, const QGLContext * shareContext = 0 ) 

Public Slots

• void updateGL () 

Protected Members

• virtual void initializeGL () 
• virtual void paintGL () 
• virtual void resizeGL ( int w, int h ) 
• virtual void paintEvent ( QPaintEvent * ) 
• virtual void resizeEvent ( QResizeEvent * ) 

Detailed Description

The QGLWidget class is a widget for rendering OpenGL graphics.

It is easy to render OpenGL graphics in Qt applications. You can create a subclass of QGLWidget and reimplement two functions: resizeGL() and paintGL(). The resizeGL() method is called whenever the widget has been resized (and also when it shown for the first time, since all newly created widgets get a resize event automatically). paintGL() is called when the widget needs to be updated.

    class MyGLDrawer : public QGLWidget
    {
        Q_OBJECT        // include this if you use Qt signals/slots

    public:
        MyGLDrawer( QWidget *parent, const char *name )
            : QGLWidget(parent,name) {}

    protected:
        void paintGL()
        {
          // draw the scene
        }

        void resizeGL( int w, int h )
        {
          // setup viewport, projection etc.
        }
    };

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

When paintGL() or resizeGL() is called, your widget 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 makeCurrent() first.

Like QGLContext, QGLWidget has advanced functions for requesting a new display format, and you can even set a new rendering context.

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 parent, name and 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.

Note: Initialization of OpenGL rendering state etc. should be done by overriding the initializeGL() function, not in the constructor of your QGLWidget subclass.

See also: QGLFormat::defaultFormat().

QGLWidget::QGLWidget ( const QGLFormat & format, 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 format argument specifies the rendering capabilities. The widget becomes invalid if the driver/hardware cannot satisfy the requested format.

The parent, name and 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.

Note: Initialization of OpenGL rendering state etc. should be done by overriding the initializeGL() function, not in the constructor of your QGLWidget subclass.

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

QGLWidget::~QGLWidget ()

Destroys the widget.

const QGLContext * QGLWidget::context () const

Returns the current context.

See also: setContext().

bool QGLWidget::doubleBuffer () const

Returns TRUE if double buffering is set in the format for this widget.

See also: QGLFormat::doubleBuffer().

const QGLFormat & QGLWidget::format () const

Returns the widget's format.

See also: setFormat().

void QGLWidget::initializeGL () [virtual protected]

This virtual function is called one time before the first call to paintGL() or resizeGL(), and then one time whenever the widget has been assigned a new OpenGL context. Reimplement it in a subclass.

This function should take care of setting OpenGL rendering flags, defining display lists, etc.

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

bool QGLWidget::isValid () const

Returns TRUE if the widget was able to satisfy the specified constraints.

void QGLWidget::makeCurrent ()

Makes this widget the current widget for OpenGL operations. I.e. makes this widget's rendering context the current OpenGL rendering context.

void QGLWidget::paintEvent ( QPaintEvent * ) [virtual protected]

Handles paint events. Calls the virtual function paintGL().

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::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. 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::setContext ( QGLContext * context, const QGLContext * shareContext = 0 )

Sets a new context for this widget. The context must be created using new. QGLWidget will delete the context when another context is set or when the widget is destroyed.

Calling setContext() will not alter any display list sharing this widget currently has, unless you explicitly request sharing with a different context by giving a shareContext parameter that points to a valid context.

See also: context() and setFormat().

void QGLWidget::setFormat ( const QGLFormat & format )

Sets a new format for this widget. The widget becomes invalid if the requested format cannot be satisfied.

Calling setFormat() will not alter any display list sharing this widget currently has.

See also: format(), setContext() and isValid().

void QGLWidget::swapBuffers ()

Swaps the screen contents with an off-screen buffer. Works only if the widget's format specifies double buffer mode.

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

void QGLWidget::updateGL () [slot]

Updates the widget by calling paintGL().

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This file is part of the Qt toolkit, copyright © 1995-98 Troll Tech, all rights reserved.

It was generated from the following files:

• qgl.h: 1998/07/03
• qgl.cpp: 1998/07/03