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QwtPlotGLCanvas(3) Qwt User's Guide QwtPlotGLCanvas(3)

NAME

QwtPlotGLCanvas - An alternative canvas for a QwtPlot derived from QGLWidget.

SYNOPSIS

#include <qwt_plot_glcanvas.h>

Inherits QGLWidget, and QwtPlotAbstractGLCanvas.

Public Slots


void replot ()

Public Member Functions


QwtPlotGLCanvas (QwtPlot *=NULL)
Constructor. QwtPlotGLCanvas (const QGLFormat &, QwtPlot *=NULL)
Constructor. virtual ~QwtPlotGLCanvas ()
Destructor. virtual Q_INVOKABLE void invalidateBackingStore () override
Invalidate the internal backing store. Q_INVOKABLE QPainterPath borderPath (const QRect &) const
virtual bool event (QEvent *) override

Protected Member Functions


virtual void paintEvent (QPaintEvent *) override
virtual void initializeGL () override
No operation - reserved for some potential use in the future. virtual void paintGL () override
Paint the plot. virtual void resizeGL (int width, int height) override
No operation - reserved for some potential use in the future.

Additional Inherited Members

Detailed Description

An alternative canvas for a QwtPlot derived from QGLWidget.

QwtPlotGLCanvas implements the very basics to act as canvas inside of a QwtPlot widget. It might be extended to a full featured alternative to QwtPlotCanvas in a future version of Qwt.

Even if QwtPlotGLCanvas is not derived from QFrame it imitates its API. When using style sheets it supports the box model - beside backgrounds with rounded borders.

Since Qt 5.4 QOpenGLWidget is available, that is used by QwtPlotOpenGLCanvas.

See also

QwtPlot::setCanvas(), QwtPlotCanvas, QwtPlotOpenGLCanvas

Note

With Qt4 you might want to use the QPaintEngine::OpenGL paint engine ( see QGL::setPreferredPaintEngine() ). On a Linux test system QPaintEngine::OpenGL2 shows very basic problems like translated geometries.

Another way for getting hardware accelerated graphics is using an OpenGL offscreen buffer ( QwtPlotCanvas::OpenGLBuffer ) with QwtPlotCanvas. Performance is worse, than rendering straight to a QGLWidget, but is usually better integrated into a desktop application.

Definition at line 45 of file qwt_plot_glcanvas.h.

Constructor & Destructor Documentation

QwtPlotGLCanvas::QwtPlotGLCanvas (QwtPlot * plot = NULL) [explicit]

Constructor.

Parameters

plot Parent plot widget

See also

QwtPlot::setCanvas()

Definition at line 56 of file qwt_plot_glcanvas.cpp.

QwtPlotGLCanvas::QwtPlotGLCanvas (const QGLFormat & format, QwtPlot * plot = NULL) [explicit]

Constructor.

Parameters

format OpenGL rendering options
plot Parent plot widget

See also

QwtPlot::setCanvas()

Definition at line 69 of file qwt_plot_glcanvas.cpp.

Member Function Documentation

QPainterPath QwtPlotGLCanvas::borderPath (const QRect & rect) const

Calculate the painter path for a styled or rounded border

When the canvas has no styled background or rounded borders the painter path is empty.

Parameters

rect Bounding rectangle of the canvas

Returns

Painter path, that can be used for clipping

Definition at line 157 of file qwt_plot_glcanvas.cpp.

bool QwtPlotGLCanvas::event (QEvent * event) [override], [virtual]

Qt event handler for QEvent::PolishRequest and QEvent::StyleChange

Parameters

event Qt Event

Returns

See QGLWidget::event()

Definition at line 110 of file qwt_plot_glcanvas.cpp.

void QwtPlotGLCanvas::paintEvent (QPaintEvent * event) [override], [protected], [virtual]

Paint event

Parameters

event Paint event

See also

QwtPlot::drawCanvas()

Definition at line 100 of file qwt_plot_glcanvas.cpp.

void QwtPlotGLCanvas::replot () [slot]

Invalidate the paint cache and repaint the canvas

See also

invalidatePaintCache()

Definition at line 131 of file qwt_plot_glcanvas.cpp.

Author

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Sun Jul 18 2021 Version 6.2.0