QwtPlotGLCanvas Class Reference

An alternative canvas for a QwtPlot derived from QGLWidget. More...

#include <qwt_plot_glcanvas.h>

Inheritance diagram for QwtPlotGLCanvas:

Classes
class	PrivateData

Public Slots
void	replot ()
	Replot the canvas.

Public Member Functions
	QwtPlotGLCanvas (QwtPlot *=nullptr)
	Constructor.
	QwtPlotGLCanvas (const QGLFormat &, QwtPlot *=nullptr)
	Constructor with QGLFormat.
	~QwtPlotGLCanvas () override
	Destructor.
virtual Q_INVOKABLE void	invalidateBackingStore () override
	Invalidate the backing store.
Q_INVOKABLE QPainterPath	borderPath (const QRect &) const
	Get the border path.
virtual bool	event (QEvent *) override
	Handle events.
Public Member Functions inherited from QwtPlotAbstractGLCanvas
	QwtPlotAbstractGLCanvas (QWidget *canvasWidget)
	Paint attributes.
void	setPaintAttribute (PaintAttribute, bool on=true)
	Changing the paint attributes.
bool	testPaintAttribute (PaintAttribute) const
	Test whether a paint attribute is enabled.
void	setFrameStyle (int style)
	Set the frame style.
int	frameStyle () const
	Get the frame style.
void	setFrameShadow (QFrame::Shadow)
	Set the frame shadow.
QFrame::Shadow	frameShadow () const
	Get the frame shadow.
void	setFrameShape (QFrame::Shape)
	Set the frame shape.
QFrame::Shape	frameShape () const
	Get the frame shape.
void	setLineWidth (int)
	Set the frame line width.
int	lineWidth () const
	Get the line width of the frame.
void	setMidLineWidth (int)
	Set the frame mid line width.
int	midLineWidth () const
	Get the midline width of the frame.
int	frameWidth () const
	Get the frame width depending on the style, line width and midline width.
QRect	frameRect () const
	Get the rectangle where the frame is drawn in.
Public Member Functions inherited from QwtPlotAbstractCanvas
	QwtPlotAbstractCanvas (QWidget *canvasWidget)
	Constructor.
QwtPlot *	plot ()
	Return parent plot widget.
const QwtPlot *	plot () const
	Return parent plot widget.
void	setFocusIndicator (FocusIndicator)
	Set the focus indicator.
FocusIndicator	focusIndicator () const
	Get the focus indicator.
void	setBorderRadius (double)
	Set the radius for the corners of the border frame.
double	borderRadius () const
	Get the radius for the corners of the border frame.

Protected Member Functions
virtual void	paintEvent (QPaintEvent *) override
	Paint event handler.
virtual void	initializeGL () override
	Initialize OpenGL.
virtual void	paintGL () override
	Paint OpenGL scene.
virtual void	resizeGL (int width, int height) override
	Resize OpenGL view.
Protected Member Functions inherited from QwtPlotAbstractGLCanvas
void	replot ()
	Invalidate the paint cache and repaint the canvas.
void	draw (QPainter *)
	Helper function for the derived plot canvas.
Protected Member Functions inherited from QwtPlotAbstractCanvas
QWidget *	canvasWidget ()
const QWidget *	canvasWidget () const
virtual void	drawFocusIndicator (QPainter *)
	Draw the focus indication.
virtual void	drawBorder (QPainter *)
	Draw the border of the canvas.
virtual void	drawBackground (QPainter *)
	Helper function for the derived plot canvas.
void	fillBackground (QPainter *)
	Helper function for the derived plot canvas.
void	drawCanvas (QPainter *)
	Draw the plot to the canvas.
void	drawStyled (QPainter *, bool)
	Helper function for the derived plot canvas.
void	drawUnstyled (QPainter *)
	Helper function for the derived plot canvas.
QPainterPath	canvasBorderPath (const QRect &rect) const
void	updateStyleSheetInfo ()
	Update the cached information about the current style sheet.

Properties
QFrame::Shadow	frameShadow
QFrame::Shape	frameShape
int	lineWidth
int	midLineWidth
int	frameWidth
QRect	frameRect
double	borderRadius

Additional Inherited Members
Public Types inherited from QwtPlotAbstractGLCanvas
enum	PaintAttribute { BackingStore = 1 , ImmediatePaint = 8 }
	Paint attributes. More...
Public Types inherited from QwtPlotAbstractCanvas
enum	FocusIndicator { NoFocusIndicator , CanvasFocusIndicator , ItemFocusIndicator }
	Focus indicator. More...

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.

Constructor & Destructor Documentation

QwtPlotGLCanvas()

QwtPlotGLCanvas::QwtPlotGLCanvas ( QwtPlot *  plot = nullptr )

explicit

Constructor.

Parameters

[in]

plot

Parent plot widget

See also

QwtPlot::setCanvas()

Constructor

Parameters

[in]	format	OpenGL rendering options
[in]	plot	Parent plot widget

See also

QwtPlot::setCanvas()

Destructor

Member Function Documentation

borderPath()

QPainterPath QwtPlotGLCanvas::borderPath

(

const QRect &

rect

)

const

Get the border path.

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

[in]

rect

Bounding rectangle of the canvas

Returns

Painter path, that can be used for clipping

event()

bool QwtPlotGLCanvas::event ( QEvent *  event )

overridevirtual

Handle events.

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

Parameters

[in]

event

Qt Event

Returns

See QGLWidget::event()

initializeGL()

void QwtPlotGLCanvas::initializeGL ( )

overrideprotectedvirtual

Initialize OpenGL.

No operation - reserved for some potential use in the future.

invalidateBackingStore()

void QwtPlotGLCanvas::invalidateBackingStore ( )

overridevirtual

Invalidate the backing store.

Invalidate the internal backing store.

Implements QwtPlotAbstractGLCanvas.

paintEvent()

void QwtPlotGLCanvas::paintEvent ( QPaintEvent *  event )

overrideprotectedvirtual

Paint event handler.

Paint event.

Parameters

event

Paint event

See also

QwtPlot::drawCanvas()

paintGL()

void QwtPlotGLCanvas::paintGL ( )

overrideprotectedvirtual

Paint OpenGL scene.

Paint the plot.

replot

void QwtPlotGLCanvas::replot ( )

slot

Replot the canvas.

Invalidate the paint cache and repaint the canvas.

See also

invalidatePaintCache()

resizeGL()

void QwtPlotGLCanvas::resizeGL ( int  width, int  height  )

overrideprotectedvirtual

Resize OpenGL view.

No operation - reserved for some potential use in the future.

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The documentation for this class was generated from the following files:

• /home/runner/work/QWT/QWT/src/plot/qwt_plot_glcanvas.h
• /home/runner/work/QWT/QWT/src/plot/qwt_plot_glcanvas.cpp