QwtPlotCanvas Class Reference

Canvas of a QwtPlot. More...

#include <qwt_plot_canvas.h>

Inheritance diagram for QwtPlotCanvas:

Public Types
enum	PaintAttribute { BackingStore = 1, Opaque = 2, HackStyledBackground = 4, ImmediatePaint = 8 }
	Paint attributes. More...
enum	FocusIndicator { NoFocusIndicator, CanvasFocusIndicator, ItemFocusIndicator }
	Focus indicator The default setting is NoFocusIndicator. More...
typedef QFlags< PaintAttribute >	PaintAttributes
	Paint attributes.

Public Slots
void	replot ()

Public Member Functions
	QwtPlotCanvas (QwtPlot *=NULL)
	Constructor. More...
virtual	~QwtPlotCanvas ()
	Destructor.
QwtPlot *	plot ()
	Return parent plot widget.
const QwtPlot *	plot () const
	Return parent plot widget.
void	setFocusIndicator (FocusIndicator)
FocusIndicator	focusIndicator () const
void	setBorderRadius (double)
double	borderRadius () const
void	setPaintAttribute (PaintAttribute, bool on=true)
	Changing the paint attributes. More...
bool	testPaintAttribute (PaintAttribute) const
const QPixmap *	backingStore () const
void	invalidateBackingStore ()
	Invalidate the internal backing store.
virtual bool	event (QEvent *)
Q_INVOKABLE QPainterPath	borderPath (const QRect &) const

Protected Member Functions
virtual void	paintEvent (QPaintEvent *)
virtual void	resizeEvent (QResizeEvent *)
virtual void	drawFocusIndicator (QPainter *)
virtual void	drawBorder (QPainter *)
void	updateStyleSheetInfo ()
	Update the cached information about the current style sheet.

Detailed Description

Canvas of a QwtPlot.

Canvas is the widget where all plot items are displayed

See also

QwtPlot::setCanvas(), QwtPlotGLCanvas

Member Enumeration Documentation

FocusIndicator

enum QwtPlotCanvas::FocusIndicator

Focus indicator The default setting is NoFocusIndicator.

See also

setFocusIndicator(), focusIndicator(), drawFocusIndicator()

Enumerator
NoFocusIndicator	Don't paint a focus indicator.
CanvasFocusIndicator	The focus is related to the complete canvas. Paint the focus indicator using drawFocusIndicator()
ItemFocusIndicator	The focus is related to an item (curve, point, ...) on the canvas. It is up to the application to display a focus indication using f.e. highlighting.

PaintAttribute

enum QwtPlotCanvas::PaintAttribute

Paint attributes.

The default setting enables BackingStore and Opaque.

See also

setPaintAttribute(), testPaintAttribute()

Enumerator
BackingStore	Paint double buffered reusing the content of the pixmap buffer when possible. Using a backing store might improve the performance significantly, when working with widget overlays ( like rubber bands ). Disabling the cache might improve the performance for incremental paints (using QwtPlotDirectPainter ). See also backingStore(), invalidateBackingStore()
Opaque	Try to fill the complete contents rectangle of the plot canvas. When using styled backgrounds Qt assumes, that the canvas doesn't fill its area completely ( f.e because of rounded borders ) and fills the area below the canvas. When this is done with gradients it might result in a serious performance bottleneck - depending on the size. When the Opaque attribute is enabled the canvas tries to identify the gaps with some heuristics and to fill those only. Warning Will not work for semitransparent backgrounds
HackStyledBackground	Try to improve painting of styled backgrounds. QwtPlotCanvas supports the box model attributes for customizing the layout with style sheets. Unfortunately the design of Qt style sheets has no concept how to handle backgrounds with rounded corners - beside of padding. When HackStyledBackground is enabled the plot canvas tries to separate the background from the background border by reverse engineering to paint the background before and the border after the plot items. In this order the border gets perfectly antialiased and you can avoid some pixel artifacts in the corners.
ImmediatePaint	When ImmediatePaint is set replot() calls repaint() instead of update(). See also replot(), QWidget::repaint(), QWidget::update()

Constructor & Destructor Documentation

QwtPlotCanvas()

QwtPlotCanvas::QwtPlotCanvas ( QwtPlot *  plot = NULL )

explicit

Constructor.

Parameters

plot	Parent plot widget

See also

QwtPlot::setCanvas()

Member Function Documentation

backingStore()

const QPixmap * QwtPlotCanvas::backingStore

(

)

const

Returns

Backing store, might be null

borderPath()

QPainterPath QwtPlotCanvas::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

borderRadius()

double QwtPlotCanvas::borderRadius

(

)

const

Returns

Radius for the corners of the border frame

See also

setBorderRadius()

drawBorder()

void QwtPlotCanvas::drawBorder ( QPainter *  painter )

protectedvirtual

Draw the border of the plot canvas

Parameters

painter

Painter

See also

setBorderRadius()

drawFocusIndicator()

void QwtPlotCanvas::drawFocusIndicator ( QPainter *  painter )

protectedvirtual

Draw the focus indication

Parameters

painter

Painter

event()

bool QwtPlotCanvas::event ( QEvent *  event )

virtual

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

Parameters

event

Qt Event

Returns

See QFrame::event()

focusIndicator()

QwtPlotCanvas::FocusIndicator QwtPlotCanvas::focusIndicator

(

)

const

Returns

Focus indicator

See also

FocusIndicator, setFocusIndicator()

paintEvent()

void QwtPlotCanvas::paintEvent ( QPaintEvent *  event )

protectedvirtual

Paint event

Parameters

event

Paint event

replot

void QwtPlotCanvas::replot ( )

slot

Invalidate the paint cache and repaint the canvas

See also

invalidatePaintCache()

resizeEvent()

void QwtPlotCanvas::resizeEvent ( QResizeEvent *  event )

protectedvirtual

Resize event

Parameters

event

Resize event

setBorderRadius()

void QwtPlotCanvas::setBorderRadius

(

double

radius

)

Set the radius for the corners of the border frame

Parameters

radius

Radius of a rounded corner

See also

borderRadius()

setFocusIndicator()

void QwtPlotCanvas::setFocusIndicator

(

FocusIndicator

focusIndicator

)

Set the focus indicator

See also

FocusIndicator, focusIndicator()

setPaintAttribute()

void QwtPlotCanvas::setPaintAttribute	(	PaintAttribute	attribute,
		bool	on = true
	)

Changing the paint attributes.

Parameters

attribute	Paint attribute
on	On/Off

See also

testPaintAttribute(), backingStore()

testPaintAttribute()

bool QwtPlotCanvas::testPaintAttribute

(

PaintAttribute

attribute

)

const

Test whether a paint attribute is enabled

Parameters

attribute

Paint attribute

Returns

true, when attribute is enabled

See also

setPaintAttribute()