Painter object trying to paint incrementally. More...

#include <qwt_plot_directpainter.h>

Inheritance diagram for QwtPlotDirectPainter:

Classes
class	PrivateData

Public Types
enum	Attribute { AtomicPainter = 0x01, FullRepaint = 0x02, CopyBackingStore = 0x04 }
	Paint attributes. More...

typedef QFlags< Attribute >	Attributes
	Paint attributes. More...

Public Member Functions
QRegion	clipRegion () const

void	drawSeries (QwtPlotSeriesItem *, int from, int to)
	Draw a set of points of a seriesItem. More...

virtual bool	eventFilter (QObject , QEvent )
	Event filter. More...

bool	hasClipping () const

	QwtPlotDirectPainter (QObject *parent=NULL)
	Constructor. More...

void	reset ()
	Close the internal QPainter. More...

void	setAttribute (Attribute, bool on)

void	setClipping (bool)

void	setClipRegion (const QRegion &)
	Assign a clip region and enable clipping. More...

bool	testAttribute (Attribute) const

virtual	~QwtPlotDirectPainter ()
	Destructor. More...

Private Attributes
PrivateData *	d_data

Detailed Description

Painter object trying to paint incrementally.

Often applications want to display samples while they are collected. When there are too many samples complete replots will be expensive to be processed in a collection cycle.

QwtPlotDirectPainter offers an API to paint subsets ( f.e all additions points ) without erasing/repainting the plot canvas.

On certain environments it might be important to calculate a proper clip region before painting. F.e. for Qt Embedded only the clipped part of the backing store will be copied to a ( maybe unaccelerated ) frame buffer.

Warning: Incremental painting will only help when no replot is triggered by another operation ( like changing scales ) and nothing needs to be erased.

Definition at line 39 of file qwt_plot_directpainter.h.

Member Typedef Documentation

typedef QFlags<Attribute> QwtPlotDirectPainter::Attributes

Paint attributes.

Definition at line 74 of file qwt_plot_directpainter.h.

Member Enumeration Documentation

enum QwtPlotDirectPainter::Attribute

Paint attributes.

See also: setAttribute(), testAttribute(), drawSeries()

Enumerator
AtomicPainter	Initializing a QPainter is an expensive operation. When AtomicPainter is set each call of drawSeries() opens/closes a temporary QPainter. Otherwise QwtPlotDirectPainter tries to use the same QPainter as long as possible.
FullRepaint	When FullRepaint is set the plot canvas is explicitly repainted after the samples have been rendered.
CopyBackingStore	When QwtPlotCanvas::BackingStore is enabled the painter has to paint to the backing store and the widget. In certain situations/environments it might be faster to paint to the backing store only and then copy the backing store to the canvas. This flag can also be useful for settings, where Qt fills the the clip region with the widget background.

Definition at line 46 of file qwt_plot_directpainter.h.

Constructor & Destructor Documentation

QwtPlotDirectPainter::QwtPlotDirectPainter ( QObject * parent = NULL )

explicit

Constructor.

Definition at line 67 of file qwt_plot_directpainter.cpp.

QwtPlotDirectPainter::~QwtPlotDirectPainter ( )

virtual

Destructor.

Definition at line 74 of file qwt_plot_directpainter.cpp.

Member Function Documentation

QRegion QwtPlotDirectPainter::clipRegion ( ) const

Returns: Currently set clip region.

See also: setClipRegion(), setClipping(), hasClipping()

Definition at line 152 of file qwt_plot_directpainter.cpp.

void QwtPlotDirectPainter::drawSeries	(	QwtPlotSeriesItem *	seriesItem,
		int	from,
		int	to
	)

Draw a set of points of a seriesItem.

When observing an measurement while it is running, new points have to be added to an existing seriesItem. drawSeries() can be used to display them avoiding a complete redraw of the canvas.

Setting plot()->canvas()->setAttribute(Qt::WA_PaintOutsidePaintEvent, true); will result in faster painting, if the paint engine of the canvas widget supports this feature.

Parameters

seriesItem	Item to be painted
from	Index of the first point to be painted
to	Index of the last point to be painted. If to < 0 the series will be painted to its last point.

Definition at line 173 of file qwt_plot_directpainter.cpp.

bool QwtPlotDirectPainter::eventFilter	(	QObject *	,
		QEvent *	event
	)

virtual

Event filter.

Definition at line 278 of file qwt_plot_directpainter.cpp.

bool QwtPlotDirectPainter::hasClipping ( ) const

Returns: true, when clipping is enabled

See also: setClipping(), clipRegion(), setClipRegion()

Definition at line 126 of file qwt_plot_directpainter.cpp.

void QwtPlotDirectPainter::reset ( )

Close the internal QPainter.

Definition at line 265 of file qwt_plot_directpainter.cpp.

void QwtPlotDirectPainter::setAttribute	(	Attribute	attribute,
		bool	on
	)

Change an attribute

Parameters

attribute	Attribute to change
on	On/Off

See also: Attribute, testAttribute()

Definition at line 87 of file qwt_plot_directpainter.cpp.

void QwtPlotDirectPainter::setClipping ( bool enable )

En/Disables clipping

Parameters

enable Enables clipping is true, disable it otherwise

See also: hasClipping(), clipRegion(), setClipRegion()

Definition at line 117 of file qwt_plot_directpainter.cpp.

void QwtPlotDirectPainter::setClipRegion ( const QRegion & region )

Assign a clip region and enable clipping.

Depending on the environment setting a proper clip region might improve the performance heavily. F.e. on Qt embedded only the clipped part of the backing store will be copied to a ( maybe unaccelerated ) frame buffer device.

Parameters

region Clip region