Sources_For_Linux/Qwt/doc/man/man3/QwtPlotDirectPainter.3

.TH "QwtPlotDirectPainter" 3 "Mon Dec 28 2020" "Version 6.1.6" "Qwt User's Guide" \" -*- nroff -*-
.ad l
.nh
.SH NAME
QwtPlotDirectPainter \- Painter object trying to paint incrementally\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <qwt_plot_directpainter\&.h>\fP
.PP
Inherits QObject\&.
.SS "Public Types"

.in +1c
.ti -1c
.RI "enum \fBAttribute\fP { \fBAtomicPainter\fP = 0x01, \fBFullRepaint\fP = 0x02, \fBCopyBackingStore\fP = 0x04 }"
.br
.RI "Paint attributes\&. "
.ti -1c
.RI "typedef QFlags< \fBAttribute\fP > \fBAttributes\fP"
.br
.RI "Paint attributes\&. "
.in -1c
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "\fBQwtPlotDirectPainter\fP (QObject *parent=NULL)"
.br
.RI "Constructor\&. "
.ti -1c
.RI "virtual \fB~QwtPlotDirectPainter\fP ()"
.br
.RI "Destructor\&. "
.ti -1c
.RI "void \fBsetAttribute\fP (\fBAttribute\fP, bool on)"
.br
.ti -1c
.RI "bool \fBtestAttribute\fP (\fBAttribute\fP) const"
.br
.ti -1c
.RI "void \fBsetClipping\fP (bool)"
.br
.ti -1c
.RI "bool \fBhasClipping\fP () const"
.br
.ti -1c
.RI "void \fBsetClipRegion\fP (const QRegion &)"
.br
.RI "Assign a clip region and enable clipping\&. "
.ti -1c
.RI "QRegion \fBclipRegion\fP () const"
.br
.ti -1c
.RI "void \fBdrawSeries\fP (\fBQwtPlotSeriesItem\fP *, int from, int to)"
.br
.RI "Draw a set of points of a seriesItem\&. "
.ti -1c
.RI "void \fBreset\fP ()"
.br
.RI "Close the internal QPainter\&. "
.ti -1c
.RI "virtual bool \fBeventFilter\fP (QObject *, QEvent *)"
.br
.RI "Event filter\&. "
.in -1c
.SH "Detailed Description"
.PP 
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\&.
.PP
\fBQwtPlotDirectPainter\fP offers an API to paint subsets ( f\&.e all additions points ) without erasing/repainting the plot canvas\&.
.PP
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\&.
.PP
\fBWarning\fP
.RS 4
Incremental painting will only help when no replot is triggered by another operation ( like changing scales ) and nothing needs to be erased\&. 
.RE
.PP

.SH "Member Enumeration Documentation"
.PP 
.SS "enum \fBQwtPlotDirectPainter::Attribute\fP"

.PP
Paint attributes\&. 
.PP
\fBSee also\fP
.RS 4
\fBsetAttribute()\fP, \fBtestAttribute()\fP, \fBdrawSeries()\fP 
.RE
.PP

.PP
\fBEnumerator\fP
.in +1c
.TP
\fB\fIAtomicPainter \fP\fP
Initializing a QPainter is an expensive operation\&. When AtomicPainter is set each call of \fBdrawSeries()\fP opens/closes a temporary QPainter\&. Otherwise \fBQwtPlotDirectPainter\fP tries to use the same QPainter as long as possible\&. 
.TP
\fB\fIFullRepaint \fP\fP
When FullRepaint is set the plot canvas is explicitly repainted after the samples have been rendered\&. 
.TP
\fB\fICopyBackingStore \fP\fP
When \fBQwtPlotCanvas::BackingStore\fP 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\&. 
.SH "Member Function Documentation"
.PP 
.SS "QRegion QwtPlotDirectPainter::clipRegion () const"

.PP
\fBReturns\fP
.RS 4
Currently set clip region\&. 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetClipRegion()\fP, \fBsetClipping()\fP, \fBhasClipping()\fP 
.RE
.PP

.SS "void QwtPlotDirectPainter::drawSeries (\fBQwtPlotSeriesItem\fP * seriesItem, int from, int to)"

.PP
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\&. \fBdrawSeries()\fP can be used to display them avoiding a complete redraw of the canvas\&.
.PP
Setting plot()->canvas()->setAttribute(Qt::WA_PaintOutsidePaintEvent, true); will result in faster painting, if the paint engine of the canvas widget supports this feature\&.
.PP
\fBParameters\fP
.RS 4
\fIseriesItem\fP Item to be painted 
.br
\fIfrom\fP Index of the first point to be painted 
.br
\fIto\fP Index of the last point to be painted\&. If to < 0 the series will be painted to its last point\&. 
.RE
.PP

.SS "bool QwtPlotDirectPainter::hasClipping () const"

.PP
\fBReturns\fP
.RS 4
true, when clipping is enabled 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsetClipping()\fP, \fBclipRegion()\fP, \fBsetClipRegion()\fP 
.RE
.PP

.SS "void QwtPlotDirectPainter::setAttribute (\fBAttribute\fP attribute, bool on)"
Change an attribute
.PP
\fBParameters\fP
.RS 4
\fIattribute\fP Attribute to change 
.br
\fIon\fP On/Off
.RE
.PP
\fBSee also\fP
.RS 4
\fBAttribute\fP, \fBtestAttribute()\fP 
.RE
.PP

.SS "void QwtPlotDirectPainter::setClipping (bool enable)"
En/Disables clipping
.PP
\fBParameters\fP
.RS 4
\fIenable\fP Enables clipping is true, disable it otherwise 
.RE
.PP
\fBSee also\fP
.RS 4
\fBhasClipping()\fP, \fBclipRegion()\fP, \fBsetClipRegion()\fP 
.RE
.PP

.SS "void QwtPlotDirectPainter::setClipRegion (const QRegion & region)"

.PP
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\&.
.PP
\fBParameters\fP
.RS 4
\fIregion\fP Clip region 
.RE
.PP
\fBSee also\fP
.RS 4
\fBclipRegion()\fP, \fBhasClipping()\fP, \fBsetClipping()\fP 
.RE
.PP

.SS "bool QwtPlotDirectPainter::testAttribute (\fBAttribute\fP attribute) const"

.PP
\fBReturns\fP
.RS 4
True, when attribute is enabled 
.RE
.PP
\fBParameters\fP
.RS 4
\fIattribute\fP Attribute to be tested 
.RE
.PP
\fBSee also\fP
.RS 4
\fBAttribute\fP, \fBsetAttribute()\fP 
.RE
.PP


.SH "Author"
.PP 
Generated automatically by Doxygen for Qwt User's Guide from the source code\&.