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+'\" t
+.TH QRegion 3qt "2 February 2007" "Trolltech AS" \" -*- nroff -*-
+.\" Copyright 1992-2007 Trolltech ASA. All rights reserved. See the
+.\" license file included in the distribution for a complete license
+.\" statement.
+.\"
+.ad l
+.nh
+.SH NAME
+QRegion \- Clip region for a painter
+.SH SYNOPSIS
+\fC#include <qregion.h>\fR
+.PP
+.SS "Public Members"
+.in +1c
+.ti -1c
+.BI "enum \fBRegionType\fR { Rectangle, Ellipse }"
+.br
+.ti -1c
+.BI "\fBQRegion\fR ()"
+.br
+.ti -1c
+.BI "\fBQRegion\fR ( int x, int y, int w, int h, RegionType t = Rectangle )"
+.br
+.ti -1c
+.BI "\fBQRegion\fR ( const QRect & r, RegionType t = Rectangle )"
+.br
+.ti -1c
+.BI "\fBQRegion\fR ( const QPointArray & a, bool winding = FALSE )"
+.br
+.ti -1c
+.BI "\fBQRegion\fR ( const QRegion & r )"
+.br
+.ti -1c
+.BI "\fBQRegion\fR ( const QBitmap & bm )"
+.br
+.ti -1c
+.BI "\fB~QRegion\fR ()"
+.br
+.ti -1c
+.BI "QRegion & \fBoperator=\fR ( const QRegion & r )"
+.br
+.ti -1c
+.BI "bool \fBisNull\fR () const"
+.br
+.ti -1c
+.BI "bool \fBisEmpty\fR () const"
+.br
+.ti -1c
+.BI "bool \fBcontains\fR ( const QPoint & p ) const"
+.br
+.ti -1c
+.BI "bool \fBcontains\fR ( const QRect & r ) const"
+.br
+.ti -1c
+.BI "void \fBtranslate\fR ( int dx, int dy )"
+.br
+.ti -1c
+.BI "QRegion \fBunite\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "QRegion \fBintersect\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "QRegion \fBsubtract\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "QRegion \fBeor\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "QRect \fBboundingRect\fR () const"
+.br
+.ti -1c
+.BI "QMemArray<QRect> \fBrects\fR () const"
+.br
+.ti -1c
+.BI "const QRegion \fBoperator|\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "const QRegion \fBoperator+\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "const QRegion \fBoperator&\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "const QRegion \fBoperator-\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "const QRegion \fBoperator^\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "QRegion & \fBoperator|=\fR ( const QRegion & r )"
+.br
+.ti -1c
+.BI "QRegion & \fBoperator+=\fR ( const QRegion & r )"
+.br
+.ti -1c
+.BI "QRegion & \fBoperator&=\fR ( const QRegion & r )"
+.br
+.ti -1c
+.BI "QRegion & \fBoperator-=\fR ( const QRegion & r )"
+.br
+.ti -1c
+.BI "QRegion & \fBoperator^=\fR ( const QRegion & r )"
+.br
+.ti -1c
+.BI "bool \fBoperator==\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "bool \fBoperator!=\fR ( const QRegion & r ) const"
+.br
+.ti -1c
+.BI "HRGN \fBhandle\fR () const"
+.br
+.in -1c
+.SH RELATED FUNCTION DOCUMENTATION
+.in +1c
+.ti -1c
+.BI "QDataStream & \fBoperator<<\fR ( QDataStream & s, const QRegion & r )"
+.br
+.ti -1c
+.BI "QDataStream & \fBoperator>>\fR ( QDataStream & s, QRegion & r )"
+.br
+.in -1c
+.SH DESCRIPTION
+The QRegion class specifies a clip region for a painter.
+.PP
+QRegion is used with QPainter::setClipRegion() to limit the paint area to what needs to be painted. There is also a QWidget::repaint() that takes a QRegion parameter. QRegion is the best tool for reducing flicker.
+.PP
+A region can be created from a rectangle, an ellipse, a polygon or a bitmap. Complex regions may be created by combining simple regions using unite(), intersect(), subtract() or eor() (exclusive or). You can move a region using translate().
+.PP
+You can test whether a region isNull(), isEmpty() or if it contains() a QPoint or QRect. The bounding rectangle is given by boundingRect().
+.PP
+The function rects() gives a decomposition of the region into rectangles.
+.PP
+Example of using complex regions:
+.PP
+.nf
+.br
+ void MyWidget::paintEvent( QPaintEvent * )
+.br
+ {
+.br
+ QPainter p; // our painter
+.br
+ QRegion r1( QRect(100,100,200,80), // r1 = elliptic region
+.br
+ QRegion::Ellipse );
+.br
+ QRegion r2( QRect(100,120,90,30) ); // r2 = rectangular region
+.br
+ QRegion r3 = r1.intersect( r2 ); // r3 = intersection
+.br
+ p.begin( this ); // start painting widget
+.br
+ p.setClipRegion( r3 ); // set clip region
+.br
+ ... // paint clipped graphics
+.br
+ p.end(); // painting done
+.br
+ }
+.br
+.fi
+.PP
+QRegion is an implicitly shared class.
+.PP
+\fBWarning:\fR Due to window system limitations, the whole coordinate space for a region is limited to the points between -32767 and 32767 on Mac OS X and Windows 95/98/ME.
+.PP
+See also QPainter::setClipRegion(), QPainter::setClipRect(), Graphics Classes, and Image Processing Classes.
+.SS "Member Type Documentation"
+.SH "QRegion::RegionType"
+Specifies the shape of the region to be created.
+.TP
+\fCQRegion::Rectangle\fR - the region covers the entire rectangle.
+.TP
+\fCQRegion::Ellipse\fR - the region is an ellipse inside the rectangle.
+.SH MEMBER FUNCTION DOCUMENTATION
+.SH "QRegion::QRegion ()"
+Constructs a null region.
+.PP
+See also isNull().
+.SH "QRegion::QRegion ( int x, int y, int w, int h, RegionType t = Rectangle )"
+Constructs a rectangular or elliptic region.
+.PP
+If \fIt\fR is Rectangle, the region is the filled rectangle (\fIx\fR, \fIy\fR, \fIw\fR, \fIh\fR). If \fIt\fR is Ellipse, the region is the filled ellipse with center at (\fIx\fR + \fIw\fR / 2, \fIy\fR + \fIh\fR / 2) and size (\fIw\fR ,\fIh\fR ).
+.SH "QRegion::QRegion ( const QRect & r, RegionType t = Rectangle )"
+This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
+.PP
+Create a region based on the rectange \fIr\fR with region type \fIt\fR.
+.PP
+If the rectangle is invalid a null region will be created.
+.PP
+See also QRegion::RegionType.
+.SH "QRegion::QRegion ( const QPointArray & a, bool winding = FALSE )"
+Constructs a polygon region from the point array \fIa\fR.
+.PP
+If \fIwinding\fR is TRUE, the polygon region is filled using the winding algorithm, otherwise the default even-odd fill algorithm is used.
+.PP
+This constructor may create complex regions that will slow down painting when used.
+.SH "QRegion::QRegion ( const QRegion & r )"
+Constructs a new region which is equal to region \fIr\fR.
+.SH "QRegion::QRegion ( const QBitmap & bm )"
+Constructs a region from the bitmap \fIbm\fR.
+.PP
+The resulting region consists of the pixels in bitmap \fIbm\fR that are \fCcolor1\fR, as if each pixel was a 1 by 1 rectangle.
+.PP
+This constructor may create complex regions that will slow down painting when used. Note that drawing masked pixmaps can be done much faster using QPixmap::setMask().
+.SH "QRegion::~QRegion ()"
+Destroys the region.
+.SH "QRect QRegion::boundingRect () const"
+Returns the bounding rectangle of this region. An empty region gives a rectangle that is QRect::isNull().
+.SH "bool QRegion::contains ( const QPoint & p ) const"
+Returns TRUE if the region contains the point \fIp\fR; otherwise returns FALSE.
+.SH "bool QRegion::contains ( const QRect & r ) const"
+This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
+.PP
+Returns TRUE if the region overlaps the rectangle \fIr\fR; otherwise returns FALSE.
+.SH "QRegion QRegion::eor ( const QRegion & r ) const"
+Returns a region which is the exclusive or (XOR) of this region and \fIr\fR.
+.PP
+<center>
+.ce 1
+.B "[Image Omitted]"
+.PP
+</center>
+.PP
+The figure shows the exclusive or of two elliptical regions.
+.SH "HRGN QRegion::handle () const"
+Returns the region's handle.
+.SH "QRegion QRegion::intersect ( const QRegion & r ) const"
+Returns a region which is the intersection of this region and \fIr\fR.
+.PP
+<center>
+.ce 1
+.B "[Image Omitted]"
+.PP
+</center>
+.PP
+The figure shows the intersection of two elliptical regions.
+.SH "bool QRegion::isEmpty () const"
+Returns TRUE if the region is empty; otherwise returns FALSE. An empty region is a region that contains no points.
+.PP
+Example:
+.PP
+.nf
+.br
+ QRegion r1( 10, 10, 20, 20 );
+.br
+ QRegion r2( 40, 40, 20, 20 );
+.br
+ QRegion r3;
+.br
+ r1.isNull(); // FALSE
+.br
+ r1.isEmpty(); // FALSE
+.br
+ r3.isNull(); // TRUE
+.br
+ r3.isEmpty(); // TRUE
+.br
+ r3 = r1.intersect( r2 ); // r3 = intersection of r1 and r2
+.br
+ r3.isNull(); // FALSE
+.br
+ r3.isEmpty(); // TRUE
+.br
+ r3 = r1.unite( r2 ); // r3 = union of r1 and r2
+.br
+ r3.isNull(); // FALSE
+.br
+ r3.isEmpty(); // FALSE
+.br
+.fi
+.PP
+See also isNull().
+.SH "bool QRegion::isNull () const"
+Returns TRUE if the region is a null region; otherwise returns FALSE.
+.PP
+A null region is a region that has not been initialized. A null region is always empty.
+.PP
+See also isEmpty().
+.SH "bool QRegion::operator!= ( const QRegion & r ) const"
+Returns TRUE if the region is different from \fIr\fR; otherwise returns FALSE.
+.SH "const QRegion QRegion::operator& ( const QRegion & r ) const"
+Applies the intersect() function to this region and \fIr\fR. \fCr1&r2\fR is equivalent to \fCr1.intersect(r2)\fR
+.PP
+See also intersect().
+.SH "QRegion & QRegion::operator&= ( const QRegion & r )"
+Applies the intersect() function to this region and \fIr\fR and assigns the result to this region. \fCr1&=r2\fR is equivalent to \fCr1=r1.intersect(r2)\fR
+.PP
+See also intersect().
+.SH "const QRegion QRegion::operator+ ( const QRegion & r ) const"
+Applies the unite() function to this region and \fIr\fR. \fCr1+r2\fR is equivalent to \fCr1.unite(r2)\fR
+.PP
+See also unite() and operator|().
+.SH "QRegion & QRegion::operator+= ( const QRegion & r )"
+Applies the unite() function to this region and \fIr\fR and assigns the result to this region. \fCr1+=r2\fR is equivalent to \fCr1=r1.unite(r2)\fR
+.PP
+See also intersect().
+.SH "const QRegion QRegion::operator- ( const QRegion & r ) const"
+Applies the subtract() function to this region and \fIr\fR. \fCr1-r2\fR is equivalent to \fCr1.subtract(r2)\fR
+.PP
+See also subtract().
+.SH "QRegion & QRegion::operator-= ( const QRegion & r )"
+Applies the subtract() function to this region and \fIr\fR and assigns the result to this region. \fCr1-=r2\fR is equivalent to \fCr1=r1.subtract(r2)\fR
+.PP
+See also subtract().
+.SH "QRegion & QRegion::operator= ( const QRegion & r )"
+Assigns \fIr\fR to this region and returns a reference to the region.
+.SH "bool QRegion::operator== ( const QRegion & r ) const"
+Returns TRUE if the region is equal to \fIr\fR; otherwise returns FALSE.
+.SH "const QRegion QRegion::operator^ ( const QRegion & r ) const"
+Applies the eor() function to this region and \fIr\fR. \fCr1^r2\fR is equivalent to \fCr1.eor(r2)\fR
+.PP
+See also eor().
+.SH "QRegion & QRegion::operator^= ( const QRegion & r )"
+Applies the eor() function to this region and \fIr\fR and assigns the result to this region. \fCr1^=r2\fR is equivalent to \fCr1=r1.eor(r2)\fR
+.PP
+See also eor().
+.SH "const QRegion QRegion::operator| ( const QRegion & r ) const"
+Applies the unite() function to this region and \fIr\fR. \fCr1|r2\fR is equivalent to \fCr1.unite(r2)\fR
+.PP
+See also unite() and operator+().
+.SH "QRegion & QRegion::operator|= ( const QRegion & r )"
+Applies the unite() function to this region and \fIr\fR and assigns the result to this region. \fCr1|=r2\fR is equivalent to \fCr1=r1.unite(r2)\fR
+.PP
+See also unite().
+.SH "QMemArray<QRect> QRegion::rects () const"
+Returns an array of non-overlapping rectangles that make up the region.
+.PP
+The union of all the rectangles is equal to the original region.
+.SH "QRegion QRegion::subtract ( const QRegion & r ) const"
+Returns a region which is \fIr\fR subtracted from this region.
+.PP
+<center>
+.ce 1
+.B "[Image Omitted]"
+.PP
+</center>
+.PP
+The figure shows the result when the ellipse on the right is subtracted from the ellipse on the left. (\fCleft-right\fR )
+.SH "void QRegion::translate ( int dx, int dy )"
+Translates (moves) the region \fIdx\fR along the X axis and \fIdy\fR along the Y axis.
+.SH "QRegion QRegion::unite ( const QRegion & r ) const"
+Returns a region which is the union of this region and \fIr\fR.
+.PP
+<center>
+.ce 1
+.B "[Image Omitted]"
+.PP
+</center>
+.PP
+The figure shows the union of two elliptical regions.
+.SH RELATED FUNCTION DOCUMENTATION
+.SH "QDataStream & operator<< ( QDataStream & s, const QRegion & r )"
+Writes the region \fIr\fR to the stream \fIs\fR and returns a reference to the stream.
+.PP
+See also Format of the QDataStream operators.
+.SH "QDataStream & operator>> ( QDataStream & s, QRegion & r )"
+Reads a region from the stream \fIs\fR into \fIr\fR and returns a reference to the stream.
+.PP
+See also Format of the QDataStream operators.
+
+.SH "SEE ALSO"
+.BR http://doc.trolltech.com/qregion.html
+.BR http://www.trolltech.com/faq/tech.html
+.SH COPYRIGHT
+Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
+license file included in the distribution for a complete license
+statement.
+.SH AUTHOR
+Generated automatically from the source code.
+.SH BUGS
+If you find a bug in Qt, please report it as described in
+.BR http://doc.trolltech.com/bughowto.html .
+Good bug reports help us to help you. Thank you.
+.P
+The definitive Qt documentation is provided in HTML format; it is
+located at $QTDIR/doc/html and can be read using Qt Assistant or with
+a web browser. This man page is provided as a convenience for those
+users who prefer man pages, although this format is not officially
+supported by Trolltech.
+.P
+If you find errors in this manual page, please report them to
+Please include the name of the manual page (qregion.3qt) and the Qt
+version (3.3.8).