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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QRegion Class Reference</h1>
<p>The QRegion class specifies a clip region for a painter.
<a href="#details">More...</a>
<p><tt>#include <<a href="qregion-h.html">qregion.h</a>></tt>
<p><a href="qregion-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li><div class=fn>enum <a href="#RegionType-enum"><b>RegionType</b></a> { Rectangle, Ellipse }</div></li>
<li><div class=fn><a href="#QRegion"><b>QRegion</b></a> ()</div></li>
<li><div class=fn><a href="#QRegion-2"><b>QRegion</b></a> ( int x, int y, int w, int h, RegionType t = Rectangle )</div></li>
<li><div class=fn><a href="#QRegion-3"><b>QRegion</b></a> ( const QRect & r, RegionType t = Rectangle )</div></li>
<li><div class=fn><a href="#QRegion-4"><b>QRegion</b></a> ( const QPointArray & a, bool winding = FALSE )</div></li>
<li><div class=fn><a href="#QRegion-5"><b>QRegion</b></a> ( const QRegion & r )</div></li>
<li><div class=fn><a href="#QRegion-6"><b>QRegion</b></a> ( const QBitmap & bm )</div></li>
<li><div class=fn><a href="#~QRegion"><b>~QRegion</b></a> ()</div></li>
<li><div class=fn>QRegion & <a href="#operator-eq"><b>operator=</b></a> ( const QRegion & r )</div></li>
<li><div class=fn>bool <a href="#isNull"><b>isNull</b></a> () const</div></li>
<li><div class=fn>bool <a href="#isEmpty"><b>isEmpty</b></a> () const</div></li>
<li><div class=fn>bool <a href="#contains"><b>contains</b></a> ( const QPoint & p ) const</div></li>
<li><div class=fn>bool <a href="#contains-2"><b>contains</b></a> ( const QRect & r ) const</div></li>
<li><div class=fn>void <a href="#translate"><b>translate</b></a> ( int dx, int dy )</div></li>
<li><div class=fn>QRegion <a href="#unite"><b>unite</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>QRegion <a href="#intersect"><b>intersect</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>QRegion <a href="#subtract"><b>subtract</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>QRegion <a href="#eor"><b>eor</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>QRect <a href="#boundingRect"><b>boundingRect</b></a> () const</div></li>
<li><div class=fn>QMemArray<QRect> <a href="#rects"><b>rects</b></a> () const</div></li>
<li><div class=fn>const QRegion <a href="#operator|"><b>operator|</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>const QRegion <a href="#operator+"><b>operator+</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>const QRegion <a href="#operator-and"><b>operator&</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>const QRegion <a href="#operator-"><b>operator-</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>const QRegion <a href="#operator^"><b>operator^</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>QRegion & <a href="#operator|-eq"><b>operator|=</b></a> ( const QRegion & r )</div></li>
<li><div class=fn>QRegion & <a href="#operator+-eq"><b>operator+=</b></a> ( const QRegion & r )</div></li>
<li><div class=fn>QRegion & <a href="#operator-and-eq"><b>operator&=</b></a> ( const QRegion & r )</div></li>
<li><div class=fn>QRegion & <a href="#operator--eq"><b>operator-=</b></a> ( const QRegion & r )</div></li>
<li><div class=fn>QRegion & <a href="#operator^-eq"><b>operator^=</b></a> ( const QRegion & r )</div></li>
<li><div class=fn>bool <a href="#operator-eq-eq"><b>operator==</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>bool <a href="#operator!-eq"><b>operator!=</b></a> ( const QRegion & r ) const</div></li>
<li><div class=fn>HRGN <a href="#handle"><b>handle</b></a> () const</div></li>
<li><div class=fn>RgnHandle <b>handle</b> ( bool require_rgn = FALSE ) const</div></li>
</ul>
<h2>Related Functions</h2>
<ul>
<li><div class=fn>QDataStream & <a href="#operator-lt-lt"><b>operator<<</b></a> ( QDataStream & s, const QRegion & r )</div></li>
<li><div class=fn>QDataStream & <a href="#operator-gt-gt"><b>operator>></b></a> ( QDataStream & s, QRegion & r )</div></li>
</ul>
<hr><a name="details"></a><h2>Detailed Description</h2>
The QRegion class specifies a clip region for a painter.
<p>
<p> QRegion is used with <a href="qpainter.html#setClipRegion">QPainter::setClipRegion</a>() to limit the paint
area to what needs to be painted. There is also a <a href="qwidget.html#repaint">QWidget::repaint</a>()
that takes a QRegion parameter. QRegion is the best tool for
reducing flicker.
<p> 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 <a href="#unite">unite</a>(), <a href="#intersect">intersect</a>(), <a href="#subtract">subtract</a>() or <a href="#eor">eor</a>() (exclusive or). You can
move a region using <a href="#translate">translate</a>().
<p> You can test whether a region <a href="#isNull">isNull</a>(), <a href="#isEmpty">isEmpty</a>() or if it <a href="#contains">contains</a>()
a <a href="qpoint.html">QPoint</a> or <a href="qrect.html">QRect</a>. The bounding rectangle is given by <a href="#boundingRect">boundingRect</a>().
<p> The function <a href="#rects">rects</a>() gives a decomposition of the region into rectangles.
<p> Example of using complex regions:
<pre>
void MyWidget::paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * )
{
<a href="qpainter.html">QPainter</a> p; // our painter
QRegion r1( QRect(100,100,200,80), // r1 = elliptic region
QRegion::<a href="#RegionType-enum">Ellipse</a> );
QRegion r2( QRect(100,120,90,30) ); // r2 = rectangular region
QRegion r3 = r1.<a href="#intersect">intersect</a>( r2 ); // r3 = intersection
p.<a href="qpainter.html#begin">begin</a>( this ); // start painting widget
p.<a href="qpainter.html#setClipRegion">setClipRegion</a>( r3 ); // set clip region
... // paint clipped graphics
p.<a href="qpainter.html#end">end</a>(); // painting done
}
</pre>
<p> QRegion is an <a href="shclass.html">implicitly shared</a> class.
<p> Due to window system limitations, the width and height of a region
is limited to 65535 on Unix/X11.
<p> <p>See also <a href="qpainter.html#setClipRegion">QPainter::setClipRegion</a>(), <a href="qpainter.html#setClipRect">QPainter::setClipRect</a>(), <a href="graphics.html">Graphics Classes</a> and <a href="images.html">Image Processing Classes</a>.
<hr><h2>Member Type Documentation</h2>
<h3 class=fn><a name="RegionType-enum"></a>QRegion::RegionType</h3>
Determines the shape of the region to be created.
<ul>
<li><tt>QRegion::Rectangle</tt> - the region covers the entire rectangle.
<li><tt>QRegion::Ellipse</tt> - the region is an ellipse inside the rectangle.
</ul>
<hr><h2>Member Function Documentation</h2>
<h3 class=fn><a name="QRegion"></a>QRegion::QRegion ()
</h3>
Constructs a null region.
<p>See also <a href="#isNull">isNull</a>().
<h3 class=fn><a name="QRegion-2"></a>QRegion::QRegion ( int x, int y, int w, int h, <a href="qregion.html#RegionType-enum">RegionType</a> t = Rectangle )
</h3>
Constructs a rectangular or elliptic region.
<p> If <em>t</em> is <a href="#RegionType-enum">Rectangle</a>, the region is the filled rectangle (<em>x</em>,
<em>y</em>, <em>w</em>, <em>h</em>). If <em>t</em> is <a href="#RegionType-enum">Ellipse</a>, the region is the filled
ellipse with center at (<em>x</em> + <em>w</em> / 2, <em>y</em> + <em>h</em> / 2) and
size (<em>w</em> ,<em>h</em> ).
<p>
<h3 class=fn><a name="QRegion-3"></a>QRegion::QRegion ( const <a href="qrect.html">QRect</a> & r, <a href="qregion.html#RegionType-enum">RegionType</a> t = Rectangle )
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Create a region based on the rectange <em>r</em> with region type <em>t</em>.
<p> If the rectangle is invalid a null region will be created.
<p> <p>See also <a href="#RegionType-enum">QRegion::RegionType</a>.
<h3 class=fn><a name="QRegion-4"></a>QRegion::QRegion ( const <a href="qpointarray.html">QPointArray</a> & a, bool winding = FALSE )
</h3>
Constructs a polygon region from the point array <em>a</em>.
<p> If <em>winding</em> is TRUE, the polygon
region is filled using the winding algorithm, otherwise the default
even-odd fill algorithm is used.
<p> This constructor may create complex regions that will slow
down painting when used.
<h3 class=fn><a name="QRegion-5"></a>QRegion::QRegion ( const <a href="qregion.html">QRegion</a> & r )
</h3>
Constructs a new region which is equal to <em>r</em>.
<h3 class=fn><a name="QRegion-6"></a>QRegion::QRegion ( const <a href="qbitmap.html">QBitmap</a> & bm )
</h3>
Constructs a region from the bitmap <em>bm</em>.
<p> The resulting region consists of the pixels in <em>bm</em> that are <tt>color1</tt>, as if each pixel was a 1 by 1 rectangle.
<p> This constructor may create complex regions that will slow
down painting when used. Note that drawing masked pixmaps
can be done much faster using <a href="qpixmap.html#setMask">QPixmap::setMask</a>().
<p>
<h3 class=fn><a name="~QRegion"></a>QRegion::~QRegion ()
</h3>
Destroys the region.
<h3 class=fn><a href="qrect.html">QRect</a> <a name="boundingRect"></a>QRegion::boundingRect () const
</h3>
Returns the bounding rectangle of this region.
An empty region gives a rectangle that is <a href="qrect.html#isNull">QRect::isNull</a>().
<h3 class=fn>bool <a name="contains"></a>QRegion::contains ( const <a href="qpoint.html">QPoint</a> & p ) const
</h3>
Returns TRUE if the region contains the point <em>p</em>, or FALSE if <em>p</em> is
outside the region.
<h3 class=fn>bool <a name="contains-2"></a>QRegion::contains ( const <a href="qrect.html">QRect</a> & r ) const
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Returns TRUE if the region overlaps the rectangle <em>r</em>; or FALSE if <em>r</em> is
completely outside the region.
<h3 class=fn><a href="qregion.html">QRegion</a> <a name="eor"></a>QRegion::eor ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Returns a region which is the exclusive or (XOR) of this region and <em>r</em>.
<p> <img src=rxor.png>
<p> The figure shows the exclusive or of two elliptical regions.
<h3 class=fn>HRGN <a name="handle"></a>QRegion::handle () const
</h3>
Returns the region's handle.
<h3 class=fn><a href="qregion.html">QRegion</a> <a name="intersect"></a>QRegion::intersect ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Returns a region which is the intersection of this region and <em>r</em>.
<p> <img src=rintersect.png>
<p> The figure shows the intersection of two elliptical regions.
<h3 class=fn>bool <a name="isEmpty"></a>QRegion::isEmpty () const
</h3>
Returns TRUE if the region is empty, or FALSE if it is non-empty.
An empty region is a region that contains no points.
<p> Example:
<pre>
QRegion r1( 10, 10, 20, 20 );
QRegion r2( 40, 40, 20, 20 );
QRegion r3;
r1.<a href="#isNull">isNull</a>(); // FALSE
r1.<a href="#isEmpty">isEmpty</a>(); // FALSE
r3.<a href="#isNull">isNull</a>(); // TRUE
r3.<a href="#isEmpty">isEmpty</a>(); // TRUE
r3 = r1.<a href="#intersect">intersect</a>( r2 ); // r3 = intersection of r1 and r2
r3.<a href="#isNull">isNull</a>(); // FALSE
r3.<a href="#isEmpty">isEmpty</a>(); // TRUE
r3 = r1.<a href="#unite">unite</a>( r2 ); // r3 = union of r1 and r2
r3.<a href="#isNull">isNull</a>(); // FALSE
r3.<a href="#isEmpty">isEmpty</a>(); // FALSE
</pre>
<p> <p>See also <a href="#isNull">isNull</a>().
<h3 class=fn>bool <a name="isNull"></a>QRegion::isNull () const
</h3>
Returns TRUE if the region is a null region, otherwise FALSE.
<p> A null region is a region that has not been initialized. A
null region is always empty.
<p> <p>See also <a href="#isEmpty">isEmpty</a>().
<h3 class=fn>bool <a name="operator!-eq"></a>QRegion::operator!= ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Returns TRUE if the region is different from <em>r</em>, or FALSE if the regions
are equal.
<h3 class=fn>const <a href="qregion.html">QRegion</a> <a name="operator-and"></a>QRegion::operator& ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Applies the <a href="#intersect">intersect</a>() function to this region and <em>r</em>.
<tt>r1&r2</tt> is equivalent to <tt>r1.intersect(r2)</tt>
<p>See also <a href="#intersect">intersect</a>().
<h3 class=fn><a href="qregion.html">QRegion</a> & <a name="operator-and-eq"></a>QRegion::operator&= ( const <a href="qregion.html">QRegion</a> & r )
</h3>
Applies the <a href="#intersect">intersect</a>() function to this region and <em>r</em> and
assigns the result to this region.
<tt>r1&=r2</tt> is equivalent to <tt>r1=r1.intersect(r2)</tt>
<p>See also <a href="#intersect">intersect</a>().
<h3 class=fn>const <a href="qregion.html">QRegion</a> <a name="operator+"></a>QRegion::operator+ ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Applies the <a href="#unite">unite</a>() function to this region and <em>r</em>.
<tt>r1+r2</tt> is equivalent to <tt>r1.unite(r2)</tt>
<p>See also <a href="#unite">unite</a>() and <a href="#operator|">operator|</a>().
<h3 class=fn><a href="qregion.html">QRegion</a> & <a name="operator+-eq"></a>QRegion::operator+= ( const <a href="qregion.html">QRegion</a> & r )
</h3>
Applies the <a href="#unite">unite</a>() function to this region and <em>r</em> and assigns the
result to this region.
<tt>r1+=r2</tt> is equivalent to <tt>r1=r1.unite(r2)</tt>
<p>See also <a href="#intersect">intersect</a>().
<h3 class=fn>const <a href="qregion.html">QRegion</a> <a name="operator-"></a>QRegion::operator- ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Applies the <a href="#subtract">subtract</a>() function to this region and <em>r</em>.
<tt>r1-r2</tt> is equivalent to <tt>r1.subtract(r2)</tt>
<p>See also <a href="#subtract">subtract</a>().
<h3 class=fn><a href="qregion.html">QRegion</a> & <a name="operator--eq"></a>QRegion::operator-= ( const <a href="qregion.html">QRegion</a> & r )
</h3>
Applies the <a href="#subtract">subtract</a>() function to this region and <em>r</em> and
assigns the result to this region.
<tt>r1-=r2</tt> is equivalent to <tt>r1=r1.subtract(r2)</tt>
<p>See also <a href="#subtract">subtract</a>().
<h3 class=fn><a href="qregion.html">QRegion</a> & <a name="operator-eq"></a>QRegion::operator= ( const <a href="qregion.html">QRegion</a> & r )
</h3>
Assigns <em>r</em> to this region and returns a reference to the
region.
<p>
<h3 class=fn>bool <a name="operator-eq-eq"></a>QRegion::operator== ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Returns TRUE if the region is equal to <em>r</em>, or FALSE if the regions are
different.
<h3 class=fn>const <a href="qregion.html">QRegion</a> <a name="operator^"></a>QRegion::operator^ ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Applies the <a href="#eor">eor</a>() function to this region and <em>r</em>.
<tt>r1^r2</tt> is equivalent to <tt>r1.eor(r2)</tt>
<p>See also <a href="#eor">eor</a>().
<h3 class=fn><a href="qregion.html">QRegion</a> & <a name="operator^-eq"></a>QRegion::operator^= ( const <a href="qregion.html">QRegion</a> & r )
</h3>
Applies the <a href="#eor">eor</a>() function to this region and <em>r</em> and
assigns the result to this region.
<tt>r1^=r2</tt> is equivalent to <tt>r1=r1.eor(r2)</tt>
<p>See also <a href="#eor">eor</a>().
<h3 class=fn>const <a href="qregion.html">QRegion</a> <a name="operator|"></a>QRegion::operator| ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Applies the <a href="#unite">unite</a>() function to this region and <em>r</em>.
<tt>r1|r2</tt> is equivalent to <tt>r1.unite(r2)</tt>
<p>See also <a href="#unite">unite</a>() and <a href="#operator+">operator+</a>().
<h3 class=fn><a href="qregion.html">QRegion</a> & <a name="operator|-eq"></a>QRegion::operator|= ( const <a href="qregion.html">QRegion</a> & r )
</h3>
Applies the <a href="#unite">unite</a>() function to this region and <em>r</em> and assigns the
result to this region.
<tt>r1|=r2</tt> is equivalent to <tt>r1=r1.unite(r2)</tt>
<p>See also <a href="#unite">unite</a>().
<h3 class=fn><a href="qmemarray.html">QMemArray</a><QRect> <a name="rects"></a>QRegion::rects () const
</h3>
Returns an array of non-overlapping rectangles that make up the region.
<p> The union of all the rectangles is equal to the original region.
<h3 class=fn><a href="qregion.html">QRegion</a> <a name="subtract"></a>QRegion::subtract ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Returns a region which is <em>r</em> subtracted from this region.
<p> <img src=rsubtract.png>
<p> The figure shows the result when the ellipse on the right is subtracted
from the ellipse on the left. (<tt>left-right</tt> )
<h3 class=fn>void <a name="translate"></a>QRegion::translate ( int dx, int dy )
</h3>
Translates (moves) the region <em>dx</em> along the X axis and <em>dy</em> along the Y axis.
<h3 class=fn><a href="qregion.html">QRegion</a> <a name="unite"></a>QRegion::unite ( const <a href="qregion.html">QRegion</a> & r ) const
</h3>
Returns a region which is the union of this region and <em>r</em>.
<p> <img src=runion.png>
<p> The figure shows the union of two elliptical regions.
<hr><h2>Related Functions</h2>
<h3 class=fn><a href="qdatastream.html">QDataStream</a> & <a name="operator-lt-lt"></a>operator<< ( <a href="qdatastream.html">QDataStream</a> & s, const <a href="qregion.html">QRegion</a> & r )
</h3>
Writes the region <em>r</em> to the stream <em>s</em> and returns a reference to
the stream.
<p> <p>See also <a href="datastreamformat.html">Format of the QDataStream operators</a>.
<h3 class=fn><a href="qdatastream.html">QDataStream</a> & <a name="operator-gt-gt"></a>operator>> ( <a href="qdatastream.html">QDataStream</a> & s, <a href="qregion.html">QRegion</a> & r )
</h3>
Reads a region from the stream <em>s</em> into <em>r</em> and returns a
reference to the stream.
<p> <p>See also <a href="datastreamformat.html">Format of the QDataStream operators</a>.
<!-- eof -->
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Copyright © 1995-2001
<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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<a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a>
<td align=right><div align=right>Qt version 3.0.2</div>
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