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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<h1 align=center>QRegion Class Reference</h1><br clear="all">
<p>
The QRegion class specifies a clip region for a painter.
<a href="#details">More...</a>
<p>
<code>#include <<a href="qregion-h.html">qregion.h</a>></code>
<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"><b>RegionType</b></a>{Rectangle, Ellipse}</div>
<li><div class="fn"><a href="#a80dd8"><b>QRegion</b></a>()</div>
<li><div class="fn"><a href="#b666cf"><b>QRegion</b></a>(intx, inty, intw, inth, RegionType=Rectangle)</div>
<li><div class="fn"><b>QRegion</b>(constQRect&, RegionType=Rectangle)</div>
<li><div class="fn"><a href="#304ab0"><b>QRegion</b></a>(constQPointArray&, boolwinding=FALSE)</div>
<li><div class="fn"><a href="#b6e7a9"><b>QRegion</b></a>(constQRegion&)</div>
<li><div class="fn"><a href="#39c9d9"><b>QRegion</b></a>(constQBitmap&)</div>
<li><div class="fn"><a href="#b4b68b"><b>~QRegion</b></a>()</div>
<li><div class="fn">QRegion&<a href="#644768"><b>operator=</b></a>(constQRegion&)</div>
<li><div class="fn">bool<a href="#a2c0d0"><b>isNull</b></a>()const</div>
<li><div class="fn">bool<a href="#507d42"><b>isEmpty</b></a>()const</div>
<li><div class="fn">bool<a href="#ea58e9"><b>contains</b></a>(constQPoint&p)const</div>
<li><div class="fn">bool<a href="#afba2f"><b>contains</b></a>(constQRect&r)const</div>
<li><div class="fn">void<a href="#595875"><b>translate</b></a>(intdx, intdy)</div>
<li><div class="fn">QRegion<a href="#2c10d0"><b>unite</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion<a href="#28e973"><b>intersect</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion<a href="#ae007f"><b>subtract</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion<a href="#d7aa83"><b>eor</b></a>(constQRegion&)const</div>
<li><div class="fn">QRect<a href="#7cb897"><b>boundingRect</b></a>()const</div>
<li><div class="fn">QArray<QRect><a href="#842bf7"><b>rects</b></a>()const</div>
<li><div class="fn">void<a href="#9c7ecf"><b>setRects</b></a>(constQRect*, int)</div>
<li><div class="fn">QRegion<a href="#4e4832"><b>operator|</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion<a href="#a61e7d"><b>operator+</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion<a href="#2ed087"><b>operator&</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion<a href="#81786a"><b>operator-</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion<a href="#953473"><b>operator^</b></a>(constQRegion&)const</div>
<li><div class="fn">QRegion&<a href="#0a5795"><b>operator|=</b></a>(constQRegion&)</div>
<li><div class="fn">QRegion&<a href="#d77322"><b>operator+=</b></a>(constQRegion&)</div>
<li><div class="fn">QRegion&<a href="#a6c103"><b>operator&=</b></a>(constQRegion&)</div>
<li><div class="fn">QRegion&<a href="#04eb26"><b>operator-=</b></a>(constQRegion&)</div>
<li><div class="fn">QRegion&<a href="#3db11a"><b>operator^=</b></a>(constQRegion&)</div>
<li><div class="fn">bool<a href="#b6887c"><b>operator==</b></a>(constQRegion&)const</div>
<li><div class="fn">bool<a href="#7c842c"><b>operator!=</b></a>(constQRegion&r)const</div>
</ul>
<h2>Related Functions</h2>
(Note that these are not member functions.)
<ul>
<li>QDataStream & <a href="qregion.html#2179e4"><b>operator>></b></a> (QDataStream & s, QRegion & r)
<li>QDataStream & <a href="qregion.html#9b85c2"><b>operator<<</b></a> (QDataStream & s, const QRegion & r)
</ul>
<hr><h2><a name="details"></a>Detailed Description</h2>
The QRegion class specifies a clip region for a painter.
<p>
QRegion is used with <a href="qpainter.html#15cc78">QPainter::setClipRegion</a>() to limit the paint area to what
needs to be painted. There is also a <a href="qwidget.html#7569b1">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="#2c10d0">unite</a>(), <a href="#28e973">intersect</a>(), <a href="#ae007f">subtract</a>() or <a href="#d7aa83">eor</a>() (exclusive or). Use
<a href="#595875">translate</a>() to move a region.
<p>You can test if a region <a href="#a2c0d0">isNull</a>(), <a href="#507d42">isEmpty</a>() or if it <a href="#afba2f">contains</a>()
a <a href="qpoint.html">QPoint</a> or <a href="qrect.html">QRect</a>. The bounding rectangle is given by <a href="#7cb897">boundingRect</a>().
<p>The function <a href="#842bf7">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
<a href="qregion.html">QRegion</a> r1( <a href="qrect.html">QRect</a>(100,100,200,80), // r1 = elliptic region
QRegion::Ellipse );
<a href="qregion.html">QRegion</a> r2( <a href="qrect.html">QRect</a>(100,120,90,30) ); // r2 = rectangular region
<a href="qregion.html">QRegion</a> r3 = r1.<a href="#28e973">intersect</a>( r2 ); // r3 = intersection
p.<a href="qpainter.html#02ed5d">begin</a>( this ); // start painting widget
p.<a href="qpainter.html#15cc78">setClipRegion</a>( r3 ); // set clip region
... // paint clipped graphics
p.<a href="qpainter.html#365784">end</a>(); // painting done
}
</pre>
<p>QRegion is an <a href="shclass.html">implicitely shared</a> class.
<p>Due to window system limitations, the width and height of a region
is limited to 65535 on Unix/X11.
<p>See also <a href="qpainter.html#15cc78">QPainter::setClipRegion</a>() and <a href="qpainter.html#898839">QPainter::setClipRect</a>().
<hr><h2>Member Type Documentation</h2>
<h3 class="fn"><a name="RegionType">QRegion::RegionType</a></h3>
Determines the shape of the region to be created.
<ul>
<li><code>Rectangle</code> - the region covers the entire rectangle
<li><code>Ellipse</code> - the region is an ellipse inside the rectangle
</ul>
<hr><h2>Member Function Documentation</h2>
<h3 class="fn"><a name="a80dd8"></a>QRegion::QRegion()</h3>
<p>Constructs a null region.
<p>See also <a href="#a2c0d0">isNull</a>().
<h3 class="fn"><a name="39c9d9"></a>QRegion::QRegion(const<a href="qbitmap.html">QBitmap</a>&bm)</h3>
<p>Constructs a region from the bitmap <em>bm.</em>
<p>The resulting region consists of the pixels in <em>bm</em> that are <code>color1,</code> 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#68a75d">QPixmap::setMask</a>().
<h3 class="fn"><a name="304ab0"></a>QRegion::QRegion(const<a href="qpointarray.html">QPointArray</a>&a, boolwinding=FALSE)</h3>
<p>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="b6e7a9"></a>QRegion::QRegion(constQRegion&r)</h3>
<p>Constructs a new region which is equal to <em>r.</em>
<h3 class="fn"><a name="b666cf"></a>QRegion::QRegion(intx, inty, intw, inth, <a href="qregion.html#RegionType">RegionType</a>t=Rectangle)</h3>
<p>Constructs a rectangular or elliptic region.
<p>If <em>t</em> is <code>Rectangle,</code> the region is the filled rectangle (<em>x, y, w, h).</em> If <em>t</em> is <code>Ellipse,</code> the region is the filled
ellipse 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> ).
<h3 class="fn"><a name="b4b68b"></a>QRegion::~QRegion()</h3>
<p>Destructs the region.
<h3 class="fn"><a href="qrect.html">QRect</a><a name="7cb897"></a>QRegion::boundingRect()const</h3>
<p>Returns the bounding rectangle of this region.
An empty region gives a rectangle that is <a href="qrect.html#3090bd">QRect::isNull</a>().
<h3 class="fn">bool<a name="ea58e9"></a>QRegion::contains(const<a href="qpoint.html">QPoint</a>&p)const</h3>
<p>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="afba2f"></a>QRegion::contains(const<a href="qrect.html">QRect</a>&r)const</h3>
<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">QRegion<a name="d7aa83"></a>QRegion::eor(constQRegion&r)const</h3>
<p>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">QRegion<a name="28e973"></a>QRegion::intersect(constQRegion&r)const</h3>
<p>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="507d42"></a>QRegion::isEmpty()const</h3>
<p>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> <a href="qregion.html">QRegion</a> r1( 10, 10, 20, 20 );
<a href="qregion.html">QRegion</a> r2( 40, 40, 20, 20 );
<a href="qregion.html">QRegion</a> r3;
r1.<a href="#a2c0d0">isNull</a>(); // FALSE
r1.<a href="#507d42">isEmpty</a>(); // FALSE
r3.<a href="#a2c0d0">isNull</a>(); // TRUE
r3.<a href="#507d42">isEmpty</a>(); // TRUE
r3 = r1.<a href="#28e973">intersect</a>( r2 ); // r3 = intersection of r1 and r2
r3.<a href="#a2c0d0">isNull</a>(); // FALSE
r3.<a href="#507d42">isEmpty</a>(); // TRUE
r3 = r1.<a href="#2c10d0">unite</a>( r2 ); // r3 = union of r1 and r2
r3.<a href="#a2c0d0">isNull</a>(); // FALSE
r3.<a href="#507d42">isEmpty</a>(); // FALSE
</pre>
<p>See also <a href="#a2c0d0">isNull</a>().
<h3 class="fn">bool<a name="a2c0d0"></a>QRegion::isNull()const</h3>
<p>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>See also <a href="#507d42">isEmpty</a>().
<h3 class="fn">bool<a name="7c842c"></a>QRegion::operator!=(constQRegion&r)const</h3>
<p>Returns TRUE if the region is different from <em>r,</em> or FALSE if the regions
are equal.
<h3 class="fn">QRegion<a name="2ed087"></a>QRegion::operator&(constQRegion&r)const</h3>
<p><code>r1&r2</code> is equivalent to <code>r1.<a href="#28e973">intersect</a>(r2)</code>
<p>See also <a href="#28e973">intersect</a>().
<h3 class="fn">QRegion&<a name="a6c103"></a>QRegion::operator&=(constQRegion&r)</h3>
<p><code>r1&=r2</code> is equivalent to <code>r1=r1.<a href="#28e973">intersect</a>(r2)</code>
<p>See also <a href="#28e973">intersect</a>().
<h3 class="fn">QRegion<a name="a61e7d"></a>QRegion::operator+(constQRegion&r)const</h3>
<p><code>r1+r2</code> is equivalent to <code>r1.<a href="#2c10d0">unite</a>(r2)</code>
<p>See also <a href="#2c10d0">unite</a>() and <a href="#4e4832">operator|</a>().
<h3 class="fn">QRegion&<a name="d77322"></a>QRegion::operator+=(constQRegion&r)</h3>
<p><code>r1+=r2</code> is equivalent to <code>r1=r1.<a href="#2c10d0">unite</a>(r2)</code>
<p>See also <a href="#28e973">intersect</a>().
<h3 class="fn">QRegion<a name="81786a"></a>QRegion::operator-(constQRegion&r)const</h3>
<p><code>r1-r2</code> is equivalent to <code>r1.<a href="#ae007f">subtract</a>(r2)</code>
<p>See also <a href="#ae007f">subtract</a>().
<h3 class="fn">QRegion&<a name="04eb26"></a>QRegion::operator-=(constQRegion&r)</h3>
<p><code>r1-=r2</code> is equivalent to <code>r1=r1.<a href="#ae007f">subtract</a>(r2)</code>
<p>See also <a href="#ae007f">subtract</a>().
<h3 class="fn">QRegion&<a name="644768"></a>QRegion::operator=(constQRegion&r)</h3>
<p>Assigns <em>r</em> to this region and returns a reference to the
region.
<h3 class="fn">bool<a name="b6887c"></a>QRegion::operator==(constQRegion&r)const</h3>
<p>Returns TRUE if the region is equal to <em>r,</em> or FALSE if the regions are
different.
<h3 class="fn">QRegion<a name="953473"></a>QRegion::operator^(constQRegion&r)const</h3>
<p><code>r1^r2</code> is equivalent to <code>r1.<a href="#d7aa83">eor</a>(r2)</code>
<p>See also <a href="#d7aa83">eor</a>().
<h3 class="fn">QRegion&<a name="3db11a"></a>QRegion::operator^=(constQRegion&r)</h3>
<p><code>r1^=r2</code> is equivalent to <code>r1=r1.<a href="#d7aa83">eor</a>(r2)</code>
<p>See also <a href="#d7aa83">eor</a>().
<h3 class="fn">QRegion<a name="4e4832"></a>QRegion::operator|(constQRegion&r)const</h3>
<p><code>r1|r2</code> is equivalent to <code>r1.<a href="#2c10d0">unite</a>(r2)</code>
<p>See also <a href="#2c10d0">unite</a>() and <a href="#a61e7d">operator+</a>().
<h3 class="fn">QRegion&<a name="0a5795"></a>QRegion::operator|=(constQRegion&r)</h3>
<p><code>r1|=r2</code> is equivalent to <code>r1=r1.<a href="#2c10d0">unite</a>(r2)</code>
<p>See also <a href="#2c10d0">unite</a>().
<h3 class="fn"><a href="qarray.html">QArray</a><<a href="qrect.html">QRect</a>><a name="842bf7"></a>QRegion::rects()const</h3>
<p>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">void<a name="9c7ecf"></a>QRegion::setRects(const<a href="qrect.html">QRect</a>*rects, intnum)</h3>
<p>Sets the region to be the given set of rectangles. The rectangles
<em>must</em> be optimal Y-X sorted bands as follows:
<ul>
<li> The rectangles must not intersect
<li> All rectangles with a given top coordinate must have the same height.
<li> No two rectangles may abut horizontally (they should be combined
into a single wider rectangle in that case).
<li> The rectangles must be sorted ascendingly by Y as the major sort key
and X as the minor sort key.
</ul>
<h3 class="fn">QRegion<a name="ae007f"></a>QRegion::subtract(constQRegion&r)const</h3>
<p>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. (<code>left-right</code> ).
<h3 class="fn">void<a name="595875"></a>QRegion::translate(intdx, intdy)</h3>
<p>Translates (moves) the region <em>dx</em> along the X axis and <em>dy</em> along the Y axis.
<h3 class="fn">QRegion<a name="2c10d0"></a>QRegion::unite(constQRegion&r)const</h3>
<p>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><a href="qdatastream.html">QDataStream</a> & <a name="2179e4"></a>operator>> (<a href="qdatastream.html">QDataStream</a> & s, QRegion & r)</h3>
<p>Reads a region from the stream <em>s</em> into <em>r</em> and returns a
reference to the stream.
<p>See also <a href="datastreamformat.html">Format of the QDataStream operators</a>
<h3><a href="qdatastream.html">QDataStream</a> & <a name="9b85c2"></a>operator<< (<a href="qdatastream.html">QDataStream</a> & s, const QRegion & r)</h3>
<p>Writes the region <em>r</em> to the stream <em>s</em> and returns a reference to
the stream.
<p>See also <a href="datastreamformat.html">Format of the QDataStream operators</a>
<hr><p>
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