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<title>Qt 4.0: QPolygon Class Reference</title>
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<td align="right" valign="top" width="230"><img src="images/trolltech-logo.png" align="right" width="203" height="32" border="0" /></td></tr></table><h1 align="center">QPolygon Class Reference</h1>
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<p>The QPolygon class provides a vector of points. <a href="#details">More...</a></p>
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<pre>#include <QPolygon></pre><p>Part of the <a href="qtgui.html">QtGui</a> module.</p>
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<p>Inherits <a href="qvector.html">QVector<QPoint></a>.</p>
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<p>Inherited by <a href="q3pointarray.html">Q3PointArray</a>.</p>
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<p><b>Note:</b> All the functions in this class are <a href="threads.html#reentrant">reentrant</a>.</p>
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<li><a href="qpolygon-members.html">List of all members, including inherited members</a></li>
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<a name="public-functions"></a>
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<h3>Public Functions</h3>
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<li><div class="fn"/><b><a href="qpolygon.html#QPolygon">QPolygon</a></b> ()</li>
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<li><div class="fn"/><b><a href="qpolygon.html#QPolygon-2">QPolygon</a></b> ( int <i>size</i> )</li>
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<li><div class="fn"/><b><a href="qpolygon.html#QPolygon-3">QPolygon</a></b> ( const QPolygon & <i>a</i> )</li>
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<li><div class="fn"/><b><a href="qpolygon.html#QPolygon-4">QPolygon</a></b> ( const QVector<QPoint> & <i>pts</i> )</li>
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<li><div class="fn"/><b><a href="qpolygon.html#QPolygon-5">QPolygon</a></b> ( const QRect & <i>r</i>, bool <i>closed</i> = false )</li>
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<li><div class="fn"/><b><a href="qpolygon.html#dtor.QPolygon">~QPolygon</a></b> ()</li>
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<li><div class="fn"/>QRect <b><a href="qpolygon.html#boundingRect">boundingRect</a></b> () const</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#point">point</a></b> ( int <i>index</i>, int * <i>x</i>, int * <i>y</i> ) const</li>
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<li><div class="fn"/>QPoint <b><a href="qpolygon.html#point-2">point</a></b> ( int <i>index</i> ) const</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#putPoints">putPoints</a></b> ( int <i>index</i>, int <i>nPoints</i>, int <i>firstx</i>, int <i>firsty</i>, ... )</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#putPoints-3">putPoints</a></b> ( int <i>index</i>, int <i>nPoints</i>, const QPolygon & <i>from</i>, int <i>fromIndex</i> = 0 )</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#setPoint">setPoint</a></b> ( int <i>index</i>, int <i>x</i>, int <i>y</i> )</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#setPoint-2">setPoint</a></b> ( int <i>i</i>, const QPoint & <i>p</i> )</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#setPoints">setPoints</a></b> ( int <i>nPoints</i>, const int * <i>points</i> )</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#setPoints-2">setPoints</a></b> ( int <i>nPoints</i>, int <i>firstx</i>, int <i>firsty</i>, ... )</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#translate">translate</a></b> ( int <i>dx</i>, int <i>dy</i> )</li>
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<li><div class="fn"/>void <b><a href="qpolygon.html#translate-2">translate</a></b> ( const QPoint & <i>offset</i> )</li>
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<li><div class="fn"/><b><a href="qpolygon.html#operator-QVariant">operator QVariant</a></b> () const</li>
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<li><div class="fn"/>62 public functions inherited from <a href="qvector.html#public-functions">QVector</a></li>
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<h3>Additional Inherited Members</h3>
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<li><div class="fn"/>2 static public members inherited from <a href="qvector.html#static-public-members">QVector</a></li>
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<a name="details"></a>
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<h2>Detailed Description</h2>
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<p>The QPolygon class provides a vector of points.</p>
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<p>A QPolygon is a <a href="qvector.html">QVector</a><<a href="qpoint.html">QPoint</a>>. It is <a href="shclass.html#implicitly-shared">implicitly shared</a>. In addition to the functions provided by <a href="qvector.html">QVector</a>, QPolygon provides some point-specific functions.</p>
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<p>The easiest way to add points to a QPolygon is to use <a href="qvector.html">QVector</a>'s streaming operators, as illustrated below:</p>
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<pre> QPolygon polygon;
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polygon << QPoint(10, 20) << QPoint(20, 30);</pre>
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<p>All other forms of manipulating a vector are available too, along with some compatibilty functions from Qt 3.</p>
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<p>For geometry operations use <a href="qpolygon.html#boundingRect">boundingRect</a>() and <a href="qpolygon.html#translate">translate</a>(). There is also the <a href="qmatrix.html#map">QMatrix::map</a>() function for more general transformations of QPolygons.</p>
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<p>Among others, QPolygon is used by <a href="qpainter-qt3.html#drawLineSegments">QPainter::drawLineSegments</a>(), <a href="qpainter.html#drawPolyline">QPainter::drawPolyline</a>(), <a href="qpainter.html#drawPolygon">QPainter::drawPolygon</a>() and <a href="qpainter-qt3.html#drawCubicBezier">QPainter::drawCubicBezier</a>().</p>
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<p>See also <a href="qpainter.html">QPainter</a>, <a href="qmatrix.html">QMatrix</a>, <a href="qvector.html">QVector</a>, and <a href="qpolygonf.html">QPolygonF</a>.</p>
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<h2>Member Function Documentation</h2>
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<h3 class="fn"><a name="QPolygon"></a>QPolygon::QPolygon ()</h3>
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<p>Constructs an empty point array.</p>
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<p>See also <a href="qvector.html#isEmpty">QVector::isEmpty</a>().</p>
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<h3 class="fn"><a name="QPolygon-2"></a>QPolygon::QPolygon ( int <i>size</i> )</h3>
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<p>Constructs a point array with room for <i>size</i> points. Makes an empty array if <i>size</i> == 0.</p>
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<p>See also <a href="qvector.html#isEmpty">QVector::isEmpty</a>().</p>
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<h3 class="fn"><a name="QPolygon-3"></a>QPolygon::QPolygon ( const QPolygon & <i>a</i> )</h3>
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<p>Constructs a copy of the point array <i>a</i>.</p>
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<h3 class="fn"><a name="QPolygon-4"></a>QPolygon::QPolygon ( const <a href="qvector.html">QVector</a><<a href="qpoint.html">QPoint</a>> & <i>pts</i> )</h3>
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<p>Constructs a pointarray containing a copy of the points specified in <i>pts</i>.</p>
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<h3 class="fn"><a name="QPolygon-5"></a>QPolygon::QPolygon ( const <a href="qrect.html">QRect</a> & <i>r</i>, bool <i>closed</i> = false )</h3>
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<p>Constructs a point array from the rectangle <i>r</i>.</p>
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<p>If <i>closed</i> is false, then the point array just contains the following four points of the rectangle ordered clockwise. The bottom-right point is located at (r.x() + r.width(), r.y() + r.height()).</p>
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<p>If <i>closed</i> is true, then a fifth point is set to r.topLeft().</p>
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<h3 class="fn"><a name="dtor.QPolygon"></a>QPolygon::~QPolygon ()</h3>
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<p>Destroys the point array.</p>
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<h3 class="fn"><a name="boundingRect"></a><a href="qrect.html">QRect</a> QPolygon::boundingRect () const</h3>
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<p>Returns the bounding rectangle of the points in the array, or <a href="qrect.html">QRect</a>(0, 0, 0, 0) if the array is empty.</p>
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<h3 class="fn"><a name="point"></a>void QPolygon::point ( int <i>index</i>, int * <i>x</i>, int * <i>y</i> ) const</h3>
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<p>Reads the coordinates of the point at position <i>index</i> within the array and writes them into <tt>*</tt><i>x</i> and <tt>*</tt><i>y</i> if they are valid pointers.</p>
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<h3 class="fn"><a name="point-2"></a><a href="qpoint.html">QPoint</a> QPolygon::point ( int <i>index</i> ) const</h3>
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<p>This is an overloaded member function, provided for convenience. It behaves essentially like the above function.</p>
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<p>Returns the point at position <i>index</i> within the array.</p>
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<h3 class="fn"><a name="putPoints"></a>void QPolygon::putPoints ( int <i>index</i>, int <i>nPoints</i>, int <i>firstx</i>, int <i>firsty</i>, ... )</h3>
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<p>Copies <i>nPoints</i> points from the variable argument list into this point array from position <i>index</i>, and resizes the point array if <tt>index+nPoints</tt> exceeds the size of the array.</p>
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<p>The example code creates an array with three points (4,5), (6,7) and (8,9), by expanding the array from 1 to 3 points:</p>
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<pre> QPolygon polygon(1);
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polygon[0] = QPoint(4, 5);
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polygon.putPoints(1, 2, 6,7, 8,9); // index == 1, points == 2</pre>
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<p>This has the same result, but here putPoints overwrites rather than extends:</p>
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<pre> QPolygon polygon(3);
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polygon.putPoints(0, 3, 4,5, 0,0, 8,9);
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polygon.putPoints(1, 1, 6,7);</pre>
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<p>The points are given as a sequence of integers, starting with <i>firstx</i> then <i>firsty</i>, and so on.</p>
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<p>See also <a href="qpolygon.html#setPoints">setPoints</a>().</p>
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<h3 class="fn"><a name="putPoints-3"></a>void QPolygon::putPoints ( int <i>index</i>, int <i>nPoints</i>, const QPolygon & <i>from</i>, int <i>fromIndex</i> = 0 )</h3>
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<p>This is an overloaded member function, provided for convenience. It behaves essentially like the above function.</p>
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<p>This version of the function copies <i>nPoints</i> from <i>from</i> into this array, starting at <i>index</i> in this array and <i>fromIndex</i> in <i>from</i>. <i>fromIndex</i> is 0 by default.</p>
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<pre> QPolygon polygon1;
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polygon1.putPoints(0, 3, 1,2, 0,0, 5,6);
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// polygon1 is now the three-point array (1,2, 0,0, 5,6);</pre>
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<p>See also <a href="qpolygon.html#setPoints">setPoints</a>().</p>
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<h3 class="fn"><a name="setPoint"></a>void QPolygon::setPoint ( int <i>index</i>, int <i>x</i>, int <i>y</i> )</h3>
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<p>Sets the point at position <i>index</i> in the array to (<i>x</i>, <i>y</i>).</p>
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<p>See also <a href="qpolygon.html#putPoints">putPoints</a>() and <a href="qpolygon.html#setPoints">setPoints</a>().</p>
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<h3 class="fn"><a name="setPoint-2"></a>void QPolygon::setPoint ( int <i>i</i>, const <a href="qpoint.html">QPoint</a> & <i>p</i> )</h3>
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<p>This is an overloaded member function, provided for convenience. It behaves essentially like the above function.</p>
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<p>Sets the point at array index <i>i</i> to <i>p</i>.</p>
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<p>See also <a href="qpolygon.html#putPoints">putPoints</a>() and <a href="qpolygon.html#setPoints">setPoints</a>().</p>
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<h3 class="fn"><a name="setPoints"></a>void QPolygon::setPoints ( int <i>nPoints</i>, const int * <i>points</i> )</h3>
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<p>Resizes the array to <i>nPoints</i> and sets the points in the array to the values taken from <i>points</i>.</p>
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<p>The example code creates an array with two points (10, 20) and (30, 40):</p>
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<pre> static const int points[] = { 10, 20, 30, 40 };
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polygon.setPoints(2, points);</pre>
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<p>See also <a href="qvector.html#resize">resize</a>(), <a href="qpolygon.html#setPoint">setPoint</a>(), and <a href="qpolygon.html#putPoints">putPoints</a>().</p>
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<h3 class="fn"><a name="setPoints-2"></a>void QPolygon::setPoints ( int <i>nPoints</i>, int <i>firstx</i>, int <i>firsty</i>, ... )</h3>
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<p>This is an overloaded member function, provided for convenience. It behaves essentially like the above function.</p>
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<p>Resizes the array to <i>nPoints</i> and sets the points in the array to the values taken from the variable argument list.</p>
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<p>The example code creates an array with two points (10, 20) and (30, 40):</p>
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<pre> QPolygon polygon;
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polygon.setPoints(2, 10, 20, 30, 40);</pre>
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<p>The points are given as a sequence of integers, starting with <i>firstx</i> then <i>firsty</i>, and so on.</p>
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<p>See also <a href="qvector.html#resize">resize</a>(), <a href="qpolygon.html#putPoints">putPoints</a>(), and <a href="qpolygon.html#setPoint">setPoint</a>().</p>
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<h3 class="fn"><a name="translate"></a>void QPolygon::translate ( int <i>dx</i>, int <i>dy</i> )</h3>
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<p>Translate all points in the array by (<i>dx</i>, <i>dy</i>).</p>
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<h3 class="fn"><a name="translate-2"></a>void QPolygon::translate ( const <a href="qpoint.html">QPoint</a> & <i>offset</i> )</h3>
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<p>This is an overloaded member function, provided for convenience. It behaves essentially like the above function.</p>
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<p>Translate all points in the array by <i>offset</i>.</p>
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<h3 class="fn"><a name="operator-QVariant"></a>QPolygon::operator QVariant () const</h3>
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<p>Returns the polygon as a <a href="qvariant.html">QVariant</a></p>
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