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231 lines
13 KiB
231 lines
13 KiB
14 years ago
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<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/kernel/qabstractlayout.cpp:56 -->
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>QLayoutItem Class</title>
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<font color="#004faf">All Classes</font></a>
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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>QLayoutItem Class Reference</h1>
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<p>The QLayoutItem class provides an abstract item that a
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QLayout manipulates.
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<a href="#details">More...</a>
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<p><tt>#include <<a href="qlayout-h.html">qlayout.h</a>></tt>
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<p>Inherited by <a href="qlayout.html">QLayout</a>, <a href="qspaceritem.html">QSpacerItem</a>, and <a href="qwidgetitem.html">QWidgetItem</a>.
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<p><a href="qlayoutitem-members.html">List of all member functions.</a>
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<h2>Public Members</h2>
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<ul>
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<li class=fn><a href="#QLayoutItem"><b>QLayoutItem</b></a> ( int alignment = 0 )</li>
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<li class=fn>virtual <a href="#~QLayoutItem"><b>~QLayoutItem</b></a> ()</li>
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<li class=fn>virtual QSize <a href="#sizeHint"><b>sizeHint</b></a> () const = 0</li>
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<li class=fn>virtual QSize <a href="#minimumSize"><b>minimumSize</b></a> () const = 0</li>
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<li class=fn>virtual QSize <a href="#maximumSize"><b>maximumSize</b></a> () const = 0</li>
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<li class=fn>virtual QSizePolicy::ExpandData <a href="#expanding"><b>expanding</b></a> () const = 0</li>
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<li class=fn>virtual void <a href="#setGeometry"><b>setGeometry</b></a> ( const QRect & r ) = 0</li>
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<li class=fn>virtual QRect <a href="#geometry"><b>geometry</b></a> () const = 0</li>
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<li class=fn>virtual bool <a href="#isEmpty"><b>isEmpty</b></a> () const = 0</li>
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<li class=fn>virtual bool <a href="#hasHeightForWidth"><b>hasHeightForWidth</b></a> () const</li>
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<li class=fn>virtual int <a href="#heightForWidth"><b>heightForWidth</b></a> ( int w ) const</li>
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<li class=fn>virtual void <a href="#invalidate"><b>invalidate</b></a> ()</li>
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<li class=fn>virtual QWidget * <a href="#widget"><b>widget</b></a> ()</li>
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<li class=fn>virtual QLayoutIterator <a href="#iterator"><b>iterator</b></a> ()</li>
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<li class=fn>virtual QLayout * <a href="#layout"><b>layout</b></a> ()</li>
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<li class=fn>virtual QSpacerItem * <a href="#spacerItem"><b>spacerItem</b></a> ()</li>
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<li class=fn>int <a href="#alignment"><b>alignment</b></a> () const</li>
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<li class=fn>virtual void <a href="#setAlignment"><b>setAlignment</b></a> ( int a )</li>
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</ul>
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<hr><a name="details"></a><h2>Detailed Description</h2>
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The QLayoutItem class provides an abstract item that a
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<a href="qlayout.html">QLayout</a> manipulates.
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<p> This is used by custom layouts.
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<p> Pure virtual functions are provided to return information about
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the layout, including, <a href="#sizeHint">sizeHint</a>(), <a href="#minimumSize">minimumSize</a>(), <a href="#maximumSize">maximumSize</a>()
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and <a href="#expanding">expanding</a>().
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<p> The layout's geometry can be set and retrieved with <a href="#setGeometry">setGeometry</a>()
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and <a href="#geometry">geometry</a>(), and its alignment with <a href="#setAlignment">setAlignment</a>() and
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<a href="#alignment">alignment</a>().
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<p> <a href="#isEmpty">isEmpty</a>() returns whether the layout is empty. <a href="#iterator">iterator</a>() returns
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an iterator for the layout's children. If the concrete item is a
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<a href="qwidget.html">QWidget</a>, it can be retrieved using <a href="#widget">widget</a>(). Similarly for
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<a href="#layout">layout</a>() and <a href="#spacerItem">spacerItem</a>().
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<p> <p>See also <a href="qlayout.html">QLayout</a>, <a href="appearance.html">Widget Appearance and Style</a>, and <a href="geomanagement.html">Layout Management</a>.
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<hr><h2>Member Function Documentation</h2>
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<h3 class=fn><a name="QLayoutItem"></a>QLayoutItem::QLayoutItem ( int alignment = 0 )
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</h3>
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<p> Constructs a layout item with an <em>alignment</em> that is a bitwise OR
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of the <a href="qt.html#AlignmentFlags-enum">Qt::AlignmentFlags</a>. Not all subclasses support
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alignment.
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<h3 class=fn><a name="~QLayoutItem"></a>QLayoutItem::~QLayoutItem ()<tt> [virtual]</tt>
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</h3>
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Destroys the QLayoutItem.
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<h3 class=fn>int <a name="alignment"></a>QLayoutItem::alignment () const
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</h3>
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<p> Returns the alignment of this item.
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<h3 class=fn><a href="qsizepolicy.html#ExpandData-enum">QSizePolicy::ExpandData</a> <a name="expanding"></a>QLayoutItem::expanding () const<tt> [pure virtual]</tt>
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</h3>
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<p> Implemented in subclasses to return the direction(s) this item
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"wants" to expand in (if any).
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<p>Reimplemented in <a href="qlayout.html#expanding">QLayout</a>, <a href="qspaceritem.html#expanding">QSpacerItem</a>, and <a href="qwidgetitem.html#expanding">QWidgetItem</a>.
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<h3 class=fn><a href="qrect.html">QRect</a> <a name="geometry"></a>QLayoutItem::geometry () const<tt> [pure virtual]</tt>
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</h3>
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<p> Returns the rectangle covered by this layout item.
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<p>Example: <a href="customlayout-example.html#x1495">customlayout/border.cpp</a>.
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<h3 class=fn>bool <a name="hasHeightForWidth"></a>QLayoutItem::hasHeightForWidth () const<tt> [virtual]</tt>
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</h3>
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Returns TRUE if this layout's preferred height depends on its
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width; otherwise returns FALSE. The default implementation returns
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FALSE.
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<p> Reimplement this function in layout managers that support height
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for width.
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<p> <p>See also <a href="#heightForWidth">heightForWidth</a>() and <a href="qwidget.html#heightForWidth">QWidget::heightForWidth</a>().
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<p>Examples: <a href="customlayout-example.html#x1496">customlayout/border.cpp</a> and <a href="customlayout-example.html#x1472">customlayout/flow.cpp</a>.
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<p>Reimplemented in <a href="qgridlayout.html#hasHeightForWidth">QGridLayout</a> and <a href="qboxlayout.html#hasHeightForWidth">QBoxLayout</a>.
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<h3 class=fn>int <a name="heightForWidth"></a>QLayoutItem::heightForWidth ( int w ) const<tt> [virtual]</tt>
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</h3>
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Returns the preferred height for this layout item, given the width
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<em>w</em>.
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<p> The default implementation returns -1, indicating that the
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preferred height is independent of the width of the item. Using
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the function <a href="#hasHeightForWidth">hasHeightForWidth</a>() will typically be much faster
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than calling this function and testing for -1.
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<p> Reimplement this function in layout managers that support height
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for width. A typical implementation will look like this:
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<pre>
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int MyLayout::heightForWidth( int w ) const
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{
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if ( cache_dirty || cached_width != w ) {
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// not all C++ compilers support "mutable"
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MyLayout *that = (MyLayout*)this;
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int h = calculateHeightForWidth( w );
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that->cached_hfw = h;
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return h;
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}
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return cached_hfw;
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}
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</pre>
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<p> Caching is strongly recommended; without it layout will take
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exponential time.
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<p> <p>See also <a href="#hasHeightForWidth">hasHeightForWidth</a>().
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<p>Example: <a href="customlayout-example.html#x1473">customlayout/flow.cpp</a>.
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<p>Reimplemented in <a href="qgridlayout.html#heightForWidth">QGridLayout</a> and <a href="qboxlayout.html#heightForWidth">QBoxLayout</a>.
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<h3 class=fn>void <a name="invalidate"></a>QLayoutItem::invalidate ()<tt> [virtual]</tt>
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</h3>
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Invalidates any cached information in this layout item.
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<p>Reimplemented in <a href="qlayout.html#invalidate">QLayout</a>.
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<h3 class=fn>bool <a name="isEmpty"></a>QLayoutItem::isEmpty () const<tt> [pure virtual]</tt>
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</h3>
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<p> Implemented in subclasses to return whether this item is empty,
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i.e. whether it contains any widgets.
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<p>Reimplemented in <a href="qlayout.html#isEmpty">QLayout</a>, <a href="qspaceritem.html#isEmpty">QSpacerItem</a>, and <a href="qwidgetitem.html#isEmpty">QWidgetItem</a>.
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<h3 class=fn><a href="qlayoutiterator.html">QLayoutIterator</a> <a name="iterator"></a>QLayoutItem::iterator ()<tt> [virtual]</tt>
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</h3>
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Returns an iterator over this item's QLayoutItem children. The
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default implementation returns an empty iterator.
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<p> Reimplement this function in subclasses that can have children.
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<p>Reimplemented in <a href="qlayout.html#iterator">QLayout</a>.
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<h3 class=fn><a href="qlayout.html">QLayout</a> * <a name="layout"></a>QLayoutItem::layout ()<tt> [virtual]</tt>
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</h3>
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If this item is a <a href="qlayout.html">QLayout</a>, it is returned as a QLayout; otherwise
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0 is returned. This function provides type-safe casting.
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<h3 class=fn><a href="qsize.html">QSize</a> <a name="maximumSize"></a>QLayoutItem::maximumSize () const<tt> [pure virtual]</tt>
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</h3>
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<p> Implemented in subclasses to return the maximum size of this item.
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<p>Reimplemented in <a href="qlayout.html#maximumSize">QLayout</a>, <a href="qspaceritem.html#maximumSize">QSpacerItem</a>, and <a href="qwidgetitem.html#maximumSize">QWidgetItem</a>.
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<h3 class=fn><a href="qsize.html">QSize</a> <a name="minimumSize"></a>QLayoutItem::minimumSize () const<tt> [pure virtual]</tt>
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</h3>
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<p> Implemented in subclasses to return the minimum size of this item.
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<p>Examples: <a href="customlayout-example.html#x1497">customlayout/border.cpp</a>, <a href="customlayout-example.html#x1515">customlayout/card.cpp</a>, and <a href="customlayout-example.html#x1474">customlayout/flow.cpp</a>.
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<p>Reimplemented in <a href="qlayout.html#minimumSize">QLayout</a>, <a href="qspaceritem.html#minimumSize">QSpacerItem</a>, and <a href="qwidgetitem.html#minimumSize">QWidgetItem</a>.
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<h3 class=fn>void <a name="setAlignment"></a>QLayoutItem::setAlignment ( int a )<tt> [virtual]</tt>
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</h3>
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Sets the alignment of this item to <em>a</em>, which is a bitwise OR of
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the <a href="qt.html#AlignmentFlags-enum">Qt::AlignmentFlags</a>. Not all subclasses support alignment.
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<p>Example: <a href="tutorial2-09.html#x2644">chart/optionsform.cpp</a>.
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<h3 class=fn>void <a name="setGeometry"></a>QLayoutItem::setGeometry ( const <a href="qrect.html">QRect</a> & r )<tt> [pure virtual]</tt>
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</h3>
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<p> Implemented in subclasses to set this item's geometry to <em>r</em>.
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<p>Examples: <a href="customlayout-example.html#x1498">customlayout/border.cpp</a>, <a href="customlayout-example.html#x1516">customlayout/card.cpp</a>, and <a href="customlayout-example.html#x1475">customlayout/flow.cpp</a>.
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<p>Reimplemented in <a href="qlayout.html#setGeometry">QLayout</a>, <a href="qspaceritem.html#setGeometry">QSpacerItem</a>, and <a href="qwidgetitem.html#setGeometry">QWidgetItem</a>.
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<h3 class=fn><a href="qsize.html">QSize</a> <a name="sizeHint"></a>QLayoutItem::sizeHint () const<tt> [pure virtual]</tt>
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</h3>
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<p> Implemented in subclasses to return the preferred size of this item.
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<p>Examples: <a href="customlayout-example.html#x1499">customlayout/border.cpp</a>, <a href="customlayout-example.html#x1517">customlayout/card.cpp</a>, and <a href="customlayout-example.html#x1476">customlayout/flow.cpp</a>.
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<p>Reimplemented in <a href="qspaceritem.html#sizeHint">QSpacerItem</a>, <a href="qwidgetitem.html#sizeHint">QWidgetItem</a>, <a href="qgridlayout.html#sizeHint">QGridLayout</a>, and <a href="qboxlayout.html#sizeHint">QBoxLayout</a>.
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<h3 class=fn><a href="qspaceritem.html">QSpacerItem</a> * <a name="spacerItem"></a>QLayoutItem::spacerItem ()<tt> [virtual]</tt>
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</h3>
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If this item is a <a href="qspaceritem.html">QSpacerItem</a>, it is returned as a QSpacerItem;
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otherwise 0 is returned. This function provides type-safe casting.
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<h3 class=fn><a href="qwidget.html">QWidget</a> * <a name="widget"></a>QLayoutItem::widget ()<tt> [virtual]</tt>
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</h3>
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If this item is a <a href="qwidget.html">QWidget</a>, it is returned as a QWidget; otherwise
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0 is returned. This function provides type-safe casting.
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<p>Reimplemented in <a href="qwidgetitem.html#widget">QWidgetItem</a>.
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<!-- eof -->
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<hr><p>
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This file is part of the <a href="index.html">Qt toolkit</a>.
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Copyright © 1995-2007
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<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>Qt 3.3.8</div>
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</table></div></address></body>
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</html>
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