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<?xml version="1.0" encoding="iso-8859-1"?>
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<html><head><title>QLayoutItem Class Reference</title><style>h3.fn,span.fn { margin-left: 1cm; text-indent: -1cm }
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</style></head><body><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr /><td align="left" valign="top" width="32"><img align="left" border="0" height="32" src="images/rb-logo.png" width="32" /></td><td width="1">  </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="modules.html"><font color="#004faf">Modules</font></a></td></table><h1 align="center">QLayoutItem Class Reference<br /><sup><sup>[<a href="qtgui.html">QtGui</a> module]</sup></sup></h1><p>The QLayoutItem class provides an abstract item that a <a href="qlayout.html">QLayout</a> manipulates. <a href="#details">More...</a></p>
<p>Inherited by <a href="qlayout.html">QLayout</a>, <a href="qspaceritem.html">QSpacerItem</a> and <a href="qwidgetitem.html">QWidgetItem</a>.</p><h3>Methods</h3><ul><li><div class="fn" /><b><a href="qlayoutitem.html#QLayoutItem">__init__</a></b> (<i>self</i>, Qt.Alignment <i>alignment</i> = 0)</li><li><div class="fn" /><b><a href="qlayoutitem.html#QLayoutItem-2">__init__</a></b> (<i>self</i>, QLayoutItem)</li><li><div class="fn" />Qt.Alignment <b><a href="qlayoutitem.html#alignment">alignment</a></b> (<i>self</i>)</li><li><div class="fn" />QSizePolicy.ControlTypes <b><a href="qlayoutitem.html#controlTypes">controlTypes</a></b> (<i>self</i>)</li><li><div class="fn" />Qt.Orientations <b><a href="qlayoutitem.html#expandingDirections">expandingDirections</a></b> (<i>self</i>)</li><li><div class="fn" />QRect <b><a href="qlayoutitem.html#geometry">geometry</a></b> (<i>self</i>)</li><li><div class="fn" />bool <b><a href="qlayoutitem.html#hasHeightForWidth">hasHeightForWidth</a></b> (<i>self</i>)</li><li><div class="fn" />int <b><a href="qlayoutitem.html#heightForWidth">heightForWidth</a></b> (<i>self</i>, int)</li><li><div class="fn" /><b><a href="qlayoutitem.html#invalidate">invalidate</a></b> (<i>self</i>)</li><li><div class="fn" />bool <b><a href="qlayoutitem.html#isEmpty">isEmpty</a></b> (<i>self</i>)</li><li><div class="fn" />QLayout <b><a href="qlayoutitem.html#layout">layout</a></b> (<i>self</i>)</li><li><div class="fn" />QSize <b><a href="qlayoutitem.html#maximumSize">maximumSize</a></b> (<i>self</i>)</li><li><div class="fn" />int <b><a href="qlayoutitem.html#minimumHeightForWidth">minimumHeightForWidth</a></b> (<i>self</i>, int)</li><li><div class="fn" />QSize <b><a href="qlayoutitem.html#minimumSize">minimumSize</a></b> (<i>self</i>)</li><li><div class="fn" /><b><a href="qlayoutitem.html#setAlignment">setAlignment</a></b> (<i>self</i>, Qt.Alignment <i>a</i>)</li><li><div class="fn" /><b><a href="qlayoutitem.html#setGeometry">setGeometry</a></b> (<i>self</i>, QRect)</li><li><div class="fn" />QSize <b><a href="qlayoutitem.html#sizeHint">sizeHint</a></b> (<i>self</i>)</li><li><div class="fn" />QSpacerItem <b><a href="qlayoutitem.html#spacerItem">spacerItem</a></b> (<i>self</i>)</li><li><div class="fn" />QWidget <b><a href="qlayoutitem.html#widget">widget</a></b> (<i>self</i>)</li></ul><a name="details" /><hr /><h2>Detailed Description</h2><p>The QLayoutItem class provides an abstract item that a <a href="qlayout.html">QLayout</a> manipulates.</p>
<p>This is used by custom layouts.</p>
<p>Pure virtual functions are provided to return information about
the layout, including, <a href="qlayoutitem.html#sizeHint">sizeHint</a>(), <a href="qlayoutitem.html#minimumSize">minimumSize</a>(), <a href="qlayoutitem.html#maximumSize">maximumSize</a>() and
expanding().</p>
<p>The layout's geometry can be set and retrieved with <a href="qlayoutitem.html#setGeometry">setGeometry</a>() and <a href="qlayoutitem.html#geometry">geometry</a>(), and its alignment with
<a href="qlayoutitem.html#setAlignment">setAlignment</a>() and
<a href="qlayoutitem.html#alignment">alignment</a>().</p>
<p><a href="qlayoutitem.html#isEmpty">isEmpty</a>() returns whether
the layout item is empty. If the concrete item is a <a href="qwidget.html">QWidget</a>, it can be retrieved using <a href="qlayoutitem.html#widget">widget</a>(). Similarly for <a href="qlayoutitem.html#layout">layout</a>() and <a href="qlayoutitem.html#spacerItem">spacerItem</a>().</p>
<p>Some layouts have width and height interdependencies. These can
be expressed using <a href="qlayoutitem.html#hasHeightForWidth">hasHeightForWidth</a>(),
<a href="qlayoutitem.html#heightForWidth">heightForWidth</a>(), and
<a href="qlayoutitem.html#minimumHeightForWidth">minimumHeightForWidth</a>().
For more explanation see the <i>Qt Quarterly</i> article <a href="http://doc.qt.digia.com/qq/qq04-height-for-width.html">Trading
Height for Width</a>.</p>
<hr /><h2>Method Documentation</h2><h3 class="fn"><a name="QLayoutItem" />QLayoutItem.__init__ (<i>self</i>, <a href="qt-alignment.html">Qt.Alignment</a> <i>alignment</i> = 0)</h3><p>Constructs a layout item with an <i>alignment</i>. Not all
subclasses support alignment.</p>
<h3 class="fn"><a name="QLayoutItem-2" />QLayoutItem.__init__ (<i>self</i>, <a href="qlayoutitem.html">QLayoutItem</a>)</h3><h3 class="fn"><a name="alignment" /><a href="qt-alignment.html">Qt.Alignment</a> QLayoutItem.alignment (<i>self</i>)</h3><p>Returns the alignment of this item.</p>
<p><b>See also</b> <a href="qlayoutitem.html#setAlignment">setAlignment</a>().</p>
<h3 class="fn"><a name="controlTypes" /><a href="qsizepolicy-controltypes.html">QSizePolicy.ControlTypes</a> QLayoutItem.controlTypes (<i>self</i>)</h3><p>Returns the control type(s) for the layout item. For a <a href="qwidgetitem.html">QWidgetItem</a>, the control type comes from the
widget's size policy; for a <a href="qlayoutitem.html">QLayoutItem</a>, the control types is derived
from the layout's contents.</p>
<p><b>See also</b> <a href="qsizepolicy.html#controlType">QSizePolicy.controlType</a>().</p>
<h3 class="fn"><a name="expandingDirections" /><a href="qt-orientations.html">Qt.Orientations</a> QLayoutItem.expandingDirections (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Returns whether this layout item can make use of more space than
<a href="qlayoutitem.html#sizeHint">sizeHint</a>(). A value of
<a href="qt.html#Orientation-enum">Qt.Vertical</a> or <a href="qt.html#Orientation-enum">Qt.Horizontal</a> means that it wants
to grow in only one dimension, whereas <a href="qt.html#Orientation-enum">Qt.Vertical</a> | <a href="qt.html#Orientation-enum">Qt.Horizontal</a> means that it wants
to grow in both dimensions.</p>
<h3 class="fn"><a name="geometry" /><a href="qrect.html">QRect</a> QLayoutItem.geometry (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Returns the rectangle covered by this layout item.</p>
<p><b>See also</b> <a href="qlayoutitem.html#setGeometry">setGeometry</a>().</p>
<h3 class="fn"><a name="hasHeightForWidth" />bool QLayoutItem.hasHeightForWidth (<i>self</i>)</h3><p>Returns true if this layout's preferred height depends on its
width; otherwise returns false. The default implementation returns
false.</p>
<p>Reimplement this function in layout managers that support height
for width.</p>
<p><b>See also</b> <a href="qlayoutitem.html#heightForWidth">heightForWidth</a>() and <a href="qwidget.html#heightForWidth">QWidget.heightForWidth</a>().</p>
<h3 class="fn"><a name="heightForWidth" />int QLayoutItem.heightForWidth (<i>self</i>, int)</h3><p>Returns the preferred height for this layout item, given the
width <i>w</i>.</p>
<p>The default implementation returns -1, indicating that the
preferred height is independent of the width of the item. Using the
function <a href="qlayoutitem.html#hasHeightForWidth">hasHeightForWidth</a>() will
typically be much faster than calling this function and testing for
-1.</p>
<p>Reimplement this function in layout managers that support height
for width. A typical implementation will look like this:</p>
<pre class="cpp">
<span class="type">int</span> MyLayout<span class="operator">.</span>heightForWidth(<span class="type">int</span> w) <span class="keyword">const</span>
{
<span class="keyword">if</span> (cache_dirty <span class="operator">|</span><span class="operator">|</span> cached_width <span class="operator">!</span><span class="operator">=</span> w) {
<span class="comment">// not all C++ compilers support "mutable"</span>
MyLayout <span class="operator">*</span>that <span class="operator">=</span> (MyLayout<span class="operator">*</span>)<span class="keyword">this</span>;
<span class="type">int</span> h <span class="operator">=</span> calculateHeightForWidth(w);
that<span class="operator">-</span><span class="operator">></span>cached_hfw <span class="operator">=</span> h;
<span class="keyword">return</span> h;
}
<span class="keyword">return</span> cached_hfw;
}
</pre>
<p>Caching is strongly recommended; without it layout will take
exponential time.</p>
<p><b>See also</b> <a href="qlayoutitem.html#hasHeightForWidth">hasHeightForWidth</a>().</p>
<h3 class="fn"><a name="invalidate" />QLayoutItem.invalidate (<i>self</i>)</h3><p>Invalidates any cached information in this layout item.</p>
<h3 class="fn"><a name="isEmpty" />bool QLayoutItem.isEmpty (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Implemented in subclasses to return whether this item is empty,
i.e. whether it contains any widgets.</p>
<h3 class="fn"><a name="layout" /><a href="qlayout.html">QLayout</a> QLayoutItem.layout (<i>self</i>)</h3><p>If this item is a <a href="qlayout.html">QLayout</a>, it is
returned as a <a href="qlayout.html">QLayout</a>; otherwise 0 is
returned. This function provides type-safe casting.</p>
<h3 class="fn"><a name="maximumSize" /><a href="qsize.html">QSize</a> QLayoutItem.maximumSize (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Implemented in subclasses to return the maximum size of this
item.</p>
<h3 class="fn"><a name="minimumHeightForWidth" />int QLayoutItem.minimumHeightForWidth (<i>self</i>, int)</h3><p>Returns the minimum height this widget needs for the given
width, <i>w</i>. The default implementation simply returns
heightForWidth(<i>w</i>).</p>
<h3 class="fn"><a name="minimumSize" /><a href="qsize.html">QSize</a> QLayoutItem.minimumSize (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Implemented in subclasses to return the minimum size of this
item.</p>
<h3 class="fn"><a name="setAlignment" />QLayoutItem.setAlignment (<i>self</i>, <a href="qt-alignment.html">Qt.Alignment</a> <i>a</i>)</h3><p>Sets the alignment of this item to <i>alignment</i>.</p>
<p><b>Note:</b> Item alignment is only supported by <a href="qlayoutitem.html">QLayoutItem</a> subclasses where it would have a
visual effect. Except for <a href="qspaceritem.html">QSpacerItem</a>, which provides blank space for
layouts, all public Qt classes that inherit <a href="qlayoutitem.html">QLayoutItem</a> support item alignment.</p>
<p><b>See also</b> <a href="qlayoutitem.html#alignment">alignment</a>().</p>
<h3 class="fn"><a name="setGeometry" />QLayoutItem.setGeometry (<i>self</i>, <a href="qrect.html">QRect</a>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Implemented in subclasses to set this item's geometry to
<i>r</i>.</p>
<p><b>See also</b> <a href="qlayoutitem.html#geometry">geometry</a>().</p>
<h3 class="fn"><a name="sizeHint" /><a href="qsize.html">QSize</a> QLayoutItem.sizeHint (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Implemented in subclasses to return the preferred size of this
item.</p>
<h3 class="fn"><a name="spacerItem" /><a href="qspaceritem.html">QSpacerItem</a> QLayoutItem.spacerItem (<i>self</i>)</h3><p>If this item is a <a href="qspaceritem.html">QSpacerItem</a>, it
is returned as a <a href="qspaceritem.html">QSpacerItem</a>;
otherwise 0 is returned. This function provides type-safe
casting.</p>
<h3 class="fn"><a name="widget" /><a href="qwidget.html">QWidget</a> QLayoutItem.widget (<i>self</i>)</h3><p>If this item is a <a href="qwidget.html">QWidget</a>, it is
returned as a <a href="qwidget.html">QWidget</a>; otherwise 0 is
returned. This function provides type-safe casting.</p>
<address><hr /><div align="center"><table border="0" cellspacing="0" width="100%"><tr class="address"><td align="left" width="25%">PyQt 4.12.1 for X11</td><td align="center" width="50%">Copyright © <a href="http://www.riverbankcomputing.com">Riverbank Computing Ltd</a> and <a href="http://www.qt.io">The Qt Company</a> 2015</td><td align="right" width="25%">Qt 4.8.7</td></tr></table></div></address></body></html>
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