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227 lines
7.9 KiB
227 lines
7.9 KiB
'\" t
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.TH QLayoutItem 3qt "2 February 2007" "Trolltech AS" \" -*- nroff -*-
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.\" Copyright 1992-2007 Trolltech ASA. All rights reserved. See the
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.\" license file included in the distribution for a complete license
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.\" statement.
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.\"
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.ad l
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.nh
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.SH NAME
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QLayoutItem \- Abstract item that a QLayout manipulates
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.SH SYNOPSIS
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\fC#include <ntqlayout.h>\fR
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.PP
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Inherited by QLayout, QSpacerItem, and QWidgetItem.
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.PP
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.SS "Public Members"
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.in +1c
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.ti -1c
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.BI "\fBQLayoutItem\fR ( int alignment = 0 )"
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.br
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.ti -1c
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.BI "virtual \fB~QLayoutItem\fR ()"
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.br
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.ti -1c
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.BI "virtual QSize \fBsizeHint\fR () const = 0"
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.br
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.ti -1c
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.BI "virtual QSize \fBminimumSize\fR () const = 0"
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.br
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.ti -1c
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.BI "virtual QSize \fBmaximumSize\fR () const = 0"
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.br
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.ti -1c
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.BI "virtual QSizePolicy::ExpandData \fBexpanding\fR () const = 0"
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.br
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.ti -1c
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.BI "virtual void \fBsetGeometry\fR ( const QRect & r ) = 0"
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.br
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.ti -1c
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.BI "virtual QRect \fBgeometry\fR () const = 0"
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.br
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.ti -1c
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.BI "virtual bool \fBisEmpty\fR () const = 0"
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.br
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.ti -1c
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.BI "virtual bool \fBhasHeightForWidth\fR () const"
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.br
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.ti -1c
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.BI "virtual int \fBheightForWidth\fR ( int w ) const"
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.br
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.ti -1c
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.BI "virtual void \fBinvalidate\fR ()"
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.br
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.ti -1c
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.BI "virtual QWidget * \fBwidget\fR ()"
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.br
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.ti -1c
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.BI "virtual QLayoutIterator \fBiterator\fR ()"
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.br
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.ti -1c
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.BI "virtual QLayout * \fBlayout\fR ()"
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.br
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.ti -1c
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.BI "virtual QSpacerItem * \fBspacerItem\fR ()"
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.br
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.ti -1c
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.BI "int \fBalignment\fR () const"
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.br
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.ti -1c
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.BI "virtual void \fBsetAlignment\fR ( int a )"
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.br
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.in -1c
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.SH DESCRIPTION
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The QLayoutItem class provides an abstract item that a QLayout manipulates.
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.PP
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This is used by custom layouts.
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.PP
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Pure virtual functions are provided to return information about the layout, including, sizeHint(), minimumSize(), maximumSize() and expanding().
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.PP
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The layout's geometry can be set and retrieved with setGeometry() and geometry(), and its alignment with setAlignment() and alignment().
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.PP
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isEmpty() returns whether the layout is empty. iterator() returns an iterator for the layout's children. If the concrete item is a QWidget, it can be retrieved using widget(). Similarly for layout() and spacerItem().
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.PP
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See also QLayout, Widget Appearance and Style, and Layout Management.
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.SH MEMBER FUNCTION DOCUMENTATION
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.SH "QLayoutItem::QLayoutItem ( int alignment = 0 )"
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Constructs a layout item with an \fIalignment\fR that is a bitwise OR of the Qt::AlignmentFlags. Not all subclasses support alignment.
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.SH "QLayoutItem::~QLayoutItem ()\fC [virtual]\fR"
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Destroys the QLayoutItem.
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.SH "int QLayoutItem::alignment () const"
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Returns the alignment of this item.
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.SH "QSizePolicy::ExpandData QLayoutItem::expanding () const\fC [pure virtual]\fR"
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Implemented in subclasses to return the direction(s) this item" wants" to expand in (if any).
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.PP
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Reimplemented in QLayout, QSpacerItem, and QWidgetItem.
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.SH "QRect QLayoutItem::geometry () const\fC [pure virtual]\fR"
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Returns the rectangle covered by this layout item.
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.PP
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Example: customlayout/border.cpp.
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.SH "bool QLayoutItem::hasHeightForWidth () const\fC [virtual]\fR"
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Returns TRUE if this layout's preferred height depends on its width; otherwise returns FALSE. The default implementation returns FALSE.
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.PP
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Reimplement this function in layout managers that support height for width.
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.PP
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See also heightForWidth() and QWidget::heightForWidth().
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.PP
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Examples:
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.)l customlayout/border.cpp and customlayout/flow.cpp.
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.PP
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Reimplemented in QGridLayout and QBoxLayout.
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.SH "int QLayoutItem::heightForWidth ( int w ) const\fC [virtual]\fR"
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Returns the preferred height for this layout item, given the width \fIw\fR.
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.PP
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The default implementation returns -1, indicating that the preferred height is independent of the width of the item. Using the function hasHeightForWidth() will typically be much faster than calling this function and testing for -1.
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.PP
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Reimplement this function in layout managers that support height for width. A typical implementation will look like this:
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.PP
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.nf
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.br
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int MyLayout::heightForWidth( int w ) const
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.br
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{
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.br
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if ( cache_dirty || cached_width != w ) {
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.br
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// not all C++ compilers support "mutable"
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.br
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MyLayout *that = (MyLayout*)this;
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.br
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int h = calculateHeightForWidth( w );
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.br
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that->cached_hfw = h;
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.br
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return h;
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.br
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}
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.br
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return cached_hfw;
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.br
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}
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.br
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.fi
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.PP
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Caching is strongly recommended; without it layout will take exponential time.
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.PP
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See also hasHeightForWidth().
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.PP
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Example: customlayout/flow.cpp.
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.PP
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Reimplemented in QGridLayout and QBoxLayout.
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.SH "void QLayoutItem::invalidate ()\fC [virtual]\fR"
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Invalidates any cached information in this layout item.
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.PP
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Reimplemented in QLayout.
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.SH "bool QLayoutItem::isEmpty () const\fC [pure virtual]\fR"
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Implemented in subclasses to return whether this item is empty, i.e. whether it contains any widgets.
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.PP
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Reimplemented in QLayout, QSpacerItem, and QWidgetItem.
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.SH "QLayoutIterator QLayoutItem::iterator ()\fC [virtual]\fR"
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Returns an iterator over this item's QLayoutItem children. The default implementation returns an empty iterator.
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.PP
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Reimplement this function in subclasses that can have children.
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.PP
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Reimplemented in QLayout.
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.SH "QLayout * QLayoutItem::layout ()\fC [virtual]\fR"
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If this item is a QLayout, it is returned as a QLayout; otherwise 0 is returned. This function provides type-safe casting.
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.SH "QSize QLayoutItem::maximumSize () const\fC [pure virtual]\fR"
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Implemented in subclasses to return the maximum size of this item.
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.PP
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Reimplemented in QLayout, QSpacerItem, and QWidgetItem.
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.SH "QSize QLayoutItem::minimumSize () const\fC [pure virtual]\fR"
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Implemented in subclasses to return the minimum size of this item.
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.PP
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Examples:
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.)l customlayout/border.cpp, customlayout/card.cpp, and customlayout/flow.cpp.
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.PP
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Reimplemented in QLayout, QSpacerItem, and QWidgetItem.
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.SH "void QLayoutItem::setAlignment ( int a )\fC [virtual]\fR"
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Sets the alignment of this item to \fIa\fR, which is a bitwise OR of the Qt::AlignmentFlags. Not all subclasses support alignment.
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.PP
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Example: chart/optionsform.cpp.
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.SH "void QLayoutItem::setGeometry ( const QRect & r )\fC [pure virtual]\fR"
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Implemented in subclasses to set this item's geometry to \fIr\fR.
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.PP
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Examples:
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.)l customlayout/border.cpp, customlayout/card.cpp, and customlayout/flow.cpp.
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.PP
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Reimplemented in QLayout, QSpacerItem, and QWidgetItem.
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.SH "QSize QLayoutItem::sizeHint () const\fC [pure virtual]\fR"
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Implemented in subclasses to return the preferred size of this item.
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.PP
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Examples:
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.)l customlayout/border.cpp, customlayout/card.cpp, and customlayout/flow.cpp.
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.PP
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Reimplemented in QSpacerItem, QWidgetItem, QGridLayout, and QBoxLayout.
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.SH "QSpacerItem * QLayoutItem::spacerItem ()\fC [virtual]\fR"
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If this item is a QSpacerItem, it is returned as a QSpacerItem; otherwise 0 is returned. This function provides type-safe casting.
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.SH "QWidget * QLayoutItem::widget ()\fC [virtual]\fR"
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If this item is a QWidget, it is returned as a QWidget; otherwise 0 is returned. This function provides type-safe casting.
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.PP
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Reimplemented in QWidgetItem.
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.SH "SEE ALSO"
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.BR http://doc.trolltech.com/qlayoutitem.html
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.BR http://www.trolltech.com/faq/tech.html
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.SH COPYRIGHT
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Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
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license file included in the distribution for a complete license
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statement.
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.SH AUTHOR
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Generated automatically from the source code.
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.SH BUGS
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If you find a bug in Qt, please report it as described in
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.BR http://doc.trolltech.com/bughowto.html .
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Good bug reports help us to help you. Thank you.
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.P
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The definitive TQt documentation is provided in HTML format; it is
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located at $TQTDIR/doc/html and can be read using TQt Assistant or with
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a web browser. This man page is provided as a convenience for those
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users who prefer man pages, although this format is not officially
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supported by Trolltech.
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.P
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If you find errors in this manual page, please report them to
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.BR qt-bugs@trolltech.com .
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Please include the name of the manual page (tqlayoutitem.3qt) and the Qt
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version (3.3.8).
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