QBoxLayout(3qt)QBoxLayout(3qt)NAMEQBoxLayout - Lines up child widgets horizontally or vertically
SYNOPSIS
#include <qlayout.h>
Inherits QLayout.
Inherited by QHBoxLayout and QVBoxLayout.
Public Members
enum Direction { LeftToRight, RightToLeft, TopToBottom, BottomToTop,
Down = TopToBottom, Up = BottomToTop }
QBoxLayout ( QWidget * parent, Direction d, int margin = 0, int spacing
= -1, const char * name = 0 )
QBoxLayout ( QLayout * parentLayout, Direction d, int spacing = -1,
const char * name = 0 )
QBoxLayout ( Direction d, int spacing = -1, const char * name = 0 )
~QBoxLayout ()
virtual void addItem ( QLayoutItem * item )
Direction direction () const
void setDirection ( Direction direction )
void addSpacing ( int size )
void addStretch ( int stretch = 0 )
void addWidget ( QWidget * widget, int stretch = 0, int alignment = 0 )
void addLayout ( QLayout * layout, int stretch = 0 )
void addStrut ( int size )
void insertSpacing ( int index, int size )
void insertStretch ( int index, int stretch = 0 )
void insertWidget ( int index, QWidget * widget, int stretch = 0, int
alignment = 0 )
void insertLayout ( int index, QLayout * layout, int stretch = 0 )
bool setStretchFactor ( QWidget * w, int stretch )
bool setStretchFactor ( QLayout * l, int stretch )
virtual QSize sizeHint () const
virtual QSize minimumSize () const
virtual QSize maximumSize () const
virtual bool hasHeightForWidth () const
virtual int heightForWidth ( int w ) const
virtual QSizePolicy::ExpandData expanding () const
virtual void invalidate ()
virtual void setGeometry ( const QRect & r )
int findWidget ( QWidget * w )
Protected Members
void insertItem ( int index, QLayoutItem * item )
DESCRIPTION
The QBoxLayout class lines up child widgets horizontally or vertically.
QBoxLayout takes the space it gets (from its parent layout or from the
mainWidget()), divides it up into a row of boxes, and makes each
managed widget fill one box.
<center>
[Image Omitted]
</center>
If the QBoxLayout's orientation is Horizontal the boxes are placed in a
row, with suitable sizes. Each widget (or other box) will get at least
its minimum size and at most its maximum size. Any excess space is
shared according to the stretch factors (more about that below).
<center>
[Image Omitted]
</center>
If the QBoxLayout's orientation is Vertical, the boxes are placed in a
column, again with suitable sizes.
The easiest way to create a QBoxLayout is to use one of the convenience
classes, e.g. QHBoxLayout (for Horizontal boxes) or QVBoxLayout (for
Vertical boxes). You can also use the QBoxLayout constructor directly,
specifying its direction as LeftToRight, Down, RightToLeft or Up.
If the QBoxLayout is not the top-level layout (i.e. it is not managing
all of the widget's area and children), you must add it to its parent
layout before you can do anything with it. The normal way to add a
layout is by calling parentLayout->addLayout().
Once you have done this, you can add boxes to the QBoxLayout using one
of four functions:
addWidget() to add a widget to the QBoxLayout and set the widget's
stretch factor. (The stretch factor is along the row of boxes.)
addSpacing() to create an empty box; this is one of the functions you
use to create nice and spacious dialogs. See below for ways to set
margins.
addStretch() to create an empty, stretchable box.
addLayout() to add a box containing another QLayout to the row and set
that layout's stretch factor.
Use insertWidget(), insertSpacing(), insertStretch() or insertLayout()
to insert a box at a specified position in the layout.
QBoxLayout also includes two margin widths:
setMargin() sets the width of the outer border. This is the width of
the reserved space along each of the QBoxLayout's four sides.
setSpacing() sets the width between neighboring boxes. (You can use
addSpacing() to get more space at a particular spot.)
The margin defaults to 0. The spacing defaults to the same as the
margin width for a top-level layout, or to the same as the parent
layout. Both are parameters to the constructor.
To remove a widget from a layout, call remove(). Calling
QWidget::hide() on a widget also effectively removes the widget from
the layout until QWidget::show() is called.
You will almost always want to use QVBoxLayout and QHBoxLayout rather
than QBoxLayout because of their convenient constructors.
See also QGrid, Layout Overview, Widget Appearance and Style, and
Layout Management.
Member Type Documentation
QBoxLayout::Direction
This type is used to determine the direction of a box layout.
QBoxLayout::LeftToRight - Horizontal, from left to right
QBoxLayout::RightToLeft - Horizontal, from right to left
QBoxLayout::TopToBottom - Vertical, from top to bottom
QBoxLayout::Down - The same as TopToBottom
QBoxLayout::BottomToTop - Vertical, from bottom to top
QBoxLayout::Up - The same as BottomToTop
MEMBER FUNCTION DOCUMENTATIONQBoxLayout::QBoxLayout ( QWidget * parent, Direction d, int margin = 0, int
spacing = -1, const char * name = 0 )
Constructs a new QBoxLayout with direction d and main widget parent.
parent may not be 0.
The margin is the number of pixels between the edge of the widget and
its managed children. The spacing is the default number of pixels
between neighboring children. If spacing is -1 the value of margin is
used for spacing.
name is the internal object name.
See also direction().
QBoxLayout::QBoxLayout ( QLayout * parentLayout, Direction d, int spacing =
-1, const char * name = 0 )
Constructs a new QBoxLayout called name, with direction d, and inserts
it into parentLayout.
The spacing is the default number of pixels between neighboring
children. If spacing is -1, the layout will inherit its parent's
spacing().
QBoxLayout::QBoxLayout ( Direction d, int spacing = -1, const char * name = 0
)
Constructs a new QBoxLayout called name, with direction d.
If spacing is -1, the layout will inherit its parent's spacing();
otherwise spacing is used.
You must insert this box into another layout.
QBoxLayout::~QBoxLayout ()
Destroys this box layout.
The layout's widgets aren't destroyed.
void QBoxLayout::addItem ( QLayoutItem * item ) [virtual]
Adds item to the end of this box layout.
Examples:
Reimplemented from QLayout.
void QBoxLayout::addLayout ( QLayout * layout, int stretch = 0 )
Adds layout to the end of the box, with serial stretch factor stretch.
When a layout is constructed with another layout as its parent, you
don't need to call addLayout(); the child layout is automatically added
to the parent layout as it is constructed.
See also insertLayout(), setAutoAdd(), addWidget(), and addSpacing().
Examples:
void QBoxLayout::addSpacing ( int size )
Adds a non-stretchable space with size size to the end of this box
layout. QBoxLayout provides default margin and spacing. This function
adds additional space.
See also insertSpacing() and addStretch().
Example: listbox/listbox.cpp.
void QBoxLayout::addStretch ( int stretch = 0 )
Adds a stretchable space with zero minimum size and stretch factor
stretch to the end of this box layout.
See also addSpacing().
Examples:
void QBoxLayout::addStrut ( int size )
Limits the perpendicular dimension of the box (e.g. height if the box
is LeftToRight) to a minimum of size. Other constraints may increase
the limit.
void QBoxLayout::addWidget ( QWidget * widget, int stretch = 0, int alignment
= 0 )
Adds widget to the end of this box layout, with a stretch factor of
stretch and alignment alignment.
The stretch factor applies only in the direction of the QBoxLayout, and
is relative to the other boxes and widgets in this QBoxLayout. Widgets
and boxes with higher stretch factors grow more.
If the stretch factor is 0 and nothing else in the QBoxLayout has a
stretch factor greater than zero, the space is distributed according to
the QWidget:sizePolicy() of each widget that's involved.
Alignment is specified by alignment which is a bitwise OR of
Qt::AlignmentFlags values. The default alignment is 0, which means that
the widget fills the entire cell.
From Qt 3.0, the alignment parameter is interpreted more aggressively
than in previous versions of Qt. A non-default alignment now indicates
that the widget should not grow to fill the available space, but should
be sized according to sizeHint().
See also insertWidget(), setAutoAdd(), addLayout(), and addSpacing().
Examples:
Direction QBoxLayout::direction () const
Returns the direction of the box. addWidget() and addSpacing() work in
this direction; the stretch stretches in this direction.
See also QBoxLayout::Direction, addWidget(), and addSpacing().
QSizePolicy::ExpandData QBoxLayout::expanding () const [virtual]
Returns whether this layout can make use of more space than sizeHint().
A value of Vertical or Horizontal means that it wants to grow in only
one dimension, whereas BothDirections means that it wants to grow in
both dimensions.
Reimplemented from QLayout.
int QBoxLayout::findWidget ( QWidget * w )
Searches for widget w in this layout (not including child layouts).
Returns the index of w, or -1 if w is not found.
bool QBoxLayout::hasHeightForWidth () const [virtual]
Returns TRUE if this layout's preferred height depends on its width;
otherwise returns FALSE.
Reimplemented from QLayoutItem.
int QBoxLayout::heightForWidth ( int w ) const [virtual]
Returns the layout's preferred height when it is w pixels wide.
Reimplemented from QLayoutItem.
void QBoxLayout::insertItem ( int index, QLayoutItem * item ) [protected]
Inserts item into this box layout at position index. If index is
negative, the item is added at the end.
Warning: Does not call QLayout::insertChildLayout() if item is a
QLayout.
See also addItem() and findWidget().
void QBoxLayout::insertLayout ( int index, QLayout * layout, int stretch = 0 )
Inserts layout at position index, with stretch factor stretch. If index
is negative, the layout is added at the end.
layout becomes a child of the box layout.
See also setAutoAdd(), insertWidget(), and insertSpacing().
void QBoxLayout::insertSpacing ( int index, int size )
Inserts a non-stretchable space at position index, with size size. If
index is negative the space is added at the end.
The box layout has default margin and spacing. This function adds
additional space.
See also insertStretch().
void QBoxLayout::insertStretch ( int index, int stretch = 0 )
Inserts a stretchable space at position index, with zero minimum size
and stretch factor stretch. If index is negative the space is added at
the end.
See also insertSpacing().
void QBoxLayout::insertWidget ( int index, QWidget * widget, int stretch = 0,
int alignment = 0 )
Inserts widget at position index, with stretch factor stretch and
alignment alignment. If index is negative, the widget is added at the
end.
The stretch factor applies only in the direction of the QBoxLayout, and
is relative to the other boxes and widgets in this QBoxLayout. Widgets
and boxes with higher stretch factors grow more.
If the stretch factor is 0 and nothing else in the QBoxLayout has a
stretch factor greater than zero, the space is distributed according to
the QWidget:sizePolicy() of each widget that's involved.
Alignment is specified by alignment, which is a bitwise OR of
Qt::AlignmentFlags values. The default alignment is 0, which means that
the widget fills the entire cell.
From Qt 3.0, the alignment parameter is interpreted more aggressively
than in previous versions of Qt. A non-default alignment now indicates
that the widget should not grow to fill the available space, but should
be sized according to sizeHint().
See also setAutoAdd(), insertLayout(), and insertSpacing().
void QBoxLayout::invalidate () [virtual]
Resets cached information.
Reimplemented from QLayout.
QSize QBoxLayout::maximumSize () const [virtual]
Returns the maximum size needed by this box layout.
Reimplemented from QLayout.
QSize QBoxLayout::minimumSize () const [virtual]
Returns the minimum size needed by this box layout.
Reimplemented from QLayout.
void QBoxLayout::setDirection ( Direction direction )
Sets the direction of this layout to direction.
void QBoxLayout::setGeometry ( const QRect & r ) [virtual]
Resizes managed widgets within the rectangle r.
Reimplemented from QLayout.
bool QBoxLayout::setStretchFactor ( QWidget * w, int stretch )
Sets the stretch factor for widget w to stretch and returns TRUE if w
is found in this layout (not including child layouts); otherwise
returns FALSE.
bool QBoxLayout::setStretchFactor ( QLayout * l, int stretch )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Sets the stretch factor for the layout l to stretch and returns TRUE if
l is found in this layout (not including child layouts); otherwise
returns FALSE.
QSize QBoxLayout::sizeHint () const [virtual]
Returns the preferred size of this box layout.
Reimplemented from QLayoutItem.
SEE ALSO
http://doc.trolltech.com/qboxlayout.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
license file included in the distribution for a complete license
statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports help us to
help you. Thank you.
The definitive Qt documentation is provided in HTML format; it is
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If you find errors in this manual page, please report them to qt-
bugs@trolltech.com. Please include the name of the manual page
(qboxlayout.3qt) and the Qt version (3.3.8).
Trolltech AS 2 February 2007 QBoxLayout(3qt)
