QBoxLayout Class Reference
The QBoxLayout class lines up child widgets horizontally or vertically.
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#include <qlayout.h>
Inherits QLayout.
Inherited by QHBoxLayout and QVBoxLayout.
List of all member functions.
Public Members
enumÂ
Direction { LeftToRight, RightToLeft, TopToBottom, BottomToTop, Down = TopToBottom, Up = BottomToTop }
QBoxLayout ( QWidget * parent, Direction, int border=0, int space = -1, const char * name=0 )Â
QBoxLayout ( QLayout * parentLayout, Direction, int space = -1, const char * name=0 )Â
QBoxLayout ( Direction, int space = -1, const char * name=0 )Â
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virtual voidÂ
addItem ( QLayoutItem * )Â
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voidÂ
addWidget ( QWidget *, int stretch = 0, int alignment = 0 )Â
voidÂ
addLayout ( QLayout * layout, int stretch = 0 )Â
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voidÂ
insertWidget ( int index, QWidget * widget, int stretch = 0, int alignment = 0 )Â
voidÂ
insertLayout ( int index, QLayout * layout, int stretch = 0 )Â
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virtual QSizePolicy::ExpandDataÂ
expanding () const
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Protected Members
voidÂ
insertItem ( int index, QLayoutItem * )Â
Detailed 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.
If the QBoxLayout is Horizontal, the boxes are beside each other,
with suitable sizes. Each widget (or other box) will get at least
its minimum sizes and at most its maximum size, and any excess space
is shared according to the stretch factors (more about that below).
If the QBoxLayout is Vertical, the boxes are above and below each
other, again with suitable sizes.
The easiest way to create a QBoxLayout is to use one of the
convenience classes 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 (ie. 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 that, 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 inter-box width. This is the width of the
automatically allocated spacing between neighbouring boxes. (You
can use addSpacing() to get more space at a .)
The outer border width defaults to 0, and the intra-widget width defaults
to the same as the border width for a top-level layout, or to the
same as the parent layout otherwise. Both can be set using
arguments to the constructor.
You will almost always want to use the convenience classes for
QBoxLayout: QVBoxLayout and QHBoxLayout, because of their simpler
constructors.
See also the Layout overview documentation
Examples:
layout/layout.cpp
customlayout/main.cpp
popup/popup.cpp
Member Type Documentation
This type is used to determine the direction of
a box layout. The possible values are:
LeftToRight - Horizontal, from left to right
RightToLeft - Horizontal, from right to left
TopToBottom - Vertical, from top to bottom
Down - An alias for TopToBottom
BottomToTop - Vertical, from bottom to top
Up - An alias for BottomToTop
Member Function Documentation
QBoxLayout::QBoxLayout ( Direction d, int space = -1, const char * name=0 )
If space is -1, this QBoxLayout will inherit its parent's
spacing(), otherwise space is used.
You have to insert this box into another layout.
Examples:
layout/layout.cpp
QBoxLayout::QBoxLayout ( QLayout * parentLayout, Direction d, int space = -1, const char * name=0 )
Constructs a new QBoxLayout with direction d and inserts it into
parentLayout.
QBoxLayout::QBoxLayout ( QWidget * parent, Direction d, int border=0, int space = -1, const char * name=0 )
Constructs a new QBoxLayout with direction d and main widget parent. parent may not be 0.
border is the number of pixels between the edge of the widget and
the managed children. space is the default number of pixels
between neighbouring children. If space is -1 the value
of border is used.
name is the internal object name
See also direction().
QBoxLayout::~QBoxLayout ()
Destructs this box.
void QBoxLayout::addItem ( QLayoutItem * item ) [virtual]
Adds item to the end of this box layout.
Reimplemented from QLayout.
void QBoxLayout::addLayout ( QLayout * layout, int stretch = 0 )
Adds layout to the end of the box, with serial stretch factor stretch.
See also insertLayout(), setAutoAdd(), addWidget() and addSpacing().
void QBoxLayout::addSpacing ( int size )
Adds a non-stretchable space with size size to the end of this
box layout. QBoxLayout gives default border and spacing. This
function adds additional space.
See also insertSpacing() and addStretch().
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().
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
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
factor 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.
Note: 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:
layout/layout.cpp
customlayout/main.cpp
popup/popup.cpp
scrollview/scrollview.cpp
QBoxLayout::Direction QBoxLayout::direction() const
Returns the (serial) direction of the box. addWidget() and addSpacing()
work in this direction; the stretch stretches in this direction.
The directions are LeftToRight, RightToLeft, TopToBottom
and BottomToTop. For the last two, the shorter aliases Down and
Up are also available.
See also addWidget() and addSpacing().
QSizePolicy::ExpandData QBoxLayout::expanding() const [virtual]
Returns the expansiveness of this layout.
Reimplemented from QLayoutItem.
int QBoxLayout::findWidget ( QWidget * w )
Searches for 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 whether this layout's preferred height depends on its width.
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 in this box layout at index 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 index index, with serial stretch
factor stretch. If index is negative, the layout is added at
the end.
See also setAutoAdd(), insertWidget() and insertSpacing().
void QBoxLayout::insertSpacing ( int index, int size )
Inserts a non-stretchable space at index index with size size.
If index is negative, the space is added at the end.
QBoxLayout gives default border and spacing. This function adds
additional space.
See also insertStretch().
void QBoxLayout::insertStretch ( int index, int stretch = 0 )
Inserts a stretchable space at index 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 index index, with a stretch
factor and 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
factor 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.
Note: 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 QLayoutItem.
QLayoutIterator QBoxLayout::iterator () [virtual]
Reimplemented for internal reasons; the API is not affected.
Reimplemented from QLayoutItem.
QSize QBoxLayout::maximumSize () const [virtual]
Returns the maximum size needed by this box.
Reimplemented from QLayoutItem.
QSize QBoxLayout::minimumSize () const [virtual]
Returns the minimum size needed by this box.
Reimplemented from QLayoutItem.
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 QLayoutItem.
bool QBoxLayout::setStretchFactor ( QLayout * l, int stretch )
Sets the stretch factor for the layout l to stretch and returns
TRUE, if l is found in this layout (not including child layouts).
Returns FALSE if l is not found.
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).
Returns FALSE if w is not found.
QSize QBoxLayout::sizeHint () const [virtual]
Returns the preferred size of this grid.
Reimplemented from QLayoutItem.
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