QSizePolicy Class Reference
The QSizePolicy class is a layout attribute describing horizontal
and vertical resizing.
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#include <qsizepolicy.h>
List of all member functions.
Public Members
enum
SizeType { Fixed = 0, Minimum = MayGrow, Maximum = MayShrink, Preferred = MayGrow | MayShrink, MinimumExpanding = MayGrow | ExpMask, Expanding = MayGrow | MayShrink | ExpMask, Ignored = ExpMask }
enum
ExpandData { NoDirection = 0, Horizontally = 1, Vertically = 2, BothDirections = Horizontally | Vertically, Horizontal = Horizontally, Vertical = Vertically }
QSizePolicy ( SizeType hor, SizeType ver, bool hfw = FALSE )
QSizePolicy ( SizeType hor, SizeType ver, uchar horStretch, uchar verStretch, bool hfw = FALSE )
Detailed Description
The QSizePolicy class is a layout attribute describing horizontal
and vertical resizing.
The size policy of a widget is an expression of its willingness to
be resized in various ways.
Widgets that reimplement QWidget::sizePolicy() return a QSizePolicy
describing the horizontal and vertical resizing policy best used
when laying out the widget. Only one of the
constructors is of interest in most applications.
QSizePolicy contains two independent SizeType objects; one describes
the widgets's horizontal size policy, and the other describes its
vertical size policy. It also contains a flag to indicate whether the
height and width of its preferred size are related.
The per-dimension SizeType objects are set in the usual constructor
and can be queried using a variety of functions, none of which are
really interesting to application programmers.
The hasHeightForWidth() flag indicates whether the widget's sizeHint()
is width-dependent (such as a word-wrapping label).
See also QSizePolicy::SizeType, Widget Appearance and Style and Layout Management.
Member Type Documentation
QSizePolicy::ExpandData
This enum type describes in which directions a widget can make use of
extra space. There are four possible values:
- QSizePolicy::NoDirection - the widget cannot make use of extra space in any
direction.
- QSizePolicy::Horizontally - the widget can usefully be wider than the sizeHint().
- QSizePolicy::Vertically - the widget can usefully be taller than the sizeHint().
- QSizePolicy::BothDirections - the widget can usefully be both wider and
taller than the sizeHint().
QSizePolicy::SizeType
The per-dimension sizing types used when constructing a QSizePolicy
are:
- QSizePolicy::Fixed - the QWidget::sizeHint() is the only acceptable alternative, so
the widget can never grow or shrink (e.g. the vertical direction of a
push button).
- QSizePolicy::Minimum - the sizeHint() is minimal, and sufficient. The
widget can be expanded, but there is no advantage to it being
larger (e.g. the horizontal direction of a push button).
- QSizePolicy::Maximum - the sizeHint() is a maximum. The widget can be
shrunk any amount without detriment if other widgets need the space
(e.g. a separator line).
- QSizePolicy::Preferred - the sizeHint() is best, but the widget can be
shrunk and still be useful. The widget can be expanded, but
there is no advantage to it being larger than sizeHint() (the default
QWidget policy).
- QSizePolicy::Expanding - the sizeHint() is a sensible size, but the
widget can be shrunk and still be useful. The widget can
make use of extra space, so it should get as much space as
possible (e.g. the horizontal direction of a slider).
- QSizePolicy::MinimumExpanding - the sizeHint() is minimal, and sufficient. The
widget can make use of extra space, so it should get as much space as
possible (e.g. the horizontal direction of a slider).
- QSizePolicy::Ignored - the sizeHint() is ignored. The widget will get as much
space as possible.
In any case, QLayout never shrinks a widget below the
QWidget::minimumSizeHint().
Member Function Documentation
QSizePolicy::QSizePolicy ()
Default constructor; produces a minimally initialized QSizePolicy.
QSizePolicy::QSizePolicy ( SizeType hor, SizeType ver, bool hfw = FALSE )
This is the constructor normally used to return a value in the
overridden QWidget::sizePolicy() function of a QWidget subclass.
It constructs a QSizePolicy with independent horizontal and vertical
sizing types, hor and ver respectively. These sizing types affect how the widget is
treated by the layout engine.
If hfw is TRUE, the preferred height of the widget is dependent on the
width of the widget (for example, a QLabel with line wrapping).
See also horData(), verData() and hasHeightForWidth().
QSizePolicy::QSizePolicy ( SizeType hor, SizeType ver, uchar horStretch, uchar verStretch, bool hfw = FALSE )
Constructs a QSizePolicy with independent horizontal and vertical
sizing types hor and ver, and stretch factors horStretch
and verStretch.
If hfw is TRUE, the preferred height of the widget is dependent on the
width of the widget.
See also horStretch() and verStretch().
ExpandData QSizePolicy::expanding () const
Returns a value indicating whether the widget can make use of extra space
(i.e. if it "wants" to grow) horizontally and/or vertically.
See also mayShrinkHorizontally(), mayGrowHorizontally(), mayShrinkVertically() and mayGrowVertically().
bool QSizePolicy::hasHeightForWidth () const
Returns TRUE if the widget's preferred height depends on its width;
otherwise returns FALSE.
See also setHeightForWidth().
SizeType QSizePolicy::horData () const
Returns the horizontal component of the size policy.
See also setHorData(), verData() and horStretch().
uint QSizePolicy::horStretch () const
Returns the horizontal stretch factor of the size policy.
See also setHorStretch() and verStretch().
bool QSizePolicy::mayGrowHorizontally () const
Returns TRUE if the widget can sensibly be wider than its sizeHint();
otherwise returns FALSE.
See also mayGrowVertically() and mayShrinkHorizontally().
bool QSizePolicy::mayGrowVertically () const
Returns TRUE if the widget can sensibly be taller than its sizeHint();
otherwise returns FALSE.
See also mayGrowHorizontally() and mayShrinkVertically().
bool QSizePolicy::mayShrinkHorizontally () const
Returns TRUE if the widget can sensibly be narrower than its
sizeHint(); otherwise returns FALSE.
See also mayShrinkVertically() and mayGrowHorizontally().
bool QSizePolicy::mayShrinkVertically () const
Returns TRUE if the widget can sensibly be shorter than its sizeHint();
otherwise returns FALSE.
See also mayShrinkHorizontally() and mayGrowVertically().
bool QSizePolicy::operator!= ( const QSizePolicy & s ) const
Returns TRUE if this policy is different from s; otherwise returns FALSE.
See also operator==().
bool QSizePolicy::operator== ( const QSizePolicy & s ) const
Returns TRUE if this policy is equal to s; otherwise returns FALSE.
See also operator!=().
void QSizePolicy::setHeightForWidth ( bool b )
Sets the hasHeightForWidth() flag to b.
See also hasHeightForWidth().
void QSizePolicy::setHorData ( SizeType d )
Sets the horizontal component of the size policy to size type d.
See also horData() and setVerData().
void QSizePolicy::setHorStretch ( uchar sf )
Sets the horizontal stretch factor of the size policy to sf.
See also horStretch() and setVerStretch().
void QSizePolicy::setVerData ( SizeType d )
Sets the vertical component of the size policy to size type d.
See also verData() and setHorData().
void QSizePolicy::setVerStretch ( uchar sf )
Sets the vertical stretch factor of the size policy to sf.
See also verStretch() and setHorStretch().
SizeType QSizePolicy::verData () const
Returns the vertical component of the size policy.
See also setVerData(), horData() and verStretch().
uint QSizePolicy::verStretch () const
Returns the vertical stretch factor of the size policy.
See also setVerStretch() and horStretch().
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