QLayoutItem Class Reference
The QLayoutItem class provides an abstract item that a
QLayout manipulates.
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#include <qabstractlayout.h>
Inherited by QSpacerItem, QWidgetItem and QLayout.
List of all member functions.
Public Members
virtual QSizePolicy::ExpandData
expanding () const
Detailed Description
The QLayoutItem class provides an abstract item that a
QLayout manipulates.
This is used by custom layouts.
See also QLayout.
Member Function Documentation
QLayoutItem::QLayoutItem ( int alignment = 0 )
Constructs a layout item with an alignment
that is a bitwise OR of Qt::AlignmentFlags.
Alignment may not be supported by some subclasses.
QLayoutItem::~QLayoutItem () [virtual]
Destroys the QLayoutItem.
int QLayoutItem::alignment () const
Returns the alignment of this item.
Implemented in subclasses to return whether this item "wants" to expand.
Reimplemented in QSpacerItem, QWidgetItem and QLayout.
QRect QLayoutItem::geometry () const [virtual]
Returns the rectangle covered by this layout item.
Example: customlayout/border.cpp.
bool QLayoutItem::hasHeightForWidth () const [virtual]
Returns TRUE if this layout's preferred height depends on its
width. The default implementation returns FALSE.
Reimplement this function in layout managers that support
height for width.
See also heightForWidth() and QWidget::heightForWidth().
Examples: customlayout/border.cpp and customlayout/flow.cpp.
Reimplemented in QGridLayout and QBoxLayout.
int QLayoutItem::heightForWidth ( int w ) const [virtual]
Returns the preferred height for this layout item, given the width
w.
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.
Reimplement this function in layout managers that support
height for width. A typical implementation will look like this:
int MyLayout::heightForWidth( int w ) const
{
if ( cache_dirty || cached_width != w ) {
// not all C++ compilers support "mutable"
MyLayout *that = (MyLayout*)this;
int h = calculateHeightForWidth( w );
that->cached_hfw = h;
return h;
}
return cached_hfw;
}
Caching is strongly recommended; without it layout will take
exponential time.
See also hasHeightForWidth().
Example: customlayout/flow.cpp.
Reimplemented in QGridLayout and QBoxLayout.
void QLayoutItem::invalidate () [virtual]
Invalidates any cached information in this layout item.
Reimplemented in QLayout.
bool QLayoutItem::isEmpty () const [virtual]
Implemented in subclasses to return whether this item is empty,
i.e. whether it contains any widgets.
Reimplemented in QSpacerItem, QWidgetItem and QLayout.
QLayoutIterator QLayoutItem::iterator () [virtual]
Returns an iterator over this item's QLayoutItem children.
The default implementation returns an empty iterator.
Reimplement this function in subclasses that can have
children.
Reimplemented in QLayout.
QLayout * QLayoutItem::layout () [virtual]
If this item is a QLayout, return it as a QLayout; otherwise return 0.
This function provides type-safe casting.
QSize QLayoutItem::maximumSize () const [virtual]
Implemented in subclasses to return the maximum size of this item.
Reimplemented in QSpacerItem, QWidgetItem and QLayout.
QSize QLayoutItem::minimumSize () const [virtual]
Implemented in subclasses to return the minimum size of this item.
Examples: customlayout/border.cpp, customlayout/card.cpp and customlayout/flow.cpp.
Reimplemented in QSpacerItem, QWidgetItem and QLayout.
void QLayoutItem::setAlignment ( int a ) [virtual]
Sets the alignment of this item to a,
which is a bitwise OR of Qt::AlignmentFlags.
void QLayoutItem::setGeometry ( const QRect & r ) [virtual]
Implemented in subclasses to set this item's geometry to r.
Examples: customlayout/border.cpp, customlayout/card.cpp and customlayout/flow.cpp.
Reimplemented in QSpacerItem, QWidgetItem and QLayout.
QSize QLayoutItem::sizeHint () const [virtual]
Implemented in subclasses to return the preferred size of this item.
Examples: customlayout/border.cpp, customlayout/card.cpp and customlayout/flow.cpp.
Reimplemented in QSpacerItem, QWidgetItem, QGridLayout and QBoxLayout.
QSpacerItem * QLayoutItem::spacerItem () [virtual]
If this item is a QSpacerItem, return it as a QSpacerItem; otherwise
return 0. This function provides type-safe casting.
QWidget * QLayoutItem::widget () [virtual]
If this item is a QWidgetItem, the managed widget is returned.
The default implementation returns 0.
Reimplemented in QWidgetItem.
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