com.trolltech.qt.gui
Class QLayoutItem

java.lang.Object
  com.trolltech.qt.internal.QSignalEmitterInternal
      com.trolltech.qt.QSignalEmitter
          com.trolltech.qt.QtJambiObject
              com.trolltech.qt.gui.QLayoutItem

All Implemented Interfaces:

QLayoutItemInterface, QtJambiInterface

public abstract class QLayoutItem
extends QtJambiObject
implements QLayoutItemInterface

The QLayoutItem class provides an abstract item that a QLayout manipulates. This is used by custom layouts.

Pure virtual functions are provided to return information about the layout, including, sizeHint(), minimumSize(), maximumSize() and expanding().

The layout's geometry can be set and retrieved with setGeometry() and geometry(), and its alignment with setAlignment() and alignment().

isEmpty() returns whether the layout item is empty. If the concrete item is a QWidget, it can be retrieved using widget(). Similarly for layout() and spacerItem().

Some layouts have width and height interdependencies. These can be expressed using hasHeightForWidth(), heightForWidth(), and minimumHeightForWidth(). For more explanation see the Qt Quarterly article Trading Height for Width.

See also:

QLayout.

Nested Class Summary

Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter

QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9

Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal

com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal

Field Summary

Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal

currentSender

Constructor Summary

QLayoutItem()
Constructs a layout item with an alignment.

QLayoutItem(Qt.Alignment alignment)
Constructs a layout item with an alignment.

QLayoutItem(Qt.AlignmentFlag[] alignment)

Method Summary

protected Qt.Alignment	align() Returns the alignment of this QlayoutItem.
Qt.Alignment	alignment() Returns the alignment of this item.
QSizePolicy.ControlTypes	controlTypes() Returns the control type(s) for the layout item.
abstract Qt.Orientations	expandingDirections() Returns whether this layout item can make use of more space than sizeHint().
abstract QRect	geometry() Returns the rectangle covered by this layout item.
boolean	hasHeightForWidth() Returns true if this layout's preferred height depends on its width; otherwise returns false.
int	heightForWidth(int arg__1) Returns the preferred height for this layout item, given the width w.
void	invalidate() Invalidates any cached information in this layout item.
abstract boolean	isEmpty() Implemented in subclasses to return whether this item is empty, i.e.
QLayout	layout() If this item is a QLayout, it is returned as a QLayout; otherwise 0 is returned.
abstract QSize	maximumSize() Implemented in subclasses to return the maximum size of this item.
int	minimumHeightForWidth(int arg__1) Returns the minimum height this widget needs for the given width, w.
abstract QSize	minimumSize() Implemented in subclasses to return the minimum size of this item.
protected void	setAlign(Qt.Alignment align)
protected void	setAlign(Qt.AlignmentFlag[] align)
void	setAlignment(Qt.Alignment a) Sets the alignment of this item to alignment.
void	setAlignment(Qt.AlignmentFlag[] a)
abstract void	setGeometry(QRect arg__1) Implemented in subclasses to set this item's geometry to r.
abstract QSize	sizeHint() Implemented in subclasses to return the preferred size of this item.
QSpacerItem	spacerItem() If this item is a QSpacerItem, it is returned as a QSpacerItem; otherwise 0 is returned.
QWidget	widget() If this item is a QWidget, it is returned as a QWidget; otherwise 0 is returned.

Methods inherited from class com.trolltech.qt.QtJambiObject

dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr

Methods inherited from class com.trolltech.qt.QSignalEmitter

blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread

Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal

__qt_signalInitialization

Methods inherited from class java.lang.Object

clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.trolltech.qt.QtJambiInterface

disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership

Constructor Detail

QLayoutItem

public QLayoutItem(Qt.AlignmentFlag[] alignment)

QLayoutItem

public QLayoutItem()

Constructs a layout item with an alignment. Not all subclasses support alignment.

QLayoutItem

public QLayoutItem(Qt.Alignment alignment)

Constructs a layout item with an alignment. Not all subclasses support alignment.

Method Detail

alignment

public final Qt.Alignment alignment()

Returns the alignment of this item.

See also:

setAlignment().

Specified by:

alignment in interface QLayoutItemInterface

controlTypes

public final QSizePolicy.ControlTypes controlTypes()

Returns the control type(s) for the layout item. For a QWidgetItem, the control type comes from the widget's size policy; for a QLayoutItem, the control types is derived from the layout's contents.

See also:

QSizePolicy::controlType().

Specified by:

controlTypes in interface QLayoutItemInterface

setAlignment

public final void setAlignment(Qt.AlignmentFlag[] a)

setAlignment

public final void setAlignment(Qt.Alignment a)

Sets the alignment of this item to alignment.

Note: Item alignment is only supported by QLayoutItem subclasses where it would have a visual effect. Except for QSpacerItem, which provides blank space for layouts, all public Qt classes that inherit QLayoutItem support item alignment.

See also:

alignment().

Specified by:

setAlignment in interface QLayoutItemInterface

expandingDirections

public abstract Qt.Orientations expandingDirections()

Returns whether this layout item can make use of more space than sizeHint(). A value of Qt::Vertical or Qt::Horizontal means that it wants to grow in only one dimension, whereas Qt::Vertical | Qt::Horizontal means that it wants to grow in both dimensions.

Specified by:

expandingDirections in interface QLayoutItemInterface

geometry

public abstract QRect geometry()

Returns the rectangle covered by this layout item.

See also:

setGeometry().

Specified by:

geometry in interface QLayoutItemInterface

hasHeightForWidth

public boolean hasHeightForWidth()

Returns true if this layout's preferred height depends on its width; otherwise returns false. The default implementation returns false.

Reimplement this function in layout managers that support height for width.

See also:

heightForWidth(), and QWidget::heightForWidth().

Specified by:

hasHeightForWidth in interface QLayoutItemInterface

heightForWidth

public int heightForWidth(int arg__1)

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:

    public int heightForWidth(int w)
    {
        if (cache_dirty || cached_width != w) {
            int h = calculateHeightForWidth(w);
            cached_hfw = h;
            return h;
        }
        return cached_hfw;
    }

Caching is strongly recommended; without it layout will take exponential time.

See also:

hasHeightForWidth().

Specified by:

heightForWidth in interface QLayoutItemInterface

invalidate

public void invalidate()

Invalidates any cached information in this layout item.

Specified by:

invalidate in interface QLayoutItemInterface

isEmpty

public abstract boolean isEmpty()

Implemented in subclasses to return whether this item is empty, i.e. whether it contains any widgets.

Specified by:

isEmpty in interface QLayoutItemInterface

layout

public QLayout layout()

If this item is a QLayout, it is returned as a QLayout; otherwise 0 is returned. This function provides type-safe casting.

Specified by:

layout in interface QLayoutItemInterface

maximumSize

public abstract QSize maximumSize()

Implemented in subclasses to return the maximum size of this item.

Specified by:

maximumSize in interface QLayoutItemInterface

minimumHeightForWidth

public int minimumHeightForWidth(int arg__1)

Returns the minimum height this widget needs for the given width, w. The default implementation simply returns heightForWidth(w).

Specified by:

minimumHeightForWidth in interface QLayoutItemInterface

minimumSize

public abstract QSize minimumSize()

Implemented in subclasses to return the minimum size of this item.

Specified by:

minimumSize in interface QLayoutItemInterface

setGeometry

public abstract void setGeometry(QRect arg__1)

Implemented in subclasses to set this item's geometry to r.

See also:

geometry().

Specified by:

setGeometry in interface QLayoutItemInterface

sizeHint

public abstract QSize sizeHint()

Implemented in subclasses to return the preferred size of this item.

Specified by:

sizeHint in interface QLayoutItemInterface

spacerItem

public QSpacerItem spacerItem()

If this item is a QSpacerItem, it is returned as a QSpacerItem; otherwise 0 is returned. This function provides type-safe casting.

Specified by:

spacerItem in interface QLayoutItemInterface

widget

public QWidget widget()

If this item is a QWidget, it is returned as a QWidget; otherwise 0 is returned. This function provides type-safe casting.

Specified by:

widget in interface QLayoutItemInterface

setAlign

protected final void setAlign(Qt.AlignmentFlag[] align)

setAlign

protected final void setAlign(Qt.Alignment align)

align

protected final Qt.Alignment align()

Returns the alignment of this QlayoutItem.