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java.lang.Objectcom.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.gui.QLayoutItem
public abstract class QLayoutItem
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.
QLayout
.
Nested Class Summary |
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Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
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com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal |
Field Summary |
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Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
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currentSender |
Constructor Summary | |
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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 |
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dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
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blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
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__qt_signalInitialization |
Methods inherited from class java.lang.Object |
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clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
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disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Constructor Detail |
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public QLayoutItem(Qt.AlignmentFlag[] alignment)
public QLayoutItem()
public QLayoutItem(Qt.Alignment alignment)
Method Detail |
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public final Qt.Alignment alignment()
setAlignment()
.
alignment
in interface QLayoutItemInterface
public final QSizePolicy.ControlTypes controlTypes()
QWidgetItem
, the control type comes from the widget's size policy; for a QLayoutItem, the control types is derived from the layout's contents. QSizePolicy::controlType()
.
controlTypes
in interface QLayoutItemInterface
public final void setAlignment(Qt.AlignmentFlag[] a)
public final void setAlignment(Qt.Alignment a)
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.
alignment()
.
setAlignment
in interface QLayoutItemInterface
public abstract Qt.Orientations expandingDirections()
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.
expandingDirections
in interface QLayoutItemInterface
public abstract QRect geometry()
setGeometry()
.
geometry
in interface QLayoutItemInterface
public boolean hasHeightForWidth()
Reimplement this function in layout managers that support height for width.
heightForWidth()
, and QWidget::heightForWidth()
.
hasHeightForWidth
in interface QLayoutItemInterface
public int heightForWidth(int arg__1)
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.
hasHeightForWidth()
.
heightForWidth
in interface QLayoutItemInterface
public void invalidate()
invalidate
in interface QLayoutItemInterface
public abstract boolean isEmpty()
isEmpty
in interface QLayoutItemInterface
public QLayout layout()
QLayout
, it is returned as a QLayout
; otherwise 0 is returned. This function provides type-safe casting.
layout
in interface QLayoutItemInterface
public abstract QSize maximumSize()
maximumSize
in interface QLayoutItemInterface
public int minimumHeightForWidth(int arg__1)
minimumHeightForWidth
in interface QLayoutItemInterface
public abstract QSize minimumSize()
minimumSize
in interface QLayoutItemInterface
public abstract void setGeometry(QRect arg__1)
geometry()
.
setGeometry
in interface QLayoutItemInterface
public abstract QSize sizeHint()
sizeHint
in interface QLayoutItemInterface
public QSpacerItem spacerItem()
QSpacerItem
, it is returned as a QSpacerItem
; otherwise 0 is returned. This function provides type-safe casting.
spacerItem
in interface QLayoutItemInterface
public QWidget widget()
QWidget
, it is returned as a QWidget
; otherwise 0 is returned. This function provides type-safe casting.
widget
in interface QLayoutItemInterface
protected final void setAlign(Qt.AlignmentFlag[] align)
protected final void setAlign(Qt.Alignment align)
protected final Qt.Alignment align()
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