com.trolltech.qt.gui
Class QGraphicsLinearLayout

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.gui.QGraphicsLayout
                  extended by com.trolltech.qt.gui.QGraphicsLinearLayout
All Implemented Interfaces:
QGraphicsLayoutItemInterface, QtJambiInterface

public class QGraphicsLinearLayout
extends QGraphicsLayout

The QGraphicsLinearLayout class provides a horizontal or vertical layout for managing widgets in Graphics View. The default orientation for a linear layout is Qt::Horizontal . You can choose a vertical orientation either by calling setOrientation(), or by passing Qt::Vertical to QGraphicsLinearLayout's constructor.

The most common way to use QGraphicsLinearLayout is to construct an object on the heap with no parent, add widgets and layouts by calling addItem(), and finally assign the layout to a widget by calling QGraphicsWidget::setLayout().

        QGraphicsScene scene = new QGraphicsScene();
        QGraphicsWidget textEdit = scene.addWidget(new QTextEdit());
        QGraphicsWidget pushButton = scene.addWidget(new QPushButton());

        QGraphicsLinearLayout layout = new QGraphicsLinearLayout();
        layout.addItem(textEdit);
        layout.addItem(pushButton);

        QGraphicsWidget form = new QGraphicsWidget();
        form.setLayout(layout);
        scene.addItem(form);
You can add widgets, layouts, stretches (addStretch(), insertStretch() or setStretchFactor()), and spacings (setItemSpacing()) to a linear layout. The layout takes ownership of the items. In some cases when the layout item also inherits from QGraphicsItem (such as QGraphicsWidget) there will be a ambiguity in ownership because the layout item belongs to two ownership hierarchies. See the documentation of QGraphicsLayoutItem::setOwnedByLayout() how to handle this. You can access each item in the layout by calling count() and itemAt(). Calling removeAt() or removeItem() will remove an item from the layout, without destroying it.

Size Hints and Size Policies in QGraphicsLinearLayout

QGraphicsLinearLayout respects each item's size hints and size policies, and when the layout contains more space than the items can fill, each item is arranged according to the layout's alignment for that item. You can set an alignment for each item by calling
setAlignment(), and check the alignment for any item by calling alignment(). By default, items are centered both vertically and horizontally.

Spacing within QGraphicsLinearLayout

Between the items, the layout distributes some space. The actual amount of space depends on the managed widget's current style, but the common spacing is 4. You can also set your own spacing by calling
setSpacing(), and get the current spacing value by calling spacing(). If you want to configure individual spacing for your items, you can call setItemSpacing().

Stretch Factor in QGraphicsLinearLayout

You can assign a stretch factor to each item to control how much space it will get compared to the other items. By default, two identical widgets arranged in a linear layout will have the same size, but if the first widget has a stretch factor of 1 and the second widget has a stretch factor of 2, the first widget will get 1/3 of the available space, and the second will get 2/3.

QGraphicsLinearLayout calculates the distribution of sizes by adding up the stretch factors of all items, and then dividing the available space accordingly. The default stretch factor is 0 for all items; a factor of 0 means the item does not have any defined stretch factor; effectively this is the same as setting the stretch factor to 1. The stretch factor only applies to the available space in the lengthwise direction of the layout (following its orientation). If you want to control both the item's horizontal and vertical stretch, you can use QGraphicsGridLayout instead.

QGraphicsLinearLayout Compared to Other Layouts

QGraphicsLinearLayout is very similar to QVBoxLayout and QHBoxLayout, but in contrast to these classes, it is used to manage QGraphicsWidget and QGraphicsLayout instead of QWidget and QLayout.

See also:
QGraphicsGridLayout, and QGraphicsWidget.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, 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
QGraphicsLinearLayout()
          Constructs a QGraphicsLinearLayout instance using Qt::Horizontal orientation.
QGraphicsLinearLayout(QGraphicsLayoutItemInterface parent)
          Constructs a QGraphicsLinearLayout instance using Qt::Horizontal orientation.
QGraphicsLinearLayout(Qt.Orientation orientation)
          Constructs a QGraphicsLinearLayout instance.
QGraphicsLinearLayout(Qt.Orientation orientation, QGraphicsLayoutItemInterface parent)
          Constructs a QGraphicsLinearLayout instance.
 
Method Summary
 void addItem(QGraphicsLayoutItemInterface item)
          This convenience function is equivalent to calling insertItem(-1, item).
 void addStretch()
          This convenience function is equivalent to calling insertStretch(-1, stretch).
 void addStretch(int stretch)
          This convenience function is equivalent to calling insertStretch(-1, stretch).
 Qt.Alignment alignment(QGraphicsLayoutItemInterface item)
          Returns the alignment for item.
 void insertItem(int index, QGraphicsLayoutItemInterface item)
          Inserts item into the layout at index, or before any item that is currently at index.
 void insertStretch(int index)
          Inserts a stretch of stretch at index, or before any item that is currently at index.
 void insertStretch(int index, int stretch)
          Inserts a stretch of stretch at index, or before any item that is currently at index.
 double itemSpacing(int index)
          Returns the spacing after item at index.
 Qt.Orientation orientation()
          This property holds the orientation of the linear layout.
 void removeItem(QGraphicsLayoutItemInterface item)
          Removes item from the layout without destroying it.
 void setAlignment(QGraphicsLayoutItemInterface item, Qt.Alignment alignment)
          Sets the alignment of item to alignment.
 void setAlignment(QGraphicsLayoutItemInterface item, Qt.AlignmentFlag[] alignment)
           
 void setItemSpacing(int index, double spacing)
          Sets the spacing after item at index to spacing.
 void setOrientation(Qt.Orientation orientation)
          This property holds the orientation of the linear layout.
 void setSpacing(double spacing)
          This property holds the layout's default spacing.
 void setStretchFactor(QGraphicsLayoutItemInterface item, int stretch)
          Sets the stretch factor for item to stretch.
 double spacing()
          This property holds the layout's default spacing.
 int stretchFactor(QGraphicsLayoutItemInterface item)
          Returns the stretch factor for item.
 
Methods inherited from class com.trolltech.qt.gui.QGraphicsLayout
activate, contentsRect, count, effectiveSizeHint, geometry, getContentsMargins, graphicsItem, invalidate, isActivated, isLayout, itemAt, maximumHeight, maximumSize, maximumWidth, minimumHeight, minimumSize, minimumWidth, ownedByLayout, parentLayoutItem, preferredHeight, preferredSize, preferredWidth, removeAt, setContentsMargins, setGeometry, setGraphicsItem, setMaximumHeight, setMaximumSize, setMaximumSize, setMaximumWidth, setMinimumHeight, setMinimumSize, setMinimumSize, setMinimumWidth, setOwnedByLayout, setParentLayoutItem, setPreferredHeight, setPreferredSize, setPreferredSize, setPreferredWidth, setSizePolicy, setSizePolicy, sizeHint, sizePolicy, updateGeometry, widgetEvent
 
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

QGraphicsLinearLayout

public QGraphicsLinearLayout()
Constructs a QGraphicsLinearLayout instance using Qt::Horizontal orientation. parent is passed to QGraphicsLayout's constructor.


QGraphicsLinearLayout

public QGraphicsLinearLayout(QGraphicsLayoutItemInterface parent)
Constructs a QGraphicsLinearLayout instance using Qt::Horizontal orientation. parent is passed to QGraphicsLayout's constructor.


QGraphicsLinearLayout

public QGraphicsLinearLayout(Qt.Orientation orientation)
Constructs a QGraphicsLinearLayout instance. You can pass the orientation for the layout, either horizontal or vertical, and parent is passed to QGraphicsLayout's constructor.


QGraphicsLinearLayout

public QGraphicsLinearLayout(Qt.Orientation orientation,
                             QGraphicsLayoutItemInterface parent)
Constructs a QGraphicsLinearLayout instance. You can pass the orientation for the layout, either horizontal or vertical, and parent is passed to QGraphicsLayout's constructor.

Method Detail

addItem

public final void addItem(QGraphicsLayoutItemInterface item)
This convenience function is equivalent to calling insertItem(-1, item).


addStretch

public final void addStretch()
This convenience function is equivalent to calling insertStretch(-1, stretch).


addStretch

public final void addStretch(int stretch)
This convenience function is equivalent to calling insertStretch(-1, stretch).


alignment

public final Qt.Alignment alignment(QGraphicsLayoutItemInterface item)
Returns the alignment for item. The default alignment is Qt::AlignCenter .

The alignment decides how the item is positioned within its assigned space in the case where there's more space available in the layout than the widgets can occupy.

See also:
setAlignment().


insertItem

public final void insertItem(int index,
                             QGraphicsLayoutItemInterface item)
Inserts item into the layout at index, or before any item that is currently at index.

See also:
addItem(), itemAt(), insertStretch(), and setItemSpacing().


insertStretch

public final void insertStretch(int index)
Inserts a stretch of stretch at index, or before any item that is currently at index.

See also:
addStretch(), setStretchFactor(), setItemSpacing(), and insertItem().


insertStretch

public final void insertStretch(int index,
                                int stretch)
Inserts a stretch of stretch at index, or before any item that is currently at index.

See also:
addStretch(), setStretchFactor(), setItemSpacing(), and insertItem().


itemSpacing

public final double itemSpacing(int index)
Returns the spacing after item at index.

See also:
setItemSpacing().


orientation

public final Qt.Orientation orientation()
This property holds the orientation of the linear layout. This property toggles the layout orientation. Changing the layout orientation will automatically invalidate the layout.

See also:
invalidate().


removeItem

public final void removeItem(QGraphicsLayoutItemInterface item)
Removes item from the layout without destroying it. Ownership of item is transferred to the caller.

See also:
removeAt(), and insertItem().


setAlignment

public final void setAlignment(QGraphicsLayoutItemInterface item,
                               Qt.AlignmentFlag[] alignment)

setAlignment

public final void setAlignment(QGraphicsLayoutItemInterface item,
                               Qt.Alignment alignment)
Sets the alignment of item to alignment. If item's alignment changes, the layout is automatically invalidated.

See also:
alignment(), and invalidate().


setItemSpacing

public final void setItemSpacing(int index,
                                 double spacing)
Sets the spacing after item at index to spacing.

See also:
itemSpacing().


setOrientation

public final void setOrientation(Qt.Orientation orientation)
This property holds the orientation of the linear layout. This property toggles the layout orientation. Changing the layout orientation will automatically invalidate the layout.

See also:
invalidate().


setSpacing

public final void setSpacing(double spacing)
This property holds the layout's default spacing. This property adjusts the layout's default spacing. The spacing applies to the vertical and horizontal distance between items.

See also:
setItemSpacing(), setStretchFactor(), and QGraphicsGridLayout::setSpacing().


setStretchFactor

public final void setStretchFactor(QGraphicsLayoutItemInterface item,
                                   int stretch)
Sets the stretch factor for item to stretch. If an item's stretch factor changes, this function will invalidate the layout.

Setting stretch to 0 removes the stretch factor from the item, and is effectively equivalent to setting stretch to 1.

See also:
stretchFactor().


spacing

public final double spacing()
This property holds the layout's default spacing. This property adjusts the layout's default spacing. The spacing applies to the vertical and horizontal distance between items.

See also:
setItemSpacing(), setStretchFactor(), and QGraphicsGridLayout::setSpacing().


stretchFactor

public final int stretchFactor(QGraphicsLayoutItemInterface item)
Returns the stretch factor for item. The default stretch factor is 0, meaning that the item has no assigned stretch factor.

See also:
setStretchFactor().