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# QGraphicsLinearLayout Class Reference
[QtGui module]

The QGraphicsLinearLayout class provides a horizontal or vertical layout for managing widgets in Graphics View. More...

     #include <QGraphicsLinearLayout>

Inherits QGraphicsLayout.

This class was introduced in Qt 4.4.

- List of all members, including inherited members

### Properties

- orientation : Qt::Orientation
- spacing : qreal

### Public Functions

- QGraphicsLinearLayout ( QGraphicsLayoutItem * parent = 0 )
- QGraphicsLinearLayout ( Qt::Orientation orientation, QGraphicsLayoutItem * parent = 0 )
- virtual ~QGraphicsLinearLayout ()
- void addItem ( QGraphicsLayoutItem * item )
- void addSpacer ( qreal minimumSize, qreal maximumSize = 0.0 )
- void addStretch ( int stretch = 1 )
- Qt::Alignment alignment ( QGraphicsLayoutItem * item ) const
- void insertItem ( int index, QGraphicsLayoutItem * item )
- void insertSpacer ( int index, qreal minimumSize, qreal maximumSize = 0.0 )
- void insertStretch ( int index, int stretch = 1 )
- Qt::Orientation orientation () const
- virtual void removeAt ( int index )
- void removeItem ( QGraphicsLayoutItem * item )
- void setAlignment ( QGraphicsLayoutItem * item, Qt::Alignment alignment )
- void setOrientation ( Qt::Orientation orientation )
- void setSpacing ( qreal spacing )
- void setStretchFactor ( QGraphicsLayoutItem * item, int stretch )
- qreal spacing () const
- int stretchFactor ( QGraphicsLayoutItem * item ) const

- 8 public functions inherited from QGraphicsLayout
- 21 public functions inherited from QGraphicsLayoutItem

### Additional Inherited Members

- 1 protected function inherited from QGraphicsLayoutItem

## Detailed Description

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 by either 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;
             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 gaps (addGap() and insertGap()) to a linear layout. The layout takes ownership of the items, with one natural exception: when a layout is assigned to a widget, all widgets inside the layout are automatically reparented to the widget, effectively signing over ownership from the layout to the layout-managed widget. 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.

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.

Between the items, the layout distributes some space (the actual amount of space depends on the managed widget's current style, but it's common with a spacing of 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 insertGap().

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 doesn't have any defined stretch factor; effectively this is the same as if the stretch factor is set 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 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.

## Property Documentation

### orientation : Qt::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.

Access functions:

- Qt::Orientation orientation () const
- void setOrientation ( Qt::Orientation orientation )

See also invalidate().

### spacing : qreal

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.

Access functions:

- qreal spacing () const
- void setSpacing ( qreal spacing )

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

## Member Function Documentation

### QGraphicsLinearLayout::QGraphicsLinearLayout ( QGraphicsLayoutItem * parent = 0 )

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

### QGraphicsLinearLayout::QGraphicsLinearLayout ( Qt::Orientation orientation, QGraphicsLayoutItem * parent = 0 )

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

### QGraphicsLinearLayout::~QGraphicsLinearLayout () `[virtual]`

Destroys the QGraphicsLinearLayout object.

### void QGraphicsLinearLayout::addItem ( QGraphicsLayoutItem * item )

This convenience function is equivalent to calling insertItem(-1, item).

### void QGraphicsLinearLayout::addSpacer ( qreal minimumSize, qreal maximumSize = 0.0 )

### void QGraphicsLinearLayout::addStretch ( int stretch = 1 )

This convenience function is equivalent to calling insertStretch(-1, stretch).

### Qt::Alignment QGraphicsLinearLayout::alignment ( QGraphicsLayoutItem * item ) const

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().

### void QGraphicsLinearLayout::insertItem ( int index, QGraphicsLayoutItem * item )

Inserts item into the layout at index, or before any item that is currently at index.

See also addItem(), itemAt(), insertStretch(), and insertGap().

### void QGraphicsLinearLayout::insertSpacer ( int index, qreal minimumSize, qreal maximumSize = 0.0 )

Inserts an invisible item with its minimum size set to minimumSize, and its maximum size set to maximumSize at index, or before any item that is currently at index. If maximumSize is less than minimumSize it will have the same value as minimumSize.

See also addGap(), addStretch(), setStretchFactor(), and insertItem().

### void QGraphicsLinearLayout::insertStretch ( int index, int stretch = 1 )

Inserts a stretch of stretch at index, or before any item that is currently at index.

See also addStretch(), setStretchFactor(), insertGap(), and insertItem().

### void QGraphicsLinearLayout::removeAt ( int index ) `[virtual]`

Removes the item at index without destroying it. Ownership of the item is transferred to the caller.

Reimplemented from QGraphicsLayout.

See also removeItem() and insertItem().

### void QGraphicsLinearLayout::removeItem ( QGraphicsLayoutItem * item )

Removes item from the layout without destroying it. Ownership of item is transferred to the caller.

See also removeAt() and insertItem().

### void QGraphicsLinearLayout::setAlignment ( QGraphicsLayoutItem * 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().

### void QGraphicsLinearLayout::setStretchFactor ( QGraphicsLayoutItem * 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().

### int QGraphicsLinearLayout::stretchFactor ( QGraphicsLayoutItem * item ) const

Returns the stretch factor for item. The default stretch factor is 0, meaning that the item has no assigned stretch factor.

See also setStretchFactor().