QGraphicsLinearLayout 類

QGraphicsLinearLayout 類提供用於在圖形視圖中管理 Widget 的水平或垂直布局。更多...

頭：	#include <QGraphicsLinearLayout>
qmake:	QT += widgets
Since:	Qt 4.4
繼承：	QGraphicsLayout

該類在 Qt 4.4 引入。

所有成員列錶，包括繼承成員

公共函數

	QGraphicsLinearLayout (Qt::Orientation orientation , QGraphicsLayoutItem * parent = nullptr)
	QGraphicsLinearLayout (QGraphicsLayoutItem * parent = nullptr)
virtual	~QGraphicsLinearLayout ()
void	addItem (QGraphicsLayoutItem * item )
void	addStretch (int stretch = 1)
Qt::Alignment	alignment (QGraphicsLayoutItem * item ) const
void	insertItem (int index , QGraphicsLayoutItem * item )
void	insertStretch (int index , int stretch = 1)
qreal	itemSpacing (int index ) const
Qt::Orientation	orientation () const
void	removeItem (QGraphicsLayoutItem * item )
void	setAlignment (QGraphicsLayoutItem * item , Qt::Alignment alignment )
void	setItemSpacing (int index , qreal spacing )
void	setOrientation (Qt::Orientation orientation )
void	setSpacing (qreal spacing )
void	setStretchFactor (QGraphicsLayoutItem * item , int stretch )
qreal	spacing () const
int	stretchFactor (QGraphicsLayoutItem * item ) const

重實現公共函數

virtual int	count () const override
virtual void	invalidate () override
virtual QGraphicsLayoutItem *	itemAt (int index ) const override
virtual void	removeAt (int index ) override
virtual void	setGeometry (const QRectF & rect ) override
virtual QSizeF	sizeHint (Qt::SizeHint which , const QSizeF & constraint = QSizeF()) const override

詳細描述

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;
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 () 或 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 (譬如 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 () 和 itemAt ()。調用 removeAt () 或 removeItem () will remove an item from the layout, without destroying it.

在 QGraphicsLinearLayout 中的大小提示和大小策略

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 aligned to the top left.

在 QGraphicsLinearLayout 中的間距

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 ().

在 QGraphicsLinearLayout 中的拉伸因子

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 代替。

QGraphicsLinearLayout 相比其它布局

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

另請參閱 QGraphicsGridLayout and QGraphicsWidget .

成員函數文檔編製

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

Constructs a QGraphicsLinearLayout instance. You can pass the orientation for the layout, either horizontal or vertical, and parent 被傳遞給 QGraphicsLayout 的構造函數。

QGraphicsLinearLayout:: QGraphicsLinearLayout ( QGraphicsLayoutItem * parent = nullptr)

Constructs a QGraphicsLinearLayout instance using Qt::Horizontal orientation. parent 被傳遞給 QGraphicsLayout 的構造函數。

`[虛擬]` QGraphicsLinearLayout:: ~QGraphicsLinearLayout ()

銷毀 QGraphicsLinearLayout 對象。

void QGraphicsLinearLayout:: addItem ( QGraphicsLayoutItem * item )

此方便函數相當於調用 insertItem (-1, item ).

void QGraphicsLinearLayout:: addStretch ( int stretch = 1)

此方便函數相當於調用 insertStretch (-1, stretch ).

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

返迴對齊方式為 item . The default alignment is Qt::AlignTop | Qt::AlignLeft .

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.

另請參閱 setAlignment ().

`[override virtual]` int QGraphicsLinearLayout:: count () const

重實現： QGraphicsLayout::count () const.

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

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

另請參閱 addItem (), itemAt (), insertStretch ()，和 setItemSpacing ().

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

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

另請參閱 addStretch (), setStretchFactor (), setItemSpacing ()，和 insertItem ().

`[override virtual]` void QGraphicsLinearLayout:: invalidate ()

重實現： QGraphicsLayout::invalidate ().

`[override virtual]` QGraphicsLayoutItem QGraphicsLinearLayout:: itemAt ( int index* ) const

重實現： QGraphicsLayout::itemAt (int i) const.

When iterating from 0 and up, it will return the items in the visual arranged order.

qreal QGraphicsLinearLayout:: itemSpacing ( int index ) const

Returns the spacing after item at index .

另請參閱 setItemSpacing ().

Qt::Orientation QGraphicsLinearLayout:: orientation () const

Returns the layout orientation.

另請參閱 setOrientation ().

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

重實現： QGraphicsLayout::removeAt (int index).

移除項在 index without destroying it. Ownership of the item is transferred to the caller.

另請參閱 removeItem () 和 insertItem ().

void QGraphicsLinearLayout:: removeItem ( QGraphicsLayoutItem * item )

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

另請參閱 removeAt () 和 insertItem ().

void QGraphicsLinearLayout:: setAlignment ( QGraphicsLayoutItem * item , Qt::Alignment alignment )

Sets the alignment of item to alignment 。若 item 's alignment changes, the layout is automatically invalidated.

另請參閱 alignment () 和 invalidate ().

`[override virtual]` void QGraphicsLinearLayout:: setGeometry (const QRectF & rect )

重實現： QGraphicsLayoutItem::setGeometry (const QRectF &rect).

void QGraphicsLinearLayout:: setItemSpacing ( int index , qreal spacing )

Sets the spacing after item at index to spacing .

另請參閱 itemSpacing ().

void QGraphicsLinearLayout:: setOrientation ( Qt::Orientation orientation )

Change the layout orientation to orientation . Changing the layout orientation will automatically invalidate the layout.

另請參閱 orientation ().

void QGraphicsLinearLayout:: setSpacing ( qreal spacing )

Sets the layout's spacing to spacing . Spacing refers to the vertical and horizontal distances between items.

另請參閱 spacing (), setItemSpacing (), setStretchFactor ()，和 QGraphicsGridLayout::setSpacing ().

void QGraphicsLinearLayout:: setStretchFactor ( QGraphicsLayoutItem * item , int stretch )

設置拉伸因子為 item to stretch . If an item's stretch factor changes, this function will invalidate the layout.

設置 stretch to 0 removes the stretch factor from the item, and is effectively equivalent to setting stretch 到 1。

另請參閱 stretchFactor ().

`[override virtual]` QSizeF QGraphicsLinearLayout:: sizeHint ( Qt::SizeHint which , const QSizeF & constraint = QSizeF()) const

重實現： QGraphicsLayoutItem::sizeHint (Qt::SizeHint which, const QSizeF &constraint) const.

qreal QGraphicsLinearLayout:: spacing () const

Returns the layout's spacing. Spacing refers to the vertical and horizontal distances between items.

另請參閱 setSpacing ().

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.

另請參閱 setStretchFactor ().