内容

• 特性
• 公共函数
• 重实现公共函数
• 重实现保护函数
• 详细描述
• 大小提示和布局

QScrollArea 类

The QScrollArea class provides a scrolling view onto another widget. 更多...

头：	#include <QScrollArea>
qmake:	QT += widgets
继承：	QAbstractScrollArea

• 所有成员列表，包括继承成员

特性

• alignment : Qt::Alignment
• widgetResizable : bool

• 3 特性继承自 QAbstractScrollArea
• 6 特性继承自 QFrame
• 59 特性继承自 QWidget
• 1 特性继承自 QObject

公共函数

	QScrollArea (QWidget * parent = Q_NULLPTR)
	~QScrollArea ()
Qt::Alignment	alignment () const
void	ensureVisible (int x , int y , int xmargin = 50, int ymargin = 50)
void	ensureWidgetVisible (QWidget * childWidget , int xmargin = 50, int ymargin = 50)
void	setAlignment ( Qt::Alignment )
void	setWidget (QWidget * widget )
void	setWidgetResizable (bool resizable )
QWidget *	takeWidget ()
QWidget *	widget () const
bool	widgetResizable () const

重实现公共函数

virtual bool	focusNextPrevChild (bool next )
virtual QSize	sizeHint () const

• 20 公共函数继承自 QAbstractScrollArea
• 14 公共函数继承自 QFrame
• 214 公共函数继承自 QWidget
• 32 公共函数继承自 QObject
• 14 公共函数继承自 QPaintDevice

重实现保护函数

virtual bool	event (QEvent * e )
virtual bool	eventFilter (QObject * o , QEvent * e )
virtual void	resizeEvent ( QResizeEvent * )
virtual void	scrollContentsBy (int dx , int dy )
virtual QSize	viewportSizeHint () const

• 20 保护函数继承自 QAbstractScrollArea
• 4 保护函数继承自 QFrame
• 35 保护函数继承自 QWidget
• 9 保护函数继承自 QObject
• 1 保护函数继承自 QPaintDevice

额外继承成员

• 19 公共槽继承自 QWidget
• 1 公共槽继承自 QObject
• 3 信号继承自 QWidget
• 2 信号继承自 QObject
• 5 静态公共成员继承自 QWidget
• 11 静态公共成员继承自 QObject
• 20 保护函数继承自 QAbstractScrollArea
• 4 保护函数继承自 QFrame
• 35 保护函数继承自 QWidget
• 9 保护函数继承自 QObject
• 1 保护函数继承自 QPaintDevice
• 1 保护槽继承自 QWidget

详细描述

The QScrollArea class provides a scrolling view onto another widget.

卷动区域用于在框架内显示子级 Widget 的内容。若 Widget 超过框架大小，视图可以提供滚动条，以便可以查看子级小部件的整个区域。指定子级 Widget 必须采用 setWidget ()。例如：

QLabel *imageLabel = new QLabel;
QImage image("happyguy.png");
imageLabel->setPixmap(QPixmap::fromImage(image));
scrollArea = new QScrollArea;
scrollArea->setBackgroundRole(QPalette::Dark);
scrollArea->setWidget(imageLabel);
					

以上代码创建包含图像标签的卷动区域 (在以下图像中展示)。当比例缩放图像时，卷动区域可以提供必要的滚动条：

滚动条外观从属目前设置的 滚动条策略 。可以控制滚动条外观使用继承功能从 QAbstractScrollArea .

例如，可以设置 QAbstractScrollArea::horizontalScrollBarPolicy and QAbstractScrollArea::verticalScrollBarPolicy properties. Or if you want the scroll bars to adjust dynamically when the contents of the scroll area changes, you can use the horizontalScrollBar() and verticalScrollBar() functions (which enable you to access the scroll bars) and set the scroll bars' values whenever the scroll area's contents change, using the QScrollBar::setValue () 函数。

You can retrieve the child widget using the widget () function. The view can be made to be resizable with the setWidgetResizable () function. The alignment of the widget can be specified with setAlignment ().

Two convenience functions ensureVisible () 和 ensureWidgetVisible () ensure a certain region of the contents is visible inside the viewport, by scrolling the contents if necessary.

大小提示和布局

When using a scroll area to display the contents of a custom widget, it is important to ensure that the size hint of the child widget is set to a suitable value. If a standard QWidget is used for the child widget, it may be necessary to call QWidget::setMinimumSize () to ensure that the contents of the widget are shown correctly within the scroll area.

If a scroll area is used to display the contents of a widget that contains child widgets arranged in a layout, it is important to realize that the size policy of the layout will also determine the size of the widget. This is especially useful to know if you intend to dynamically change the contents of the layout. In such cases, setting the layout's size constraint property to one which provides constraints on the minimum and/or maximum size of the layout (e.g., QLayout::SetMinAndMaxSize ) will cause the size of the scroll area to be updated whenever the contents of the layout changes.

For a complete example using the QScrollArea class, see the 图像查看器 example. The example shows how to combine QLabel and QScrollArea 以显示图像。

另请参阅 QAbstractScrollArea , QScrollBar ，和 图像查看器范例 .

特性文档编制

alignment : Qt::Alignment

This property holds the alignment of the scroll area's widget

A valid alignment is a combination of the following flags:

• Qt::AlignLeft
• Qt::AlignHCenter
• Qt::AlignRight
• Qt::AlignTop
• Qt::AlignVCenter
• Qt::AlignBottom

By default, the widget stays rooted to the top-left corner of the scroll area.

该特性在 Qt 4.2 引入。

访问函数：

Qt::Alignment	alignment () const
void	setAlignment ( Qt::Alignment )

widgetResizable : bool

This property holds whether the scroll area should resize the view widget

If this property is set to false (the default), the scroll area honors the size of its widget. Regardless of this property, you can programmatically resize the widget using widget ()-> resize (), and the scroll area will automatically adjust itself to the new size.

If this property is set to true, the scroll area will automatically resize the widget in order to avoid scroll bars where they can be avoided, or to take advantage of extra space.

访问函数：

bool	widgetResizable () const
void	setWidgetResizable (bool resizable )

成员函数文档编制

QScrollArea:: QScrollArea ( QWidget * parent = Q_NULLPTR)

构造空的卷动区域采用给定 parent .

另请参阅 setWidget ().

QScrollArea:: ~QScrollArea ()

销毁卷动区域及其子级 Widget。

另请参阅 setWidget ().

void QScrollArea:: ensureVisible ( int x , int y , int xmargin = 50, int ymargin = 50)

Scrolls the contents of the scroll area so that the point ( x , y ) is visible inside the region of the viewport with margins specified in pixels by xmargin and ymargin 。若无法到达指定点，内容卷动到最近有效位置。2 边距的默认值为 50 像素。

void QScrollArea:: ensureWidgetVisible ( QWidget * childWidget , int xmargin = 50, int ymargin = 50)

Scrolls the contents of the scroll area so that the childWidget of QScrollArea::widget () is visible inside the viewport with margins specified in pixels by xmargin and ymargin 。若无法到达指定点，内容卷动到最近有效位置。2 边距的默认值为 50 像素。

该函数在 Qt 4.2 引入。

[virtual protected] bool QScrollArea:: event ( QEvent * e )

重实现自 QObject::event ().

[virtual protected] bool QScrollArea:: eventFilter ( QObject * o , QEvent * e )

重实现自 QObject::eventFilter ().

[虚拟] bool QScrollArea:: focusNextPrevChild ( bool next )

重实现自 QWidget::focusNextPrevChild ().

[virtual protected] void QScrollArea:: resizeEvent ( QResizeEvent * )

重实现自 QWidget::resizeEvent ().

[virtual protected] void QScrollArea:: scrollContentsBy ( int dx , int dy )

重实现自 QAbstractScrollArea::scrollContentsBy ().

void QScrollArea:: setWidget ( QWidget * widget )

设置卷动区域 widget .

The widget becomes a child of the scroll area, and will be destroyed when the scroll area is deleted or when a new widget is set.

Widget 的 autoFillBackground 特性会被设为 true .

若卷动区域可见当 widget 有添加，必须 show() it explicitly.

Note that You must add the layout of widget before you call this function; if you add it later, the widget will not be visible - regardless of when you show() the scroll area. In this case, you can also not show() the widget later.

另请参阅 widget ().

[虚拟] QSize QScrollArea:: sizeHint () const

重实现自 QWidget::sizeHint ().

QWidget *QScrollArea:: takeWidget ()

移除卷动区域 Widget，并将 Widget 的所有权传递给调用者。

另请参阅 widget ().

[virtual protected] QSize QScrollArea:: viewportSizeHint () const

重实现自 QAbstractScrollArea::viewportSizeHint ().

QWidget *QScrollArea:: widget () const

Returns the scroll area's widget, or 0 if there is none.

另请参阅 setWidget ().