QScrollArea 類

QScrollArea 類為其它 Widget 提供捲動視圖。 更多...

頭：	#include <QScrollArea>
qmake:	QT += widgets
繼承：	QAbstractScrollArea

• 所有成員列錶，包括繼承成員

特性

• alignment : Qt::Alignment
• widgetResizable : bool

公共函數

	QScrollArea (QWidget * parent = nullptr)
virtual	~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

重實現公共函數

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

重實現保護函數

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

詳細描述

捲動區域用於在框架內顯示子級 Widget 的內容。若 Widget 超過框架大小，視圖可以提供滾動條，以便可以查看子級小部件的整個區域。指定子級 Widget 必須采用 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);
					

以上代碼創建包含圖像標簽的捲動區域 (在以下圖像中展示)。當比例縮放圖像時，捲動區域可以提供必要的滾動條：

滾動條外觀從屬目前設置的 滾動條策略 。可以控製滾動條外觀使用繼承功能從 QAbstractScrollArea .

例如，可以設置 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 () 函數。

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 圖像查看器 example. The example shows how to combine QLabel and QScrollArea to display an image.

另請參閱 QAbstractScrollArea , QScrollBar ，和 圖像查看器範例 .

特性文檔編製

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.

該特性在 Qt 4.2 引入。

訪問函數：

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.

訪問函數：

bool	widgetResizable () const
void	setWidgetResizable (bool resizable )

成員函數文檔編製

QScrollArea:: QScrollArea ( QWidget * parent = nullptr)

構造空的捲動區域采用給定 parent .

另請參閱 setWidget ().

[虛擬] QScrollArea:: ~QScrollArea ()

銷毀捲動區域及其子級 Widget。

另請參閱 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 。若無法到達指定點，內容捲動到最近有效位置。2 邊距的默認值為 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 。若無法到達指定點，內容捲動到最近有效位置。2 邊距的默認值為 50 像素。

該函數在 Qt 4.2 引入。

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

重實現： QAbstractScrollArea::event (QEvent *event).

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

重實現： QObject::eventFilter (QObject *watched, QEvent *event).

[override virtual] bool QScrollArea:: focusNextPrevChild ( bool next )

重實現： QWidget::focusNextPrevChild (bool next).

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

重實現： QAbstractScrollArea::resizeEvent (QResizeEvent *event).

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

重實現： QAbstractScrollArea::scrollContentsBy (int dx, int dy).

void QScrollArea:: setWidget ( QWidget * widget )

設置捲動區域 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 特性會被設為 true .

若捲動區域可見當 widget 有添加，必須 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.

另請參閱 widget ().

[override virtual] QSize QScrollArea:: sizeHint () const

重實現： QAbstractScrollArea::sizeHint () const.

QWidget *QScrollArea:: takeWidget ()

移除捲動區域 Widget，並將 Widget 的所有權傳遞給調用者。

另請參閱 widget ().

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

重實現： QAbstractScrollArea::viewportSizeHint () const.

QWidget *QScrollArea:: widget () const

返迴捲動區域 Widget，或 nullptr 若沒有。

另請參閱 setWidget ().

內容

1. 特性

2. 公共函數

3. 重實現公共函數

4. 重實現保護函數

5. 詳細描述

6. 大小提示和布局