内容

• 特性
• 公共函数
• 重实现公共函数
• 静态公共成员
• 保护函数
• 重实现保护函数
• 详细描述
• 标准角色和数据类型
• 子类化
• QStyledItemDelegate vs. QItemDelegate

QItemDelegate 类

The QItemDelegate 类为来自模型的数据项，提供显示和编辑设施。 更多...

头：	#include <QItemDelegate>
qmake:	QT += widgets
继承：	QAbstractItemDelegate

• 所有成员列表，包括继承成员
• 过时成员

特性

• clipping : bool

• 1 特性继承自 QObject

公共函数

	QItemDelegate (QObject * parent = nullptr)
virtual	~QItemDelegate ()
bool	hasClipping () const
QItemEditorFactory *	itemEditorFactory () const
void	setClipping (bool clip )
void	setItemEditorFactory (QItemEditorFactory * factory )

重实现公共函数

virtual QWidget *	createEditor (QWidget * parent , const QStyleOptionViewItem & option , const QModelIndex & index ) const override
virtual void	paint (QPainter * painter , const QStyleOptionViewItem & option , const QModelIndex & index ) const override
virtual void	setEditorData (QWidget * editor , const QModelIndex & index ) const override
virtual void	setModelData (QWidget * editor , QAbstractItemModel * model , const QModelIndex & index ) const override
virtual QSize	sizeHint (const QStyleOptionViewItem & option , const QModelIndex & index ) const override
virtual void	updateEditorGeometry (QWidget * editor , const QStyleOptionViewItem & option , const QModelIndex & index ) const override

• 9 公共函数继承自 QAbstractItemDelegate
• 31 公共函数继承自 QObject

静态公共成员

const QMetaObject

staticMetaObject

• 9 静态公共成员继承自 QObject

保护函数

void	drawBackground (QPainter * painter , const QStyleOptionViewItem & option , const QModelIndex & index ) const
virtual void	drawCheck (QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect , Qt::CheckState state ) const
virtual void	drawDecoration (QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect , const QPixmap & pixmap ) const
virtual void	drawDisplay (QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect , const QString & text ) const
virtual void	drawFocus (QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect ) const

重实现保护函数

virtual bool	editorEvent (QEvent * event , QAbstractItemModel * model , const QStyleOptionViewItem & option , const QModelIndex & index ) override
virtual bool	eventFilter (QObject * editor , QEvent * event ) override

• 9 保护函数继承自 QObject

额外继承成员

• 1 公共槽继承自 QObject
• 3 信号继承自 QAbstractItemDelegate
• 2 信号继承自 QObject

详细描述

The QItemDelegate 类为来自模型的数据项，提供显示和编辑设施。

QItemDelegate 可以用于提供自定义显示特征和编辑器 Widget 为项视图基于 QAbstractItemView 子类。为此用途使用委托允许定制显示和编辑机制，且开发独立于模型/视图。

The QItemDelegate 类是一种 模型/视图类 且属于 Qt 的 模型/视图框架 。注意， QStyledItemDelegate 已接管绘制 Qt 项视图的作业。推荐使用 QStyledItemDelegate 当创建新委托时。

在标准视图显示来自自定义模型的项时，经常是足够的，只需确保模型返回适当数据为各 roles 以确定视图中的项外观。用于 Qt 标准视图的默认委托，使用此角色信息以用户期望的大多数常见形式显示项。不管怎样，有时甚至有必要拥有更多项外观控制，相比默认委托可以提供的。

此类提供用于在视图中描绘项数据，和编辑来自项模型的数据的函数的默认实现。默认实现的 paint () 和 sizeHint () 虚函数，定义在 QAbstractItemDelegate ，的提供以确保委托实现视图所期望的正确基本行为。可以在子类中重实现这些函数，以定制项外观。

当编辑项视图中的数据时， QItemDelegate 提供编辑器 Widget，是编辑发生时放置在视图顶部的 Widget。编辑器的创建是采用 QItemEditorFactory ; a default static instance provided by QItemEditorFactory is installed on all item delegates. You can set a custom factory using setItemEditorFactory () or set a new default factory with QItemEditorFactory::setDefaultFactory (). It is the data stored in the item model with the Qt::EditRole that is edited.

Only the standard editing functions for widget-based delegates are reimplemented here:

• createEditor () returns the widget used to change data from the model and can be reimplemented to customize editing behavior.
• setEditorData () provides the widget with data to manipulate.
• updateEditorGeometry () ensures that the editor is displayed correctly with respect to the item view.
• setModelData () returns updated data to the model.

The closeEditor () signal indicates that the user has completed editing the data, and that the editor widget can be destroyed.

标准角色和数据类型

The default delegate used by the standard views supplied with Qt associates each standard role (defined by Qt::ItemDataRole ) with certain data types. Models that return data in these types can influence the appearance of the delegate as described in the following table.

角色	接受类型
Qt::BackgroundRole	QBrush
Qt::BackgroundColorRole	QColor (过时；使用 Qt::BackgroundRole 代替)
Qt::CheckStateRole	Qt::CheckState
Qt::DecorationRole	QIcon , QPixmap and QColor
Qt::DisplayRole	QString 和按字符串表示的类型
Qt::EditRole	见 QItemEditorFactory 了解细节
Qt::FontRole	QFont
Qt::SizeHintRole	QSize
Qt::TextAlignmentRole	Qt::Alignment
Qt::ForegroundRole	QBrush
Qt::TextColorRole	QColor (过时；使用 Qt::ForegroundRole 代替)

If the default delegate does not allow the level of customization that you need, either for display purposes or for editing data, it is possible to subclass QItemDelegate to implement the desired behavior.

子类化

当子类化 QItemDelegate to create a delegate that displays items using a custom renderer, it is important to ensure that the delegate can render items suitably for all the required states; e.g. selected, disabled, checked. The documentation for the paint () function contains some hints to show how this can be achieved.

可以提供自定义编辑器通过使用 QItemEditorFactory 。 色彩编辑器工厂范例 shows how a custom editor can be made available to delegates with the default item editor factory. This way, there is no need to subclass QItemDelegate . An alternative is to reimplement createEditor (), setEditorData (), setModelData ()，和 updateEditorGeometry (). This process is described in the 自旋框委托范例 .

QStyledItemDelegate vs. QItemDelegate

从 Qt 4.4 起，有 2 个委托类： QItemDelegate and QStyledItemDelegate 。不管怎样，默认委托为 QStyledItemDelegate . These two classes are independent alternatives to painting and providing editors for items in views. The difference between them is that QStyledItemDelegate uses the current style to paint its items. We therefore recommend using QStyledItemDelegate as the base class when implementing custom delegates or when working with Qt style sheets. The code required for either class should be equal unless the custom delegate needs to use the style for drawing.

另请参阅 委托类 , QStyledItemDelegate , QAbstractItemDelegate , 自旋框委托范例 , 设置编辑器范例 ，和 图标范例 .

特性文档编制

clipping : bool

若委托应裁剪描绘事件

This property will set the paint clip to the size of the item. The default value is on. It is useful for cases such as when images are larger than the size of the item.

该特性在 Qt 4.2 引入。

访问函数：

bool	hasClipping () const
void	setClipping (bool clip )

成员函数文档编制

QItemDelegate:: QItemDelegate ( QObject * parent = nullptr)

构造项委托采用给定 parent .

[virtual] QItemDelegate:: ~QItemDelegate ()

销毁项委托。

[override virtual] QWidget *QItemDelegate:: createEditor ( QWidget * parent , const QStyleOptionViewItem & option , const QModelIndex & index ) const

重实现自 QAbstractItemDelegate::createEditor ().

Returns the widget used to edit the item specified by index for editing. The parent widget and style option are used to control how the editor widget appears.

另请参阅 QAbstractItemDelegate::createEditor ().

[protected] void QItemDelegate:: drawBackground ( QPainter * painter , const QStyleOptionViewItem & option , const QModelIndex & index ) const

渲染项背景为给定 index ，使用给定 painter 和样式 option .

该函数在 Qt 4.2 引入。

[virtual protected] void QItemDelegate:: drawCheck ( QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect , Qt::CheckState state ) const

Renders a check indicator within the rectangle specified by rect ，使用给定 painter 和样式 option ，使用给定 state .

[virtual protected] void QItemDelegate:: drawDecoration ( QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect , const QPixmap & pixmap ) const

渲染装饰 pixmap 在矩形内指定通过 rect 使用给定 painter 和样式 option .

[virtual protected] void QItemDelegate:: drawDisplay ( QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect , const QString & text ) const

渲染项视图 text 在矩形内指定通过 rect 使用给定 painter 和样式 option .

[virtual protected] void QItemDelegate:: drawFocus ( QPainter * painter , const QStyleOptionViewItem & option , const QRect & rect ) const

Renders the region within the rectangle specified by rect , indicating that it has the focus, using the given painter 和样式 option .

[override virtual protected] bool QItemDelegate:: editorEvent ( QEvent * event , QAbstractItemModel * model , const QStyleOptionViewItem & option , const QModelIndex & index )

重实现自 QAbstractItemDelegate::editorEvent ().

[override virtual protected] bool QItemDelegate:: eventFilter ( QObject * editor , QEvent * event )

重实现自 QObject::eventFilter ().

返回 true 若给定 editor 有效 QWidget 和给定 event 有处理；否则返回 false . The following key press events are handled by default:

• Tab
• Backtab
• Enter
• 返回
• Esc

In the case of Tab , Backtab , Enter and 返回 key press events, the editor 's data is committed to the model and the editor is closed. If the event 是 Tab key press the view will open an editor on the next item in the view. Likewise, if the event 是 Backtab key press the view will open an editor on the previous item in the view.

If the event is a Esc key press event, the editor is closed without committing its data.

另请参阅 commitData () 和 closeEditor ().

QItemEditorFactory *QItemDelegate:: itemEditorFactory () const

Returns the editor factory used by the item delegate. If no editor factory is set, the function will return null.

另请参阅 setItemEditorFactory ().

[override virtual] void QItemDelegate:: paint ( QPainter * painter , const QStyleOptionViewItem & option , const QModelIndex & index ) const

重实现自 QAbstractItemDelegate::paint ().

Renders the delegate using the given painter 和样式 option 为项指定通过 index .

When reimplementing this function in a subclass, you should update the area held by the option's rect variable, using the option's state variable to determine the state of the item to be displayed, and adjust the way it is painted accordingly.

For example, a selected item may need to be displayed differently to unselected items, as shown in the following code:

    if (option.state & QStyle::State_Selected)
        painter->fillRect(option.rect, option.palette.highlight());
    int size = qMin(option.rect.width(), option.rect.height());
    int brightness = index.model()->data(index, Qt::DisplayRole).toInt();
    double radius = (size / 2.0) - (brightness / 255.0 * size / 2.0);
    if (radius == 0.0)
        return;
    painter->save();
    painter->setRenderHint(QPainter::Antialiasing, true);
    painter->setPen(Qt::NoPen);
    if (option.state & QStyle::State_Selected)
        painter->setBrush(option.palette.highlightedText());
    else
    ...
					

After painting, you should ensure that the painter is returned to its the state it was supplied in when this function was called. For example, it may be useful to call QPainter::save () before painting and QPainter::restore () afterwards.

另请参阅 QStyle::State .

[override virtual] void QItemDelegate:: setEditorData ( QWidget * editor , const QModelIndex & index ) const

重实现自 QAbstractItemDelegate::setEditorData ().

Sets the data to be displayed and edited by the editor from the data model item specified by the model index .

The default implementation stores the data in the editor 小部件的 用户特性 .

另请参阅 QMetaProperty::isUser ().

void QItemDelegate:: setItemEditorFactory ( QItemEditorFactory * factory )

Sets the editor factory to be used by the item delegate to be the factory specified. If no editor factory is set, the item delegate will use the default editor factory.

另请参阅 itemEditorFactory ().

[override virtual] void QItemDelegate:: setModelData ( QWidget * editor , QAbstractItemModel * model , const QModelIndex & index ) const

重实现自 QAbstractItemDelegate::setModelData ().

获取数据从 editor 小部件并将它存储在指定 model 在项 index .

The default implementation gets the value to be stored in the data model from the editor 小部件的 用户特性 .

另请参阅 QMetaProperty::isUser ().

[override virtual] QSize QItemDelegate:: sizeHint (const QStyleOptionViewItem & option , const QModelIndex & index ) const

重实现自 QAbstractItemDelegate::sizeHint ().

返回委托要显示项所需的大小指定通过 index ，考虑样式信息提供通过 option .

When reimplementing this function, note that in case of text items, QItemDelegate adds a margin (i.e. 2 * QStyle::PM_FocusFrameHMargin ) to the length of the text.

[override virtual] void QItemDelegate:: updateEditorGeometry ( QWidget * editor , const QStyleOptionViewItem & option , const QModelIndex & index ) const

重实现自 QAbstractItemDelegate::updateEditorGeometry ().

更新 editor 为项指定通过 index 根据样式 option 给定。