QItemDelegate class provides display and editing facilities for data items from a model. 更多...
| 头： | #include <QItemDelegate> |
| qmake: | QT += widgets |
| 继承： | QAbstractItemDelegate |
| 继承者： |
| QItemDelegate (QObject * parent = Q_NULLPTR) | |
| ~QItemDelegate () | |
| bool | hasClipping () const |
| QItemEditorFactory * | itemEditorFactory () const |
| void | setClipping (bool clip ) |
| void | setItemEditorFactory (QItemEditorFactory * factory ) |
| virtual QWidget * | createEditor (QWidget * parent , const QStyleOptionViewItem & option , const QModelIndex & index ) const |
| virtual void | paint (QPainter * painter , const QStyleOptionViewItem & option , const QModelIndex & index ) const |
| virtual void | setEditorData (QWidget * editor , const QModelIndex & index ) const |
| virtual void | setModelData (QWidget * editor , QAbstractItemModel * model , const QModelIndex & index ) const |
| virtual QSize | sizeHint (const QStyleOptionViewItem & option , const QModelIndex & index ) const |
| virtual void | updateEditorGeometry (QWidget * editor , const QStyleOptionViewItem & option , const QModelIndex & index ) const |
| 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 |
| virtual bool | editorEvent (QEvent * event , QAbstractItemModel * model , const QStyleOptionViewItem & option , const QModelIndex & index ) |
| virtual bool | eventFilter (QObject * editor , QEvent * event ) |
QItemDelegate class provides display and editing facilities for data items from a model.
QItemDelegate can be used to provide custom display features and editor widgets for item views based on 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。
QItemDelegate 类是一种 模型/视图类 且属于 Qt 的 模型/视图框架 。注意， QStyledItemDelegate has taken over the job of drawing Qt's item views. We recommend the use of QStyledItemDelegate when creating new delegates.
When displaying items from a custom model in a standard view, it is often sufficient to simply ensure that the model returns appropriate data for each of the roles that determine the appearance of items in views. The default delegate used by Qt's standard views uses this role information to display items in most of the common forms expected by users. However, it is sometimes necessary to have even more control over the appearance of items than the default delegate can provide.
This class provides default implementations of the functions for painting item data in a view and editing data from item models. Default implementations of the paint () 和 sizeHint () virtual functions, defined in QAbstractItemDelegate , are provided to ensure that the delegate implements the correct basic behavior expected by views. You can reimplement these functions in subclasses to customize the appearance of items.
When editing data in an item view, QItemDelegate provides an editor widget, which is a widget that is placed on top of the view while editing takes place. Editors are created with a 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:
closeEditor () signal indicates that the user has completed editing the data, and that the editor widget can be destroyed.
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 (obsolete; use Qt::BackgroundRole instead) |
| Qt::CheckStateRole | Qt::CheckState |
| Qt::DecorationRole | QIcon , QPixmap and QColor |
| Qt::DisplayRole | QString and types with a string representation |
| Qt::EditRole | 见 QItemEditorFactory for details |
| Qt::FontRole | QFont |
| Qt::SizeHintRole | QSize |
| Qt::TextAlignmentRole | Qt::Alignment |
| Qt::ForegroundRole | QBrush |
| Qt::TextColorRole | QColor (obsolete; use Qt::ForegroundRole instead) |
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.
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 .
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 .
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 ) |
构造项委托采用给定 parent .
销毁项委托。
[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 .
[virtual protected]
bool
QItemDelegate::
editorEvent
(
QEvent
*
event
,
QAbstractItemModel
*
model
, const
QStyleOptionViewItem
&
option
, const
QModelIndex
&
index
)
重实现自 QAbstractItemDelegate::editorEvent ().
[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:
In the case of Tab , Backtab , Enter and Return key press events, the editor 's data is comitted 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 ().
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 ().
[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 .
[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 ().
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 ().
[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 ().
[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.
[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。