Item delegate with a check indicator that can be toggled on or off. 更多...
import 语句: | import QtQuick.Controls |
继承: |
(since QtQuick.Controls 2.4 (Qt 5.11))
CheckDelegate presents an item delegate that can be toggled on (checked) or off (unchecked). Check delegates are typically used to select one or more options from a set of options in a list. For smaller sets of options, or for options that need to be uniquely identifiable, consider using CheckBox 代替。
CheckDelegate inherits its API from ItemDelegate , which is inherited from AbstractButton . For instance, you can set text , and react to clicks 使用 AbstractButton API. The state of the check delegate can be set with the checked 特性。
In addition to the checked and unchecked states, there is a third state: partially checked. The partially checked state can be enabled using the tristate property. This state indicates that the regular checked/unchecked state can not be determined; generally because of other states that affect the check delegate. This state is useful when several child nodes are selected in a treeview, for example.
ListView { model: ["Option 1", "Option 2", "Option 3"] delegate: CheckDelegate { text: modelData } }
另请参阅 Customizing CheckDelegate , 委托控件 ,和 CheckBox .
checkState : enumeration |
This property determines the check state of the check delegate.
Available states:
常量 | 描述 |
---|---|
Qt.Unchecked
|
The delegate is unchecked. |
Qt.PartiallyChecked
|
The delegate is partially checked. This state is only used when tristate is enabled. |
Qt.Checked
|
The delegate is checked. |
nextCheckState
:
function
|
This property holds a callback function that is called to determine the next check state whenever the check delegate is interactively toggled by the user via touch, mouse, or keyboard.
By default, a normal check delegate cycles between
Qt.Unchecked
and
Qt.Checked
states, and a tri-state check delegate cycles between
Qt.Unchecked
,
Qt.PartiallyChecked
,和
Qt.Checked
状态。
The
nextCheckState
callback function can override the default behavior. The following example implements a tri-state check delegate that can present a partially checked state depending on external conditions, but never cycles to the partially checked state when interactively toggled by the user.
CheckDelegate { tristate: true checkState: allChildrenChecked ? Qt.Checked : anyChildChecked ? Qt.PartiallyChecked : Qt.Unchecked nextCheckState: function() { if (checkState === Qt.Checked) return Qt.Unchecked else return Qt.Checked } }
This property was introduced in QtQuick.Controls 2.4 (Qt 5.11).
tristate : bool |
This property determines whether the check delegate has three states.
In the animation below, the first checkdelegate is tri-state:
默认为
false
, i.e., the delegate has only two states.