Item delegate with a check indicator that can be toggled on or off. 更多...
导入语句: | import QtQuick.Controls 2.2 |
Since: | Qt 5.7 |
继承: | ItemDelegate |
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. |
[since QtQuick.Controls 2.4 (Qt 5.11)] 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。
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.