CheckDelegate QML Type

Item delegate with a check indicator that can be toggled on or off. 更多...

import 语句：	import QtQuick.Controls 2.5
Since:	Qt 5.7
继承：	ItemDelegate

所有成员列表，包括继承成员

特性

checkState : enumeration
nextCheckState : function
tristate : bool

详细描述

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 .

特性文档编制

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.

另请参阅 tristate and 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.