MouseArea does not pass click to CheckBox

Question

Take a look at this QML snipped:

import QtQuick 2.4
import QtQuick.Controls 2.4

Rectangle {
    
    color: "blue"
    width: 50
    height: 50
    
    CheckBox {
        MouseArea {
            anchors.fill: parent
            propagateComposedEvents: true
        }    
    }
}

I want to add MouseArea over CheckBox so I can handle doubleclick. However no matter how and what I do CheckBox stops working (clicking it won't show checked mark) as soon as there is MouseArea over it.

What's wrong here?

Answer 1

You can programmatically toggle Qt Quick 2 CheckBox with AbstractButton.toggle(). Also, MouseArea propagateComposedEvents property works only with other MouseAreas and not with Qt Quick Controls QML types.

I don't know your use case so I add few possibilities below.

Signal connect() method

Easiest way to achieve toggling through MouseArea is to create signal chain by connecting MouseArea clicked to CheckBox clicked.

Rectangle {
    anchors.centerIn: parent
    color: "blue"
    width: 50
    height: 50
    CheckBox {
        id: checkBox
        onClicked: toggle()
        MouseArea {
            id: mouseArea
            anchors.fill: parent
        }
        Component.onCompleted: mouseArea.clicked.connect(clicked)
    }
}

Note that double click always starts with a single click. If you want to catch double clicks with MouseArea you can e.g. use a Timer for preventing propagating clicks to CheckBox.

Rectangle {
    anchors.centerIn: parent
    color: "blue"
    width: 50
    height: 50
    CheckBox {
        id: checkBox
        MouseArea {
            id: mouseArea
            anchors.fill: parent
            onClicked: {
                if (timer.running) {
                    return
                }
                checkBox.toggle()
                timer.start()
            }
            Timer {
                id: timer
                interval: 250
                repeat: false
            }
        }
    }
}

If you want to support CheckBox's pressed visualization and/or if you want to use bigger MouseArea than the size of the CheckBox you can take a look into this answer of the question Can't click button below a MouseArea.