nooLight/MenuBackButton.qml

import QtQuick 2.0

Item {
    id: root
    signal clicked()
    signal back()

    MouseArea {
        id: ma

        anchors.fill: parent
        anchors.margins: -8
    }

    Rectangle {
        id: bar1
        x: 0
        y: root.height / 6
        width: root.height
        height: root.height / 9
        antialiasing: true
    }

    Rectangle {
        id: bar2
        x: 0
        y: root.height / 2 - height / 2
        width: root.height
        height: root.height / 9
        antialiasing: true
    }

    Rectangle {
        id: bar3
        x: 0
        y: root.height / 2 + height * 2
        width: root.height
        height: root.height / 9
        antialiasing: true
    }

    property int animationDuration: 450

    state: "menu"
    states: [
        State {
            name: "menu"
            PropertyChanges { target: ma; onClicked: root.clicked() }
        },

        State {
            name: "back"
            PropertyChanges { target: root; rotation: 180 }
            PropertyChanges { target: bar1; rotation: 45; width: root.height / 3 * 2; x: root.height / 2; y: root.height / 4 }
            PropertyChanges { target: bar2; width: root.height / 6 * 5 + 1; x: root.height / 9 }
            PropertyChanges { target: bar3; rotation: -45; width: root.height / 3 * 2; x: root.height / 2; y: root.height / 3 * 2 }
            PropertyChanges { target: ma; onClicked: root.back() }
        }
    ]

    transitions: [
        Transition {
            RotationAnimation { target: root; direction: RotationAnimation.Clockwise; duration: animationDuration; easing.type: Easing.InOutQuad }
            PropertyAnimation { target: bar1; properties: "rotation, width, x, y"; duration: animationDuration; easing.type: Easing.InOutQuad }
            PropertyAnimation { target: bar2; properties: "rotation, width, x, y"; duration: animationDuration; easing.type: Easing.InOutQuad }
            PropertyAnimation { target: bar3; properties: "rotation, width, x, y"; duration: animationDuration; easing.type: Easing.InOutQuad }
        }
    ]
}