Canvas inside checkbox - how to draw border when checkbox unchecked

[PawlosCK]

I am trying to make custom checkbox and I have problem with border.

                CheckBox
                {
                    id: checkbox_finished
                    text: qsTr("Finished alarms")
                    checked: true

                    indicator: Rectangle
                    {
                        implicitWidth: rectangle_checkbox_alarm_finished.width
                        implicitHeight: rectangle_checkbox_alarm_finished.height
//                        border.color: checkbox_finished.down ? "black" : "red"
                        border.color: "black"
                        border.width: 1

                        Rectangle
                        {
                            width: 20
                            height: 20
                            x: 0
                            y: 0
//                            color: checkbox_finished.down ? "black" : "red"
                            color: "red"
                            border.width: 1
                            visible: checkbox_finished.checked

                            Canvas
                            {
                                id: drawingCanvas
                                width: rectangle_checkbox_alarm_finished.width
                                height: rectangle_checkbox_alarm_finished.height

                                anchors.fill: parent
                                onPaint:
                                {
                                    var ctx = getContext("2d")

                                    ctx.fillStyle = "white"
                                    ctx.fillRect(0,0,drawingCanvas.width ,drawingCanvas.height )

                                    ctx.lineWidth = 2;
                                    ctx.strokeStyle = "black"
                                    ctx.beginPath()
                                    ctx.moveTo(0, 0)
                                    ctx.lineTo(drawingCanvas.width, drawingCanvas.height)
                                    ctx.moveTo(drawingCanvas.width, 0)
                                    ctx.lineTo(0, drawingCanvas.height)
                                    //ctx.closePath()

                                    ctx.rect(0, 0, drawingCanvas.width, drawingCanvas.height)

                                    ctx.stroke()
                                }
                            }

                        }


                    }