Отцентрировать рамку и дать привязку к максимальному увеличению

import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Layouts 1.11
import QtQuick.Controls 2.15

Window {
id: window
width: 640
height: 480
visible: true
title: qsTr("Hello World")

ColumnLayout {

id: columnLayout
anchors.fill: parent
spacing: none.none


Rectangle {
id: rectangle
width: 200
height: 200
color: "#cca2ca"
Layout.fillWidth: false
Layout.fillHeight: true
}
}



RowLayout {
id: rowLayout
x: 0
y: 0
width: 199
height: 256

Text {
id: text1
text: qsTr("Высота")
font.pixelSize: 12
}

Slider {
id: slider
Layout.fillWidth: true
width: 100
height: 24
from: 0.0
to: 1.0

}


}

RowLayout {
id: rowLayout1
x: 0
y: 0
width: 199
height: 159

Text {
id: text2
text: qsTr("Толщина")
font.pixelSize: 12
}

Slider {
id: slider1
Layout.fillWidth:true
width: 100
height: 24
from: 0.0
to: 1.0
}


}

RowLayout {
id: rowLayout2
x: 0
y: 0
width: 199
height: 61

Text {
id: text3
text: qsTr("Ширина")
font.pixelSize: 12
}

Slider {
id: slider2
Layout.fillWidth: true
width: 100
height: 24
from: 0.0
to: 1.0
}


}

Rectangle {
property int maxWidth: 400
property int maxHeight: 400
width: maxWidth*slider2.value
height: maxHeight * slider.value
anchors.verticalCenter: parent.verticalCenter
anchors.verticalCenterOffset: -21
anchors.horizontalCenterOffset: 172
anchors.horizontalCenter: parent.horizontalCenter
border {
width: 220*slider1.value
color: "red"
}
}


}