How to set font size to given height?

Hi!
I want to make custom button with image (2/3 parent height) and text (should have 1/3 parent height). But I have problem with this. I can set image height properly. But I can't found way to set font height properly. When I put image and text to column layout, then I have set manually height for image and text (!), and when I do these some part of the text (bottom parts) was printed outside parent! You can see it on the image 1.
Then I got advice that this simple button I should manage manually (x, y, height, margins and spacing). So I did it. Attachment 12770 The problem which I see is that I subtract (by hand) 5 pix from text.height and this value I set as font.pixelSize. Now it looks good on Windows, but what will happen on mobile devices?!? I have no idea... So my question is:
How to set font size to given height? (in my case it will be 1/3 parent height)

The current button code is as follow:

Code:

---

//Import the declarative plugins
import QtQuick 2.7
import QtQuick.Layouts 1.3
import QtQuick.Dialogs 1.2
 
//Implementation of the Button control.
Rectangle {
    id: button
    color: "#ffffff"
    property alias text: text.text
    property alias source: image.source
    signal clicked
    property bool hovered
    anchors.margins: 0
 
    Image {
        id: image
        smooth: true
        fillMode: Image.PreserveAspectFit
        source: ""
        height: parent.height * 0.66
        anchors.margins: 0
        x: (parent.width - implicitWidth) / 2
        y: 2
    }
    Text {
        id: text
        color: "black"
        font.bold: true
        horizontalAlignment: Text.AlignHCenter
        Layout.fillWidth: true
        height: parent.height - 2 - image.height - 3
        font.pixelSize: height - 5
        anchors.margins: 0
        x: (parent.width - implicitWidth) / 2
        y: image.height + 2 + 3
    }
 
    MouseArea {
        anchors.fill: button
        onClicked: { button.clicked(); /*messageDialog.open()*/ }
        hoverEnabled: true
        onEntered: button.hovered = true
        onExited: button.hovered = false
    }
}

---