For info I found also another alternative:
...
import QtQuick.Controls 2.12
import QtQuick.Controls.Material.impl 2.12
...
ProgressBar
{
...
id: pbProgress
contentItem: ProgressBarImpl
{
implicitHeight: pbProgress.height
anchors.fill: parent
anchors.margins: 0
scale: pbProgress.mirrored ? -1 : 1
progress: pbProgress.position
indeterminate: pbProgress.visible && pbProgress.indeterminate
color: "#5014ad"
}
...
}
