QtQuick 2.0 Image from Canvas

Hi guys, I’m trying to get an Image item from a Canvas item in QtQuick 2.0. The reason why I try this is because I want to provide the Canvas’ image as a ShaderEffectSource. I thought maybe the method Canvas::getImageData should do the job, but unfortunately I get the error “TypeError: Object QQuickCanvasItem(…) has no method ‘getImageData’”. Is this even a good method to get an Image from a Canvas? And if so, am I the only one who is not able to call the method getImageData? Thanks in advance!