Unconstrained Image given an @2x source has incorrect width/height

When setting as the source of an Image a PNG for which only exists a high dpi version (@2x suffix), Image.width and Image.height should be set to the width/height of the PNG divided by the devicePixelRatio set on the QImage backing the Image.

Edit: In addition, the correct image should be (re)loaded on screen changes if the scale factor changes.