I suggest orienting the loop previewer to be independent of device orientation. And, perhaps allowing the user to custom place the Loupe so that it reappears in the same location relative to device orientation.

For instance, currently, when masking, the loupe is above the area where the user is drawing or editing the mask because it is designed to assume that the user is always going to use the device in a vertical orientation.

Myself, coming from working with a graphics tablet background, I tend to actually turn the device so that I can always draw my masks using strokes that are comfortable and also aid my accuracy.

The problem that I'm running into is as I turn my iPhone the loupe previewer is not aware that the device has turned so it's to the left, or to the right, or sometimes even underneath, where I'm actually drawing. If the loupe could be coded to be orientation independent and use data from the phone to be made aware of it's orientation, then loop preview would always be on top of where the work is being performed an aid the user.