Description of the problem

pix2deg() currently assumes that the eye is projected orthogonal to the center of the screen.

It's not always the case that the eye is perfectly centered and so an offset vector should to be specified.

Description of the solution

The offset would be best implemented in the center_origin() function in pymovements.gaze.transforms.

The offset should be given in centimeters and is expected to be a tuple of floats with a zero default (center_offset: tuple[float, float] = (0, 0)).

The calculation should be pretty straight forward.

Minimum viable acceptance criteria

• add center_offset argument to center_origin()
• test offset in tests/unit/gaze/transforms/center_origin_test.py
• reuse center_offset argument in pix2deg()
• test offset in tests/unit/gaze/transforms/pix2deg_test.py
• test offset in tests/unit/gaze/gaze_transform_test.py