def _add_roi(project_id, stack_id, user_id, x_min, x_max, y_min, y_max, z,
zoom_level, rotation_cw):
""" Add a new ROI database object and return it.
"""
# Calculate ROI center and extent
cx = (x_max + x_min) * 0.5
cy = (y_max + y_min) * 0.5
cz = z
width = abs(x_max - x_min)
height = abs(y_max - y_min)
# Create a new ROI class instance
roi = RegionOfInterest()
roi.user_id = user_id
roi.editor_id = user_id
roi.project_id = project_id
roi.stack_id = stack_id
roi.zoom_level = zoom_level
roi.location_x = cx
roi.location_y = cy
roi.location_z = cz
roi.width = width
roi.height = height
roi.rotation_cw = rotation_cw
roi.save()
# Create cropped image, if wanted
if settings.ROI_AUTO_CREATE_IMAGE:
file_name, file_path = create_roi_path(roi.id)
create_roi_image(request.user, project_id, roi.id, file_path)
return roi
