sns_instrument.py

# Mantid Repository : https://github.com/mantidproject/mantid
#
# Copyright © 2018 ISIS Rutherford Appleton Laboratory UKRI,
#   NScD Oak Ridge National Laboratory, European Spallation Source,
#   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
# SPDX - License - Identifier: GPL - 3.0 +
#pylint: disable=invalid-name
"""
    Instrument-specific utility functions for EQSANS
"""
from .hfir_instrument import _get_pixel_info


def get_pixel_from_coordinate(x, y, workspace):
    """
        Returns the pixel coordinates corresponding to the
        given real-space position.

        This assumes that the center of the detector is aligned
        with the beam. An additional offset may need to be applied

        @param x: real-space x coordinate [m]
        @param y: real-space y coordinate [m]
        @param workspace: the pixel number and size info will be taken from the workspace
    """
    nx_pixels, ny_pixels, pixel_size_x, pixel_size_y = _get_pixel_info(workspace)

    return [-x/pixel_size_x*1000.0 + nx_pixels/2.0-0.5,
            y/pixel_size_y*1000.0 + ny_pixels/2.0-0.5]


def get_coordinate_from_pixel(x, y, workspace):
    """
        Returns the real-space coordinates corresponding to the
        given pixel coordinates [m].

        This assumes that the center of the detector is aligned
        with the beam. An additional offset may need to be applied

        @param x: pixel x coordinate
        @param y: pixel y coordinate
        @param workspace: the pixel number and size info will be taken from the workspace
    """
    nx_pixels, ny_pixels, pixel_size_x, pixel_size_y = _get_pixel_info(workspace)

    return [(nx_pixels/2.0-0.5-x) * pixel_size_x/1000.0,
            (y-ny_pixels/2.0+0.5) * pixel_size_y/1000.0]


def get_masked_pixels(nx_low, nx_high, ny_low, ny_high, workspace):
    """
        Generate a list of masked pixels.
        @param nx_low: number of pixels to mask on the lower-x side of the detector
        @param nx_high: number of pixels to mask on the higher-x side of the detector
        @param ny_low: number of pixels to mask on the lower-y side of the detector
        @param ny_high: number of pixels to mask on the higher-y side of the detector
        @param workspace: the pixel number and size info will be taken from the workspace
    """
    nx_pixels, ny_pixels, pixel_size_x, pixel_size_y = _get_pixel_info(workspace)
    if nx_low<0 or nx_high<0 or ny_low<0 or ny_high<0:
        raise RuntimeError("Pixel edges should be greater than zero")

    masked_x = list(range(0, nx_low))
    masked_x.extend(list(range(nx_pixels-nx_high, nx_pixels)))

    masked_y = list(range(0, ny_low))
    masked_y.extend(list(range(ny_pixels-ny_high, ny_pixels)))

    masked_pts = []
    for y in masked_y:
        masked_pts.extend([ [x,y] for x in range(nx_pixels) ])
    for x in masked_x:
        masked_pts.extend([ [x,y] for y in range(ny_low, ny_pixels-ny_high) ])

    return masked_pts


def get_detector_from_pixel(pixel_list, workspace):
    """
        Returns a list of detector IDs from a list of [x,y] pixels,
        where the pixel coordinates are in pixel units.
        @param workspace: the pixel number and size info will be taken from the workspace
    """
    nx_pixels, ny_pixels, pixel_size_x, pixel_size_y = _get_pixel_info(workspace)
    return [ ny_pixels*p[0] + p[1] for p in pixel_list ]