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# coding: utf-8
#
# Project: X-ray image reader
# https://github.com/silx-kit/fabio
#
#
# Copyright (C) European Synchrotron Radiation Facility, Grenoble, France
#
# Principal author: Jérôme Kieffer (Jerome.Kieffer@ESRF.eu)
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE
"""Reads a bytestream
Authors: Jon Wright Henning O. Sorensen & Erik Knudsen
ESRF Risoe National Laboratory
"""
import logging
import numpy
logger = logging.getLogger(__name__)
DATATYPES = {
# type sign bytes
("int", 'n', 1): numpy.uint8,
("int", 'n', 2): numpy.uint16,
("int", 'n', 4): numpy.uint32,
("int", 'y', 1): numpy.int8,
("int", 'y', 2): numpy.int16,
("int", 'y', 4): numpy.int32,
('float', 'y', 4): numpy.float32, # does this occur in bruker?
('double', 'y', 4): numpy.float64
}
def readbytestream(fil,
offset,
x,
y,
nbytespp,
datatype='int',
signed='n',
swap='n',
typeout=numpy.uint16):
"""
Reads in a bytestream from a file (which may be a string indicating
a filename, or an already opened file (should be "rb"))
offset is the position (in bytes) where the pixel data start
nbytespp = number of bytes per pixel
type can be int or float (4 bytes pp) or double (8 bytes pp)
signed: normally signed data 'y', but 'n' to try to get back the
right numbers when unsigned data are converted to signed
(python once had no unsigned numeric types.)
swap, normally do not bother, but 'y' to swap bytes
typeout is the numpy type to output, normally uint16,
but more if overflows occurred
x and y are the pixel dimensions
TODO : Read in regions of interest
PLEASE LEAVE THE STRANGE INTERFACE ALONE -
IT IS USEFUL FOR THE BRUKER FORMAT
"""
tin = "dunno"
length = nbytespp * x * y # bytes per pixel times number of pixels
if datatype in ['float', 'double']:
signed = 'y'
key = (datatype, signed, nbytespp)
try:
tin = DATATYPES[key]
except KeyError:
logger.warning("datatype, signed, nbytespp: %s", str(key))
raise Exception("Unknown combination of types to readbytestream")
# Did we get a string (filename) or a readable stream object?
if hasattr(fil, "read") and hasattr(fil, "seek"):
infile = fil
opened = False
else:
infile = open(fil, 'rb')
opened = True
infile.seek(offset)
data = numpy.frombuffer(infile.read(length), tin)
arr = numpy.array(numpy.reshape(data, (x, y)), typeout)
if swap == 'y':
arr.byteswap(True)
if opened:
infile.close()
return arr
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