#!/usr/bin/env python
# FormatTIFF.py
#   Copyright (C) 2011 Diamond Light Source, Graeme Winter
#
#   This code is distributed under the BSD license, a copy of which is
#   included in the root directory of this package.
#
# Implementation of an ImageFormat class to read TIFF format image but not -
# in the first instance - actually provide a full image representation. This
# is simply there to set everything up for the Mar / Rayonix CCD readers
# which really will acquire the full image including header information
# and generate the experimental model representations.

from __future__ import division

from dxtbx.format.Format import Format
from dxtbx.format.FormatTIFFHelpers import read_basic_tiff_header
from dxtbx.format.FormatTIFFHelpers import LITTLE_ENDIAN
from dxtbx.format.FormatTIFFHelpers import BIG_ENDIAN

class FormatTIFF(Format):
  '''An image reading class for TIFF format images i.e. those from Dectris
  and Rayonix, which start with a standard TIFF header (which is what is
  handled here) and have their own custom header following, which must
  be handled by the inheriting subclasses.'''

  LITTLE_ENDIAN = LITTLE_ENDIAN
  BIG_ENDIAN = BIG_ENDIAN

  @staticmethod
  def understand(image_file):
    '''Check to see if this looks like an TIFF format image, i.e. we can
    make sense of it.'''

    try:
      width, height, depth, header, order = read_basic_tiff_header(
          image_file)
      return True

    except: # intentional
      pass

    return False

  @staticmethod
  def get_tiff_header(image_file):
    '''Pun to get to the image header etc.'''

    width, height, depth, header, order = read_basic_tiff_header(
        image_file)

    header_bytes = FormatTIFF.open_file(image_file, 'rb').read(header)

    return width, height, depth // 8, order, header_bytes

  def __init__(self, image_file):
    '''Initialise the image structure from the given file.'''

    assert(self.understand(image_file))

    Format.__init__(self, image_file)

    return

  def _start(self):
    '''Open the image file, read the image header, copy it into memory
    for future inspection.'''

    width, height, depth, header, order = read_basic_tiff_header(
        self._image_file)

    self._tiff_width = width
    self._tiff_height = height
    self._tiff_depth = depth // 8
    self._tiff_header_bytes = FormatTIFF.open_file(
        self._image_file, 'rb').read(header)
    self._tiff_byte_order = order

    return