simplest_img_dict.py

'''
While the code in test.py aims to test as much of the ImageMetaTag
functionality as possible, this routine aims to show the simplest possible
code that keeps 'best practice' to use an ImageMetaTag database of
metadata to produce a webpage.

.. moduleauthor:: Melissa Brooks https://github.com/melissaebrooks

(C) Crown copyright Met Office. All rights reserved.
Released under BSD 3-Clause License. See LICENSE for more details.
'''

# minimal set of imports:
import datetime

# import ImageMetaTag:
import ImageMetaTag as imt

# we are going to use just a couple of things from the test.py routine:
from test import get_webdir, define_imt_db, DATE_FORMAT_WWW


def __main__():
    # define the web page directory and image database
    # Any real application of an ImageDict web page would need to
    # define the locations of the web page and database for its own
    # requirements.
    # In this case, we are using the same functions in test, to be sure that
    # they are consistent.
    webdir = get_webdir()
    imt_db = define_imt_db()

    # these are the image tags that are present in the metadata, and
    # the sort order we want to present them with on a web page:
    img_tags = ['plot type', 'number of rolls', 'plot color',
                'image trim', 'border', 'image compression']
    # and how those tags are to be sorted:
    sort_methods = ['sort', 'numeric', 'reverse_sort', 'sort',
                    'reverse_numeric', 'sort']

    # Now load in the database:
    tag_str = []
    img_list, images_and_tags = imt.db.read(imt_db,
                                            required_tags=img_tags,
                                            tag_strings=tag_str)
    # we have supplied the database read with the image tags we expect,
    # and an empty list of values so that we can construct what is returned
    # (and therefore the ImageDict) in a memory efficient way.

    # the img_list is a list of the images in the databse file:
    print(img_list)

    # now assemble the ImageDict in the simple way. See test.py for examples
    # of how to parallelise this.
    img_dict = None
    for img_file, img_info in images_and_tags.items():
        # make a temporary ordered dictionary for this image:
        tmp_dict = imt.dict_heirachy_from_list(img_info, img_file, img_tags)
        if not img_dict:
            # turn it into an ImageDict
            img_dict = imt.ImageDict(tmp_dict)
        else:
            # append this tmp_dict to the ImageDict
            img_dict.append(imt.ImageDict(tmp_dict))
    # printing the img_dict will show it's heirachy (but is a lot of text):
    print(img_dict)
    # now sort the keys of each level of the ImageDict according to the
    # sort_method
    img_dict.sort_keys(sort_methods)

    # now write a webpage:
    page_filename = '{}/simple.html'.format(webdir)
    # the title:
    page_title = 'Simple ImageMetaTag wegbpage'
    # html content to go at the top of the page:
    webpage_preamble = '<h3>This is the simplest page ImageMetaTag can produce</h3>'
    # and some html content at the bottom:
    dt_now_str = datetime.datetime.now().strftime(DATE_FORMAT_WWW)
    webpage_postamble = '<i>Page produced {}</i>'.format(dt_now_str)
    imt.webpage.write_full_page(img_dict, page_filename, page_title,
                                preamble=webpage_preamble,
                                postamble=webpage_postamble)

    # and sign off as completed:
    print('completed, using ImageMetaTag at {}'.format(imt.__path__[0]))


if __name__ == '__main__':
    __main__()