webp.py

#! /usr/bin/python
import os
import sys

cwebp = '/usr/bin/cwebp'
gif2webp = '/usr/bin/gif2webp'

#create new images by default.
mode = os.environ.get('MODE','CREATE')

# This dict ensures we don't even attempt to process files whose extensions are not in here.
# We certainly could attempt to do that, but then the output would be cluttered with cwebp errors.
# Also, webp is mapped to None so we don't try to re-process the webp files that this script generates.
extensionMap = {
    '.png': cwebp,
    '.jpeg': cwebp,
    '.jpg': cwebp,
    '.jpe': cwebp,
    '.jif': cwebp,
    '.jfif': cwebp,
    '.jfi': cwebp,
    '.jp2': cwebp,
    '.j2k': cwebp,
    '.jpf': cwebp,
    '.jpx': cwebp,
    '.jpm': cwebp,
    '.mj2': cwebp,
    '.tiff': cwebp,
    '.gif': gif2webp,
    '.GIF': gif2webp,
    '.webp': None
}

def main():
    if len(sys.argv) == 1:
        print("webp: No target directory provided. Exiting.")
        sys.exit(1)

    # Any valid options that cwebp accepts; if invalid options are provided, the tool will complain anyway
    options = str.join(' ', sys.argv[1:-1])

    # Assume the user is competent and provides this
    target_dir = sys.argv[-1]

    # Walk the directory and any nested directories
    for dir_name, subdir_list, file_list in os.walk(target_dir):

        for file in file_list:
            img, ext = os.path.splitext(file)
            ext = ext.lower()

            # To prevent a key error, we have to check if ext is in the map
            conversion_tool = extensionMap[ext] if ext in extensionMap else None

            # conversion_tool may be None if the file's extension is 'webp', for example, since we don't
            # want to reprocess files we've generated ourselves
            if not conversion_tool:
                continue

            img_path = os.path.join(dir_name, img)

            # if file does not exist or mode is update, generate new image
            if mode == "UPDATE" or not os.path.isfile("{}.webp".format(img_path)):
              #print(img_path)
              print("FILE: {}{}\n\n".format(img_path, ext))
              os.system("{} {} {}{} -o {}.webp".format(conversion_tool, options, img_path, ext, img_path))
              print('\n')



if __name__ == "__main__":
    main()