def test_filepath_wrong_extension(self):
filepath = "C:\\Users\\User\\Documents\\example.png"
self.assertNotEqual(
filepath,
check_filename("C:\\Users\\User\\Documents\\example.png",
extension=".txt"))
filepath = "/home/user/example.png"
self.assertNotEqual(
filepath, check_filename("/home/user/example.png",
extension=".txt"))
def test_filepath_without_extension_trailing_slash(self):
filepath = "C:\\Users\\User\\Documents\\example\\"
self.assertEqual(
"C:\\Users\\User\\Documents\\example" + ".txt",
check_filename("C:\\Users\\User\\Documents\\example\\",
extension=".txt"))
filepath = "/home/user/example/"
self.assertEqual(
"/home/user/example" + ".txt",
check_filename("/home/user/example", extension=".txt"))
def encode(text, image_path, limit=256):
"""
Take a string of text and encode it into an 8-bit grayscale image.
:param str text: Text may be ASCII or UTF-8 but limit value must be changed accordingly.
:param str image_path: Path to image file. Should have a '.png' extension or no extension
:param int limit: The value limit for each pixel. 256 = 8 bit meaning all character encoding schemes using 8 or
fewer bit can be encoded. If limit is 65536 then character encoding schemes using 16 bits or less can be applied
e.g. UTF-8. When a character is used from a character set greater than the limit, the character value will be
divided by the limit value. e.g. limit=256 character=Ĭ (value=300), resulting value will be 44. For values equal to
the limit, the resulting value will be 1 to avoid NULL within the encoded data. Limit is the number of possible
values in decimal from 1 to a max value. (default=256 i.e. 8 bit pixels/ 1- 256 means 255 possible values)
:return str: The path to the image produced.
"""
if type(text) is not str:
raise TypeError("Parameter 'text' must be a string.")
text_length = len(text)
print(text_length)
size = get_image_size(text_length)
print(size)
result_path = check_filename(image_path, extension=".png")
img = Image.new("L", size) # grayscale, blank black image
ind = 0
for row in range(0, size[0]):
for col in range(0, size[1]):
if ind < text_length: # only change pixel value for length of text
pixel_value = convert_char_to_int(text[ind], limit=limit)
img.putpixel((row, col), pixel_value)
ind += 1
else: # end of text, leave remaining pixel(s) black to indicate null
break
img.save(result_path)
return result_path
def decode_to_file(image_path, file_path):
"""
Take an encoded png image and produce a text file with the decoded text.
:param str image_path: Path to a png image with encoded text to be extracted.
:param str file_path: Path to file where decoded text will be stored. Should be a plain text file '.txt'.
:return str: Path to output text file.
"""
if not path.isfile(image_path):
raise FileExistsError("Image file {0} does not exist. Cannot decode a nonexistent image".format(image_path))
if image_path[-4:].lower() != ".png":
raise TypeError("Image {0} must be a png image file with a '.png' file extension".format(image_path))
file_path = check_filename(file_path)
decoded_text = decode(image_path)
with open(file_path, "w") as f:
f.write(decoded_text)
return file_path
def test_simple_filename_with_extension(self):
filename = "example.txt"
self.assertEqual(filename,
check_filename("example.txt", extension=".txt"))
def test_linux_filepath_without_extension(self):
filepath = "/home/user/example"
self.assertEqual(
"/home/user/example" + ".txt",
check_filename("/home/user/example", extension=".txt"))
def test_windows_filepath_without_extension(self):
filepath = r"C:\Users\User\Documents\example"
self.assertEqual(
filepath + ".txt",
check_filename(r"C:\Users\User\Documents\example",
extension=".txt"))