ascii/ascii.py

#! /usr/bin/env python3
# -*- coding: utf-8 -*-
"""
ASCII
"""
from io import BytesIO

import requests
from PIL import Image, ImageFont, ImageDraw
#import imageio
import numpy as np
import numpngw

ASCII_CHARS = "$@%#*+=-:. "
HEADERS = {'User-Agent': 'Gimme ascii.'}


def scale_image(image, maxDim=100):
	"""
	Resizes an image while preserving the aspect ratio. Chooses the
	dimension to scale by based on whichever is larger, ensuring that
	neither width or height is ever larger than the maxDim argument.

	Because text characters are typically pretty close to a 1:2 rectangle,
	we weight the width twice as much.
	"""
	original_width, original_height = image.size
	original_width = original_width * 2
	if original_width > original_height:
		if original_width > maxDim:
			new_width = maxDim
			aspect_ratio = original_height/float(original_width)
			new_height = int(aspect_ratio * new_width)
		else:
			new_width, new_height = image.size
	else:
		if original_height > maxDim:
			new_height = maxDim
			aspect_ratio = original_width/float(original_height)
			new_width = int(aspect_ratio * new_height)
		else:
			new_width, new_height = image.size
	image = image.resize((new_width, new_height))
	return image


def pixels_to_chars(image, reverse=False):
	"""
	Maps each pixel to an ascii char based on where it falls in the range
	0-255 normalized to the length of ASCII_CHARS.
	"""
	range_width = int(255 / len(ASCII_CHARS)) + (255 % len(ASCII_CHARS) > 0)

	pixels = list(image.getdata())
	chars = []
	for pixel in pixels:
		if reverse:
			index = -int(pixel/range_width)-1
		else:
			index = int(pixel/range_width)
		chars.append(ASCII_CHARS[index])

	chars = "".join(chars)
	chars = [chars[i:i + image.size[0]] for i in range(0, len(chars),
		image.size[0])]
	return "\n".join(chars)


def char_color(pixel, code="irc"):
	"""
	Maps a color to a character based on the original pixel color.
	Calculates the distance from the provided color to each of the 16
	colors in the IRC and ANSI color codes and selects the closest match.
	"""
	colors_index = ["white", "black", "blue", "green", "red", "brown", "purple",
		"orange", "yellow", "light green", "teal", "cyan", "light blue", "pink",
		"grey", "silver"]

	colors_rgb = {"white": (0,0,0), "black": (255,255,255), "blue": (0,0,255),
		"green": (0,255,0), "red": (255,0,0), "brown": (150,75,0),
		"purple": (128,0,128), "orange": (255,128,0), "yellow": (255,255,0),
		"light green": (191,255,0), "teal": (0,128,128), "cyan": (0,255,255),
		"light blue": (65,105,225), "pink":(255,192,203), "grey": (128,128,128),
		"silver": (192,192,192)}

	colors_irc = {"white": "0", "black": "1", "blue": "2", "green": "3",
		"red": "4", "brown": "5", "purple": "6", "orange": "7", "yellow": "8",
		"light green": "9", "teal": "10", "cyan": "11", "light blue": "12",
		"pink": "13", "grey": "14", "silver": "15"}

	colors_ansi = {"white": "[1;37m", "black": "[0;30m", "blue": "[0;34m",
		"green": "[0;32m", "red": "[0;31m", "brown": "[0;33m",
		"purple": "[0;35m", "orange": "[1;31m", "yellow": "[1;33m",
		"light green": "[1;32m", "teal": "[0;36m", "cyan": "[1;36m",
		"light blue": "[1;34m", "pink": "[1;35m", "grey": "[1;30m",
		"silver": "[0;37m"}

	dist = [(abs(pixel[0] - colors_rgb[color][0])**2
		+ abs(pixel[1] - colors_rgb[color][1])**2
		+ abs(pixel[2] - colors_rgb[color][2])**2)**0.5
		for color in colors_index]

	color = colors_index[dist.index(min(dist))]

	if code == "irc":
		return colors_irc[color]
	elif code == "ansi":
		return colors_ansi[color]


def open_image(imagePath):
	"""
	Opens the image at the supplied file path in PIL. If an internet URL
	is supplied, it will download the image and then open it. Returns a
	PIL image object.
	"""
	try:
		if imagePath.startswith("http"):
			res = requests.get(imagePath, headers=HEADERS, verify=True,
				timeout=20)
			if res.status_code == 404:
				return "404: file not found."
			res.raise_for_status()
			image = Image.open(BytesIO(res.content))
		else:
			image = Image.open(imagePath)
	except FileNotFoundError:
		return f"File not found: {imagePath}"
	except Exception as e:
		return(f"Error opening image: {imagePath}\n{e}")

	return image


def colorize(chars, image, code):
	"""
	Colorizes the ascii matrix. Moves iteratively through the matrix and
	calls char_color on each pixel/character. Spaces are skipped to save
	time and CPU cycles.
	"""
	prefix = {"irc": "\03", "ansi":"\033"}
	chars = chars.split("\n")
	for j in range(0, image.size[1]):
		new_row = ""
		for k in range(0, image.size[0]):
			if chars[j][k] == " ":
				continue
			new_row += prefix[code] + char_color(image.getpixel((k,j)), code)
			new_row += chars[j][k]
		chars[j] = new_row

	chars = "\n".join(chars)
	if code == "ansi":
		chars += "\033[0m" # to avoid lingering effects in terminals
	return chars


def image_to_ascii(image, reverse=False, colors=None):
	"""
	Reads an image file and converts it to ascii art. Returns a
	newline-delineated string. If reverse is True, the ascii scale is
	reversed.
	"""
	image = scale_image(image)
	image_grey = image.convert('L')	# convert to grayscale

	chars = pixels_to_chars(image_grey, reverse)

	if colors:
		chars = colorize(chars, image, colors)
	image.close()
	image_grey.close()
	del(image)
	del(image_grey)
	return chars


def ascii_to_image(image_ascii):
	"""
	Creates a plain image and draws text on it.
	"""
	# TODO: make font type, size and color non-fixed
	width = len(image_ascii[:image_ascii.index("\n")]) * 8
	height = (image_ascii.count("\n")+1) * 12 + 4

	font = ImageFont.truetype("LiberationMono-Regular.ttf", 14)
	image = Image.new("RGB", (width, height), (255,255,255))
	draw = ImageDraw.Draw(image)
	draw.text((0,0), image_ascii, (0,0,0), font=font, spacing=0)
	return image


def handle_gif(image, output, reverse=False):
	"""
	Handle gifs seperately.
	"""
	image = open_image(args.imagePath)
	ascii_seq = []
	new_image = ascii_to_image(image_to_ascii(image, reverse))
	image.seek(1)
	while True:
		try:
			im = ascii_to_image(image_to_ascii(image, reverse))
			ascii_seq.append(im)
			image.seek(image.tell()+1)
		except EOFError:
			break # end of sequence

	# new_image.save(output, save_all=True, append_images=ascii_seq,
		# duration=60, loop=0, optimize=True)
	ascii_seq = [new_image] + ascii_seq
	np_ascii_seq = [np.array(im) for im in ascii_seq]
	with open(output, "wb") as file:
		numpngw.write_apng(file, np_ascii_seq)


if __name__=='__main__':
	import argparse

	parser = argparse.ArgumentParser(
		description="Converts an image file to ascii art.")
	parser.add_argument(
		"imagePath",
		help="The path to the image file. May be a local path or internet URL.")
	parser.add_argument(
		"-r",
		"--reverse",
		action="store_true",
		help="Reverses the ascii scale.")
	parser.add_argument(
		"-o",
		"--output",
		help="Outputs the ascii art into a file at the specified path.")
	parser.add_argument(
		"-i",
		"--image",
		action="store_true",
		help="Outputs the ascii art as an image rather than text. Requires \
		--output.")
	parser.add_argument(
		"-a",
		"--animated",
		action="store_true",
		help="Handles animated GIFs. Includes --image.")
	parser.add_argument(
		"-c",
		"--color",
		type=str,
		help="Colorizes the ascii matrix. Currently supported modes are 'irc' \
		and 'ansi' for generating color codes compliant with those standards.")
	parser.add_argument(
		"--ansi",
		dest="color",
		action="store_const",
		const="ansi",
		help="Shortcut for '--color ansi'.")
	parser.add_argument(
		"--irc",
		dest="color",
		action="store_const",
		const="irc",
		help="Shortcut for '--color irc'.")
	args = parser.parse_args()

	if args.animated:	# --animated includes --image
		args.image = True
	if args.image:		# --image requires --output
		if not args.output:
			parser.error("--image requires --output")

	image = open_image(args.imagePath)
	if args.animated:
		handle_gif(image, args.output, args.reverse)
		exit()

	image_ascii = image_to_ascii(image, args.reverse, args.color)
	if args.image:
		image = ascii_to_image(image_ascii)
		image.save(args.output, "PNG")
	elif args.output:
		with open(args.output, "w+") as file:
			file.write(image_ascii)
	else:
		print(image_ascii)