簡易PNGエンコーダ

pngencoder.py

#coding:utf-8
#Make a PNG file

IMAGE = (
    '0000000000000000',
    '0000000000000000',
    '0111111111111110',
    '0000000000000000',
    '0000111111110000',
    '0000010000010000',
    '0000010000000000',
    '0000010000000000',
    '0000011111000000',
    '0000010000000000',
    '0000010000000000',
    '0000010000000000',
    '0000111100000000',
    '0000000000000000',
    '0111111111111110',
    '0000000000000000',
    )

outname = 'test.png'

import struct
import binascii
import zlib


def crcMaker(data):
    return binascii.crc32(data)

def chunkMaker(name, chunkData):
    CRC = crcMaker(name + chunkData)
    body_len = len(chunkData)
    chunk = struct.pack('> I 4s {}s I'.format(body_len),
                        body_len, name, chunkData, CRC)
    return chunk

def split_str(s, n):
    length = len(s)
    return [s[i:i+n] for i in range(0, length, n)]

def hexize(data):
    out = list(map(lambda x:int(x,2), split_str(data, 8)))
    return out
        

data = bytes()

#header
data += bytes((0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A))

#IHDR
width = len(IMAGE[0])
height = len(IMAGE)
depth = 1
colourType = 0
compress = 0
filterType = 0
adam7 = False
chunkData = struct.pack('> I I B B B B ?',
            width, height, depth, colourType, compress, filterType, adam7)
data += chunkMaker(b'IHDR', chunkData)

#IDAT
filteredImage = bytes()
filterMode = [0x00,]
inputLine = list()
[inputLine.extend(filterMode+hexize(l)) for l in IMAGE]
chunkData = zlib.compress(bytes(inputLine))
data += chunkMaker(b'IDAT', chunkData)

#IEND
data += chunkMaker(b'IEND', b'')

with open(outname, 'wb') as f:
    f.write(data)