适用于Code128条码字体的Python Code128编码器

问题描述

就像标题中所说的，我有一个Code128字体，我想用它来打印条形码.但是，该字符串需要在Code128中进行编码才能使条形码字体起作用.我的应用程序使用Python3语言.

Like the title says, I have a Code128 font that I would like to print barcodes with. However, the string needs to be encoded in Code128 to make the barcode font work. My app uses the Python3 language.

网络上曾经有一个示例，该示例说明如何为Code128字体编码字符串，但是我找不到了.

There used to be an example on the web somewhere how to encode the string for a Code128 font, but I can't find it anymore.

我确实不希望将字符串转换为.svg转换器.我特别想将字符串转换为Code128编码的字符串.

I do NOT want a string to .svg converter. I specifically want to convert a string to a Code128 encoded string.

任何参考，Python3中的代码段或文档都将不胜感激.

Any references, code snippets in Python3 or documentation would be appreciated.

我在此处使用字体.

推荐答案

这是一个可以接受的答案，因此我将原始代码放在下面.但我更喜欢这种改进.

This is an accepted answer, so I'm leaving the original code underneath. But I prefer this refinement.

def list_join(seq):
    ''' Join a sequence of lists into a single list, much like str.join
        will join a sequence of strings into a single string.
    '''
    return [x for sub in seq for x in sub]

code128B_mapping = dict((chr(c), [98, c+64] if c < 32 else [c-32]) for c in range(128))
code128C_mapping = dict([(u'%02d' % i, [i]) for i in range(100)] + [(u'%d' % i, [100, 16+i]) for i in range(10)])
code128_chars = u''.join(chr(c) for c in [212] + list(range(33,126+1)) + list(range(200,211+1)))

def encode128(s):
    ''' Code 128 conversion for a font as described at
        https://en.wikipedia.org/wiki/Code_128 and downloaded
        from http://www.barcodelink.net/barcode-font.php
        Only encodes ASCII characters, does not take advantage of
        FNC4 for bytes with the upper bit set. Control characters
        are not optimized and expand to 2 characters each.
        Coded for https://stackoverflow.com/q/52710760/5987
    '''
    if s.isdigit() and len(s) >= 2:
        # use Code 128C, pairs of digits
        codes = [105] + list_join(code128C_mapping[s[i:i+2]] for i in range(0, len(s), 2))
    else:
        # use Code 128B and shift for Code 128A
        codes = [104] + list_join(code128B_mapping[c] for c in s)
    check_digit = (codes[0] + sum(i * x for i,x in enumerate(codes))) % 103
    codes.append(check_digit)
    codes.append(106) # stop code
    return u''.join(code128_chars[x] for x in codes)

---

def encode128(s):
    ''' Code 128 conversion for a font as described at
        https://en.wikipedia.org/wiki/Code_128 and downloaded
        from http://www.barcodelink.net/barcode-font.php
        Only encodes ASCII characters, does not take advantage of
        FNC4 for bytes with the upper bit set.
        It does not attempt to optimize the length of the string,
        Code B is the default to prefer lower case over control characters.
        Coded for https://stackoverflow.com/q/52710760/5987
    '''
    s = s.encode('ascii').decode('ascii')
    if s.isdigit() and len(s) % 2 == 0:
        # use Code 128C, pairs of digits
        codes = [105]
        for i in range(0, len(s), 2):
            codes.append(int(s[i:i+2], 10))
    else:
        # use Code 128B and shift for Code 128A
        mapping = dict((chr(c), [98, c + 64] if c < 32 else [c - 32]) for c in range(128))
        codes = [104]
        for c in s:
            codes.extend(mapping[c])
    check_digit = (codes[0] + sum(i * x for i,x in enumerate(codes))) % 103
    codes.append(check_digit)
    codes.append(106) # stop code
    chars = (b'\xd4' + bytes(range(33,126+1)) + bytes(range(200,211+1))).decode('latin-1')
    return ''.join(chars[x] for x in codes)

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