code128.py

Hello,

After using reportlab for creating barcodes, I realised the optimization
for Code128 was not correct. It was only optimizing the end of the barcode
string.

I made modifications for the trailingDigitsToC function. See below. Now all
string will be analysed for optimizations. Probably there will be a better
algorithm, but this is working.

   def _trailingDigitsToC(self, l):
        # Optimization: trailing digits -> set C double-digits

        i = 0
        nl = []
        while i < len(l):
            startpos = i
            rl = ['TO_C']
            savings = -1 # the TO_C costs one character
            while i < len(l):
                if l[i] in (['START_B','TO_A','TO_B']):
                    set = 'TO' + l[i][-2:]
                    break
                elif l[i] == '\xf1':
                    rl.append(l[i])
                    i += 1
                    continue
                elif len(l[i]) == 1 and l[i] in digits \
                 and len(l[i+1]) == 1 and l[i+1] in digits:
                    rl.append(l[i] + l[i+1])
                    i += 2
                    savings += 1
                    continue
                else:
                    break

            if savings > 0:
                nl = nl + rl
                if not l[i]=='STOP':
                    nl.append(set)
                nl.append(l[i])
            else:
                nl = nl + l[startpos:i+1]
            i += 1
        return nl