JavaScript and Ruby EAN13 code generator. JS VERSION DEMO
ean13.js
(JavaScript library)ean13.rb
(Ruby library)
周末闲得没事干,偶然看见了一个包装袋上的条形码,觉得很有意思,之前写过一个PDF417的生成器,大体上原理差不多,这次用JavaScript写了段EAN13条形码的生成器,可以得到二进制码,从而进行Canvas绘图。
代码在这里:https://github.com/jamesliu96/ean13/blob/master/ean13.js
Demo地址:https://ean13.jamesliu.info
EAN13是European Article Number 13的缩写,正如其名,它拥有13位数字,是国际上普遍使用的商品标识码。
EAN13码的结构大体上是这样的:
- 前3位:国家码,我国可以使用的是690到699。
- 之后4位:生产商代码,如3943。
- 后5位:产品代码,如03457。
最后一位是生成的校验码,算法如下:
假设前12位是690123456789,遍历将奇数位和偶数位分别求和:
1. 奇数位和 = 6 + 0 + 2 + 4 + 6 + 8 = 26
2. 偶数位和 = 9 + 1 + 3 + 5 + 7 + 9 = 34
奇数位和和偶数位和的3倍相加,得到总和:
总和 = 奇数位和 + 偶数位和 * 3 = 26 + 34 * 3 = 128
取总和的个位数:
个位 = 总和 % 10 = 8
将10与个位相减,得到校验位:
校验位 = 10 - 个位 = 2
//注意:如果个位为0,校验位不是10 - 0 = 10而是0
我们可以使用判断但是这里有一个更好的算法就是将相减之后的数再除以10取余:
校验位 = (10 - 个位) % 10 = 2
这样我们就得到了整个EAN13码:6901234567892
接下来就是生成二进制的码。
生成二进制码的时候我们将第一位(e.g. 6)看作前置码,来决定使用的码集。
- 索引:
{
0: [0, 0, 0, 0, 0, 0],
1: [0, 0, 1, 0, 1, 1],
2: [0, 0, 1, 1, 0, 1],
3: [0, 0, 1, 1, 1, 0],
4: [0, 1, 0, 0, 1, 1],
5: [0, 1, 1, 0, 0, 1],
6: [0, 1, 1, 1, 0, 0],
7: [0, 1, 0, 1, 0, 1],
8: [0, 1, 0, 1, 1, 0],
9: [0, 1, 1, 0, 1, 0]
}
- 码集:
{
0: ["0001101", "0100111", "1110010"],
1: ["0011001", "0110011", "1100110"],
2: ["0010011", "0011011", "1101100"],
3: ["0111101", "0100001", "1000010"],
4: ["0100011", "0011101", "1011100"],
5: ["0110001", "0111001", "1001110"],
6: ["0101111", "0000101", "1010000"],
7: ["0111011", "0010001", "1000100"],
8: ["0110111", "0001001", "1001000"],
9: ["0001011", "0010111", "1110100"]
}
如果前置码是6,我们就用[0, 1, 1, 1, 0, 0]这个码集。
前6位码得到的二进制码就是:000101101001110110011001101101111010100011
同样后6位则是:100111010100001000100100100011101001101100
前面加上101
起始符后面加上101
终止符,前6位和后6位之间加上01010
分隔符即可。
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