npos

A ESC/POS library for node

Installation

$ npm install --save npos

Parser

Parse ESC/POS binary buffer.

parse

varnpos=require('npos');varparser=npos.parser();varbuffer=fs.readFileSync('sample.bin');parser.parse(buffer).then(function(ast){console.log(ast);});

The ast form parse is like:

{
raw: <Buffer ...>,
error: <error>,
tree: [
{
code: 27, // command code in decimal hex: '1B', // command code in hex
ascii: 'ESC', // command code in ascii name
offset: 0, // data offset from buffer
length: 2, // data length fn: '@', // command fn charater
},
....
],
entries: [ // decoded entries
{
type: 'raster',
nodes: [ // nodes handled by codec from ast
...
],
data: <Object> // data decoded by codec
},
...
]
}

rules

rules is used to parse esc/pos binary to ast tree.

Example rules:

varnpos=require('npos');varrules={};rules[npos.ESC]={// 'ESC' commands'!': 1,// 'ESC !' command. Swallow one parameter byte'$': 2,'%': 1,'&': [0,ycc],// 'ESC &' command. Using 'ycc' function to decode from offset 0'*': [0,'bitimage'],// 'ESC *' command. Using builtin decoder to decode from offset 0.'-': 1,'2': 0,'3': 1,'=': 1,'?': 1,'@': 0,'D': [0,'escd'],'E': 1,'G': 1,'J': 1,'L': 0,'M': 1,'R': 1,'S': 0,'T': 1,'V': 1,'W': 8,'\\': 2,'a': 1,'c': 2,'d': 1,'p': 3,'r': 0,// Select print color't': 1,'{': 1,'B': 2,// Unknown Command'Z': [3,'d16']};// Custom splitter with parameter buffer and offset specified with rule.functionycc(buf,offset){if(buf.length-offset<3){returnbuf.length;}vark=buf[offset+2]-buf[offset+1]+1;varnum=3;for(vari=0;i<k;i++){num+=buf[offset+num]*buf[offset]+1;}returnnum;};

or extend the builtin rules:

varnpos=require('npos');npos.rules[npos.ESC]['&']=[0,ycc];

Here are builtin rules and builtin splitters.

codec

npos use codec to decode from ast tree parsed from binary.

Here are builtin codecs

We can extend codecs as need. For example:

// sampleCodec.js// commands supportedexports.commands=['GSv0'];// decode from raw data and nodesexports.decode=function(raw,nodes){// traverse nodes to decode and return result decoded}

varnpos=require('npos');npos.codecs['sampleCodec']=require('./sampleCodec');

to pdf

See: example

License

© taoyuan