npos
v0.1.19
Published
A ESC/POS library for node.js
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npos
A ESC/POS library for node
Installation
$ npm install --save npos
Parser
Parse ESC/POS binary buffer.
parse
var npos = require('npos');
var parser = npos.parser();
var buffer = 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:
var npos = require('npos');
var rules = {};
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.
function ycc(buf, offset) {
if (buf.length - offset < 3) {
return buf.length;
}
var k = buf[offset + 2] - buf[offset + 1] + 1;
var num = 3;
for (var i = 0; i < k; i++) {
num += buf[offset + num] * buf[offset] + 1;
}
return num;
};
or extend the builtin rules:
var npos = 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 supported
exports.commands = ['GSv0'];
// decode from raw data and nodes
exports.decode = function (raw, nodes) {
// traverse nodes to decode and return result decoded
}
var npos = require('npos');
npos.codecs['sampleCodec'] = require('./sampleCodec');
to pdf
See: example
License
© taoyuan