qr-image/lib/png.js

QR Code generator (png, svg, pdf, eps)

"use strict";

var zlib = require('zlib');

var crc32 = require('./crc32');

var PNG_HEAD = new Buffer([137,80,78,71,13,10,26,10]);
var PNG_IHDR = new Buffer([0,0,0,13,73,72,68,82,0,0,0,0,0,0,0,0,8,0,0,0,0,0,0,0,0]);
var PNG_IDAT = new Buffer([0,0,0,0,73,68,65,84]);
var PNG_IEND = new Buffer([0,0,0,0,73,69,78,68,174,66,96,130]);

function png(bitmap, stream) {
    stream.push(PNG_HEAD);

    var IHDR = Buffer.concat([PNG_IHDR]);
    IHDR.writeUInt32BE(bitmap.size, 8);
    IHDR.writeUInt32BE(bitmap.size, 12);
    IHDR.writeUInt32BE(crc32(IHDR.slice(4, -4)), 21);
    stream.push(IHDR);

    var IDAT = Buffer.concat([
        PNG_IDAT,
        zlib.deflateSync(bitmap.data, { level: 9 }),
        new Buffer(4)
    ]);
    IDAT.writeUInt32BE(IDAT.length - 12, 0);
    IDAT.writeUInt32BE(crc32(IDAT.slice(4, -4)), IDAT.length - 4);
    stream.push(IDAT);

    stream.push(PNG_IEND);
    stream.push(null);
}

function bitmap(matrix, size, margin) {
    var N = matrix.length;
    var X = (N + 2 * margin) * size;
    var data = new Buffer((X + 1) * X);
    data.fill(255);
    for (var i = 0; i < X; i++) {
        data[i * (X + 1)] = 0;
    }

    for (var i = 0; i < N; i++) {
        for (var j = 0; j < N; j++) {
            if (matrix[i][j]) {
                var offset = ((margin + i) * (X + 1) + (margin + j)) * size + 1;
                data.fill(0, offset, offset + size);
                for (var c = 1; c < size; c++) {
                    data.copy(data, offset + c * (X + 1), offset, offset + size);
                }
            }
        }
    }

    return {
        data: data,
        size: X
    }
}

module.exports = {
    bitmap: bitmap,
    png: png
}