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node-bwipjs
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node-bwipjs
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// file: node-bwipjs
//
// Copyright (c) 2011-2015 Mark Warren
//
// See the LICENSE file in the bwip-js root directory
// for the extended copyright notice.
//
var url = require('url'),
fs = require('fs'),
vm = require('vm'),
zlibPNG = require(__dirname + '/node-zlibPNG')
;
// The global inside a sandboxed context is virtually useless. None of
// the goodies available in a primary context.
// Emscripten uses the existence of require() and process to decide whether it is
// running in node. And console is really nice to have.
// And it cannot run without all of the TypedArray constructors.
var sandbox = vm.createContext({
require:require,
process:process,
console:console,
ArrayBuffer:ArrayBuffer, DataView:DataView,
Int8Array:Int8Array, Uint8Array:Uint8Array,
Uint8ClampedArray:Uint8ClampedArray,
Int16Array:Int16Array, Uint16Array:Uint16Array,
Int32Array:Int32Array, Uint32Array:Uint32Array,
Float32Array:Float32Array, Float64Array:Float64Array,
// The .mem image makes it really hard to use as a library module
Module:{ memoryInitializerPrefixURL : __dirname + '/' }
});
load('freetype.js');
// We will use a synchronous demand-loader as each module's load-cost is
// a one-time hit and it prevents any potential race conditions.
function load(path) {
var text = fs.readFileSync(__dirname + '/' + path);
if (!text)
throw new Error(path + ": could not read file");
vm.runInContext(text, sandbox, { filename:path });
}
// This module's primary export is the bwip-js HTTP request handler
module.exports = function(req, res) {
var args = url.parse(req.url, true).query;
// Convert boolean empty parameters to true
for (var id in args) {
if (args[id] === '')
args[id] = true;
}
module.exports.toBuffer(args, function(err, png) {
if (err) {
res.writeHead(400, { 'Content-Type':'text/plain' });
res.end(err, 'ascii');
} else {
res.writeHead(200, { 'Content-Type':'image/png' });
res.end(png, 'binary');
}
});
}
//
// bwipjs.toBuffer(options, callback)
//
// Generates a PNG-encoded image in a buffer.
//
// `options` are the bwip-js/BWIPP options wrapped in an object.
// `callback` is an event handler with prototype:
//
// function callback(err, png)
//
// `err` is an Error object or string. If `err` is set, `png` is null.
// `png` is a node Buffer containing the PNG image.
//
module.exports.toBuffer = function(args, callback) {
// Finish loading bwip-js?
if (typeof sandbox.BWIPJS === 'undefined') {
load('bwip.js');
sandbox.BWIPJS.load = load;
}
// Set the defaults
var scale = args.scale || 2;
var scaleX = +args.scaleX || scale;
var scaleY = +args.scaleY || scaleX;
var rot = args.rotate || 'N';
var mono = args.monochrome || false;
// The required parameters
var bcid = args.bcid;
var text = args.text;
if (!text)
return callback('Bar code text not specified.');
if (!bcid)
return callback('Bar code type not specified.');
if (!fs.existsSync(__dirname + '/bwipp/' + bcid + '.js'))
return callback('Bar code type "' + bcid + '" unknown.');
// Remove the non-BWIPP options
delete args.scale;
delete args.scaleX;
delete args.scaleY;
delete args.rotate;
delete args.text;
delete args.bcid;
delete args.monochrome;
// Initialize a barcode writer object
var bw = new sandbox.BWIPJS;
// Set the options
var opts = {};
for (var id in args) {
opts[id] = bw.value(args[id]);
}
// Fix a disconnect in the BWIPP rendering logic
if (opts.alttext)
opts.includetext = bw.value(true);
// We use mm rather than inches for height - except pharmacode2 height
// is explicitly in mm
if (opts.height && bcid != 'pharmacode2')
opts.height = opts.height / 25.4 || 0.5;
// Enable/disable monochrome font rendering
sandbox.BWIPJS.ft_monochrome(mono ? 1 : 0);
// Feature or bug, BWIPP does not extend the background color into the
// human readable text. Fix that in the bitmap interface.
if (opts.backgroundcolor) {
bw.bitmap(new Bitmap(parseInt(''+opts.backgroundcolor, 16)));
delete opts.backgroundcolor;
} else {
bw.bitmap(new Bitmap);
}
bw.scale(scaleX, scaleY);
bw.push(text);
bw.push(opts);
bw.call(bcid, function(e) {
if (e) {
callback('BWIP-JS ERROR: ' + e);
} else {
bw.bitmap().getPNG(rot, callback);
}
});
}
module.exports.loadFont = function(fontname, sizemult, fontfile) {
sandbox.Module.FS_createDataFile('/', fontname, fontfile, true, false);
var load_font = sandbox.Module.cwrap("load_font", 'number',
['string','string','number']);
var rv = load_font('/' + fontname, fontname, sizemult);
if (rv != 0) {
sandbox.FS.unlink('/' + fontname);
throw 'Error: font load failed [' + rv + ']';
}
}
module.exports.unloadFont = function(fontname) {
// Unload from freetype
var close_font = sandbox.Module.cwrap("close_font", 'number', ['string']);
close_font(fontname);
// Delete from emscripten
sandbox.FS.unlink('/' + fontname);
}
// bwip-js bitmap interface
// Must export to the PostScript emulation:
// this.color(r, g, b) ## The color to use for subsequent set()'s.
// this.set(x, y, a) ## Sets the pixel at (x,y) using the current
// ## color with alpha-a.
//
// bgcolor is optional. If specified, if must be an integer or string RGB value.
// Alpha channel is not supported.
function Bitmap(bgcolor) {
var _clrr = 0; // current red
var _clrg = 0; // current green
var _clrb = 0; // current blue
var _pixs = {}; // x,y = argb
var _minx = Infinity;
var _miny = Infinity;
var _maxx = 0;
var _maxy = 0;
if (typeof bgcolor === 'string')
bgcolor = (0xff000000 | parseInt(bgcolor, 16)) >>> 0;
else if (bgcolor !== undefined)
bgcolor = (0xff000000 | bgcolor) >>> 0;
this.color = function(r,g,b) {
_clrr = r;
_clrg = g;
_clrb = b;
}
this.set = function(x, y, a) {
// postscript graphics work with floating-pt numbers
x = Math.floor(x);
y = Math.floor(y);
if (_minx > x) _minx = x;
if (_maxx < x) _maxx = x;
if (_miny > y) _miny = y;
if (_maxy < y) _maxy = y;
var xy = x + ',' + y;
var cx = _pixs[xy];
var r, g, b;
if (cx === undefined)
cx = bgcolor;
if (cx === undefined) {
r = _clrr;
g = _clrg;
b = _clrb;
} else {
// alpha-blend with the existing color
// dst is the existing "background" color
// src is the new color
var dsta = (cx >>> 24) / 255;
var dstr = (cx >>> 16) & 0xff;
var dstg = (cx >>> 8) & 0xff;
var dstb = cx & 0xff;
var srca = a / 255;
var newa = srca + dsta * (1 - srca); // new alpha 0.0 - 1.0
if (!newa) {
r = g = b = a = 0;
} else {
r = ((_clrr * srca + dstr * dsta * (1 - srca)) / newa)|0;
g = ((_clrg * srca + dstg * dsta * (1 - srca)) / newa)|0;
b = ((_clrb * srca + dstb * dsta * (1 - srca)) / newa)|0;
a = (newa * 255)|0;
}
}
_pixs[xy] = ((a << 24) | (r << 16) | (g << 8) | b) >>> 0;
}
// `rot` is the desired image rotation
// `callback` prototype: function(err, png)
this.getPNG = function(rot, callback) {
// determine image width and height
if (rot == 'R' || rot == 'L') {
var h = _maxx-_minx+1;
var w = _maxy-_miny+1;
} else {
var w = _maxx-_minx+1;
var h = _maxy-_miny+1;
}
var png = new zlibPNG(w, h, bgcolor);
for (var xy in _pixs) {
var pts = xy.split(',');
var x = +pts[0] - _minx;
var y = +pts[1] - _miny;
// PostScript builds bottom-up, we build top-down.
if (rot == 'N') {
y = h - y - 1; // Invert y
} else if (rot == 'I') {
x = w - x - 1; // Invert x
} else {
y = w - y; // Invert y
if (rot == 'L') {
var t = y;
y = h - x - 1;
x = t - 1;
} else {
var t = x;
x = w - y;
y = t;
}
}
png.set(x, y, _pixs[xy]);
}
return png.render(callback);
}
}