How to Make Node Barcode Reader Addon on Linux

• Download source code

If you want to make a Web barcode reader app using node.js, you may find a node barcode module with npm or build it yourself. Node addons are the bridge between C/C++ libraries and JavaScript. In this tutorial, I will illustrate how to create node barcode addon on Ubuntu with DBR (Dynamsoft Barcode Reader for Linux).

Download & Installation

If you want to use the latest node version, do not install node and npm with the apt-get utility, which only fetches the old version and will cause the error – ‘FunctionCallbackInfo’ does not name a type:

Install Node

Download the latest node package: node-v5.3.0-linux-x64.tar.gz.

Extract the node package as follows:

tar -xzf node-v5.3.0-linux-x64.tar.gz

Open .bashrc:

nano ~/.bashrc

Export node path and save .bashrc:

export PATH=$(YOUR_HOME)/Downloads/node-v5.3.0-linux-x64/bin:$PATH

Install node-gyp:

npm install -g node-gyp

Install DBR

Download v4.0.0-pre-alpha.tar.gz.

Extract the dbr package:

tar -xzf v4.0.0-pre-alpha.tar.gz

To find the shared library when building the project with make, create a symbolic link of barcode shared library:

sudo ln -s $(DynamsoftBarcodeReader)/Redist/libDynamsoftBarcodeReaderx64.so 
	/usr/lib/libDynamsoftBarcodeReaderx64.so

How to Make Node Barcode Addon

Create binding.gyp and specify the paths of DBR header files and shared libraries:

{
  "targets": [
    {
      "target_name": "dbr",
      "sources": [ "dbr.cc" ],
      "include_dirs" : [
        "$(DynamsoftBarcodeReader)/Include"
      ],
      "libraries": [
        "-lDynamsoftBarcodeReaderx64", "-L$(DynamsoftBarcodeReader)/Redist"
      ]
    }
  ]
}

Create dbr.cc using the sample code provided by Dynamsoft Barcode Reader SDK:

#include <node.h>
#include "If_DBR.h"
#include "BarcodeFormat.h"
#include "BarcodeStructs.h"
#include "ErrorCode.h"

using namespace v8;

// Barcode format
const char * GetFormatStr(__int64 format)
{
	if (format == CODE_39)
		return "CODE_39";
	if (format == CODE_128)
		return "CODE_128";
	if (format == CODE_93)
		return "CODE_93";
	if (format == CODABAR)
		return "CODABAR";
	if (format == ITF)
		return "ITF";
	if (format == UPC_A)
		return "UPC_A";
	if (format == UPC_E)
		return "UPC_E";
	if (format == EAN_13)
		return "EAN_13";
	if (format == EAN_8)
		return "EAN_8";
	if (format == INDUSTRIAL_25)
		return "INDUSTRIAL_25";
	if (format == QR_CODE)
		return "QR_CODE";
	if (format == PDF417)
		return "PDF417";
	if (format == DATAMATRIX)
		return "DATAMATRIX";

	return "UNKNOWN";
}

void DecodeFile(const FunctionCallbackInfo<Value>& args) {

	Isolate* isolate = Isolate::GetCurrent();
	HandleScope scope(isolate);

	// convert v8 string to char *
	String::Utf8Value fileName(args[0]->ToString());
	String::Utf8Value license(args[1]->ToString());
	char *pFileName = *fileName;
	char *pszLicense = *license;
	// Dynamsoft Barcode Reader: init
	__int64 llFormat = (OneD | QR_CODE | PDF417 | DATAMATRIX);
	int iMaxCount = 0x7FFFFFFF;
	ReaderOptions ro = {0};
	pBarcodeResultArray pResults = NULL;

	// Initialize license
	if (pszLicense)
	{
		printf("license: %s\n", pszLicense);
		DBR_InitLicense(pszLicense);
	}
	else
		DBR_InitLicense("AC4561856D63EF392F46D7454052372D");

	ro.llBarcodeFormat = llFormat;
	ro.iMaxBarcodesNumPerPage = iMaxCount;

	// Decode barcode image
	int ret = DBR_DecodeFile(pFileName, &ro, &pResults);
	printf("ret: %d\n", ret);

	if (ret == DBR_OK){
		int count = pResults->iBarcodeCount;
		pBarcodeResult* ppBarcodes = pResults->ppBarcodes;
		pBarcodeResult tmp = NULL;

		// javascript callback function
		Local<Function> cb = Local<Function>::Cast(args[2]);
		const unsigned argc = 1;

		// array for storing barcode results
		Local<Array> barcodeResults = Array::New(isolate);

		for (int i = 0; i < count; i++)
		{
			tmp = ppBarcodes[i];

			Local<Object> result = Object::New(isolate);
			result->Set(String::NewFromUtf8
			(isolate, "format"), Number::New(isolate, tmp->llFormat));
			result->Set(String::NewFromUtf8
			(isolate, "value"), String::NewFromUtf8(isolate, tmp->pBarcodeData));

			barcodeResults->Set(Number::New(isolate, i), result);
		}

		// release memory
		DBR_FreeBarcodeResults(&pResults);

		Local<Value> argv[argc] = { barcodeResults };
		cb->Call(isolate->GetCurrentContext()->Global(), argc, argv);
	}
}

void Init(Handle<Object> exports) {
	NODE_SET_METHOD(exports, "decodeFile", DecodeFile);
}

NODE_MODULE(dbr, Init)

Automatically generate the project build files:

node-gyp configure

Build the project to produce dbr.node:

node-gyp build

Write a test dbr.js which loads SDK license and invokes native reader methods:

var dbr = require('./build/Release/dbr');
var readline = require('readline');
var fs = require('fs');

fs.readFile('./license.txt', 'utf8', function (err, data) {
  if (err) throw err;
  var rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
  });

  var license = data.trim();
  rl.question("Please input a barcode image path: ", function(answer) {

    dbr.decodeFile(
      answer, license,
      function(msg){
        var result = null;
        for (index in msg) {
          result = msg[index]
          console.log(result['format']);
          console.log(result['value']);
          console.log("##################");
        }
      }
    );

    rl.close();
  });
});

Run the script:

node dbr.js