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这期内容当中小编将会给大家带来有关Node.js 中怎么实现一个条形码识别程序,文章内容丰富且以专业的角度为大家分析和叙述,阅读完这篇文章希望大家可以有所收获。
Node.js 扩展使用 C/C++ 编写的动态链接的共享对象。如果你没有接触过这方面的技术,可以阅读 官方教程 。
创建名为 dbr.cc 的文件,并添加方法 DecodeFile:
#include <node.h> #include <string.h> #include "If_DBR.h" #include "BarcodeFormat.h" #include "BarcodeStructs.h" #include "ErrorCode.h" using namespace v8; void DecodeFile(const FunctionCallbackInfo<Value>& args) { } //在此我向大家推荐一个前端全栈开发交流圈:619586920 突破技术瓶颈,提升思维能力 void Init(Handle<Object> exports) { NODE_SET_METHOD(exports, "decodeFile", DecodeFile); } NODE_MODULE(dbr, Init)
解析来自 JavaScript 传递过来的参数
Isolate* isolate = Isolate::GetCurrent(); HandleScope scope(isolate); String::Utf8Value license(args[0]->ToString()); String::Utf8Value fileName(args[1]->ToString()); char *pFileName = *fileName; char *pszLicense = *license; __int64 llFormat = args[2]->IntegerValue(); Local<Function> cb = Local<Function>::Cast(args[3]);
解析条形码图像:
int iMaxCount = 0x7FFFFFFF; ReaderOptions ro = {0}; pBarcodeResultArray pResults = NULL; ro.llBarcodeFormat = llFormat; ro.iMaxBarcodesNumPerPage = iMaxCount; DBR_InitLicense(pszLicense); // Decode barcode image int ret = DBR_DecodeFile(pFileName, &ro, &pResults);
将条形码转成字符串:
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"; }
将结果转成 v8 对象:
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"), String::NewFromUtf8(isolate, GetFormatStr(tmp->llFormat))); result->Set(String::NewFromUtf8(isolate, "value"), String::NewFromUtf8(isolate, tmp->pBarcodeData)); barcodeResults->Set(Number::New(isolate, i), result); } //在此我向大家推荐一个前端全栈开发交流圈:619586920 突破技术瓶颈,提升思维能力
要求:
Windows: 需要安装 DBR for Windows, Visual Studio, and Python .
Linux: 安装 DBR for Linux.
Mac: 安装 DBR for Mac 和 Xcode.
安装 node-gyp:
npm install -g node-gyp
创建 binding.gyp 用于多平台编译:
{ "targets": [ { 'target_name': "dbr", 'sources': [ "dbr.cc" ], 'conditions': [ ['OS=="linux"', { 'defines': [ 'LINUX_DBR', ], 'include_dirs': [ "/home/xiao/Dynamsoft/BarcodeReader4.0/Include" ], 'libraries': [ "-lDynamsoftBarcodeReaderx64", "-L/home/xiao/Dynamsoft/BarcodeReader4.0/Redist" ], 'copies': [ { 'destination': 'build/Release/', 'files': [ '/home/xiao/Dynamsoft/BarcodeReader4.0/Redist/libDynamsoftBarcodeReaderx64.so' ] }] }], ['OS=="win"', { 'defines': [ 'WINDOWS_DBR', ], 'include_dirs': [ "F:/Program Files (x86)/Dynamsoft/Barcode Reader 4.1/Components/C_C++/Include" ], 'libraries': [ "-lF:/Program Files (x86)/Dynamsoft/Barcode Reader 4.1/Components/C_C++/Lib/DBRx64.lib" ], 'copies': [ { 'destination': 'build/Release/', 'files': [ 'F:/Program Files (x86)/Dynamsoft/Barcode Reader 4.1/Components/C_C++/Redist/DynamsoftBarcodeReaderx64.dll' ] }] }], ['OS=="mac"', { 'defines': [ 'MAC_DBR', ], 'include_dirs' : [ "/Applications/Dynamsoft/Barcode/ Reader/ 4.1/Include" ], 'libraries': [ "-lDynamsoftBarcodeReader" ] }] ] } //在此我向大家推荐一个前端全栈开发交流圈:619586920 突破技术瓶颈,提升思维能力 ] }
将 DRB 安装目录替换成你机器上的实际目录。
配置构建环境:
node-gyp configure</pre>
可以在 Mac 上你会碰到下面的错误:
error: xcodeselect: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
解决办法是:
sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
构建项目:
node-gyp build
你已经成功的构建了 Node 的条形码解析模块,现在可以创建一个简单的条形码读取应用。
安装 Express 和 Formidable:
npm install express npm install formidable
使用 Express 创建一个简单应用:
var formidable = require('formidable'); var util = require('util'); var express = require('express'); var fs = require('fs'); var app = express(); var path = require('path'); var dbr = require('./build/Release/dbr'); var http = require('http'); fs.readFile('./license.txt', 'utf8', function(err, data) { app.use(express.static(__dirname)); app.use(function(req, res, next) { res.header("Access-Control-Allow-Origin", "*"); res.header("Access-Control-Allow-Methods", "PUT, POST, GET, DELETE, OPTIONS"); res.header("Access-Control-Allow-Headers", "X-Requested-With, content-type"); res.header("Access-Control-Allow-Credentials", true); next(); }); var server = app.listen(2019, function() { var host = server.address().address; var port = server.address().port; console.log('listening at http://%s:%s', host, port); }); });
使用 Formidable 从表单中提取图像数据:
app.post('/upload', function(req, res) { var form = new formidable.IncomingForm(); form.parse(req, function(err, fields, files) { var dir = 'uploads'; fs.mkdir(dir, function(err) { var flag = fields.uploadFlag; var barcodeType = parseInt(fields.barcodetype); console.log('flag: ' + flag); if (flag === '1') { // read barcode image file fs.readFile(files.fileToUpload.path, function(err, data) { // save file from temp dir to new dir var fileName = path.join(__dirname, dir, files.fileToUpload.name); console.log(fileName); fs.writeFile(fileName, data, function(err) { if (err) throw err; }); }); } else { // read barcode image url var tmpFileName = path.join(__dirname, dir, 'tmp.jpg'); var tmp = fs.createWriteStream(tmpFileName); var url = fields.fileToDownload; console.log('url: ' + url); http.get(url, function(response) { response.pipe(tmp); tmp.on('finish', function() { tmp.close(function() { }); }); }); } //在此我向大家推荐一个前端全栈开发交流圈:619586920 突破技术瓶颈,提升思维能力 }); }); });
导入条形码模块用来解析图像文件:
decodeBarcode(res, license, tmpFileName, barcodeType);
运行应用:
node server.js
访问 http://localhost:2019/index.htm:
上述就是小编为大家分享的Node.js 中怎么实现一个条形码识别程序了,如果刚好有类似的疑惑,不妨参照上述分析进行理解。如果想知道更多相关知识,欢迎关注亿速云行业资讯频道。
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