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Xiao Ling
Xiao Ling

Posted on • Edited on • Originally published at dynamsoft.com

Building Cross-platform Document Scanning and Management Application with Electron

#electron #documentmanagement

Electron is a framework for building cross-platform desktop applicationss with HTML, JavaScript, and CSS. Since Dynamic Web TWAIN is also a cross-platform JavaScript library for document scanning and management, we can combine Electron and Dynamic Web TWAIN to implement a desktop document scanning and management application for Windows, Linux, and macOS.

What You Should Know About Dynamic Web TWAIN

Electron Installation 

npm install -g electron
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Reference

Electron Application for Document Scanning and Management

Let's get started with electron-quick-start:

git clone https://github.com/electron/electron-quick-start cd electron-quick-start npm install npm start
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Here is the basic structure of an Electron project:

app/ ├── package.json ├── main.js └── index.html
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The main.js file is the entry point of Electron defined in the package.json file:

"main": "main.js", "scripts": { "start": "electron main.js" },
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The index.html file is loaded in the main.js file:

mainWindow.loadURL('file://' + __dirname + '/index.htm'); // or mainWindow.loadFile('index.html');
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Although the default code works fine, if you want to make the window bigger and resizable, you can change the code:

mainWindow = new BrowserWindow({ width: 1024, height: 1024, resizable: true });
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To implement document scanning and document management, We just need to put some efforts into the HTML5 code in index.html. There is no difference comparing to building a web application.

The JavaScript library files of Dynamic Web TWAIN are in the Dynamic Web TWAIN SDK <version number>\Resources folder. So we copy the folder to the Electron project, and then include the *.js files in index.html:

<head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Document Scanner</title> <script type="text/javascript" src="Resources/dynamsoft.webtwain.initiate.js"></script> <script type="text/javascript" src="Resources/dynamsoft.webtwain.config.js"></script> </head>
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To make the SDK work, we must set the license string in Resources/dynamsoft.webtwain.config.js:

Dynamsoft.DWT.ProductKey = 'LICENSE-KEY';
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We create a select element for selecting connected document scanners, a div element as the document image container, and three buttons for scanning, loading and saving images:

<select size="1" id="source"></select> <div id="dwtcontrolContainer"></div> <input type="button" value="Scan" onclick="scanImage();" /> <input type="button" value="Load" onclick="loadImage();" /> <input type="button" value="Save" onclick="saveImage();" />
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The following JavaScript code implementation includes the initialization of Dynamic Web TWAIN object and the corresponding button events:

window.onload = function () { Dynamsoft.DWT.RegisterEvent('OnWebTwainReady', Dynamsoft_OnReady); }; var DWObject; function Dynamsoft_OnReady() { DWObject = Dynamsoft.DWT.GetWebTwain('dwtcontrolContainer'); DWObject.Width = 640; DWObject.Height = 640; if (DWObject) { var count = DWObject.SourceCount; for (var i = 0; i < count; i++) document.getElementById("source").options.add(new Option(DWObject.GetSourceNameItems(i), i)); } } function scanImage() { if (DWObject) { var OnAcquireImageSuccess, OnAcquireImageFailure; OnAcquireImageSuccess = OnAcquireImageFailure = function () { DWObject.CloseSource(); }; DWObject.SelectSourceByIndex(document.getElementById("source").selectedIndex); DWObject.OpenSource(); DWObject.IfDisableSourceAfterAcquire = true; DWObject.AcquireImage(OnAcquireImageSuccess, OnAcquireImageFailure); } } function loadImage() { if (DWObject) { DWObject.IfShowFileDialog = true; DWObject.LoadImageEx("", Dynamsoft.DWT.EnumDWT_ImageType.IT_ALL, function OnSuccess() {}, function OnFailure () {}); } } function saveImage() { if (DWObject) { if (DWObject.HowManyImagesInBuffer > 0) { DWObject.IfShowFileDialog = true; if (DWObject.GetImageBitDepth(DWObject.CurrentImageIndexInBuffer) == 1) { DWObject.ConvertToGrayScale(DWObject.CurrentImageIndexInBuffer); } DWObject.SaveAsJPEG("DynamicWebTWAIN.jpg", DWObject.CurrentImageIndexInBuffer); } } }
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Now save the changes and reload the UI. A simple desktop document scanning application is done.

Electron document scanning and management

Application Distribution

To distribute the Electron project:

  1. Pack the app with asar.

    npm install -g asar asar pack your-app app.asar

  2. Download Electron prebuilt package and put app.asar into the recourses folder.

    electron distribution

  3. Double-click electron.exe to check whether your application can run successfully.

  4. Compress the whole folder into a zip file for distribution.

Source Code

https://github.com/yushulx/web-twain-document-scan-management/tree/main/examples/electron

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