Release v1.1: USB Barcode Scanner Library

This commit introduces version 1.1 of the USB Barcode Scanner Library for the .NET framework, developed by BasselTech in C#. This library enables the capture of barcode scans from USB barcode scanners in both C# and VB .NET applications.

The library employs Win32 API functions to monitor keyboard key-down events and detects scanned barcodes based on the timing between keystrokes. Upon successful barcode detection, the BarcodeScanned event is triggered, providing a BarcodeScannedEventArgs object containing the scanned barcode.

This release marks the initial version of the library, offering fundamental barcode scanning functionality for .NET applications.

Properties/AssemblyInfo.cs

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+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("USB Barcode Scanner")]
+[assembly: AssemblyDescription("USB Barcode Scanner")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("BasselTech")]
+[assembly: AssemblyProduct("USB Barcode Scanner")]
+[assembly: AssemblyCopyright("Copyright © BasselTech. All rights reserved.")]
+[assembly: AssemblyTrademark("BasselTech")]
+[assembly: AssemblyCulture("")]
+
+// Setting ComVisible to false makes the types in this assembly not visible
+// to COM components.  If you need to access a type in this assembly from
+// COM, set the ComVisible attribute to true on that type.
+[assembly: ComVisible(false)]
+
+// The following GUID is for the ID of the typelib if this project is exposed to COM
+[assembly: Guid("ec90583a-a843-42ad-ad7b-e8096ca65871")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.1.0.0")]
+[assembly: AssemblyFileVersion("1.1.0.0")]

UsbBarcodeScanner.cs

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+using System;
+using System.Runtime.InteropServices;
+using System.Collections.Generic;
+using System.Windows.Forms;
+using System.Text;
+
+namespace BasselTech
+{
+    namespace UsbBarcodeScanner
+    {
+        public class BarcodeScannedEventArgs : EventArgs
+        {
+            public BarcodeScannedEventArgs(string barcode)
+            {
+                Barcode = barcode;
+            }
+
+            public string Barcode { get; }
+        }
+
+        public class UsbBarcodeScanner
+        {
+            #region WinAPI Declarations
+
+            [DllImport("kernel32.dll")]
+            private static extern IntPtr LoadLibrary(string lpLibFileName);
+
+            [DllImport("user32.dll")]
+            private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hInstance, uint threadId);
+
+            [DllImport("user32.dll")]
+            private static extern bool UnhookWindowsHookEx(IntPtr hhk);
+
+            [DllImport("user32.dll")]
+            private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
+
+            [DllImport("user32.dll")]
+            private static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr lpdwProcessId);
+
+            [DllImport("user32.dll")]
+            private static extern IntPtr GetKeyboardLayout(uint idThread);
+
+            [DllImport("user32.dll")]
+            static extern bool GetKeyboardState(byte[] lpKeyState);
+
+            [DllImport("user32.dll")]
+            static extern uint MapVirtualKey(uint uCode, uint uMapType);
+
+            [DllImport("user32.dll")]
+            static extern int ToUnicodeEx(uint wVirtKey, uint wScanCode, byte[] lpKeyState, [Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pwszBuff, int cchBuff, uint wFlags, IntPtr dwhkl);
+
+            #endregion
+
+            #region Delegates and Constants
+
+            private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
+            private const int WH_KEYBOARD_LL = 13;
+            private const int WM_KEYDOWN = 0x0100;
+
+            #endregion
+
+            #region Private Fields
+
+            private static IntPtr _hookId = IntPtr.Zero;
+            private readonly List<Keys> _keys = new List<Keys>();
+            private readonly Timer _timer = new Timer();
+
+            #endregion
+
+            #region Events
+
+            public event EventHandler<BarcodeScannedEventArgs> BarcodeScanned;
+
+            #endregion
+
+            #region Constructor
+
+            public UsbBarcodeScanner()
+            {
+                _timer.Interval = 20;
+                _timer.Tick += (sender, args) => _keys.Clear();
+                _timer.Stop();
+            }
+
+            public void Start()
+            {
+                if (IsCapturing())
+                    return;
+                _hookId = SetHook(KeyboardHookCallback);
+                _timer.Start();
+            }
+
+            public void Stop()
+            {
+                if (!IsCapturing())
+                    return;
+                UnhookWindowsHookEx(_hookId);
+                _hookId = IntPtr.Zero;
+                _timer.Stop();
+                _keys.Clear();
+            }
+
+            public bool IsCapturing()
+            {
+                return _hookId != IntPtr.Zero;
+            }
+
+            #endregion
+
+            #region Private Methods
+
+            private IntPtr SetHook(LowLevelKeyboardProc proc)
+            {
+                using (var curProcess = System.Diagnostics.Process.GetCurrentProcess())
+                using (var curModule = curProcess.MainModule)
+                {
+                    return SetWindowsHookEx(WH_KEYBOARD_LL, proc, LoadLibrary("user32"), 0);
+                }
+            }
+
+            private string GetBarcodeString()
+            {
+                var barcodeBuilder = new StringBuilder();
+                var shiftFlag = false;
+
+                foreach (var key in _keys)
+                {
+                    if (key == Keys.ShiftKey || key == Keys.LShiftKey || key == Keys.RShiftKey)
+                    {
+                        shiftFlag = true;
+                        continue;
+                    }
+
+                    barcodeBuilder.Append(KeyCodeToUnicode(key, shiftFlag));
+                    shiftFlag = false;
+                }
+
+                return barcodeBuilder.ToString();
+            }
+
+            private string KeyCodeToUnicode(Keys key, bool shiftFlag)
+            {
+                var lpKeyState = new byte[255];
+                GetKeyboardState(lpKeyState);
+
+                if (shiftFlag)
+                    lpKeyState[(int)Keys.ShiftKey] = 0x80;
+
+                var wVirtKey = (uint)key;
+                var wScanCode = MapVirtualKey(wVirtKey, 0);
+
+                var pwszBuff = new StringBuilder();
+                ToUnicodeEx(wVirtKey, wScanCode, lpKeyState, pwszBuff, 5, 0, GetKeyboardLayout(0));
+
+                return pwszBuff.ToString();
+            }
+
+            private IntPtr KeyboardHookCallback(int nCode, IntPtr wParam, IntPtr lParam)
+            {
+                if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN)
+                {
+                    // Extract the virtual key code
+                    var vkCode = Marshal.ReadInt32(lParam);
+
+                    // Convert the virtual key code to a Keys enum value
+                    var key = (Keys)vkCode;
+
+                    _timer.Stop();
+                    if (key == Keys.Enter)
+                    {
+                        if (_keys.Count > 0)
+                        {
+                            var barcode = GetBarcodeString();
+                            BarcodeScanned?.Invoke(this, new BarcodeScannedEventArgs(barcode));
+                        }
+                        _keys.Clear();
+                    }
+                    else
+                    {
+                        _keys.Add(key);
+                        _timer.Start();
+                    }
+                }
+
+                return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam);
+            }
+
+            #endregion
+
+            #region Destructor
+
+            ~UsbBarcodeScanner()
+            {
+                Stop();
+            }
+
+            #endregion
+        }
+
+    }
+}

usb-barcode-scanner-lib.csproj

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{EC90583A-A843-42AD-AD7B-E8096CA65871}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>BasselTech</RootNamespace>
+    <AssemblyName>USB-Barcode-Scanner</AssemblyName>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+    <Deterministic>true</Deterministic>
+    <TargetFrameworkProfile />
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Windows.Forms" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="UsbBarcodeScanner.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+</Project>

usb-barcode-scanner-lib.sln

@@ -0,0 +1,25 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.34729.46
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "usb-barcode-scanner-lib", "usb-barcode-scanner-lib.csproj", "{EC90583A-A843-42AD-AD7B-E8096CA65871}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{EC90583A-A843-42AD-AD7B-E8096CA65871}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{EC90583A-A843-42AD-AD7B-E8096CA65871}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{EC90583A-A843-42AD-AD7B-E8096CA65871}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{EC90583A-A843-42AD-AD7B-E8096CA65871}.Release|Any CPU.Build.0 = Release|Any CPU
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+	EndGlobalSection
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+	EndGlobalSection
+EndGlobal