How to Build .NET 6 Barcode and QR Code SDK for Windows, Linux & macOS

Microsoft .NET 6 SDK empowers C# developers to build cross-platform DotNet applications for Windows, Linux, and macOS from one codebase. This article describes the steps to build a .NET 6 barcode and QR code decoding library based on Dynamsoft C/C++ Barcode SDK, as well as how to pack the library into a NuGet package.

.NET 6 SDK Installation

• Windows
• Linux
• Mac

Dynamsoft Barcode Reader

1. Download C/C++ SDK v9.0.
2. Get a valid license key for activating the SDK.

Steps to Develop and Build .NET 6 Barcode and QR Code SDK

1. Create a new library project:
   

   dotnet new classlib -o BarcodeQRCodeSDK

2. Copy shared library files from the C/C++ SDK package to the project root directory. For different platforms, the minimum required shared library files are:

- Windows: `DynamsoftBarcodeReader.dll`, `vcomp110.dll`- Linux: `libDynamsoftBarcodeReader.so`- macOS: `libDynamsoftBarcodeReader.dylib`    

1. Rename Class1.cs to BarcodeQRCodeReader.cs.

2. P/Invoke is the technology used for bridging C/C++ and .NET. In the BarcodeQRCodeReader.cs file, we use DllImport to load the unmanaged shared library (e.g. *.dll, *.so, *.dylib) and define some managed methods to communicate with the native component.
   

   [DllImport("DynamsoftBarcodeReader")]static extern IntPtr DBR_CreateInstance();[DllImport("DynamsoftBarcodeReader")]static extern void DBR_DestroyInstance(IntPtr hBarcode);[DllImport("DynamsoftBarcodeReader")]static extern int DBR_InitLicense(string license, [Out] byte[] errorMsg, int errorMsgSize);[DllImport("DynamsoftBarcodeReader")]static extern int DBR_DecodeFile(IntPtr hBarcode, string filename, string template);[DllImport("DynamsoftBarcodeReader")]static extern int DBR_FreeTextResults(ref IntPtr pTextResultArray);[DllImport("DynamsoftBarcodeReader")]static extern void DBR_GetAllTextResults(IntPtr hBarcode, ref IntPtr pTextResultArray);[DllImport("DynamsoftBarcodeReader")]static extern int DBR_DecodeBuffer(IntPtr hBarcode, IntPtr pBufferBytes, int width, int height, int stride, ImagePixelFormat format, string template);[DllImport("DynamsoftBarcodeReader")]static extern int DBR_DecodeBase64String(IntPtr hBarcode, string base64string, string template);

3. In addition, we need to define some native structs in C#:
   

   [StructLayout(LayoutKind.Sequential, Pack = 1)]internal struct PTextResult{    BarcodeFormat emBarcodeFormat;    public string barcodeFormatString;    BarcodeFormat_2 barcodeFormat_2;    string barcodeFormatString_2;    public string barcodeText;    IntPtr barcodeBytes;    int barcodeBytesLength;    IntPtr localizationResult;    IntPtr detailedResult;    int resultsCount;    IntPtr results;    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 56)]    char[] reserved;}[StructLayout(LayoutKind.Sequential, Pack = 1)]internal struct TextResultArray{    public int resultsCount;    public IntPtr results;}

4. The memory operation between the managed structure and the unmanaged pointer is a little bit tricky. We need to use Marshal to convert data:
   

   IntPtr pTextResultArray = IntPtr.Zero;DBR_GetAllTextResults(hBarcode, ref pTextResultArray);if (pTextResultArray != IntPtr.Zero){    string[]? resultArray = null;    TextResultArray? results = (TextResultArray?)Marshal.PtrToStructure(pTextResultArray, typeof(TextResultArray));    if (results != null)    {        int count = results.Value.resultsCount;        if (count > 0)        {            IntPtr[] barcodes = new IntPtr[count];            Marshal.Copy(results.Value.results, barcodes, 0, count);            resultArray = new string[count];            for (int i = 0; i < count; i++)            {                PTextResult? result = (PTextResult?)Marshal.PtrToStructure(barcodes[i], typeof(PTextResult));                if (result != null)                {                    resultArray[i] = result.Value.barcodeText;                }            }        }    }    DBR_FreeTextResults(ref pTextResultArray);    return resultArray;}

5. Once the communication problem between managed and unmanaged code is solved, we can define some high-level C# methods:
   

   public class BarcodeQRCodeReader{    private IntPtr hBarcode;    private static string? licenseKey;    public static void InitLicense(string license) {        byte[] errorMsg = new byte[512];        licenseKey = license;        DBR_InitLicense(license, errorMsg, 512);        Console.WriteLine(Encoding.ASCII.GetString(errorMsg) + "
   ");    }    private BarcodeQRCodeReader()    {        hBarcode = DBR_CreateInstance();    }    public static BarcodeQRCodeReader Create()    {        if (licenseKey == null)        {            throw new Exception("Please call InitLicense first.");        }        return new BarcodeQRCodeReader();    }    ~BarcodeQRCodeReader()    {        if (hBarcode != IntPtr.Zero)        {            DBR_DestroyInstance(hBarcode);            hBarcode = IntPtr.Zero;        }    }    public void Destroy()    {        if (hBarcode != IntPtr.Zero)        {            DBR_DestroyInstance(hBarcode);            hBarcode = IntPtr.Zero;        }    }    public string[]? DecodeFile(string filename)    {        if (hBarcode == IntPtr.Zero) return null;        int ret = DBR_DecodeFile(hBarcode, filename, "");        return OutputResults();    }}

6. Build the source code to generate the *.dll file.
   

   dotnet build --configuration Release

How to Generate and Publish NuGet Package

To generate the *.nupkg file, the easiest way is to add <GeneratePackageOnBuild>true</GeneratePackageOnBuild> to the *.csproj file:

<PropertyGroup>  ...  <GeneratePackageOnBuild>true</GeneratePackageOnBuild>  ...</PropertyGroup>

Then the *.nupkg file will be generated automatically when you build the project.

Our package contains some native library files. To pack them into the *.nupkg file correctly, we set the corresponding PackagePath in *.csproj file according to the Runtime Identifier:

<ItemGroup>  <None CopyToOutputDirectory="Always" Include="DynamsoftBarcodeReader.dll" Pack="true" PackagePath="runtimes/win-x64/native/DynamsoftBarcodeReader.dll" />  <None CopyToOutputDirectory="Always" Include="vcomp110.dll" Pack="true" PackagePath="runtimes/win-x64/native/vcomp110.dll" />  <None CopyToOutputDirectory="Always" Include="libDynamsoftBarcodeReader.dylib" Pack="true" PackagePath="runtimes/osx-x64/native/libDynamsoftBarcodeReader.dylib" />  <None CopyToOutputDirectory="Always" Include="libDynamsoftBarcodeReader.so" Pack="true" PackagePath="runtimes/linux-x64/native/libDynamsoftBarcodeReader.so" /></ItemGroup>

As the *.nupkg file is ready, we can publish it to the NuGet Gallery either via the dotnet command:

dotnet nuget push *.nupkg -k <api-key> -s https://api.nuget.org/v3/index.json

or the NuGet online page.

Here is the final page of BarcodeQRCodeSDK:
https://www.nuget.org/packages/BarcodeQRCodeSDK/

How to Add a .NET Library Project as a Reference Locally

For source code, add <ProjectReference> in *.csproj file:

<ItemGroup>    <ProjectReference Include="..\..\BarcodeQRCodeSDK.csproj" /></ItemGroup>

For generated *.nupkg file, add the package directory to NuGet source list and then install the package via dotnet add package:

dotnet nuget add source <package directory>dotnet add package <package name>

A Simple .NET 6 Command-line Example

1. Create a new .NET console app:
   

   dotnet new console -o Test

2. Install the .NET Barcode and QR Code SDK:
   

   dotnet add package BarcodeQRCodeSDK

3. Use the following code to decode barcode and QR code from an image file:
   

   using System;using System.Runtime.InteropServices;using Dynamsoft;namespace Test{    class Program    {        static void Main(string[] args)        {            BarcodeQRCodeReader.InitLicense("LICENSE-KEY");            BarcodeQRCodeReader? reader = null;            try {                reader = BarcodeQRCodeReader.Create();                Console.WriteLine("Please enter an image file: ");                string? filename = Console.ReadLine();                if (filename != null) {                    string[]? results = reader.DecodeFile(filename);                    if (results != null) {                        foreach (string result in results) {                            Console.WriteLine(result);                        }                    }                    else {                        Console.WriteLine("No barcode found.");                    }                }            }            catch (Exception e)            {                Console.WriteLine(e.Message);            }            finally            {                if (reader != null)                {                    reader.Destroy();                }            }        }    }}

4. Run the application in Windows, Linux or macOS:
   

   dotnet run

   

Source Code

https://github.com/yushulx/dotnet-barcode-qr-code-sdk