ASP.NET Barcode-Scanner: Datei-Upload und REST-API mit IronBarcode

Install-Package BarCode

dotnet add package BarCode

using IronBarCode;

Imports IronBarCode

// Server-side processing -- recommended for most ASP.NET scenarios
var options = new BarcodeReaderOptions
{
    Speed = ReadingSpeed.Balanced,
    ExpectMultipleBarcodes = true,
    UseConfidenceThreshold = true,
    ConfidenceThreshold = 0.85
};

var results = BarcodeReader.Read(stream, options);

foreach (var barcode in results)
{
    Console.WriteLine($"Type: {barcode.BarcodeType}, Value: {barcode.Text}");
}

Imports System

' Server-side processing -- recommended for most ASP.NET scenarios
Dim options As New BarcodeReaderOptions With {
    .Speed = ReadingSpeed.Balanced,
    .ExpectMultipleBarcodes = True,
    .UseConfidenceThreshold = True,
    .ConfidenceThreshold = 0.85
}

Dim results = BarcodeReader.Read(stream, options)

For Each barcode In results
    Console.WriteLine($"Type: {barcode.BarcodeType}, Value: {barcode.Text}")
Next

@* Razor view -- barcode upload form *@
<form method="post" enctype="multipart/form-data" id="barcodeForm">
    <div class="form-group">
        <label for="barcodeFile">Select Barcode Image:</label>
        <input type="file" name="barcodeFile" id="barcodeFile"
               accept="image/*,.pdf" class="form-control"
               capture="environment" />
    </div>
    <button type="submit" class="btn btn-primary" id="scanBtn">
        <span class="spinner-border spinner-border-sm d-none" role="status"></span>
        Scan Barcode
    </button>
</form>
<div id="results">
    @ViewBag.BarcodeResult
</div>

@* Razor view -- barcode upload form *@
<form method="post" enctype="multipart/form-data" id="barcodeForm">
    <div class="form-group">
        <label for="barcodeFile">Select Barcode Image:</label>
        <input type="file" name="barcodeFile" id="barcodeFile"
               accept="image/*,.pdf" class="form-control"
               capture="environment" />
    </div>
    <button type="submit" class="btn btn-primary" id="scanBtn">
        <span class="spinner-border spinner-border-sm d-none" role="status"></span>
        Scan Barcode
    </button>
</form>
<div id="results">
    @ViewBag.BarcodeResult
</div>

[HttpPost]
[ValidateAntiForgeryToken]
[RequestSizeLimit(10_000_000)] // 10MB limit
public async Task<IActionResult> ScanBarcode(IFormFile barcodeFile)
{
    var allowedExtensions = new[] { ".jpg", ".jpeg", ".png", ".gif",
                                    ".tiff", ".bmp", ".pdf" };
    var extension = Path.GetExtension(barcodeFile.FileName).ToLowerInvariant();

    if (!allowedExtensions.Contains(extension))
    {
        ModelState.AddModelError("", "Invalid file type");
        return View();
    }

    if (barcodeFile != null && barcodeFile.Length > 0)
    {
        using var stream = new MemoryStream();
        await barcodeFile.CopyToAsync(stream);
        stream.Position = 0;

        var options = new BarcodeReaderOptions
        {
            Speed = ReadingSpeed.Balanced,
            ExpectMultipleBarcodes = true,
            ExpectBarcodeTypes = BarcodeEncoding.AllOneDimensional |
                                BarcodeEncoding.QRCode |
                                BarcodeEncoding.DataMatrix,
            ImageFilters = new ImageFilterCollection
            {
                new SharpenFilter(),
                new ContrastFilter()
            }
        };

        var results = BarcodeReader.Read(stream, options);

        ViewBag.BarcodeResult = results.Any()
            ? string.Join("<br/>", results.Select(r => $"<strong>{r.BarcodeType}:</strong> {r.Text}"))
            : "No barcodes found in the image.";
    }

    return View();
}

Imports Microsoft.AspNetCore.Mvc
Imports Microsoft.AspNetCore.Http
Imports System.IO
Imports System.Threading.Tasks
Imports ZXing

<HttpPost>
<ValidateAntiForgeryToken>
<RequestSizeLimit(10_000_000)> ' 10MB limit
Public Async Function ScanBarcode(barcodeFile As IFormFile) As Task(Of IActionResult)
    Dim allowedExtensions As String() = {".jpg", ".jpeg", ".png", ".gif", ".tiff", ".bmp", ".pdf"}
    Dim extension As String = Path.GetExtension(barcodeFile.FileName).ToLowerInvariant()

    If Not allowedExtensions.Contains(extension) Then
        ModelState.AddModelError("", "Invalid file type")
        Return View()
    End If

    If barcodeFile IsNot Nothing AndAlso barcodeFile.Length > 0 Then
        Using stream As New MemoryStream()
            Await barcodeFile.CopyToAsync(stream)
            stream.Position = 0

            Dim options As New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Balanced,
                .ExpectMultipleBarcodes = True,
                .ExpectBarcodeTypes = BarcodeEncoding.AllOneDimensional Or
                                      BarcodeEncoding.QRCode Or
                                      BarcodeEncoding.DataMatrix,
                .ImageFilters = New ImageFilterCollection From {
                    New SharpenFilter(),
                    New ContrastFilter()
                }
            }

            Dim results = BarcodeReader.Read(stream, options)

            ViewBag.BarcodeResult = If(results.Any(),
                String.Join("<br/>", results.Select(Function(r) $"<strong>{r.BarcodeType}:</strong> {r.Text}")),
                "No barcodes found in the image.")
        End Using
    End If

    Return View()
End Function

[ApiController]
[Route("api/[controller]")]
public class BarcodeController : ControllerBase
{
    private readonly ILogger<BarcodeController> _logger;
    private readonly IMemoryCache _cache;

    public BarcodeController(ILogger<BarcodeController> logger, IMemoryCache cache)
    {
        _logger = logger;
        _cache = cache;
    }

    [HttpPost("scan")]
    [ProducesResponseType(typeof(BarcodeResponse), 200)]
    [ProducesResponseType(typeof(ErrorResponse), 400)]
    public async Task<IActionResult> ScanBarcode([FromBody] BarcodeRequest request)
    {
        try
        {
            if (string.IsNullOrEmpty(request.ImageBase64))
                return BadRequest(new ErrorResponse { Error = "Image data is required" });

            var cacheKey = $"barcode_{request.ImageBase64.GetHashCode()}";
            if (_cache.TryGetValue(cacheKey, out BarcodeResponse cachedResult))
                return Ok(cachedResult);

            byte[] imageBytes = Convert.FromBase64String(request.ImageBase64);

            if (imageBytes.Length > 10 * 1024 * 1024)
                return BadRequest(new ErrorResponse { Error = "Image size exceeds 10MB limit" });

            var options = new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Faster,
                ExpectMultipleBarcodes = request.ExpectMultiple ?? false,
                UseConfidenceThreshold = true,
                ConfidenceThreshold = 0.8
            };

            var results = await Task.Run(() => BarcodeReader.Read(imageBytes, options));

            var response = new BarcodeResponse
            {
                Success = true,
                Barcodes = results.Select(r => new BarcodeData
                {
                    Type = r.BarcodeType.ToString(),
                    Value = r.Text,
                    Confidence = r.Confidence,
                    Position = new BarcodePosition
                    {
                        X = r.Points.Select(p => p.X).Min(),
                        Y = r.Points.Select(p => p.Y).Min(),
                        Width = r.Width,
                        Height = r.Height
                    }
                }).ToList()
            };

            _cache.Set(cacheKey, response, TimeSpan.FromMinutes(5));
            return Ok(response);
        }
        catch (FormatException)
        {
            return BadRequest(new ErrorResponse { Error = "Invalid base64 image data" });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error processing barcode scan");
            return StatusCode(500, new ErrorResponse { Error = "Internal server error" });
        }
    }
}

public record BarcodeRequest(string ImageBase64, bool? ExpectMultiple);

public record BarcodeResponse
{
    public bool Success { get; init; }
    public List<BarcodeData> Barcodes { get; init; } = new();
}

public record BarcodeData
{
    public string Type { get; init; }
    public string Value { get; init; }
    public double Confidence { get; init; }
    public BarcodePosition Position { get; init; }
}

public record BarcodePosition(int X, int Y, int Width, int Height);

public record ErrorResponse
{
    public bool Success => false;
    public string Error { get; init; }
}

Imports System
Imports Microsoft.AspNetCore.Mvc
Imports Microsoft.Extensions.Logging
Imports Microsoft.Extensions.Caching.Memory
Imports System.Threading.Tasks

<ApiController>
<Route("api/[controller]")>
Public Class BarcodeController
    Inherits ControllerBase

    Private ReadOnly _logger As ILogger(Of BarcodeController)
    Private ReadOnly _cache As IMemoryCache

    Public Sub New(logger As ILogger(Of BarcodeController), cache As IMemoryCache)
        _logger = logger
        _cache = cache
    End Sub

    <HttpPost("scan")>
    <ProducesResponseType(GetType(BarcodeResponse), 200)>
    <ProducesResponseType(GetType(ErrorResponse), 400)>
    Public Async Function ScanBarcode(<FromBody> request As BarcodeRequest) As Task(Of IActionResult)
        Try
            If String.IsNullOrEmpty(request.ImageBase64) Then
                Return BadRequest(New ErrorResponse With {.Error = "Image data is required"})
            End If

            Dim cacheKey = $"barcode_{request.ImageBase64.GetHashCode()}"
            Dim cachedResult As BarcodeResponse = Nothing
            If _cache.TryGetValue(cacheKey, cachedResult) Then
                Return Ok(cachedResult)
            End If

            Dim imageBytes As Byte() = Convert.FromBase64String(request.ImageBase64)

            If imageBytes.Length > 10 * 1024 * 1024 Then
                Return BadRequest(New ErrorResponse With {.Error = "Image size exceeds 10MB limit"})
            End If

            Dim options = New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Faster,
                .ExpectMultipleBarcodes = request.ExpectMultiple.GetValueOrDefault(False),
                .UseConfidenceThreshold = True,
                .ConfidenceThreshold = 0.8
            }

            Dim results = Await Task.Run(Function() BarcodeReader.Read(imageBytes, options))

            Dim response = New BarcodeResponse With {
                .Success = True,
                .Barcodes = results.Select(Function(r) New BarcodeData With {
                    .Type = r.BarcodeType.ToString(),
                    .Value = r.Text,
                    .Confidence = r.Confidence,
                    .Position = New BarcodePosition With {
                        .X = r.Points.Select(Function(p) p.X).Min(),
                        .Y = r.Points.Select(Function(p) p.Y).Min(),
                        .Width = r.Width,
                        .Height = r.Height
                    }
                }).ToList()
            }

            _cache.Set(cacheKey, response, TimeSpan.FromMinutes(5))
            Return Ok(response)
        Catch ex As FormatException
            Return BadRequest(New ErrorResponse With {.Error = "Invalid base64 image data"})
        Catch ex As Exception
            _logger.LogError(ex, "Error processing barcode scan")
            Return StatusCode(500, New ErrorResponse With {.Error = "Internal server error"})
        End Try
    End Function
End Class

Public Class BarcodeRequest
    Public Property ImageBase64 As String
    Public Property ExpectMultiple As Boolean?
End Class

Public Class BarcodeResponse
    Public Property Success As Boolean
    Public Property Barcodes As List(Of BarcodeData) = New List(Of BarcodeData)()
End Class

Public Class BarcodeData
    Public Property Type As String
    Public Property Value As String
    Public Property Confidence As Double
    Public Property Position As BarcodePosition
End Class

Public Class BarcodePosition
    Public Property X As Integer
    Public Property Y As Integer
    Public Property Width As Integer
    Public Property Height As Integer
End Class

Public Class ErrorResponse
    Public ReadOnly Property Success As Boolean
        Get
            Return False
        End Get
    End Property
    Public Property Error As String
End Class

public class AdvancedBarcodeProcessor
{
    private readonly ILogger<AdvancedBarcodeProcessor> _logger;

    public async Task<List<ScannedBarcode>> ProcessChallengingImage(Stream imageStream)
    {
        // First pass -- fast, minimal processing
        var fastOptions = new BarcodeReaderOptions
        {
            Speed = ReadingSpeed.Balanced,
            ExpectMultipleBarcodes = true,
            AutoRotate = false,
            UseConfidenceThreshold = true,
            ConfidenceThreshold = 0.85
        };

        var results = BarcodeReader.Read(imageStream, fastOptions);

        if (!results.Any())
        {
            // Second pass -- aggressive image correction
            imageStream.Position = 0;

            var detailedOptions = new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.ExtremeDetail,
                ExpectMultipleBarcodes = true,
                AutoRotate = true,
                RemoveFalsePositive = true,
                UseConfidenceThreshold = true,
                ConfidenceThreshold = 0.6,
                Multithreaded = true,
                ExpectBarcodeTypes = BarcodeEncoding.All,
                ImageFilters = new ImageFilterCollection
                {
                    new SharpenFilter(2.5f),
                    new ContrastFilter(2.0f),
                    new BrightnessFilter(1.2f),
                    new InvertFilter()
                }
            };

            results = BarcodeReader.Read(imageStream, detailedOptions);
            _logger.LogInformation("Second pass detected {Count} barcodes", results.Count());
        }

        return results.Select(r => new ScannedBarcode
        {
            Value = r.Text,
            BarcodeType = r.BarcodeType.ToString(),
            Confidence = r.Confidence,
            RotationAngle = r.RotationAngle,
            PageNumber = r.PageNumber
        }).ToList();
    }
}

public record ScannedBarcode
{
    public string Value { get; init; }
    public string BarcodeType { get; init; }
    public double Confidence { get; init; }
    public float RotationAngle { get; init; }
    public int PageNumber { get; init; }
}

Imports System.IO
Imports System.Collections.Generic
Imports System.Linq
Imports System.Threading.Tasks

Public Class AdvancedBarcodeProcessor
    Private ReadOnly _logger As ILogger(Of AdvancedBarcodeProcessor)

    Public Async Function ProcessChallengingImage(imageStream As Stream) As Task(Of List(Of ScannedBarcode))
        ' First pass -- fast, minimal processing
        Dim fastOptions As New BarcodeReaderOptions With {
            .Speed = ReadingSpeed.Balanced,
            .ExpectMultipleBarcodes = True,
            .AutoRotate = False,
            .UseConfidenceThreshold = True,
            .ConfidenceThreshold = 0.85
        }

        Dim results = BarcodeReader.Read(imageStream, fastOptions)

        If Not results.Any() Then
            ' Second pass -- aggressive image correction
            imageStream.Position = 0

            Dim detailedOptions As New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.ExtremeDetail,
                .ExpectMultipleBarcodes = True,
                .AutoRotate = True,
                .RemoveFalsePositive = True,
                .UseConfidenceThreshold = True,
                .ConfidenceThreshold = 0.6,
                .Multithreaded = True,
                .ExpectBarcodeTypes = BarcodeEncoding.All,
                .ImageFilters = New ImageFilterCollection From {
                    New SharpenFilter(2.5F),
                    New ContrastFilter(2.0F),
                    New BrightnessFilter(1.2F),
                    New InvertFilter()
                }
            }

            results = BarcodeReader.Read(imageStream, detailedOptions)
            _logger.LogInformation("Second pass detected {Count} barcodes", results.Count())
        End If

        Return results.Select(Function(r) New ScannedBarcode With {
            .Value = r.Text,
            .BarcodeType = r.BarcodeType.ToString(),
            .Confidence = r.Confidence,
            .RotationAngle = r.RotationAngle,
            .PageNumber = r.PageNumber
        }).ToList()
    End Function
End Class

Public Class ScannedBarcode
    Public Property Value As String
    Public Property BarcodeType As String
    Public Property Confidence As Double
    Public Property RotationAngle As Single
    Public Property PageNumber As Integer
End Class

@* Razor view with progressive enhancement *@
<div class="barcode-scanner-container">
    @* Camera capture -- hidden until JavaScript confirms support *@
    <div id="cameraSection" class="d-none">
        <video id="videoPreview" class="w-100" autoplay></video>
        <button id="captureBtn" class="btn btn-primary mt-2">Capture and Scan</button>
    </div>

    @* File upload -- always available as fallback *@
    <div id="uploadSection">
        <form method="post" enctype="multipart/form-data"
              asp-action="ScanBarcode" asp-controller="Barcode">
            <div class="form-group">
                <label>Upload Barcode Image:</label>
                <input type="file" name="file" accept="image/*,.pdf"
                       class="form-control" required />
            </div>
            <button type="submit" class="btn btn-primary">Upload and Scan</button>
        </form>
    </div>
</div>

@* Razor view with progressive enhancement *@
<div class="barcode-scanner-container">
    @* Camera capture -- hidden until JavaScript confirms support *@
    <div id="cameraSection" class="d-none">
        <video id="videoPreview" class="w-100" autoplay></video>
        <button id="captureBtn" class="btn btn-primary mt-2">Capture and Scan</button>
    </div>

    @* File upload -- always available as fallback *@
    <div id="uploadSection">
        <form method="post" enctype="multipart/form-data"
              asp-action="ScanBarcode" asp-controller="Barcode">
            <div class="form-group">
                <label>Upload Barcode Image:</label>
                <input type="file" name="file" accept="image/*,.pdf"
                       class="form-control" required />
            </div>
            <button type="submit" class="btn btn-primary">Upload and Scan</button>
        </form>
    </div>
</div>