using IronQr;
using IronSoftware.Drawing;
private string? qrImageSrc;
private string scannedText = string.Empty;
private async Task OnFileSelected(InputFileChangeEventArgs e)
{
var file = e.File;
var tempPath = Path.Combine(Path.GetTempPath(), file.Name);
await using var stream = file.OpenReadStream(maxAllowedSize: 10_000_000);
await using var fs = File.Create(tempPath);
await stream.CopyToAsync(fs);
qrImageSrc = tempPath;
}
private async Task ScanQRCode()
{
// Load the scanned QR code
var inputBmp = AnyBitmap.FromFile(qrImageSrc!);
var imageInput = new QrImageInput(inputBmp);
var reader = new QrReader();
// Read the scanned QR code
var results = reader.Read(imageInput);
// Check if a result was found
var firstResult = results.FirstOrDefault();
if (firstResult != null)
{
// Save the QR code value as a string
scannedText = firstResult.Value;
}
else
{
scannedText = "No QR code found in the selected image.";
}
}
Imports IronQr
Imports IronSoftware.Drawing
Imports System.IO
Imports Microsoft.AspNetCore.Components.Forms
Imports System.Threading.Tasks
Private qrImageSrc As String = Nothing
Private scannedText As String = String.Empty
Private Async Function OnFileSelected(e As InputFileChangeEventArgs) As Task
Dim file = e.File
Dim tempPath = Path.Combine(Path.GetTempPath(), file.Name)
Await Using stream = file.OpenReadStream(maxAllowedSize:=10000000)
Await Using fs = File.Create(tempPath)
Await stream.CopyToAsync(fs)
End Using
End Using
qrImageSrc = tempPath
End Function
Private Async Function ScanQRCode() As Task
' Load the scanned QR code
Dim inputBmp = AnyBitmap.FromFile(qrImageSrc)
Dim imageInput = New QrImageInput(inputBmp)
Dim reader = New QrReader()
' Read the scanned QR code
Dim results = reader.Read(imageInput)
' Check if a result was found
Dim firstResult = results.FirstOrDefault()
If firstResult IsNot Nothing Then
' Save the QR code value as a string
scannedText = firstResult.Value
Else
scannedText = "No QR code found in the selected image."
End If
End Function
Install-Package IronQR
Blazor QR Code Scanner
Use IronQR to scan QR codes in a Blazor Server application. Upload an image through the browser with Blazor's InputFile component, then decode it server-side with QrReader.Read().
5-step guide for scanning a QR code in Blazor
using IronQr;
using IronSoftware.Drawing;
await using var stream = file.OpenReadStream(maxAllowedSize: 10_000_000);
var inputBmp = AnyBitmap.FromFile(qrImageSrc!);
var results = reader.Read(imageInput);
Code Explanation
InputFile.OnChange fires when the user selects a file. OpenReadStream streams the browser upload to a temporary server path, which is then passed to AnyBitmap.FromFile to decode the image format. A QrImageInput wraps the bitmap for IronQR, and QrReader.Read returns an IEnumerable<QrResult>. FirstOrDefault safely retrieves the first result without throwing on images that contain no QR code.