Where does QrReader live in the IronQR API?

QrReader is a class in the IronQr namespace, shipped in IronQr.dll. Construct it with new QrReader() and call Read or ReadAsync with an IQrInput such as QrImageInput.

How do you read a QR code from an image in C#?

Create a QrReader, wrap the image in a QrImageInput with a QrScanMode, and call Read to get an IEnumerable . Read each result's Value for the decoded text. Use ReadAsync for the non-blocking form.

Can IronQR read multiple QR codes from one image?

Yes. QrReader.Read returns an IEnumerable with one entry per code detected in the image, so iterate the results. Each QrResult also reports its position through the Points property.

Class QrReader

Provides functionality to read QR codes with optional settings.

Inheritance

System.Object

QrReader

Namespace: IronQr

Assembly: IronQr.dll

Syntax

public class QrReader : Object

Reading QR codes from an image in C# runs through QrReader. A single reader detects and decodes every QR code in a supplied image, so one call handles a photo or scan that contains one code or several. It is the entry point a developer reaches for behind a search like "C# QR code reader".

Create one with new QrReader() and call Read, passing an IQrInput. The usual input is a QrImageInput wrapping an AnyBitmap loaded from a file, stream, or bytes, with a QrScanMode that selects the detection strategy. Read returns an IEnumerable<QrResult>, one entry per code found, and ReadAsync is the awaitable form for keeping the call off the UI or request thread.

Each QrResult carries the decoded Value, a parsed Url when the value is a link, the detected QrType as a QrEncoding, and the corner Points that locate the code in the image. Because a single image can hold multiple codes, iterate the results rather than assuming one. Set QrScanMode.Auto on the input for difficult photos, where the machine-learning model improves detection, and a basic mode for clean, generated images. IronQR reads from photos, screenshots, and scanned documents, not only crisp generated images, which is why the default mode favors detection accuracy, and the same reader handles a QR code on a PDF page once that page is rendered to a bitmap.

using IronQr;
using IronSoftware.Drawing;

var reader = new QrReader();
using var input = new QrImageInput(AnyBitmap.FromFile("qr.png"), QrScanMode.Auto);
foreach (QrResult result in reader.Read(input))
    Console.WriteLine(result.Value);

The read QR code example covers a basic read, the read from image how-to handles real images, and the scan modes how-to tunes detection.

Constructors

QrReader()

Initializes a new instance of the QrReader class.

Declaration

public QrReader()

Methods

Read(IQrInput)

Detects and reads all QR code(s) in the frame(s) of the IQrInput provided and wraps all results in a QrResult with coordinates and value information.

Declaration

public IEnumerable<QrResult> Read(IQrInput input)

Parameters

Type	Name	Description
IQrInput	input	Wrapped frame bitmap

Returns

Type	Description
System.Collections.Generic.IEnumerable<QrResult>	Object with 4 IronSoftware.Drawing.PointF coordinate values, and QR Code value

Remarks

If using the IronQr.Slim package alone without IronQr, the operation will not use the Machine Learning model to detect QR Codes resulting in a longer, lower quality read.

ReadAsync(IQrInput)

Detects and reads all QR code(s) in the frame(s) of the IQrInput provided asynchronously and wraps all results in a QrResult with coordinates and value information.

Declaration

public Task<IEnumerable<QrResult>> ReadAsync(IQrInput input)

Parameters

Type	Name	Description
IQrInput	input	Wrapped frame bitmap

Returns

Type	Description
System.Threading.Tasks.Task<System.Collections.Generic.IEnumerable<QrResult>>	A task that represents the asynchronous read operation. The value of the TResult parameter contains an object with 4 IronSoftware.Drawing.PointF coordinate values, and QR Code value.

Remarks

If using the IronQr.Slim package alone without IronQr, the operation will not use the Machine Learning model to detect QR Codes resulting in a longer, lower quality read.