Class QrCode

Represents a QR code containing text or binary data.

Instances of this class represent an immutable square grid of dark and light pixels (called modules by the QR code specification). Static factory methods are provided to create QR codes from text or binary data. Some of the methods provide detailed control about the encoding parameters such a QR code size (called version by the standard), error correction level and mask.

QR codes are a type of two-dimensional barcodes, invented by Denso Wave and described in the ISO/IEC 18004 standard.

This class covers the QR Code Model 2 specification, supporting all versions (sizes) from 1 to 40, all 4 error correction levels, and 4 character encoding modes.

Inheritance

System.Object

QrCode

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

Namespace: Net.Codecrete.QrCodeGenerator

Assembly: QrCodeGenerator.dll

Syntax

public class QrCode

Remarks

To create a QR code instance:

High level: Take the payload data and call EncodeText(String, QrCode.Ecc) or EncodeBinary(Byte[], QrCode.Ecc).
Mid level: Custom-make a list of QrSegment instances and call EncodeSegments(List<QrSegment>, QrCode.Ecc, Int32, Int32, Int32, Boolean)
Low level: Custom-make an array of data codeword bytes (including segment headers and final padding, excluding error correction codewords), supply the appropriate version number, and call the QrCode(Int32, QrCode.Ecc, Byte[], Int32).

Constructors

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QrCode(Int32, QrCode.Ecc, Byte[], Int32)

Constructs a QR code with the specified version number, error correction level, data codeword bytes, and mask number.

Declaration

public QrCode(int version, QrCode.Ecc ecl, byte[] dataCodewords, int mask = -1)

Parameters

Type	Name	Description
System.Int32	version	The version (size) to use (between 1 to 40).
QrCode.Ecc	ecl	The error correction level to use.
System.Byte[]	dataCodewords	The bytes representing segments to encode (without ECC).
System.Int32	mask	The mask pattern to use (either -1 for automatic selection, or a value from 0 to 7 for fixed choice).

Remarks

This is a low-level API that most users should not use directly. A mid-level API is the EncodeSegments(List<QrSegment>, QrCode.Ecc, Int32, Int32, Int32, Boolean) function.

Exceptions

Type	Condition
System.ArgumentNullException	`ecl` or `dataCodewords` is `null`.
System.ArgumentOutOfRangeException	The version or mask value is out of range, or the data has an invalid length for the specified version and error correction level.

Fields

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MaxVersion

The maximum version (size) supported in the QR Code Model 2 standard – namely 40.

Declaration

public const int MaxVersion = 40

Field Value

Type	Description
System.Int32	The maximum version.

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MinVersion

The minimum version (size) supported in the QR Code Model 2 standard – namely 1.

Declaration

public const int MinVersion = 1

Field Value

Type	Description
System.Int32	The minimum version.

Properties

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ErrorCorrectionLevel

The error correction level used for this QR code.

Declaration

public QrCode.Ecc ErrorCorrectionLevel { get; }

Property Value

Type	Description
QrCode.Ecc	The error correction level.

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Mask

The index of the mask pattern used fort this QR code (between 0 and 7).

Even if a QR code is created with automatic mask selection (mask = 1), this property returns the effective mask used.

Declaration

public int Mask { get; }

Property Value

Type	Description
System.Int32	The mask pattern index.

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Size

The width and height of this QR code, in modules (pixels). The size is a value between 21 and 177. This is equal to version × 4 + 17.

Declaration

public int Size { get; }

Property Value

Type	Description
System.Int32	The QR code size.

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Version

The version (size) of this QR code (between 1 for the smallest and 40 for the biggest).

Declaration

public int Version { get; }

Property Value

Type	Description
System.Int32	The QR code version (size).

Methods

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EncodeBinary(Byte[], QrCode.Ecc)

Creates a QR code representing the specified binary data using the specified error correction level.

This function encodes the data in the binary segment mode. The maximum number of bytes allowed is 2953. The smallest possible QR code version is automatically chosen. The resulting ECC level will be higher than the one specified if it can be achieved without increasing the size (version).

Declaration

public static QrCode EncodeBinary(byte[] data, QrCode.Ecc ecl)

Parameters

Type	Name	Description
System.Byte[]	data	The binary data to encode.
QrCode.Ecc	ecl	The minimum error correction level to use.

Returns

Type	Description
QrCode	The created QR code representing the specified data.

Exceptions

Type	Condition
System.ArgumentNullException	`data` or `ecl` is `null`.
DataTooLongException	The specified data is too long to fit in the largest QR code size (version) at the specified error correction level.

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EncodeSegments(List<QrSegment>, QrCode.Ecc, Int32, Int32, Int32, Boolean)

Creates a QR code representing the specified segments with the specified encoding parameters.

The smallest possible QR code version (size) is used. The range of versions can be restricted by the minVersion and maxVersion parameters.

If boostEcl is true, the resulting ECC level will be higher than the one specified if it can be achieved without increasing the size (version).

The QR code mask is usually automatically chosen. It can be explicitly set with the mask parameter by using a value between 0 to 7 (inclusive). -1 is for automatic mode (which may be slow).

This function allows the user to create a custom sequence of segments that switches between modes (such as alphanumeric and byte) to encode text in less space and gives full control over all encoding parameters.

Declaration

public static QrCode EncodeSegments(List<QrSegment> segments, QrCode.Ecc ecl, int minVersion = 1, int maxVersion = 40, int mask = -1, bool boostEcl = true)

Parameters

Type	Name	Description
System.Collections.Generic.List<QrSegment>	segments	The segments to encode.
QrCode.Ecc	ecl	The minimal or fixed error correction level to use .
System.Int32	minVersion	The minimum version (size) of the QR code (between 1 and 40).
System.Int32	maxVersion	The maximum version (size) of the QR code (between 1 and 40).
System.Int32	mask	The mask number to use (between 0 and 7), or -1 for automatic mask selection.
System.Boolean	boostEcl	If `true` the ECC level wil be increased if it can be achieved without increasing the size (version).

Returns

Type	Description
QrCode	The created QR code representing the segments.

Remarks

This is a mid-level API; the high-level APIs are EncodeText(String, QrCode.Ecc) and EncodeBinary(Byte[], QrCode.Ecc).

Exceptions

Type	Condition
System.ArgumentNullException	`segments`, any list element, or `ecl` is `null`.
System.ArgumentOutOfRangeException	1 ≤ minVersion ≤ maxVersion ≤ 40 or -1 ≤ mask ≤ 7 is violated.
DataTooLongException	The segments are too long to fit in the largest QR code size (version) at the specified error correction level.

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EncodeText(String, QrCode.Ecc)

Creates a QR code representing the specified text using the specified error correction level.

As a conservative upper bound, this function is guaranteed to succeed for strings with up to 738 Unicode code points (not UTF-16 code units) if the low error correction level is used. The smallest possible QR code version (size) is automatically chosen. The resulting ECC level will be higher than the one specified if it can be achieved without increasing the size (version).

Declaration

public static QrCode EncodeText(string text, QrCode.Ecc ecl)

Parameters

Type	Name	Description
System.String	text	The text to be encoded. The full range of Unicode characters may be used.
QrCode.Ecc	ecl	The minimum error correction level to use.

Returns

Type	Description
QrCode	The created QR code instance representing the specified text.

Exceptions

Type	Condition
System.ArgumentNullException	`text` or `ecl` is `null`.
DataTooLongException	The text is too long to fit in the largest QR code size (version) at the specified error correction level.

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GetModule(Int32, Int32)

Gets the color of the module (pixel) at the specified coordinates.

The top left corner has the coordinates (x=0, y=0). x-coordinates extend from left to right, y-coordinates extend from top to bottom.

If coordinates outside the bounds of this QR code are specified, light (false) is returned.

Declaration

public bool GetModule(int x, int y)

Parameters

Type	Name	Description
System.Int32	x	The x coordinate.
System.Int32	y	The y coordinate.

Returns

Type	Description
System.Boolean	The color of the specified module: `true` for dark modules and `false` for light modules (or if the coordinates are outside the bounds).

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RgbColor(Byte, Byte, Byte)

Creates an RGB color value in little endian format.

Declaration

public int RgbColor(byte red, byte green, byte blue)

Parameters

Type	Name	Description
System.Byte	red	Red component.
System.Byte	green	Green component.
System.Byte	blue	Blue component.

Returns

Type	Description
System.Int32	RGB color value

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ToBmpBitmap(Int32, Int32)

Creates bitmap in the BMP format data using black for dark modules and white for light modules.

The bitmap uses 1 bit per pixel and a color table with 2 entries.

Declaration

public byte[] ToBmpBitmap(int border = 0, int scale = 1)

Parameters

Type	Name	Description
System.Int32	border	The border width, as a factor of the module (QR code pixel) size.
System.Int32	scale	The width and height, in pixels, of each module.

Returns

Type	Description
System.Byte[]	Bitmap data

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	Thrown if `border` is negative, `scale` is less than 1 or the resulting image is wider than 32,768 pixels.

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ToBmpBitmap(Int32, Int32, Int32, Int32)

Creates a bitmap in the BMP format.

The bitmap uses 1 bit per pixel and a color table with 2 entries.

Color values can be created with RgbColor(Byte, Byte, Byte).

Declaration

public byte[] ToBmpBitmap(int border, int scale, int foreground, int background)

Parameters

Type	Name	Description
System.Int32	border	The border width, as a factor of the module (QR code pixel) size.
System.Int32	scale	The width and height, in pixels, of each module.
System.Int32	foreground	The foreground color (dark modules), in RGB value (little endian).
System.Int32	background	The background color (light modules), in RGB value (little endian).

Returns

Type	Description
System.Byte[]	Bitmap data

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	Thrown if `border` is negative, `scale` is less than 1 or the resulting image is wider than 32,768 pixels.

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ToGraphicsPath(Int32)

Creates a graphics path of this QR code valid in SVG or XAML.

The graphics path uses a coordinate system where each module is 1 unit wide and tall, and the top left module is offset vertically and horizontally by border units.

Note that a border width other than 0 only make sense if the bounding box of the QR code is explicitly set by the graphics using this path. If the bounding box of this path is automatically derived, at least the right and bottom border will be missing.

The path will look like this: M3,3h7v1h-7z M12,3h1v4h-1z ... M70,71h1v1h-1z. It is valid for SVG (<path d="M3,3h..." />) and for XAML (<Path Data="M3,3h..." />). For programmatic geometry creation in WPF see Geometry.Parse(String).

Declaration

public string ToGraphicsPath(int border = 0)

Parameters

Type	Name	Description
System.Int32	border	The border width, as a factor of the module (QR code pixel) size

Returns

Type	Description
System.String	The graphics path

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	Thrown if border is negative

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ToSvgString(Int32)

Creates an SVG image of this QR code.

The images uses Unix newlines (\n), regardless of the platform.

Declaration

public string ToSvgString(int border)

Parameters

Type	Name	Description
System.Int32	border	The border width, as a factor of the module (QR code pixel) size

Returns

Type	Description
System.String	The SVG image as a string.

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ToSvgString(Int32, String, String)

Creates an SVG image of this QR code.

The images uses Unix newlines (\n), regardless of the platform.

Colors are specified using CSS color data type. Examples of valid values are "#339966", "fuchsia", "rgba(137, 23, 89, 0.3)".

Declaration

public string ToSvgString(int border, string foreground, string background)

Parameters

Type	Name	Description
System.Int32	border	The border width, as a factor of the module (QR code pixel) size
System.String	foreground	The foreground color.
System.String	background	The background color.

Returns

Type	Description
System.String