Client and backend. This class is shared: the same code is compiled into your app and into your server, so everything on this page works in both.

public final class QrCode

Object
QrCode

A QR code, generated from text or bytes: the module grid, and SVG for a page. The class is shared with the backend, which has no images: a client draws one with QrCodeImage, a server serves toSvg().

A device shows one so a phone can pair with it – the address and a one-time token in a URL – and a server puts one on an enrolment page:

QrCode code = QrCode.encode("https://10.0.0.5:8443/pair?t=4F9A2C", QrCode.ECC_MEDIUM);
Image image = QrCodeImage.create(code, 8);

Byte mode with UTF-8 text, versions 1 to 40, the four standard error correction levels and the mask with the lowest penalty (ISO/IEC 18004). The smallest version that holds the data is chosen.

Fields

`public static final int ECC_LOW = 0`	Recovers about 7% of the code.
`public static final int ECC_MEDIUM = 1`	Recovers about 15%; the usual choice.
`public static final int ECC_QUARTILE = 2`	Recovers about 25%.
`public static final int ECC_HIGH = 3`	Recovers about 30%, for a code printed where it gets scuffed.

Methods

`public static` `QrCode encode(String text, int ecc)`	Encodes text as UTF-8.
`public static` `QrCode encode(byte[] data, int ecc)`	Encodes bytes.
`public int getSize()`	Modules per side, `17 + 4 * version`, without the quiet zone.
`public int getVersion()`	The version, 1 to 40.
`public int getErrorCorrection()`	The error correction level, `ECC_LOW` to `ECC_HIGH`.
`public int getMask()`	The mask pattern chosen, 0 to 7.
`public boolean isDark(int x, int y)`	True for a dark module; false outside the grid, which is the quiet zone.
`public` `String toSvg()`	The code as an SVG document, one unit per module with a four module quiet zone, for a web page or a printed label.

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone, finalize

Field details

ECC_LOW

public static final int ECC_LOW = 0

Recovers about 7% of the code.

ECC_MEDIUM

public static final int ECC_MEDIUM = 1

Recovers about 15%; the usual choice.

ECC_QUARTILE

public static final int ECC_QUARTILE = 2

Recovers about 25%.

ECC_HIGH

public static final int ECC_HIGH = 3

Recovers about 30%, for a code printed where it gets scuffed.

Method details

encode

public static QrCode encode(String text, int ecc)

Encodes text as UTF-8.

encode

public static QrCode encode(byte[] data, int ecc)

Encodes bytes. Throws IllegalArgumentException when they do not fit a version 40 code at this level (2953 bytes at ECC_LOW).

getSize

public int getSize()

Modules per side, 17 + 4 * version, without the quiet zone.

getVersion

public int getVersion()

The version, 1 to 40.

getErrorCorrection

public int getErrorCorrection()

The error correction level, ECC_LOW to ECC_HIGH.

getMask

public int getMask()

The mask pattern chosen, 0 to 7.

isDark

public boolean isDark(int x, int y)

True for a dark module; false outside the grid, which is the quiet zone.

toSvg

public String toSvg()

The code as an SVG document, one unit per module with a four module quiet zone, for a web page or a printed label.