QR Code

QR Code is a 2D symbology widely used for URLs and contact details.

See also

QR code on Wikipedia for background on the symbology itself.

Note

The QR support in pyStrich is less actively maintained than the other symbologies. If your project’s main need is QR codes, consider whether python-qrcode is a better fit – it has a larger feature set (logos, styled modules). pyStrich’s QR support is most useful when you also need one of its other symbologies and want a single dependency.

Example

from pystrich.qrcode import QRCodeEncoder

encoder = QRCodeEncoder("https://github.com/mmulqueen/pyStrich")
encoder.save_svg("qrcode-example.svg")

Sizing and quiet zone

The cellsize argument to save() and get_imagedata() sets the pixel side length of one module (default 5).

See also

Printing barcodes for guidance on selecting cellsize for printed output.

encoder = QRCodeEncoder("https://github.com/mmulqueen/pyStrich")
encoder.save("qrcode-large.png", cellsize=10)

Output formats

SVG output

For embedding in web pages or any workflow that benefits from resolution-independent output, use save_svg() (or get_svg() to receive the SVG as a string).

from pystrich.marks import MarkShape

QRCodeEncoder("https://github.com/mmulqueen/pyStrich").save_svg("qr.svg")
QRCodeEncoder("https://github.com/mmulqueen/pyStrich").save_svg(
    "qr-circles.svg", mark_shape=MarkShape.CIRCULAR_CELLS
)

Default	mark_shape=MarkShape.CIRCULAR_CELLS

The SVG’s viewBox is in module units, while width and height scale by cellsize. The mark_shape keyword selects how matched cells are drawn – horizontal runs of rectangles (the default) or one filled circle per cell.

Note

Circular cells fall outside the standard module shape and decoder support varies. Test with your target scanner before deploying.

Added in version 0.12.

PNG output

For raster output, use save() to write a PNG file or get_imagedata() to receive the raw PNG bytes.

QRCodeEncoder("https://github.com/mmulqueen/pyStrich").save("qrcode.png")

EPS output

For embedding in LaTeX (\includegraphics) or other vector print workflows, use save_eps() (or get_eps() to receive the EPS as a string).

QRCodeEncoder("https://github.com/mmulqueen/pyStrich").save_eps("qr.eps")

The cellsize argument is the side length of one module in PostScript points (1 point = 1/72 inch).

Added in version 0.12.

Terminal output

For quick on-screen display, get_terminal_art() returns a scannable rendering using Unicode half-block characters. Each character represents two matrix rows and one column, so cells appear roughly square in a typical fixed-width terminal font.

print(QRCodeEncoder("https://github.com/mmulqueen/pyStrich").get_terminal_art())

                                     
                                     
    █▀▀▀▀▀█ █▄█▀▀▀▄ ███▀▀ █▀▀▀▀▀█    
    █ ███ █ ▄▀██ ▀ █▀▄ ▀█ █ ███ █    
    █ ▀▀▀ █  ▄█▄█▀█▀▀▀▀█▄ █ ▀▀▀ █    
    ▀▀▀▀▀▀▀ █ ▀ ▀▄█ ▀▄█ ▀ ▀▀▀▀▀▀▀    
    █ ▀▀ ▀▀█ ▄█▄▀▀▀▀█▀▀▄▄ █▄▄▀ ▀█    
     ▄█ ▄▀▀▀█ ▄ ▀▄█▄▄▀█▄▄█▄▀▄ ▀▀▄    
    █▄ ▄█▄▀▀▀█▀█▀▄ ███ █  ▄  ▀█▄▄    
     ▀▄▄█ ▀▀  █▀▄▄▀▄█ ▀██▄█▄▄ ▀█▀    
    ▄▀▀▄██▀▄▀▀█ ▀▄ ▄▀ ▀▀▀  ▄▀█▄█     
    ▄█▄██ ▀▀█▄ █   █▀▄▄ ▀ ███ █      
    ▀  ▀ ▀▀▀▄▀██ █▄▄▄██ █▀▀▀███▄▄    
    █▀▀▀▀▀█ █▄▄▀ ▀  █ ▀▀█ ▀ ██ █▄    
    █ ███ █ ▄▄█▄▄ █▄█▀▀▄▀█▀██▄▀ ▄    
    █ ▀▀▀ █ ▀▀ ▀██ ▄▀▀▀ █▄ █ ▄▀▄▀    
    ▀▀▀▀▀▀▀ ▀▀ ▀ ▀▀ ▀ ▀▀▀▀▀    ▀     
                                     
                                     

By default the output is wrapped in ANSI escape codes that force a white background and black foreground, so the symbol scans regardless of the terminal’s colour scheme. Pass ansi_bg=False for plain output (correct only on a light-themed terminal).

Added in version 0.12.

DXF (CAD) output

For direct part marking applications, get_dxf() returns a DXF representation of the symbol that CAD and CAM tools can read directly. The cellsize is in your chosen units (default "mm") rather than pixels.

encoder = QRCodeEncoder("WDBCA45D2HA327260")
with open("part.dxf", "w") as f:
    f.write(encoder.get_dxf(cellsize=0.5, units="mm"))

The default inverse=True emits geometry for the light modules, including the quiet zone – so the bounding box frames the symbol. Pass inverse=False to emit only the dark modules instead, matching the symbol’s normal appearance; the bounding box then hugs the dark cells and the quiet zone has to be reintroduced downstream.

Error correction level

QR Codes embed redundant data so that a partly-damaged symbol can still be read. The error correction level (ECL) sets how much redundancy is added, and is one of:

"L"	Low: ~7% of codewords recoverable. Smallest symbol.
"M"	Medium: ~15%. Default if ecl is not supplied.
"Q"	Quartile: ~25%.
"H"	High: ~30%. Largest symbol; tolerates the most damage.

Higher levels produce a denser symbol for the same payload (or, equivalently, require a larger symbol to fit the same payload), so pick the lowest level that meets your durability needs. "H" is typically reserved for symbols that may be partly obscured (e.g. by a logo) or printed on surfaces likely to be scratched, smudged or torn.

QRCodeEncoder("https://en.wikipedia.org/wiki/Kings_River_(California)", ecl="H").save("qr-high.png")

GS1 Digital Link

GS1 Digital Link encodes a GTIN (with optional batch, expiry, serial, …) as a URL. It’s just a URL – pass it to QRCodeEncoder directly:

QRCodeEncoder("https://id.gs1.org/01/05050070007664/10/W126").save("dl.png")

Raw AI-syntax GS1 QR (FNC1 mode indicator) is not supported; for that, use Data Matrix.

API

class QRCodeEncoder(text: str, ecl: Literal['L', 'M', 'Q', 'H'] | None = None)

Bases: Matrix2DEncoder[int]

Encode a string as a QR Code 2D barcode.

Typical use:

encoder = QRCodeEncoder("https://d-nb.info/gnd/135514053")
encoder.save("qr.png")

Variables:

• matrix – 2D list describing the symbol prior to rendering.

• width – Pixel width of the most recently rendered image.

• height – Pixel height of the most recently rendered image.

init_renderer() → QRCodeRenderer

Construct a QRCodeRenderer for the encoded matrix.

Updates width and height with the renderer’s dimensions and returns the renderer.

get_ascii() → str

Return an ASCII-art rendering of the symbol.

Return type:

str

get_dxf(cellsize: float = 1.0, inverse: bool = True, units: Literal['in', 'ft', 'mi', 'mm', 'cm', 'm'] | None = 'mm', *, mark_shape: MarkShape = MarkShape.SQUARE_CELLS) → str

Return a DXF (CAD) representation of the symbol.

Parameters:

• cellsize – Side length of one module in units.

• inverse – If True (the default), light modules are drawn as filled cells. If False, dark modules are drawn, matching the normal appearance of the symbol.

• units – One of "in", "ft", "mi", "mm", "cm" or "m", or None for Unspecified ($INSUNITS=0).

• mark_shape – How matched cells are grouped and drawn.

Return type:

str

Added in version 0.9.

Changed in version 0.12: units now supports "in", "ft", "mi", "cm", "m" and None (Unspecified); previously any value other than "mm" was silently treated as unspecified.

get_eps(cellsize: int = 5, *, inverse: bool = False, mark_shape: MarkShape = MarkShape.HORIZONTAL_RUNS) → str

Render the symbol and return EPS markup.

Parameters:

• cellsize – Side length in PostScript points of one module.

• inverse – If True, mark the light cells instead of the dark ones.

• mark_shape – How matched cells are grouped and drawn.

Return type:

str

Added in version 0.12.

get_imagedata(cellsize: int = 5) → bytes

Render the symbol and return PNG bytes.

Parameters:

cellsize – Side length in pixels of one module.

Returns:

PNG-encoded image data.

Return type:

bytes

get_pilimage(cellsize: int = 5) → PIL.Image.Image

Render the symbol and return a Pillow image.

Parameters:

cellsize – Side length in pixels of one module.

Returns:

The rendered symbol.

Return type:

PIL.Image.Image

Added in version 0.11.

get_svg(cellsize: int = 5, *, inverse: bool = False, mark_shape: MarkShape = MarkShape.HORIZONTAL_RUNS) → str

Render the symbol and return SVG markup.

Parameters:

• cellsize – Side length in user units of one module.

• inverse – If True, mark the light cells instead of the dark ones.

• mark_shape – How matched cells are grouped and drawn.

Return type:

str

Added in version 0.12.

get_terminal_art(*, ansi_bg: bool = True) → str

Render the symbol using Unicode half-block characters for terminals.

Each character represents two matrix rows and one column, producing approximately square cells in a typical fixed-width font and yielding a result that is scannable on screen.

Parameters:

ansi_bg – If True (the default), wrap each line in ANSI escape codes that force a white background and black foreground, making the symbol scannable regardless of the terminal’s colour scheme. Set to False for plain output (correct only on a light-themed terminal).

Return type:

str

Added in version 0.12.

save(filename: str | PathLike[str], cellsize: int = 5) → None

Save the symbol as a PNG. Pass a .png filename.

Parameters:

• filename – PNG output path.

• cellsize – Side length in pixels of one module.

save_eps(filename: str | PathLike[str], cellsize: int = 5, *, inverse: bool = False, mark_shape: MarkShape = MarkShape.HORIZONTAL_RUNS) → None

Save the symbol as an EPS file. Pass an .eps filename.

Parameters:

• filename – EPS output path.

• cellsize – Side length in PostScript points of one module.

• inverse – If True, mark the light cells instead of the dark ones.

• mark_shape – How matched cells are grouped and drawn.

Added in version 0.12.

save_svg(filename: str | PathLike[str], cellsize: int = 5, *, inverse: bool = False, mark_shape: MarkShape = MarkShape.HORIZONTAL_RUNS) → None

Save the symbol as an SVG file. Pass a .svg filename.

Parameters:

• filename – SVG output path.

• cellsize – Side length in user units of one module.

• inverse – If True, mark the light cells instead of the dark ones.

• mark_shape – How matched cells are grouped and drawn.

Added in version 0.12.