qrio – Low-level QR code decoding

Provides the QRDecoder object used for decoding QR codes. For more information about working with QR codes, see this Learn guide.

Note

This module only handles decoding QR codes. If you are looking to generate a QR code, use the adafruit_miniqr library

Available on these boards
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class qrio.PixelPolicy
EVERY_BYTE: PixelPolicy

The input buffer to QRDecoder.decode consists of greyscale values in every byte

EVEN_BYTES: PixelPolicy

The input buffer to QRDecoder.decode consists of greyscale values in positions 0, 2, …, and ignored bytes in positions 1, 3, …. This can decode directly from YUV images where the even bytes hold the Y (luminance) data.

ODD_BYTES: PixelPolicy

The input buffer to QRDecoder.decode consists of greyscale values in positions 1, 3, …, and ignored bytes in positions 0, 2, …. This can decode directly from YUV images where the odd bytes hold the Y (luminance) data

RGB565_SWAPPED: PixelPolicy

The input buffer to QRDecoder.decode consists of RGB565 values in byte-swapped order. Most cameras produce data in byte-swapped order. The green component is used.

RGB565: PixelPolicy

The input buffer to QRDecoder.decode consists of RGB565 values in native order. The green component is used.

class qrio.QRDecoder(width: int, height: int)

Construct a QRDecoder object

Parameters:
  • width (int) – The pixel width of the image to decode

  • height (int) – The pixel height of the image to decode

width: int

The width of image the decoder expects

height: int

The height of image the decoder expects

decode(buffer: circuitpython_typing.ReadableBuffer, pixel_policy: PixelPolicy = PixelPolicy.EVERY_BYTE) List[QRInfo]

Decode zero or more QR codes from the given image. The size of the buffer must be at least length``×``width bytes for EVERY_BYTE, and 2×``length``×``width`` bytes for EVEN_BYTES or ODD_BYTES.

find(buffer: circuitpython_typing.ReadableBuffer, pixel_policy: PixelPolicy = PixelPolicy.EVERY_BYTE) List[QRPosition]

Find all visible QR codes from the given image. The size of the buffer must be at least length``×``width bytes for EVERY_BYTE, and 2×``length``×``width`` bytes for EVEN_BYTES or ODD_BYTES.

class qrio.QRInfo

Information about a decoded QR code

payload: bytes

The content of the QR code

data_type: str | int

The encoding of the payload as a string (if a standard encoding) or int (if not standard)

class qrio.QRPosition

Information about a non-decoded QR code

top_left_x: int

X coordinate of the top left corner

top_left_y: int

Y coordinate of the top left corner

top_right_x: int

X coordinate of the top right corner

top_right_y: int

Y coordinate of the top right corner

bottom_right_x: int

X coordinate of the bottom right corner

bottom_right_y: int

Y coordinate of the bottom right corner

bottom_left_x: int

X coordinate of the bottom left corner

bottom_left_y: int

Y coordinate of the bottom left corner

size: int

The number of bits the code contains