shylinux.com/x/go-qrcode

Package qrcode implements a QR Code encoder. A QR Code is a matrix (two-dimensional) barcode. Arbitrary content may be encoded. A QR Code contains error recovery information to aid reading damaged or obscured codes. There are four levels of error recovery: qrcode.{Low, Medium, High, Highest}. QR Codes with a higher recovery level are more robust to damage, at the cost of being physically larger. Three functions cover most use cases: - Create a PNG image: - Create a PNG image and write to a file: - Create a PNG image with custom colors and write to file: All examples use the qrcode.Medium error Recovery Level and create a fixed 256x256px size QR Code. The last function creates a white on black instead of black on white QR Code. To generate a variable sized image instead, specify a negative size (in place of the 256 above), such as -4 or -5. Larger negative numbers create larger images: A size of -5 sets each module (QR Code "pixel") to be 5px wide/high. - Create a PNG image (variable size, with minimum white padding) and write to a file: The maximum capacity of a QR Code varies according to the content encoded and the error recovery level. The maximum capacity is 2,953 bytes, 4,296 alphanumeric characters, 7,089 numeric digits, or a combination of these. This package implements a subset of QR Code 2005, as defined in ISO/IEC 18004:2006.