Simon Law
3e45e5b420
QR codes are used by `tailscale up --qr` to provide an easy way to open a web-page without transcribing a difficult URI. However, there’s no need for this feature if the client will never be called interactively. So this PR adds the `ts_omit_qrcodes` build tag. Updates #18182 Signed-off-by: Simon Law <sfllaw@tailscale.com>
60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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//go:build !ts_omit_qrcodes
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// Package qrcodes provides functions to render or format QR codes.
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package qrcodes
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import (
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"fmt"
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"io"
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"strings"
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qrcode "github.com/skip2/go-qrcode"
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)
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// Fprintln formats s according to [Format] and writes a QR code to w, along
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// with a newline. It returns the number of bytes written and any write error
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// encountered.
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func Fprintln(w io.Writer, format Format, s string) (n int, err error) {
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const inverse = false // Modern scanners can read QR codes of any colour.
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q, err := qrcode.New(s, qrcode.Medium)
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if err != nil {
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return 0, fmt.Errorf("QR code error: %w", err)
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}
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if format == FormatAuto {
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format, err = detectFormat(w, inverse)
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if err != nil {
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return 0, fmt.Errorf("QR code error: %w", err)
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}
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}
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var out string
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switch format {
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case FormatASCII:
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out = q.ToString(inverse)
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out = strings.ReplaceAll(out, "█", "#")
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case FormatLarge:
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out = q.ToString(inverse)
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case FormatSmall:
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out = q.ToSmallString(inverse)
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default:
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return 0, fmt.Errorf("unknown QR code format: %q", format)
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}
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return fmt.Fprintln(w, out)
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}
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// EncodePNG renders a QR code for s as a PNG, with a width and height of size
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// pixels.
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func EncodePNG(s string, size int) ([]byte, error) {
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q, err := qrcode.New(s, qrcode.Medium)
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if err != nil {
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return nil, err
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}
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return q.PNG(size)
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}
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