::qr Experimental

Syntax

https://name.rt.ht/docs/::qr
https://name.rt.ht/::qr?t=Hello
https://new.rt.ht/::qr?fg=%23e74c3c&bg=none&ec=H

The path ends in ::qr. It works on any URL of any host the platform serves, for example https://webpdf.pro/docs/::qr or https://rtcode.io/::qr.

Parameters

t

The text to encode. It overrides the URL. An empty value encodes the empty string.

s

The module size in pixels. The default is 6. 0, an empty value and values that are not numbers fall back to 6. Negative values clamp to 1.

m

The quiet-zone margin, in modules. The default is 2 when the parameter is absent. When it is present, the value is the integer, at least 0, so m= gives 0.

fg

The foreground color. The default is #000. Encode the # as %23.

bg

The background color. The default is #fff. none or transparent leaves out the background rectangle.

ec

The error-correction level: L, M, Q or H, in either case. The default is M. An invalid value becomes L.

What is encoded

Without t, the code encodes the request URL, with these changes:

• The path loses /*::qr…, so the slash before ::qr is dropped too: /docs/::qr encodes https://host/docs, and /::qr encodes https://host/.
• The parameters t, s, m, fg, bg and ec are removed.
• The remaining query is re-serialized: ?foo becomes ?foo=, and a bare ? disappears.
• A fragment is never included, because the server never receives it.

To encode an edit URL such as https://host/?, pass it with t, URL-encoded.

Response

Success responses carry Cache-Control: public, max-age=86400 and Access-Control-Allow-Origin: *.

The SVG has viewBox="0 0 W W", a width and height of W times s, and shape-rendering="crispEdges". An optional background <rect> is followed by a single <path> filled with fg. W is the module count plus twice the margin. The data is encoded in byte mode (UTF-8), and the QR version (1 to 40) and mask are chosen automatically.

Access

Anyone can use it, on any URL, without signing in.

Examples

A QR code for the documentation

HTML

<img src="https://rtcode.io/::qr?t=https%3A%2F%2Frtcode.io%2Fdocs%2F&s=4" alt="QR code for rtcode.io/docs/">

Result

Any text, with high error correction

<img src="https://new.rt.ht/::qr?t=mailto:support@elefunc.com&ec=H&fg=%23e74c3c" alt="Email support">

This encodes the t text instead of the URL. The # in a color must be sent as %23. An invalid ec silently becomes L. The value is quoted because it contains =.

The current page

<img src="::qr?s=8&bg=none" alt="QR code for this page">

A relative ::qr encodes the current page, with 8-pixel modules and a transparent background. On https://name.rt.ht/docs/ it encodes https://name.rt.ht/docs, and the platform's 307 adds the slash back when the code is scanned.

Specifications

Not part of any specification. ::qr is an RTEdge.net feature. The code and the image follow:

Availability

See also

• URL suffixes
• ::clear
• ?::/h:
• Reserved paths
• Limits and quotas
• Linking and embedding