Lua Requires Chilkat v11.7.0+

QR Code with Non-English Text (UTF-8 and ECI)

See more QR Code Examples

Demonstrates text outside ASCII. QrCode always stores text as UTF-8 bytes, which is what phones expect. A QR code can also say so explicitly with an ECI header: setting encoding.eci to 26 declares the bytes to be UTF-8, for readers that would otherwise assume another character set. The header costs a little space, and a few older readers do not understand it, so it is off by default. Lua

local chilkat = require("chilkat")

-- This example requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

-- The text is "Gruesse aus Muenchen" written with u-umlaut and sharp s.  It is given here with
-- JSON escapes only so that this source is plain ASCII.  Decode turns the escapes into characters.
local sbText = chilkat.StringBuilder.new()
sbText:append("Gr\195\188\195\159e aus M\195\188nchen")
sbText:decode("json", "utf-8")

local json = chilkat.JsonObject.new()
json:update_sb("payload.text", sbText)
json:update_string("output.path", "qa_output/qr_utf8.png")
json:update_bool("output.overwrite", true)
json:update_string("output.return", "none")

local fmt = chilkat.Formats.new()
local jsonOut = chilkat.JsonObject.new()
local success = fmt:qr_code("generate", json, jsonOut)
if not success then
    print(fmt.last_error_text)
    return
end

-- 17 characters, three of which take two bytes in UTF-8.
print("characters: " .. sbText.length)
print("bytes encoded: " .. jsonOut:int_of("symbols[0].payloadBytes"))
print("ECI header: " .. tostring(jsonOut:has_member("symbols[0].selectedEncoding.eci")))

-- Without an ECI header (qa_output/qr_utf8.png):

-- 

-- The same text with an ECI header declaring UTF-8.
json:update_int("encoding.eci", 26)
json:update_string("output.path", "qa_output/qr_utf8_eci.png")
success = fmt:qr_code("generate", json, jsonOut)
if not success then
    print(fmt.last_error_text)
    return
end

print("with encoding.eci = 26, ECI header: " .. tostring(jsonOut:has_member("symbols[0].selectedEncoding.eci")) .. ", value " .. jsonOut:int_of("symbols[0].selectedEncoding.eci"))

-- With the ECI header (qa_output/qr_utf8_eci.png).  Both scan as the same text:

-- 

-- Sample output:

-- characters: 17
-- bytes encoded: 20
-- ECI header: False
-- with encoding.eci = 26, ECI header: True, value 26