Ruby Requires Chilkat v11.7.0+

QR Code Error Correction Levels

See more QR Code Examples

Demonstrates the four QR error-correction levels. L, M, Q and H allow a reader to recover the data when about 7%, 15%, 25% and 30% of the symbol is damaged or covered. More error correction leaves less room for data, so the same text needs a larger symbol at a higher level. The default is M. The example also shows boostErrorCorrection, which raises the level for free when the chosen version has room to spare. Ruby

require 'chilkat'

success = false

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

fmt = Chilkat::CkFormats.new()
json = Chilkat::CkJsonObject.new()
jsonOut = Chilkat::CkJsonObject.new()
json.UpdateString("payload.text","https://www.chilkatsoft.com/barcode_overview.asp")

#  Encode the same text at each level.
levels = Chilkat::CkJsonArray.new()
levels.Load("[\"L\",\"M\",\"Q\",\"H\"]")

for i in 0 .. 3
    json.UpdateString("encoding.qr.errorCorrection",levels.stringAt(i))
    success = fmt.QrCode("generate",json,jsonOut)
    if (success == false)
        print fmt.lastErrorText() + "\n";
        exit
    end

    print "level " + levels.stringAt(i) + ": version " + jsonOut.IntOf("symbols[0].selectedEncoding.version").to_s() + ", " + jsonOut.IntOf("symbols[0].dimensions.modulesWide").to_s() + 
        " modules wide" + "\n";
end

#  The four symbols.  They hold the same text, and the higher the level, the larger the symbol:

#  

#  A symbol often has room left over.  boostErrorCorrection uses it: the level is raised
#  as far as the same version allows, so the symbol is no larger but is more robust.
json2 = Chilkat::CkJsonObject.new()
json2.UpdateString("payload.text","https://chilkatsoft.com")
json2.UpdateString("encoding.qr.errorCorrection","L")
success = fmt.QrCode("generate",json2,jsonOut)
if (success == false)
    print fmt.lastErrorText() + "\n";
    exit
end

print "level L requested: version " + jsonOut.IntOf("symbols[0].selectedEncoding.version").to_s() + ", level " + jsonOut.stringOf("symbols[0].selectedEncoding.errorCorrection") + "\n";

json2.UpdateBool("encoding.qr.boostErrorCorrection",true)
success = fmt.QrCode("generate",json2,jsonOut)
if (success == false)
    print fmt.lastErrorText() + "\n";
    exit
end

print "level L with boost: version " + jsonOut.IntOf("symbols[0].selectedEncoding.version").to_s() + ", level " + jsonOut.stringOf("symbols[0].selectedEncoding.errorCorrection") + "\n";

#  Level L, and level M reached by the boost.  The two symbols are the same size:

#  

#  Sample output:

#  level L: version 3, 29 modules wide
#  level M: version 4, 33 modules wide
#  level Q: version 5, 37 modules wide
#  level H: version 6, 41 modules wide
#  level L requested: version 2, level L
#  level L with boost: version 2, level M