Python 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. Chilkat2-Python

import sys
import chilkat2

success = False

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

fmt = chilkat2.Formats()
json = chilkat2.JsonObject()
jsonOut = chilkat2.JsonObject()
json.UpdateString("payload.text","https://www.chilkatsoft.com/barcode_overview.asp")

# Encode the same text at each level.
levels = chilkat2.JsonArray()
levels.Load("[\"L\",\"M\",\"Q\",\"H\"]")

for i in range(0,4):
    json.UpdateString("encoding.qr.errorCorrection",levels.StringAt(i))
    success = fmt.QrCode("generate",json,jsonOut)
    if (success == False):
        print(fmt.LastErrorText)
        sys.exit()

    print("level " + levels.StringAt(i) + ": version " + str(jsonOut.IntOf("symbols[0].selectedEncoding.version")) + ", " + str(jsonOut.IntOf("symbols[0].dimensions.modulesWide"))\
         + " modules wide")

# 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 = chilkat2.JsonObject()
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)
    sys.exit()

print("level L requested: version " + str(jsonOut.IntOf("symbols[0].selectedEncoding.version")) + ", level " + jsonOut.StringOf("symbols[0].selectedEncoding.errorCorrection"))

json2.UpdateBool("encoding.qr.boostErrorCorrection",True)
success = fmt.QrCode("generate",json2,jsonOut)
if (success == False):
    print(fmt.LastErrorText)
    sys.exit()

print("level L with boost: version " + str(jsonOut.IntOf("symbols[0].selectedEncoding.version")) + ", level " + jsonOut.StringOf("symbols[0].selectedEncoding.errorCorrection"))

# 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