Go 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. Go

    success := false

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

    fmt := chilkat.NewFormats()
    json := chilkat.NewJsonObject()
    jsonOut := chilkat.NewJsonObject()
    json.UpdateString("payload.text","https://www.chilkatsoft.com/barcode_overview.asp")

    //  Encode the same text at each level.
    levels := chilkat.NewJsonArray()
    levels.Load("[\"L\",\"M\",\"Q\",\"H\"]")
    var i int
    for i = 0; i <= 3; i++ {
        json.UpdateString("encoding.qr.errorCorrection",*levels.StringAt(i))
        success = fmt.QrCode("generate",json,jsonOut)
        if success == false {
            fmt.Println(fmt.LastErrorText())
            fmt.DisposeFormats()
            json.DisposeJsonObject()
            jsonOut.DisposeJsonObject()
            levels.DisposeJsonArray()
            return
        }

        fmt.Println("level ", *levels.StringAt(i), ": version ", jsonOut.IntOf("symbols[0].selectedEncoding.version"), ", ", 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 := chilkat.NewJsonObject()
    json2.UpdateString("payload.text","https://chilkatsoft.com")
    json2.UpdateString("encoding.qr.errorCorrection","L")
    success = fmt.QrCode("generate",json2,jsonOut)
    if success == false {
        fmt.Println(fmt.LastErrorText())
        fmt.DisposeFormats()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        levels.DisposeJsonArray()
        json2.DisposeJsonObject()
        return
    }

    fmt.Println("level L requested: version ", 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 {
        fmt.Println(fmt.LastErrorText())
        fmt.DisposeFormats()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        levels.DisposeJsonArray()
        json2.DisposeJsonObject()
        return
    }

    fmt.Println("level L with boost: version ", 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

    fmt.DisposeFormats()
    json.DisposeJsonObject()
    jsonOut.DisposeJsonObject()
    levels.DisposeJsonArray()
    json2.DisposeJsonObject()