B4X Requires Chilkat v11.7.0+

Get the Modules of a QR Code (Bit Matrix)

See more QR Code Examples

Demonstrates getting the QR code itself, as a grid of dark and light modules, to draw with something other than the built-in PNG and SVG output: on a canvas, in a PDF, on a display, or with a label printer language. With output.includeModuleData the response has symbols[0].moduleData, a bit matrix with one bit per module, each row starting on a new byte, most significant bit first, 1 for dark. The quiet zone is not part of the matrix. The example prints the symbol using two characters per module. B4X

Dim success As Boolean = False

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

Dim json As ChilkatJsonObject
json.Initialize
json.UpdateString("payload.text", "CHILKAT")
json.UpdateBool("output.includeModuleData", True)

Dim fmt As ChilkatFormats
fmt.Initialize
Dim jsonOut As ChilkatJsonObject
jsonOut.Initialize
success = fmt.QrCode("generate", json, jsonOut)
If success = False Then
    Log(fmt.LastErrorText)
    Return
End If


Dim width As Int = jsonOut.IntOf("symbols[0].moduleData.width")
Dim height As Int = jsonOut.IntOf("symbols[0].moduleData.height")
Dim rowBytes As Int = jsonOut.IntOf("symbols[0].moduleData.rowBytes")
Log("kind: " & jsonOut.StringOf("symbols[0].moduleData.kind"))
Log("modules: " & width & " x " & height & ", " & rowBytes & " bytes per row")

'  The matrix is height rows of rowBytes bytes.
Dim bd As ChilkatBinData
bd.Initialize
success = bd.AppendEncoded(jsonOut.StringOf("symbols[0].moduleData.bytesBase64"), "base64")
If success = False Then
    Log(bd.LastErrorText)
    Return
End If


Dim sbRow As ChilkatStringBuilder
sbRow.Initialize
Dim row As Int
Dim col As Int
Dim b As Int
Dim mask As Int = 128
For row = 0 To height - 1
    sbRow.Clear
    For col = 0 To width - 1
        '  The module at (col,row) is a bit of the byte at (row * rowBytes) + (col / 8).
        '  The leftmost module of each byte is its most significant bit.
        If (col Mod 8) = 0 Then
            mask = 128
        End If

        b = bd.GetByte((row * rowBytes) + (col / 8))
        If ((b / mask) Mod 2) = 1 Then
            sbRow.Append("##")
        Else
            sbRow.Append("  ")
        End If

        mask = mask / 2
    Next
    Log(sbRow.GetAsString)
Next

'  The same symbol as the PNG that the call also returned:

'  

'  Sample output:

'  kind: bitMatrix
'  modules: 21 x 21, 3 bytes per row
'  ##############              ##############
'  ##          ##      ####    ##          ##
'  ##  ######  ##  ##  ####    ##  ######  ##
'  ##  ######  ##  ##          ##  ######  ##
'  ##  ######  ##  ##  ##  ##  ##  ######  ##
'  ##          ##  ####  ##    ##          ##
'  ##############  ##  ##  ##  ##############
'                  ####
'  ##  ##########      ####    ##########
'      ####          ##  ########    ######
'  ####  ########    ####  ##  ####      ####
'        ##  ##      ############    ####  ##
'    ######  ####  ######  ##    ##  ##
'                  ##  ##  ##    ##  ##    ##
'  ##############        ##  ##    ##      ##
'  ##          ##  ##  ##        ######  ####
'  ##  ######  ##  ####  ##  ##    ##
'  ##  ######  ##  ##  ############    ##
'  ##  ######  ##  ##      ##  ####  ##
'  ##          ##    ##  ########          ##
'  ##############  ##      ##      ######