Generate random valid EAN13 barcode string:
How to draw it see this.
B4X:
Public Sub BarcodeEAN13() As String
Dim brcod As String = Rnd(100000000,214000000)
brcod = "950" & brcod '<<< change the beginning 3 digits according country, see: https://en.wikipedia.org/wiki/List_of_GS1_country_codes
Dim x As Int = 0
If brcod.Length=12 Then
Dim odds,evens As List
odds.Initialize
evens.Initialize
For i=0 To 11
If i=0 Or i=2 Or i=4 Or i=6 Or i=8 Or i=10 Then odds.Add(brcod.CharAt(i))
If i=1 Or i=3 Or i=5 Or i=7 Or i=9 Or i=11 Then evens.Add(brcod.CharAt(i))
Next
Dim od As Int = odds.Get(0) + odds.Get(1) +odds.Get(2) +odds.Get(3) +odds.Get(4) +odds.Get(5)
Dim ev As Int = (evens.Get(0) + evens.Get(1) +evens.Get(2) +evens.Get(3) +evens.Get(4) +evens.Get(5)) * 3
Dim tt As String = od + ev
Dim ld As String = tt.SubString2(tt.Length-1,tt.Length)
If ld=0 Then
x = 0
Else
x = 10 - ld
End If
End If
Return brcod & x
End Sub