Zhang-Suen thinning algorithm: Difference between revisions
→{{header|VBA}}
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</pre>
=={{header|VBA}}==
{{trans|Phix}}
<lang vb>Public n As Variant
Private Sub init()
n = [{-1,0;-1,1;0,1;1,1;1,0;1,-1;0,-1;-1,-1;-1,0}]
End Sub
Private Function AB(text As Variant, y As Integer, x As Integer, step As Integer) As Variant
Dim wtb As Integer
Dim bn As Integer
Dim prev As String: prev = "#"
Dim next_ As String
Dim p2468 As String
For i = 1 To UBound(n)
next_ = Mid(text(y + n(i, 1)), x + n(i, 2), 1)
wtb = wtb - (prev = "." And next_ <= "#")
bn = bn - (i > 1 And next_ <= "#")
If (i And 1) = 0 Then p2468 = p2468 & prev
prev = next_
Next i
If step = 2 Then '-- make it p6842
p2468 = Mid(p2468, 3, 2) & Mid(p2468, 1, 2)
'p2468 = p2468(3..4)&p2468(1..2)
End If
Dim ret(2) As Variant
ret(0) = wtb
ret(1) = bn
ret(2) = p2468
AB = ret
End Function
Private Sub Zhang_Suen(text As Variant)
Dim wtb As Integer
Dim bn As Integer
Dim changed As Boolean, changes As Boolean
Dim p2468 As String '-- (p6842 for step 2)
Dim x As Integer, y As Integer, step As Integer
Do While True
changed = False
For step = 1 To 2
changes = False
For y = 1 To UBound(text) - 1
For x = 2 To Len(text(y)) - 1
If Mid(text(y), x, 1) = "#" Then
ret = AB(text, y, x, step)
wtb = ret(0)
bn = ret(1)
p2468 = ret(2)
If wtb = 1 _
And bn >= 2 And bn <= 6 _
And InStr(1, Mid(p2468, 1, 3), ".") _
And InStr(1, Mid(p2468, 2, 3), ".") Then
changes = True
text(y) = Left(text(y), x - 1) & "!" & Right(text(y), Len(text(y)) - x)
End If
End If
Next x
Next y
If changes Then
For y = 1 To UBound(text) - 1
text(y) = Replace(text(y), "!", ".")
Next y
changed = True
End If
Next step
If Not changed Then Exit Do
Loop
Debug.Print Join(text, vbCrLf)
End Sub
Public Sub main()
init
Dim Small_rc(9) As String
Small_rc(0) = "................................"
Small_rc(1) = ".#########.......########......."
Small_rc(2) = ".###...####.....####..####......"
Small_rc(3) = ".###....###.....###....###......"
Small_rc(4) = ".###...####.....###............."
Small_rc(5) = ".#########......###............."
Small_rc(6) = ".###.####.......###....###......"
Small_rc(7) = ".###..####..###.####..####.###.."
Small_rc(8) = ".###...####.###..########..###.."
Small_rc(9) = "................................"
Zhang_Suen (Small_rc)
End Sub</lang>{{out}}
<pre>................................
...######.........######........
...#....#.........#....##.......
...#....#.........#......#......
...#....#.........#.............
...####.#.........#.............
.......##.........#.............
........#....#....#....##...#...
.........#....#....####......#..
................................</pre>
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