Imports System.Text
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Drawing.Drawing2D
Class CaptchaBox
Inherits PictureBox
#Region "Properties"
Private _textcolor As Color = Color.Black
Public Property TextColor() As Color
Get
Return _textcolor
End Get
Set(value As Color)
_textcolor = value
Invalidate()
End Set
End Property
Private _font As New Font("Segoe UI", 20)
Public Overrides Property Font() As Font
Get
Return _font
End Get
Set(value As Font)
_font = value
Invalidate()
End Set
End Property
Private _texttouse As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmopqrstuvwxyz!#$%^&*()1234567890"
Public Property RandomCharacters() As String
Get
Return _texttouse
End Get
Set(value As String)
_texttouse = value
Invalidate()
End Set
End Property
Private _captchalength As Integer = 8
Public Property CaptchaTextLength() As Integer
Get
Return _captchalength
End Get
Set(value As Integer)
_captchalength = value
Invalidate()
End Set
End Property
Private _numberoflines As Integer = 50
Public Property NumberOfLines() As Integer
Get
Return _numberoflines
End Get
Set(value As Integer)
_numberoflines = value
Invalidate()
End Set
End Property
#End Region
#Region "Events"
Public Sub New()
SetStyle(ControlStyles.AllPaintingInWmPaint, True)
SetStyle(ControlStyles.ResizeRedraw, True)
SetStyle(ControlStyles.UserPaint, True)
SetStyle(ControlStyles.OptimizedDoubleBuffer, True)
SetStyle(ControlStyles.SupportsTransparentBackColor, True)
End Sub
Protected Overrides Sub CreateHandle()
MyBase.CreateHandle()
Me.Size = New Size(241, 69)
Me.BorderStyle = BorderStyle.FixedSingle
End Sub
Public CaptchaText As String = String.Empty
Private rnd As New Random()
Protected Overrides Sub OnPaint(e As PaintEventArgs)
Dim B As New Bitmap(Width, Height)
Dim G As Graphics = Graphics.FromImage(B)
Dim BoxSize As New Rectangle(0, 0, Me.Width, Me.Height)
Dim txtcolor As Brush = New SolidBrush(Color.FromArgb(rnd.[Next](160, 255), _textcolor))
G.SmoothingMode = SmoothingMode.HighQuality
G.Clear(BackColor)
For I As Integer = 0 To _numberoflines - 1
G.DrawLine(New Pen(Color.FromArgb(rnd.[Next](128, 255), CreateRandomColor())), rnd.[Next](0, BoxSize.Width), rnd.[Next](0, BoxSize.Height), rnd.[Next](BoxSize.Width), rnd.[Next](BoxSize.Height))
Next
Dim SFormat As New StringFormat()
SFormat.Alignment = StringAlignment.Center
SFormat.LineAlignment = StringAlignment.Center
G.RotateTransform(rnd.[Next](-7, 7), MatrixOrder.Append)
Dim randomstr As String = CreateRandomString()
G.DrawString(randomstr, Font, txtcolor, BoxSize, SFormat)
CaptchaText = randomstr
e.Graphics.DrawImage(B, 0, 0)
G.Dispose()
B.Dispose()
End Sub
#End Region
#Region "Create Randoms"
Private Function CreateRandomColor() As Color
Return Color.FromArgb(100, rnd.[Next](255), rnd.[Next](255), rnd.[Next](255))
End Function
Private Function CreateRandomString() As String
Dim buffer As Char() = New Char(_captchalength - 1) {}
For i As Integer = 0 To _captchalength - 1
If _texttouse = String.Empty Then
Dim newtext As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmopqrstuvwxyz1234567890"
buffer(i) = newtext(rnd.[Next](newtext.Length))
Else
buffer(i) = _texttouse(rnd.[Next](_texttouse.Length))
End If
Next
Return New String(buffer)
End Function
#End Region
End Class
