asp无组件生成验证码 GIF图片格式

<% 
Option Explicit ' 显示声明 
Class Com_GifCode_Class 
''''''''''''''''''''''''''''''''''''''''''''' 
' Author: Layen support@ssaw.net 84815733(QQ) 
' Thanks: Laomi, Laomiao, NetRube 
' 2006-01-02 
''''''''''''''''''''''''''''''''''''''''''''' 
Public Noisy, Count, Width, Height, Angle, Offset, Border 
Private Graph(), Margin(3) 
Private Sub Class_Initialize() 
Randomize 
Noisy = 16 ' 干扰点出现的概率 
Count = 4 ' 字符数量 
Width = 80 ' 图片宽度 
Height = 20 ' 图片高度 
Angle = 2 ' 角度随机变化量 
Offset = 20 ' 偏移随机变化量 
Border = 1 ' 边框大小 
End Sub 
Public Function Create() 
Const cCharSet = "123456789" 
Dim i, x, y 
Dim vValidCode : vValidCode = "" 
Dim vIndex 
ReDim Graph(Width-1, Height-1) 
For i = 0 To Count - 1 
vIndex = Int(Rnd * Len(cCharSet)) 
vValidCode = vValidCode + Mid(cCharSet, vIndex+1 , 1) 
SetDraw vIndex, i 
Next 
Create = vValidCode 
End Function 
Sub SetDot(pX, pY) 
If pX * (Width-pX-1) >= 0 And pY * (Height-pY-1) >= 0 Then 
Graph(pX, pY) = 1 
End If 
End Sub 
Public Sub SetDraw(pIndex, pNumber) 
' 字符数据 
Dim DotData(8) 
DotData(0) = Array(30, 15, 50, 1, 50, 100) 
DotData(1) = Array(1 ,34 ,30 ,1 ,71, 1, 100, 34, 1, 100, 93, 100, 100, 86) 
DotData(2) = Array(1, 1, 100, 1, 42, 42, 100, 70, 50, 100, 1, 70) 
DotData(3) = Array(100, 73, 6, 73, 75, 6, 75, 100) 
DotData(4) = Array(100, 1, 1, 1, 1, 50, 50, 35, 100, 55, 100, 80, 50, 100, 1, 95) 
DotData(5) = Array(100, 20, 70, 1, 20, 1, 1, 30, 1, 80, 30, 100, 70, 100, 100, 80, 100, 60, 70, 50, 30, 50, 1, 60) 
DotData(6) = Array(6, 26, 6, 6, 100, 6, 53, 100) 
DotData(7) = Array(100, 30, 100, 20, 70, 1, 30, 1, 1, 20, 1, 30, 100, 70, 100, 80, 70, 100, 30, 100, 1, 80, 1, 70, 100, 30) 
DotData(8) = Array(1, 80, 30, 100, 80, 100, 100, 70, 100, 20, 70, 1, 30, 1, 1, 20, 1, 40, 30, 50, 70, 50, 100, 40) 
Dim vExtent : vExtent = Width / Count 
Margin(0) = Border + vExtent * (Rnd * Offset) / 100 + Margin(1) 
Margin(1) = vExtent * (pNumber + 1) - Border - vExtent * (Rnd * Offset) / 100 
Margin(2) = Border + Height * (Rnd * Offset) / 100 
Margin(3) = Height - Border - Height * (Rnd * Offset) / 100 
Dim vStartX, vEndX, vStartY, vEndY 
Dim vWidth, vHeight, vDX, vDY, vDeltaT 
Dim vAngle, vLength 
vWidth = Int(Margin(1) - Margin(0)) 
vHeight = Int(Margin(3) - Margin(2)) 
' 起始坐标 
vStartX = Int((DotData(pIndex)(0)-1) * vWidth / 100) 
vStartY = Int((DotData(pIndex)(1)-1) * vHeight / 100) 
Dim i, j 
For i = 1 To UBound(DotData(pIndex), 1)/2 
If DotData(pIndex)(2*i-2) <> 0 And DotData(pIndex)(2*i) <> 0 Then 
' 终点坐标 
vEndX = (DotData(pIndex)(2*i)-1) * vWidth / 100 
vEndY = (DotData(pIndex)(2*i+1)-1) * vHeight / 100 
' 横向差距 
vDX = vEndX - vStartX 
' 纵向差距 
vDY = vEndY - vStartY 
' 倾斜角度 
If vDX = 0 Then 
vAngle = Sgn(vDY) * 3.14/2 
Else 
vAngle = Atn(vDY / vDX) 
End If 
' 两坐标距离 
If Sin(vAngle) = 0 Then 
vLength = vDX 
Else 
vLength = vDY / Sin(vAngle) 
End If 
' 随机转动角度 
vAngle = vAngle + (Rnd - 0.5) * 2 * Angle * 3.14 * 2 / 100 
vDX = Int(Cos(vAngle) * vLength) 
vDY = Int(Sin(vAngle) * vLength) 
If Abs(vDX) > Abs(vDY) Then vDeltaT = Abs(vDX) Else vDeltaT = Abs(vDY) 
For j = 1 To vDeltaT 
SetDot Margin(0) + vStartX + j * vDX / vDeltaT, Margin(2) + vStartY + j * vDY / vDeltaT 
Next 
vStartX = vStartX + vDX 
vStartY = vStartY + vDY 
End If 
Next 
End Sub 
Public Sub Output() 
Response.Expires = -9999 
Response.AddHeader "pragma", "no-cache" 
Response.AddHeader "cache-ctrol", "no-cache" 
Response.ContentType = "image/gif" 
' 文件类型 
Response.BinaryWrite ChrB(Asc("G")) & ChrB(Asc("I")) & ChrB(Asc("F")) 
' 版本信息 
Response.BinaryWrite ChrB(Asc("8")) & ChrB(Asc("9")) & ChrB(Asc("a")) 
' 逻辑屏幕宽度 
Response.BinaryWrite ChrB(Width Mod 256) & ChrB((Width / 256) Mod 256) 
' 逻辑屏幕高度 
Response.BinaryWrite ChrB(Height Mod 256) & ChrB((Height / 256) Mod 256) 
Response.BinaryWrite ChrB(128) & ChrB(0) & ChrB(0) 
' 全局颜色列表 
Response.BinaryWrite ChrB(255) & ChrB(255) & ChrB(255) 
Response.BinaryWrite ChrB(0) & ChrB(85) & ChrB(255) 
' 图象标识符 
Response.BinaryWrite ChrB(Asc(",")) 
Response.BinaryWrite ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) 
' 图象宽度 
Response.BinaryWrite ChrB(Width Mod 256) & ChrB((Width / 256) Mod 256) 
' 图象高度 
Response.BinaryWrite ChrB(Height Mod 256) & ChrB((Height / 256) Mod 256) 
Response.BinaryWrite ChrB(0) & ChrB(7) & ChrB(255) 
Dim x, y, i : i = 0 
For y = 0 To Height - 1 
For x = 0 To Width - 1 
If Rnd < Noisy / 100 Then 
Response.BinaryWrite ChrB(1-Graph(x, y)) 
Else 
If x * (x-Width) = 0 Or y * (y-Height) = 0 Then 
Response.BinaryWrite ChrB(Graph(x, y)) 
Else 
If Graph(x-1, y) = 1 Or Graph(x, y) Or Graph(x, y-1) = 1 Then 
Response.BinaryWrite ChrB(1) 
Else 
Response.BinaryWrite ChrB(0) 
End If 
End If 
End If 
If (y * Width + x + 1) Mod 126 = 0 Then 
Response.BinaryWrite ChrB(128) 
i = i + 1 
End If 
If (y * Width + x + i + 1) Mod 255 = 0 Then 
If (Width*Height - y * Width - x - 1) > 255 Then 
Response.BinaryWrite ChrB(255) 
Else 
Response.BinaryWrite ChrB(Width * Height Mod 255) 
End If 
End If 
Next 
Next 
Response.BinaryWrite ChrB(128) & ChrB(0) & ChrB(129) & ChrB(0) & ChrB(59) 
End Sub 
End Class 
Dim mCode 
Set mCode = New Com_GifCode_Class 
Session("GetCode") = mCode.Create() 
mCode.Output() 
Set mCode = Nothing 
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