VerifyCode(asp),gif验证码生成技术源码精华教程

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'--------------------------------------
'Fly38.com - VerifyCode Class
' gif 验证码生成类
' 原作者：NetRube
'--------------------------------------
Class Fly38_VerifyCode
Public GlobalColorTable(), LocalColorTable()
Public TransparentColorIndex, UseTransparency
Public GIF89a
Public Comment

Private FGroundColorIndex, BGroundColorIndex
Private Image
Private GlobalColorTableSize, GlobalColorTableFlag, LocalColorTableSize, LocalColorTableFlag
Private Width_, Height_
Private LeftPosition, TopPosition
Private Bits, ColorResolution, CodeSize
Private PixelAspectRatio
Private SortFlag, InterlaceFlag
Private Seperator, GraphicControl, EndOfImage
Private Reserved

Private Font
Private Letter(19)

Private Sub Class_Initialize()
Image = ""

GIF89a = False

ReDim GlobalColorTable(256)
GlobalColorTableSize = 7
GlobalColorTableFlag = True

GlobalColorTable(2) = RGB(255, 0, 0)
GlobalColorTable(3) = RGB(0, 255, 0)
GlobalColorTable(4) = RGB(0, 0, 255)
GlobalColorTable(5) = RGB(255, 255, 0)
GlobalColorTable(6) = RGB(0, 255, 255)
GlobalColorTable(7) = RGB(255, 0, 255)

ReDim LocalColorTable(0)
LocalColorTableSize = 0
LocalColorTableFlag = False

ColorResolution = 7
Bits = 7
CodeSize = 7

BGroundColorIndex = 0
FGroundColorIndex = 1
TransparentColorIndex = 0
UseTransparency = False

LeftPosition = 0
TopPosition = 0
Width_ = 20
Height_ = 20

Clear

PixelAspectRatio = 0
SortFlag = False
InterlaceFlag = False
Seperator = Asc(",")
GraphicControl = Asc("!")
EndOfImage = Asc(";")

Comment = ""

Reserved = 0

Set Font = Server.CreateObject("Scripting.Dictionary")

Letter(0) = "00000000000000"
Letter(1) = "00001111100000"
Letter(2) = "00011111110000"
Letter(3) = "00111000111000"
Letter(4) = "00110000011100"
Letter(5) = "01110000001100"
Letter(6) = "01100000001110"
Letter(7) = "01100000001110"
Letter(8) = "11100000001110"
Letter(9) = "11000000001110"
Letter(10) = "11000000001110"
Letter(11) = "11100000001110"
Letter(12) = "11100000001100"
Letter(13) = "11100000001100"
Letter(14) = "01100000001100"
Letter(15) = "01110000011100"
Letter(15) = "00111000011000"
Letter(16) = "00011111110000"
Letter(17) = "00001111100000"
Letter(18) = "00000000000000"
Font.Add "0", Letter

Letter(0) = "00000000000000"
Letter(1) = "00000001110000"
Letter(2) = "00000001110000"
Letter(3) = "00000011100000"
Letter(4) = "00000011000000"
Letter(5) = "00000011000000"
Letter(6) = "00000011000000"
Letter(7) = "00000111000000"
Letter(8) = "00000111000000"
Letter(9) = "00000111000000"
Letter(10) = "00000110000000"
Letter(11) = "00000110000000"
Letter(12) = "00000110000000"
Letter(13) = "00000110000000"
Letter(14) = "00000110000000"
Letter(15) = "00000110000000"
Letter(15) = "00000110000000"
Letter(16) = "00000110000000"
Letter(17) = "00000010000000"
Letter(18) = "00000000000000"
Font.Add "1", Letter

Letter(0) = "00000000000000"
Letter(1) = "00001111110000"
Letter(2) = "00011111111000"
Letter(3) = "00111000011100"
Letter(4) = "01110000011100"
Letter(5) = "01110000011000"
Letter(6) = "01100000011000"
Letter(7) = "00000000111000"
Letter(8) = "00000001110000"
Letter(9) = "00000001110000"
Letter(10) = "00000011000000"
Letter(11) = "00000111000000"
Letter(12) = "00001110000000"
Letter(13) = "00011000000000"
Letter(14) = "00011000000000"
Letter(15) = "00110000011100"
Letter(16) = "01101111111100"
Letter(17) = "01111111111110"
Letter(18) = "01111100000000"
Letter(19) = "00000000000000"
Font.Add "2", Letter

Letter(0) = "00000000000000"
Letter(1) = "00001111111000"
Letter(2) = "00111111111000"
Letter(3) = "01110000111100"
Letter(4) = "01100000011000"
Letter(5) = "01000000111000"
Letter(6) = "00000000111000"
Letter(7) = "00000001110000"
Letter(8) = "00000011000000"
Letter(9) = "00000111110000"
Letter(10) = "00000100111000"
Letter(11) = "00000000011100"
Letter(12) = "00000000011100"
Letter(13) = "00000000011100"
Letter(14) = "00000000011100"
Letter(15) = "00000000011000"
Letter(16) = "11100000111000"
Letter(17) = "11111111110000"
Letter(18) = "01111111100000"
Letter(19) = "00000000000000"
Font.Add "3", Letter

Letter(0) = "00000000000000"
Letter(1) = &qu