1Imports System.ComponentModel
  2Imports System.Web
  3Imports System.Web.UI
  4Imports System.Web.UI.WebControls
  5Imports System.Collections
  6Imports System.Collections.Specialized
  7
  8/**/''' <summary>
  9''' CAPTCHA ASP.NET 2.0 user control
 10''' </summary>
 11''' <remarks>
 12''' add a reference to this DLL and add the CaptchaControl to your toolbox;
 13''' then just drag and drop the control on a web form and set properties on it.
 14''' 该源码下载自www.51aspx.com(５1ａｓｐｘ．ｃｏｍ)
 15''' Jeff Atwood
 16''' http://www.codinghorror.com/
 17''' </remarks>
 18<DefaultProperty("Text")> _
 19Public Class CaptchaControlClass CaptchaControl
 20    Inherits System.Web.UI.WebControls.WebControl
 21    Implements INamingContainer
 22    Implements IPostBackDataHandler
 23    Implements IValidator
 24
 25    Public Enum LayoutEnum Layout
 26        Horizontal
 27        Vertical
 28    End Enum
 29
 30    Public Enum CacheTypeEnum CacheType
 31        HttpRuntime
 32        Session
 33    End Enum
 34
 35    Private _timeoutSecondsMax As Integer = 90
 36    Private _timeoutSecondsMin As Integer = 3
 37    Private _userValidated As Boolean = True
 38    Private _text As String = "Enter the code shown:"
 39    Private _font As String = ""
 40    Private _captcha As CaptchaImage = New CaptchaImage
 41    Private _layoutStyle As Layout = Layout.Horizontal
 42    Private _prevguid As String
 43    Private _errorMessage As String = ""
 44    Private _cacheStrategy As CacheType = CacheType.HttpRuntime
 45
 46Public Properties#Region "  Public Properties"
 47
 48    <Browsable(False), _
 49    Bindable(True), _
 50    Category("Appearance"), _
 51    DefaultValue("The text you typed does not match the text in the image."), _
 52    Description("Message to display in a Validation Summary when the CAPTCHA fails to validate.")> _
 53    Public Property ErrorMessage()Property ErrorMessage() As String Implements System.Web.UI.IValidator.ErrorMessage
 54        Get
 55            If Not _userValidated Then
 56                Return _errorMessage
 57            Else
 58                Return ""
 59            End If
 60        End Get
 61        Set(ByVal value As String)
 62            _errorMessage = value
 63        End Set
 64    End Property
 65
 66    <Browsable(False), _
 67    Category("Behavior"), _
 68    DefaultValue(True), _
 69    Description("Is Valid"), _
 70    DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)> _
 71    Public Property IsValid()Property IsValid() As Boolean Implements System.Web.UI.IValidator.IsValid
 72        Get
 73            Return _userValidated
 74        End Get
 75        Set(ByVal value As Boolean)
 76        End Set
 77    End Property
 78
 79    Public Overrides Property Enabled()Property Enabled() As Boolean
 80        Get
 81            Return MyBase.Enabled
 82        End Get
 83        Set(ByVal value As Boolean)
 84            MyBase.Enabled = value
 85            ' When a validator is disabled, generally, the intent is not to
 86            ' make the page invalid for that round trip.
 87            If Not value Then
 88                _userValidated = True
 89            End If
 90        End Set
 91    End Property
 92
 93
 94    <DefaultValue("Enter the code shown above:"), _
 95    Description("Instructional text displayed next to CAPTCHA image."), _
 96    Category("Appearance")> _
 97    Public Property [()Property [Text]() As String
 98        Get
 99            Return _text
100        End Get
101        Set(ByVal Value As String)
102            _text = Value
103        End Set
104    End Property
105
106    <DefaultValue(GetType(CaptchaControl.Layout), "Horizontal"), _
107    Description("Determines if image and input area are displayed horizontally, or vertically."), _
108    Category("Captcha")> _
109    Public Property LayoutStyle()Property LayoutStyle() As Layout
110        Get
111            Return _layoutStyle
112        End Get
113        Set(ByVal Value As Layout)
114            _layoutStyle = Value
115        End Set
116    End Property
117
118    <DefaultValue(GetType(CaptchaControl.CacheType), "HttpRuntime"), _
119    Description("Determines if CAPTCHA codes are stored in HttpRuntime (fast, but local to current server) or Session (more portable across web farms)."), _
120    Category("Captcha")> _
121    Public Property CacheStrategy()Property CacheStrategy() As CacheType
122        Get
123            Return _cacheStrategy
124        End Get
125        Set(ByVal value As CacheType)
126            _cacheStrategy = value
127        End Set
128    End Property
129
130    <Description("Returns True if the user was CAPTCHA validated after a postback."), _
131    Category("Captcha")> _
132    Public ReadOnly Property UserValidated()Property UserValidated() As Boolean
133        Get
134            Return _userValidated
135        End Get
136    End Property
137
138
139    <DefaultValue(""), _
140    Description("Font used to render CAPTCHA text. If font name is blank, a random font will be chosen."), _
141    Category("Captcha")> _
142    Public Property CaptchaFont()Property CaptchaFont() As String
143        Get
144            Return _font
145        End Get
146        Set(ByVal Value As String)
147            _font = Value
148            _captcha.Font = _font
149        End Set
150    End Property
151
152    <DefaultValue(""), _
153    Description("Characters used to render CAPTCHA text. A character will be picked randomly from the string."), _
154    Category("Captcha")> _
155    Public Property CaptchaChars()Property CaptchaChars() As String
156        Get
157            Return _captcha.TextChars
158        End Get
159        Set(ByVal Value As String)
160            _captcha.TextChars = Value
161        End Set
162    End Property
163
164    <DefaultValue(5), _
165    Description("Number of CaptchaChars used in the CAPTCHA text"), _
166    Category("Captcha")> _
167    Public Property CaptchaLength()Property CaptchaLength() As Integer
168        Get
169            Return _captcha.TextLength
170        End Get
171        Set(ByVal Value As Integer)
172            _captcha.TextLength = Value
173        End Set
174    End Property
175
176    <DefaultValue(2), _
177    Description("Minimum number of seconds CAPTCHA must be displayed before it is valid. If you're too fast, you must be a robot. Set to zero to disable."), _
178    Category("Captcha")> _
179    Public Property CaptchaMinTimeout()Property CaptchaMinTimeout() As Integer
180        Get
181            Return _timeoutSecondsMin
182        End Get
183        Set(ByVal Value As Integer)
184            If Value > 15 Then
185                Throw New ArgumentOutOfRangeException("CaptchaTimeout", "Timeout must be less than 15 seconds. Humans aren't that slow!")
186            End If
187            _timeoutSecondsMin = Value
188        End Set
189    End Property
190
191    <DefaultValue(90), _
192    Description("Maximum number of seconds CAPTCHA will be cached and valid. If you're too slow, you may be a CAPTCHA hack attempt. Set to zero to disable."), _
193    Category("Captcha")> _
194    Public Property CaptchaMaxTimeout()Property CaptchaMaxTimeout() As Integer
195        Get
196            Return _timeoutSecondsMax
197        End Get
198        Set(ByVal Value As Integer)
199            If Value < 15 And Value <> 0 Then
200                Throw New ArgumentOutOfRangeException("CaptchaTimeout", "Timeout must be greater than 15 seconds. Humans can't type that fast!")
201            End If
202            _timeoutSecondsMax = Value
203        End Set
204    End Property
205
206    <DefaultValue(50), _
207    Description("Height of generated CAPTCHA image."), _
208    Category("Captcha")> _
209    Public Property CaptchaHeight()Property CaptchaHeight() As Integer
210        Get
211            Return _captcha.Height
212        End Get
213        Set(ByVal Value As Integer)
214            _captcha.Height = Value
215        End Set
216    End Property
217
218    <DefaultValue(180), _
219    Description("Width of generated CAPTCHA image."), _
220    Category("Captcha")> _
221    Public Property CaptchaWidth()Property CaptchaWidth() As Integer
222        Get
223            Return _captcha.Width
224        End Get
225        Set(ByVal Value As Integer)
226            _captcha.Width = Value
227        End Set
228    End Property
229
230    <DefaultValue(GetType(CaptchaImage.FontWarpFactor), "Low"), _
231    Description("Amount of random font warping used on the CAPTCHA text"), _
232    Category("Captcha")> _
233    Public Property CaptchaFontWarping()Property CaptchaFontWarping() As CaptchaImage.FontWarpFactor
234        Get
235            Return _captcha.FontWarp
236        End Get
237        Set(ByVal Value As CaptchaImage.FontWarpFactor)
238            _captcha.FontWarp = Value
239        End Set
240    End Property
241
242    <DefaultValue(GetType(CaptchaImage.BackgroundNoiseLevel), "Low"), _
243    Description("Amount of background noise to generate in the CAPTCHA image"), _
244    Category("Captcha")> _
245    Public Property CaptchaBackgroundNoise()Property CaptchaBackgroundNoise() As CaptchaImage.BackgroundNoiseLevel
246        Get
247            Return _captcha.BackgroundNoise
248        End Get
249        Set(ByVal Value As CaptchaImage.BackgroundNoiseLevel)
250            _captcha.BackgroundNoise = Value
251        End Set
252    End Property
253
254    <DefaultValue(GetType(CaptchaImage.LineNoiseLevel), "None"), _
255    Description("Add line noise to the CAPTCHA image"), _
256    Category("Captcha")> _
257    Public Property CaptchaLineNoise()Property CaptchaLineNoise() As CaptchaImage.LineNoiseLevel
258        Get
259            Return _captcha.LineNoise
260        End Get
261        Set(ByVal Value As CaptchaImage.LineNoiseLevel)
262            _captcha.LineNoise = Value
263        End Set
264    End Property
265#End Region
266
267    Public Sub Validate()Sub Validate() Implements System.Web.UI.IValidator.Validate
268        '-- a no-op, since we validate in LoadPostData
269    End Sub
270
271    Private Function GetCachedCaptcha()Function GetCachedCaptcha(ByVal guid As String) As CaptchaImage
272        If _cacheStrategy = CacheType.HttpRuntime Then
273            Return CType(HttpRuntime.Cache.Get(guid), CaptchaImage)
274        Else
275            Return CType(HttpContext.Current.Session.Item(guid), CaptchaImage)
276        End If
277    End Function
278
279    Private Sub RemoveCachedCaptcha()Sub RemoveCachedCaptcha(ByVal guid As String)
280        If _cacheStrategy = CacheType.HttpRuntime Then
281            HttpRuntime.Cache.Remove(guid)
282        Else
283            HttpContext.Current.Session.Remove(guid)
284        End If
285    End Sub
286
287    /**/''' <summary>
288    ''' are we in design mode?
289    ''' </summary>
290    Private ReadOnly Property IsDesignMode()Property IsDesignMode() As Boolean
291        Get
292            Return HttpContext.Current Is Nothing
293        End Get
294    End Property
295
296    /**/''' <summary>
297    ''' Validate the user's text against the CAPTCHA text
298    ''' </summary>
299    Private Sub ValidateCaptcha()Sub ValidateCaptcha(ByVal userEntry As String)
300
301        If Not Visible Or Not Enabled Then
302            _userValidated = True
303            Return
304        End If