# <Captcha>

The Captcha tag renders as a CAPTCHA control at run time.

# Syntax

<Captcha 
    BackColor="color name|#dddddd" 
    BackgroundColor="color name|#dddddd" 
    BackgroundImage="url" 
    BorderColor="color name|#dddddd" 
    BorderStyle="NotSet|None|Dotted|Dashed|Solid|Double|Groove|Ridge| Inset|Outset" 
    BorderWidth="size" 
    CaptchaChars="string"
    CaptchaHeight="size"
    CaptchaLength="integer"
    CaptchaWidth="size"
    CssClass="string" 
    ErrorMessage="string" 
    ErrorStyle-BackColor="color name|#dddddd"
    ErrorStyle-BorderColor="color name|#dddddd"
    ErrorStyle-BorderStyle="NotSet|None|Dotted|Dashed|Solid|Double|Groove|Ridge|Inset|OutSet"
    ErrorStyle-BorderWidth="size"
    ErrorStyle-Font-Bold="True|False"
    ErrorStyle-Font-Italic="True|False" 
    ErrorStyle-Font-Names="string" 
    ErrorStyle-Font-Overline="True|False" 
    ErrorStyle-Font-Size="string|Smaller|Larger|XX-Small|X-Small|Small|Medium| Large|X-Large|XX-Large" 
    ErrorStyle-Font-Strikeout="True|False" 
    ErrorStyle-Font-Underline="True|False" 
    ErrorStyle-ForeColor="color name|#dddddd" 
    Expiration="integer"
    Font-Bold="True|False" 
    Font-Italic="True|False" 
    Font-Names="string" 
    Font-Overline="True|False" 
    Font-Size="string|Smaller|Larger|XX-Small|X-Small|Small|Medium| Large|X-Large|XX-Large" 
    Font-Strikeout="True|False" 
    Font-Underline="True|False" 
    ForeColor="color name|#dddddd" 
    Height="size" 
    ID="string" 
    Text="string"
    Width="size"
/> 

# Remarks

If your forms are available to the public, chances are you'll get web 'bots filling in those forms with bogus information. To help protect against this, you can add a CAPTCHA control to your form. The control attempts to prove the user is an actual human by asking them to view a series of characters and typing those characters into a box for verification. The characters are rendered as an image and are skewed and obfuscated so that (hopefully) only a human could read them. While it is no guarantee your forms won't get spammed, the control typically reduces the frequency of those attacks.

• BackColor: Color of the background of the control.

• BackgroundColor: Gets and sets the background color.

• BackgroundImage: A URL to an image file to use as the background on which the characters will be placed. (optional).

• BorderColor: Color of the border around the control.

• BorderStyle: Style of the border around the control.

• BorderWidth: Width of the border around the control, specified in units.

• CaptchaChars: If you wish to specify your own characters that will be used to make up the code the user must type, you can specify them in this property.

• CaptchaHeight: The height of the area in which the characters will be displayed.

• CaptchaLength: The number of characters to use for the code.

• CaptchaWidth: The width of the area in which the characters will be displayed.

• CssClass: Name of the Cascading Style Sheets (CSS) class used to style this control.

• ErrorMessage: The message to display to the user if Captcha validation failed.

• ErrorStyle: The style to use for displaying the error message. ErrorStyle is specified using the following syntax: ErrorStyle-styleAttributeName where styleAttributeName is the name of the style attribute such as ForeColor or Font-Bold. See the syntax section above for more.

• Expiration: Gets and sets the Expiration time in seconds.

• Font Properties: A series of attributes such as font-bold, font-size, etc. that allow you to control how the text in the control is displayed. More

• ForeColor: Sets the foreground color (typically the color of the text) of the control.

• Height: Height of the control, specified in units.

• ID: Name, consisting of letters and numbers, beginning with a letter, that uniquely identifies the control within the form.

• Text: The caption to display.

• Width: Width of the control in units.

# Example

<AddForm>
  ...
  <table>
    <tr>
      <td>
        <Label For="txtFirstName" Text="First Name" /> 
        <Textbox id="txtFirstName" DataField="FirstName" DataType="string" />
      </td>
    </tr>
    <tr>
      <td>
        <Label For="txtLastName" Text="First Name" /> 
        <Textbox Id="txtLastName" DataField="LastName" DataType="string" />
       </td>
    </tr>
    <tr>
      <td>
        <Captcha CaptchaLength="5" />
      </td>
    </tr>
    <tr>
      <td colspan="2">
        <AddbButton Text="Add"/>&nbsp; <CancelButton Text="Cancel"/>
      </td>
    </tr>
  </table>
</AddForm>