FormShield – Dynamically Generates CAPTCHA Style Images

After fighting with comments spam I took an hour to implement CAPTCHA on my blog. The implementation based on amazing FormShield control .FormShield control is free for both personal and commercial use.

Download

http://www.dotnetfreak.co.uk/controls/dotNetFreak.WebControls.FormShield.zip

Integrating with the .Text Blogging Engine

Quick guide on integrating FormShield with .Text to prevent spam on your blog by Davide Mauri.

http://www.dotnetfreak.co.uk/docs/FormShield-dotText.zip

FormShield Control Features:

  • Generates BMP, GIF, JPEG, PNG or TIFF images.
  • Choose the pixel format and smoothing mode used to render the image.
  • Set the height, width and alignment of the image as well as the alternate text displayed.
  • Image is built using 3 layers – Background, foreground and noise.
  • Provides 6 fill styles, 4 gradient styles, 53 hatch styles and 2 colors for each layer.
  • Set the length and case (lower, mixed or upper) of the automatically generated text.
  • Choose the type of characters you want to use to generate the text (alpha, numeric, symbols or a combination).
  • Choose the fonts you want to use to draw the text as well as the font style (4 combinable styles, 16 in total).
  • Pick a text effect (5 combinable effects, 23 in total) and decrease the noise level to decrease readability.
  • Draw a border on the image using one of 5 styles and your choice of color.
  • Randomise the fill style, gradient style, hatch style, font style, text case, text style, text effect and border style.
  • 6 Presets included; Default, Fire, Forest, Sand, Sea, ChessBoard.
  • Supports 3 persistent methods; ViewState, SessionState or FormField (hidden input field) – ideal if ViewState and/or SessionState isn’t available to persist property values on postback.
  • Values stored using any of the persistent methods are automatically encrypted for additional security.
  • Image is rendered on demand (either inline or using an Image Provider), and not saved as a file.
  • Encrypts the querystring to prevent deciphering by reading the HTML source.
  • Works with existing ASP.NET validation controls as well as StringCompareValidator.
  • Can be used on standalone WebForms as well as UserControls.
  • Supports .Text Blogging Engine (no compile needed) to prevent spam on blogs.
  • Full Visual Studio .NET designer integration, including optional rendering whilst in design mode.

 
 
 

2 Responses to “FormShield – Dynamically Generates CAPTCHA Style Images”

  1. anonymous
    11. July 2005 at 03:05

    Hi can you please tell me how you validate this control? How do u test what you entered in the control matches the input text?

  2. Taras
    11. July 2005 at 19:58

    More information about integrating FormShield with .Text to prevent spam on your blog can be found on Davide Mauri blog.

    http://www.davidemauri.it/Formshield%20Integration.zip

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