New Update Captcha Image Control

I have updated my captcha image control. I believe it is sleeker and is overall better code wise.

Initiates an asynchronous call, and the returned result, will be a single image of alphanumeric characters. Image’s characters are presented in various font sizes and or (+/-) rotated in some degree.

This project offers the complete Visual Studio 2012 solution within a compressed zip file. Download the complete solution from CodePlex.

Shown below is the Captcha type which generates randomly selected characters and draws an image displaying those specific random characters.

Two files are involved rendering the Captcha image:

• CaptchaControl.cs and CaptchaHandler.ashx
• CaptchaControl.cs is a generic control rendering out an image and an Image Button. The rendered image’s ImageUrl property is dynamically set, and calls CaptchaHandler.ashx with an attached query string. The query string has a particular name/value pair specifying the particular Captcha characters.

CaptchaControl.cs generates and encodes characters appending the generated string to the rendering image’s query string.

CaptchaHandler.ashx returns a HTTPResponse bitmap and is displayed on the client side webpage.

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CaptchaControl Class

Namespace: Captcha.Control
Assembly: CaptchaControl.dll

Syntax
public CaptchaControl : WebControl

Constructors

CaptchaControl(): base(HtmlTextWriterTag.Fieldset)

Initializes a new instance of the CaptchaControl class

Properties

string RefreshButtonPath	Absolute path to the Image Button’s image
string CaptchaHandlerUrl	Absolute path to the Captcha Handler
int Minimum	Minimum number of characters to be selected
int Maximum	Maximum number of characters to be selected
int Overlap	Amount of overlap between character placement.
int ImageWidth	Captcha image’s width
int ImageHeight	Captcha image’s height
string CharacterSet	The character domain to select from. Default character set: ABDEGHMNQRTabdeghmnqr3456789#@&$%