<?php 
   /************************ Class Info ***************************/
   /*
   
   Basic Usage Steps
   -----------------
   
   1. Create a file to call the class
   2. Include the file as the src of an img tag in your HTML form
   3. Check the user entered code against the generated code using the static method
      PhpCaptcha::Validate(string sCode). This takes one argument - the user entered code
     
   Additional Options
   ------------------
   
   There are two ways to set additional options to change the behaviour and look
   and feel of the generated CAPTCHA
   
   1. Specify the options in the class constructor - only the first parameter is required
   2. Use the corresponding "Set" method. Available ones shown below:
   
      SetWidth(int iWidth) - width in pixels
      SetHeight(int iHeight) - height in pixels
      SetNumChars(int iNumchars) - number of characters to generate, default 5
      SetNumLines(int iNumLines) - number of noise lines to generate, default 70
      DisplayShadow(bool bCharShadow) - display character shadow, default false
      SetOwnerText(string sOwnerText) - display owner identification text at bottom on CAPTCHA
      SetCharSet(array aCharSet) - specify custom array of characters to generate code from - default (A-Z)
      SetBackgroundImage(string sBackgroundImage) - specify a custom background to display, filename for jpeg image, noise lines are turned off if used
      SetMinFontSize(int iMinFontSize) - minimum font size to select from (pts)
      SetMaxFontSize(int iMaxFontSize) - max font size to select from (pts)
      UseColour(bool bUseColour) - use coloured lines and characters instead of greyscale, default false
      SetFileType() - 'gif', 'png' or 'jpeg' (default 'jpeg')
     
   Sub-Classing
   ------------
   Creating a sub class will allow you to control which options you expose in the constructor or allow you to pre-set
   options for use in multiple places
     
   Other Info
   ----------
   
   If you use the class in a real world situation, drop me a line or post on my site - I'd
   love to hear about it
   
   */
   /************************ End Class Info ***********************/
   
   /************************ Default Options **********************/
   
   // start a PHP session - this class uses sessions to store the generated
   // code. Comment out if you are calling already from your application
   session_start();
   
   // class defaults - change to effect globally
   
   define('CAPTCHA_WIDTH', 200); // max 500
   define('CAPTCHA_HEIGHT', 50); // max 200
   define('CAPTCHA_NUM_CHARS', 5);
   define('CAPTCHA_NUM_LINES', 70);
   define('CAPTCHA_CHAR_SHADOW', false);
   define('CAPTCHA_OWNER_TEXT', '');
   define('CAPTCHA_BACKGROUND_IMAGE', '');
   define('CAPTCHA_MIN_FONT_SIZE', 16);
   define('CAPTCHA_MAX_FONT_SIZE', 25);
   define('CAPTCHA_USE_COLOUR', false);
   define('CAPTCHA_FILE_TYPE', 'jpeg');
   
   /************************ End Default Options **********************/
   
   // don't edit below this line (unless you want to change the class!)
   
   class PhpCaptcha {
      var $oImage;
      var $aFonts;
      var $iWidth;
      var $iHeight;
      var $iNumChars;
      var $iNumLines;
      var $iSpacing;
      var $bCharShadow;
      var $sOwnerText;
      var $aCharSet;
      var $sBackgroundImage;
      var $iMinFontSize;
      var $iMaxFontSize;
      var $bUseColour;
      var $sFileType;
      var $sCode;
     
      function PhpCaptcha(
         $aFonts, // array of TypeType fonts to use - specify full path
         $iWidth = CAPTCHA_WIDTH, // width of image
         $iHeight = CAPTCHA_HEIGHT, // height of image
         $iNumChars = CAPTCHA_NUM_CHARS, // number of characters to draw
         $iNumLines = CAPTCHA_NUM_LINES, // number of noise lines to draw
         $bCharShadow = CAPTCHA_CHAR_SHADOW, // add shadow to generated characters to further obscure code
         $sOwnerText = CAPTCHA_OWNER_TEXT, // add owner text to bottom of CAPTCHA, usually your site address
         $aCharSet = array(), // array of characters to select from - if blank uses upper case A - Z
         $sBackgroundImage = CAPTCHA_BACKGROUND_IMAGE, // background image to use - if blank creates image with white background
         $iMinFontSize = CAPTCHA_MIN_FONT_SIZE, // set the minimum font size that can be selected
         $iMaxFontSize = CAPTCHA_MAX_FONT_SIZE, // set the maximum font size that can be used
         $bUseColour = CAPTCHA_USE_COLOUR, // determines whether or not to use colour to draw lines and characters
         $sFileType = CAPTCHA_FILE_TYPE // set the output file type
      ) {
         // get parameters
         $this->aFonts = $aFonts;
         $this->SetNumChars($iNumChars);
         $this->SetNumLines($iNumLines);
         $this->DisplayShadow($bCharShadow);
         $this->SetOwnerText($sOwnerText);
         $this->SetCharSet($aCharSet);
         $this->SetBackgroundImage($sBackgroundImage);
         $this->SetMinFontSize($iMinFontSize);
         $this->SetMaxFontSize($iMaxFontSize);
         $this->UseColour($bUseColour);
         $this->SetFileType($sFileType);   
         $this->SetWidth($iWidth);
         $this->SetHeight($iHeight);
         
         // calculate spacing between characters based on width of image
         $this->CalculateSpacing();
      }
     
      function CalculateSpacing() {
         $this->iSpacing = (int)($this->iWidth / $this->iNumChars);
      }
     
      function SetWidth($iWidth) {
         $this->iWidth = $iWidth;
         if ($this->iWidth > 500) $this->iWidth = 500; // to prevent perfomance impact
         $this->CalculateSpacing();
      }
     
      function SetHeight($iHeight) {
         $this->iHeight = $iHeight;
         if ($this->iHeight > 200) $this->iHeight = 200; // to prevent performance impact
      }
     
      function SetNumChars($iNumChars) {
         $this->iNumChars = $iNumChars;
         $this->CalculateSpacing();
      }
     
      function SetNumLines($iNumLines) {
         $this->iNumLines = $iNumLines;
      }
     
      function DisplayShadow($bCharShadow) {
         $this->bCharShadow = $bCharShadow;
      }
     
      function SetOwnerText($sOwnerText) {
         $this->sOwnerText = $sOwnerText;
      }
     
      function SetCharSet($aCharSet) {
         $this->aCharSet = $aCharSet;
      }
     
      function SetBackgroundImage($sBackgroundImage) {
         $this->sBackgroundImage = $sBackgroundImage;
      }
     
      function SetMinFontSize($iMinFontSize) {
         $this->iMinFontSize = $iMinFontSize;
      }
     
      function SetMaxFontSize($iMaxFontSize) {
         $this->iMaxFontSize = $iMaxFontSize;
      }
     
      function UseColour($bUseColour) {
         $this->bUseColour = $bUseColour;
      }
     
      function SetFileType($sFileType) {
         // check for valid file type
         if (in_array($sFileType, array('gif', 'png', 'jpeg'))) {
            $this->sFileType = $sFileType;
         } else {
            $this->sFileType = 'jpeg';
         }
      }
     
      function DrawLines() {
         for ($i = 0; $i < $this->iNumLines; $i++) {
            // allocate colour
            if ($this->bUseColour) {
               $iLineColour = imagecolorallocate($this->oImage, rand(100, 250), rand(100, 250), rand(100, 250));
            } else {
               $iRandColour = rand(100, 250);
               $iLineColour = imagecolorallocate($this->oImage, $iRandColour, $iRandColour, $iRandColour);
            }
           
            // draw line
            imageline($this->oImage, rand(0, $this->iWidth), rand(0, $this->iHeight), rand(0, $this->iWidth), rand(0, $this->iHeight), $iLineColour);
         }
      }
     
      function DrawOwnerText() {
         // allocate owner text colour
         $iBlack = imagecolorallocate($this->oImage, 0, 0, 0);
         // get height of selected font
         $iOwnerTextHeight = imagefontheight(2);

         // calculate overall height
         $iLineHeight = $this->iHeight - $iOwnerTextHeight - 4;
         
         // draw line above text to separate from CAPTCHA
         imageline($this->oImage, 0, $iLineHeight, $this->iWidth, $iLineHeight, $iBlack);
         
         // write owner text
         imagestring($this->oImage, 2, 3, $this->iHeight - $iOwnerTextHeight - 3, $this->sOwnerText, $iBlack);
         
         // reduce available height for drawing CAPTCHA
         $this->iHeight = $this->iHeight - $iOwnerTextHeight - 5;
      }
     
      function GenerateCode() {
         // reset code
         $this->sCode = '';
         
         // loop through and generate the code letter by letter
         for ($i = 0; $i < $this->iNumChars; $i++) {
            if (count($this->aCharSet) > 0) {
               // select random character and add to code string
               $this->sCode .= $this->aCharSet[array_rand($this->aCharSet)];
            } else {
               // select random character and add to code string
               $this->sCode .= chr(rand(65, 90));
            }
         }
         
         // save code in session variable
         $_SESSION['php_captcha'] = md5(strtoupper($this->sCode));
      }
     
      function DrawCharacters() {
         // loop through and write out selected number of characters
         for ($i = 0; $i < strlen($this->sCode); $i++) {
            // select random font
            $sCurrentFont = $this->aFonts[array_rand($this->aFonts)];
           
            // select random colour
            if ($this->bUseColour) {
               $iTextColour = imagecolorallocate($this->oImage, rand(0, 100), rand(0, 100), rand(0, 100));
           
               if ($this->bCharShadow) {
                  // shadow colour
                  $iShadowColour = imagecolorallocate($this->oImage, rand(0, 100), rand(0, 100), rand(0, 100));
               }
            } else {
               $iRandColour = rand(0, 100);
               $iTextColour = imagecolorallocate($this->oImage, $iRandColour, $iRandColour, $iRandColour);
           
               if ($this->bCharShadow) {
                  // shadow colour
                  $iRandColour = rand(0, 100);
                  $iShadowColour = imagecolorallocate($this->oImage, $iRandColour, $iRandColour, $iRandColour);
               }
            }
           
            // select random font size
            $iFontSize = rand($this->iMinFontSize, $this->iMaxFontSize);
           
            // select random angle
            $iAngle = rand(-30, 30);
           
            // get dimensions of character in selected font and text size
            $aCharDetails = imageftbbox($iFontSize, $iAngle, $sCurrentFont, $this->sCode[$i], array());
           
            // calculate character starting coordinates
            $iX = $this->iSpacing / 4 + $i * $this->iSpacing;
            $iCharHeight = $aCharDetails[2] - $aCharDetails[5];
            $iY = $this->iHeight / 2 + $iCharHeight / 4;
           
            // write text to image
            imagefttext($this->oImage, $iFontSize, $iAngle, $iX, $iY, $iTextColour, $sCurrentFont, $this->sCode[$i], array());
           
            if ($this->bCharShadow) {
               $iOffsetAngle = rand(-30, 30);
               
               $iRandOffsetX = rand(-5, 5);
               $iRandOffsetY = rand(-5, 5);
               
               imagefttext($this->oImage, $iFontSize, $iOffsetAngle, $iX + $iRandOffsetX, $iY + $iRandOffsetY, $iShadowColour, $sCurrentFont, $this->sCode[$i], array());
            }
         }
      }
     
      function WriteFile($sFilename) {
         if ($sFilename == '') {
            // tell browser that data is jpeg
            header("Content-type: image/$this->sFileType");
         }
         
         switch ($this->sFileType) {
            case 'gif':
               $sFilename != '' ? imagegif($this->oImage, $sFilename) : imagegif($this->oImage);
               break;
            case 'png':
               $sFilename != '' ? imagepng($this->oImage, $sFilename) : imagepng($this->oImage);
               break;
            default:
               $sFilename != '' ? imagejpeg($this->oImage, $sFilename) : imagejpeg($this->oImage);
         }
      }
     
      function Create($sFilename = '') {
         // check for required gd functions
         if (!function_exists('imagecreate') || !function_exists("image$this->sFileType") || ($this->sBackgroundImage != '' && !function_exists('imagecreatetruecolor'))) {
            return false;
         }
         
         // get background image if specified and copy to CAPTCHA
         if ($this->sBackgroundImage != '') {
            // create new image
            $this->oImage = imagecreatetruecolor($this->iWidth, $this->iHeight);
           
            // create background image
            $oBackgroundImage = imagecreatefromjpeg($this->sBackgroundImage);
           
            // copy background image
            imagecopy($this->oImage, $oBackgroundImage, 0, 0, 0, 0, $this->iWidth, $this->iHeight);
           
            // free memory used to create background image
            imagedestroy($oBackgroundImage);
         } else {
            // create new image
            $this->oImage = imagecreate($this->iWidth, $this->iHeight);
         }
         
         // allocate white background colour
         imagecolorallocate($this->oImage, 255, 255, 255);
         
         // check for owner text
         if ($this->sOwnerText != '') {
            $this->DrawOwnerText();
         }
         
         // check for background image before drawing lines
         if ($this->sBackgroundImage == '') {
            $this->DrawLines();
         }
         
         $this->GenerateCode();
         $this->DrawCharacters();
         
         // write out image to file or browser
         $this->WriteFile($sFilename);
         
         // free memory used in creating image
         imagedestroy($this->oImage);
         
         return true;
      }
     
      // call this method statically
      function Validate($sUserCode) {
         if (md5(strtoupper($sUserCode)) == $_SESSION['php_captcha']) {
            // clear to prevent re-use
            $_SESSION['php_captcha'] = '';
           
            return true;
         }
         
         return false;
      }
   }
   
   // example sub class
   class PhpCaptchaColour extends PhpCaptcha {
      function PhpCaptchaColour($aFonts, $iWidth = CAPTCHA_WIDTH, $iHeight = CAPTCHA_HEIGHT) {
         // call parent constructor
         parent::PhpCaptcha($aFonts, $iWidth, $iHeight);
         
         // set options
         $this->UseColour(true);
      }
   }
?>

<?php
    // include captcha class
    require('includes/php-captcha.inc.php');
   
    // define fonts
    $aFonts = array('fonts/arial.ttf', 'fonts/comic.ttf', 'fonts/impact.ttf');
   
    // create new image
    $oPhpCaptcha = new PhpCaptcha($aFonts, 200, 50);
    $oPhpCaptcha->SetOwnerText('Created for: codepost.org');    
    $oPhpCaptcha->UseColour(true);
    $oPhpCaptcha->Create(); 
?>

<?php
    // include captcha class
    require('includes/php-captcha.inc.php');
?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Untitled Document</title>
</head>

<body>
    <?
        if (PhpCaptcha::Validate($_POST['code'])) {
            echo 'Successful';
        } else { echo 'Failed'; }
    ?>
   
   <form method="post" action="index.php">
      <fieldset>
         <legend>Login</legend>
         <label for="username">Username:</label><input type="text" name="username" id="username" value="" />
         <label for="password">Password:</label><input type="password" name="password" id="password" value="" />
         <div id="security"><img src="create_img.php" width="200" height="50" alt="Security Image" /></div>
         <label for="code">Security Image:</label><input type="text" name="code" id="code" value="" />
         <input type="submit" name="login" id="login" value="Login" />
      </fieldset>
   </form>

</body>
</html>