Zend Captcha

1. ASCII captcha (最簡單的用法)
   ex.
   
   $captcha = new Zend_Form_Element_Captcha( 'captcha', array(
  'label' => 'Please enter the 5 letters displayed below:',
  'name' => 'captcha', //回傳post欄位的名稱
  'required' => true,
  'captcha' => array('captcha' => 'Figlet', 'wordLen' => 5, 'timeout' => 300)
));
echo captcha;

   判斷是否正確
   $captcha = $request->getPost('captcha');
$captchaId = $captcha['id'];
// And here's the user submitted word...
$captchaInput = $captcha['input'];
// We are accessing the session with the corresponding namespace
// Try overwriting this, hah!
$captchaSession = new Zend_Session_Namespace('Zend_Form_Captcha_'.$captchaId);
// To access what's inside the session, we need the Iterator
// So we get one...
$captchaIterator = $captchaSession->getIterator();
// And here's the correct word which is on the image...

$captchaWord = $captchaIterator['word'] ;
// Now just compare them...
if ($captchaInput == $captchaWord)
echo "valid";
else
echo "invalid";

   
   
2. 圖文表示
   ex.
   
   
   
   注意事項
   
   • 要給ttf字型檔
   $this->view->captcha = new Zend_Form_Element_Captcha(
  'captcha', // This is the name of the input field
  array('label' => 'Write the chars to the field',
   'captcha' => array( // Here comes the magic...
   // First the type...
   'captcha' => 'Image',
   // Length of the word...
   'wordLen' => 4,
   // Captcha timeout, 5 mins
   'timeout' => 300,
   // What font to use...
   'font' => 'captcha/arial.ttf',
   // Where to put the image
   'imgDir' => 'captcha/tmp/',
   //<img src="?" > 的位置
   'imgUrl' => 'http://' . $this->_request->getHttpHost() . $this->_request->getBaseUrl() . '/captcha/tmp/'
   )
  )
);
3. 自定背景
   ex.
   
   
   
   注意事項
   由於預設會將底色用白，所以直接改圖沒用
   到/library/Zend/Captcha/Image.php改程式碼
   p.s. 因為機車johnny又在唸不喜歡彎彎的字及干擾的點及線，因此順便把扭曲的程式碼拿掉了
   
   不要點及線只要在建構子下...
   $captcha = new Zend_Form_Element_Captcha(
'captcha', // This is the name of the input field
array(
...
'lineNoiseLevel' => 0,
'dotNoiseLevel' => 0,
...
)
)
);
   
   如果不要扭曲的字型，那就把_generateImage方法的內容改成以下程式碼
   protected function _generateImage($id, $word)
{
  if (!extension_loaded("gd")) {
   require_once 'Zend/Captcha/Exception.php';
   throw new Zend_Captcha_Exception("Image CAPTCHA requires GD extension");
  }

  if (!function_exists("imagepng")) {
   require_once 'Zend/Captcha/Exception.php';
   throw new Zend_Captcha_Exception("Image CAPTCHA requires PNG support");
  }

  if (!function_exists("imageftbbox")) {
   require_once 'Zend/Captcha/Exception.php';
   throw new Zend_Captcha_Exception("Image CAPTCHA requires FT fonts support");
  }

  $font = $this->getFont();

  if (empty($font)) {
   require_once 'Zend/Captcha/Exception.php';
   throw new Zend_Captcha_Exception("Image CAPTCHA requires font");
  }

  $w = $this->getWidth();
  $h = $this->getHeight();
  $fsize = $this->getFontSize();

  $img_file = $this->getImgDir() . $id . $this->getSuffix();
  if(empty($this->_startImage)) {
   $img = imagecreatetruecolor($w, $h);
  } else {
   $img = imagecreatefrompng($this->_startImage);
   if(!$img) {
    require_once 'Zend/Captcha/Exception.php';
    throw new Zend_Captcha_Exception("Can not load start image");
   }
   $w = imagesx($img);
   $h = imagesy($img);
  }
  $text_color = imagecolorallocate($img, 255, 255, 255);
  //$bg_color = imagecolorallocate($img, 255, 255, 255);
  //imagefilledrectangle($img, 0, 0, $w-1, $h-1, $bg_color);
  $textbox = imageftbbox($fsize, 0, $font, $word);
  $x = ($w - ($textbox[2] - $textbox[0])) / 2;
  $y = ($h - ($textbox[7] - $textbox[1])) / 2;
  imagefttext($img, $fsize, 0, $x, $y, $text_color, $font, $word);
  imagepng($img, $img_file);
}
4. 自定captcha版面格式
   很機車的johnny不喜歡預設拆成兩行的樣子，硬要我併成一行
   只好硬著頭皮又去改原碼了
   有2個地方要改
   1.到fucntion render()
   public function render(Zend_View_Interface $view = null, $element = null)
{
  return '<img alt="'.$this->getImgAlt().'" height="'.$this->getHeight().'" src="' . $this->getImgUrl() . $this->getId() . $this->getSuffix() . '" width="'.$this->getWidth().'" /><br>'; //將br拿掉
}
   另外如果還要拿掉dt,dd等，則需要下個步驟
   
   2.到library/form/Element/Zend_Form_Element_Captcha.php 改function loadDefaultDecorators()
   

References
Zend Reference Guide - Captcha Operation
A Zend_Captcha example
Captcha problem
Zend_Form_Element_Captcha