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<?php
class MathCaptcha extends SimpleCaptcha {
/** Validate a captcha response */
function keyMatch( $answer, $info ) {
return (int)$answer == (int)$info['answer'];
}
function addCaptchaAPI( &$resultArr ) {
list( $sum, $answer ) = $this->pickSum();
$index = $this->storeCaptcha( array( 'answer' => $answer ) );
$resultArr['captcha']['type'] = 'math';
$resultArr['captcha']['mime'] = 'text/tex';
$resultArr['captcha']['id'] = $index;
$resultArr['captcha']['question'] = $sum;
}
/** Produce a nice little form */
function getForm() {
list( $sum, $answer ) = $this->pickSum();
$index = $this->storeCaptcha( array( 'answer' => $answer ) );
$form = '<table><tr><td>' . $this->fetchMath( $sum ) . '</td>';
$form .= '<td>' . Html::input( 'wpCaptchaWord', false, false, array( 'tabindex' => '1', 'autocomplete' => 'off', 'required' ) ) . '</td></tr></table>';
$form .= Html::hidden( 'wpCaptchaId', $index );
return $form;
}
/** Pick a random sum */
function pickSum() {
$a = mt_rand( 0, 100 );
$b = mt_rand( 0, 10 );
$op = mt_rand( 0, 1 ) ? '+' : '-';
$sum = "{$a} {$op} {$b} = ";
$ans = $op == '+' ? ( $a + $b ) : ( $a - $b );
return array( $sum, $ans );
}
/** Fetch the math */
function fetchMath( $sum ) {
if ( MWInit::classExists( 'MathRenderer' ) ) {
$math = MathRenderer::getRenderer( $sum, array(), MW_MATH_PNG );
} else {
throw new MWException( 'MathCaptcha requires the Math extension for MediaWiki versions 1.18 and above.' );
}
$html = $math->render();
return preg_replace( '/alt=".*?"/', '', $html );
}
}
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