3 class MathCaptcha extends SimpleCaptcha {
5 /** Validate a captcha response */
6 function keyMatch( $answer, $info ) {
7 return (int)$answer == (int)$info['answer'];
10 /** Produce a nice little form */
12 list( $sum, $answer ) = $this->pickSum();
13 $index = $this->storeCaptcha( array( 'answer' => $answer ) );
15 $form = '<table><tr><td>' . $this->fetchMath( $sum ) . '</td>';
16 $form .= '<td>' . wfInput( 'wpCaptchaAnswer', false, false, array( 'tabindex' => '1' ) ) . '</td></tr></table>';
17 $form .= wfHidden( 'wpCaptchaId', $index );
21 /** Pick a random sum */
23 $a = mt_rand( 0, 100 );
24 $b = mt_rand( 0, 10 );
25 $op = mt_rand( 0, 1 ) ? '+' : '-';
26 $sum = "{$a} {$op} {$b} = ";
27 $ans = $op == '+' ? ( $a + $b ) : ( $a - $b );
28 return array( $sum, $ans );
32 function fetchMath( $sum ) {
33 $math = new MathRenderer( $sum );
34 $math->setOutputMode( MW_MATH_PNG );
35 $html = $math->render();
36 return preg_replace( '/alt=".*"/', '', $html );