php容易验证码

length; $i ++) { //循环随机取字符生成字符串
			$strNum .= $strings [rand ( 0, $count - 1 )];
		}
		session_start ();
		$_SESSION ["verifycode"] = $strNum;
		$this->im = imagecreate ( $this->width, $this->height );
		$backgroundcolor = imagecolorallocate ( $this->im, 255, 255, 255 ); //生成背景色
		$frameColor = imageColorAllocate ( $this->im, 0, 255, 0 );
		for($i = 0; $i < $this->length; $i ++) {
			$charY = ($this->height + 9) / 2 + rand ( - 1, 1 ); //定义字符Y坐标
			$charX = $i * 15 + 8; //定义字符X坐标
			//            $text_color = imagecolorallocate($this->im, 255, 0, 0);                                                //生成字符颜色
			$text_color = imagecolorallocate ( $this->im, mt_rand ( 50, 255 ), mt_rand ( 50, 128 ), mt_rand ( 50, 200 ) );
			$angle = rand ( - 20, 20 ); //生成字符角度
			//写入字符
			imagettftext ( $this->im, $this->fontSize, $angle, $charX, $charY, $text_color, $this->font, $strNum [$i] );
		}
		for($i = 0; $i <= 5; $i ++) { //循环画背景线
			$linecolor = imagecolorallocate ( $this->im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) );
			$linex = mt_rand ( 1, $this->width - 1 );
			$liney = mt_rand ( 1, $this->height - 1 );
			imageline ( $this->im, $linex, $liney, $linex + mt_rand ( 0, 4 ) - 2, $liney + mt_rand ( 0, 4 ) - 2, $linecolor );
		}
		for($i = 0; $i <= 32; $i ++) { //循环画背景点,生成麻点效果
			$pointcolor = imagecolorallocate ( $this->im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) );
			imagesetpixel ( $this->im, mt_rand ( 1, $this->width - 1 ), mt_rand ( 1, $this->height - 1 ), $pointcolor );
		}
		imagerectangle ( $this->im, 0, 0, $this->width - 1, $this->height - 1, $frameColor ); //画边框
		ob_clean ();
		header ( 'Content-type:image/png' );
		imagepng ( $this->im );
		imagedestroy ( $this->im );
	}
}
$img = new VerifyImg ();
$img->Build ();
?>