<?php
class Tool_Captcha{
	private $width;
	private $height;
	private $codeNum;
	private $code;
	private $im;

	function __construct($width = 80, $height = 20, $codeNum = 4){
		$this->width = $width;
		$this->height = $height;
		$this->codeNum = $codeNum;
	}

	function showImg(){
		# 创建图片
		$this->createImg();
		# 设置干扰元素
		$this->setDisturb();
		# 设置验证码
		$this->setCaptcha();
		# 输出图片
		$this->outputImg();
	}

	function getCaptcha(){
		return $this->code;
	}

	private function createImg(){
		$this->im = imagecreatetruecolor($this->width, $this->height);
		$bgColor = imagecolorallocate($this->im, 0, 0, 0);
		imagefill($this->im, 0, 0, $bgColor);
	}

	private function setDisturb(){
		$area = ($this->width * $this->height) / 20;
		$disturbNum = ($area > 250)? 250: $area;
		# 加入点干扰
		for($i = 0; $i < $disturbNum; $i++){
			$color = imagecolorallocate($this->im, rand(0, 255), rand(0, 255), rand(0, 255));
			imagesetpixel($this->im, rand(1, $this->width - 2), rand(1, $this->height - 2), $color);
		}
		# 加入弧线
		for($i = 0; $i <= 5; $i++){
			$color = imagecolorallocate($this->im, rand(128, 255), rand(125, 255), rand(100, 255));
			imagearc($this->im, rand(0, $this->width), rand(0, $this->height), rand(30, 300), rand(20, 200), 50, 30, $color);
		}
	}

	private function createCode(){
		$str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKMNPQRSTUVWXYZ";
		for($i = 0; $i < $this->codeNum; $i++){
			$this->code .= $str{rand(0, strlen($str) - 1)};
		}
	}

	private function setCaptcha(){
		$this->createCode();
		$tCode = '';
		for($i = 0; $i < $this->codeNum; $i++){
			$color = imagecolorallocate($this->im, rand(200, 250), rand(200, 250), rand(228, 250));
			$size = rand(floor($this->height / 5), floor($this->height / 3));
			$x = floor($this->width / $this->codeNum) * $i + 5;
			$y = rand(0, $this->height - 20);
			imagechar($this->im, $size, $x, $y, $this->code{$i}, $color);
			$tCode .= $this->code{$i};
		}
		$_SESSION['captcha'] = $tCode;
	}

	private function outputImg(){
		if(imagetypes() & IMG_PNG){
			header('Content-type:image/png');
			imagejpeg($this->im);
		}
		elseif(imagetypes() & IMG_GIF){
			header('Content-type: image/gif');
			imagegif($this->im);
		}
		elseif(imagetype() & IMG_JPG){
			header('Content-type: image/jpeg');
			imagepng($this->im);
		}
		else{
			die("Don't support image type!");
		}
	}
}