不显示验证码，只有一个白色的方块
<?php
Class Captcha{
//字体文件
private $_fontfile='';
//字体大小
private $_size=20;
//宽度
private $_width=200;
//高度
private $_height=50;
//验证码长度
private $_length=4;
//画布资源
private $_image=null;
//干扰元素
//雪花*的个数
private $_snow=0;
//像素个数
private $_pixel=0;
//线段个数
private $_line=0;
//初始化数据
public function _construct($config=array()){
if(is_array($config)&&count($config)>0){
//检测字体文件是否存在并且可读
if(isset($config['fontfile'])&&is_file($config['fontfile'])&&is_readable($config['fontfile'])){
$this->_fontfile=$config['fontfile'];
}else{
return false;
}
//检测是否设置画布宽或高
if(isset($config['width'])&&$config['width']>0){
$this->_width=(int)$config['width'];
}
if(isset($config['height'])&&$config['height']>0){
$this->_height=(int)$config['height'];
}
//检测是否设置字体大小
if(isset($config['size'])&&$config['size']>0){
$this->_size=(int)$config['size'];
}
//检测是否设置验证码长度
if(isset($config['length'])&&$config['length']>0){
$this->_length=(int)$config['length'];
}
//配置干扰元素
if(isset($config['snow'])&&$config['snow']>0){
$this->_snow=(int)$config['snow'];
}
if(isset($config['pixel'])&&$config['pixel']>0){
$this->_pixel=(int)$config['pixel'];
}
if(isset($config['line'])&&$config['line']>0){
$this->_line=(int)$config['line'];
}
$this->_image=imagecreatetruecolor($this->_width, $this->_height);
return $this->_image;
}else{
return false;
}
}
public function getCaptcha(){
$white=imagecolorallocate($this->_image,255,255,255);
//填充矩形
imagefilledrectangle($this->_image,0,0,$this->_width,$this->_height,$white);
//生成验证码
$str=$this->_generateStr($this->_length);
if($str==false){
return false;
}
$fontfile=$this->_fontfile;
//绘制验证码
for($i=0;$i<$this->_length;$i++){
$size=$this->_size;
$angle=mt_rand(-15,15);
$x=ceil($this->_width/$this->_length)*$i+mt_rand(5,10);
$y=ceil($this->_height/1.5);
$color=$this->_getRandColor();
//$text=mb_substr($str,$i,1,'utf-8');
$text=$str{$i};
imagettftext($this->_image,$size, $angle, $x, $y, $color, $fontfile, $text);
}
//产生干扰元素
if($this->_snow){
//使用雪花当干扰元素
$this->_getSnow();
}else{
if($this->_pixel){
$this->_getPixel();
}
if($this->_line){
$this->_getLine();
}
}
//输出图像
header('content-type:image/png');
imagepng($this->_image);
imagedestroy($this->_image);
return strtolower($str);
}
private function _getSnow(){
for($i=1;$i<=$this->_snow;$i++){
imagestring($this->_image,mt_rand(1,5),mt_rand(0,$this->_width),mt_rand(0,$this->_height),'*', $this->_getRandColor());
}
}
private function _getPixel(){
for($i=1;$i<=$this->_pixel;$i++){
imagesetpixel($this->_image,mt_rand(0,$this->_width),mt_rand(0,$this->_height),$this->_getRandColor());
}
}
private function _getLine(){
for($i=1;$i<=$this->_line;$i++){
imageline($this->_image,mt_rand(0,$this->_width),mt_rand(0,$this->_height),mt_rand(0,$this->_width),mt_rand(0,$this->_height),$this->_getRandColor());
}
}
//产生验证码字符
private function _generateStr($length=4){
if($length<1 || $length>10){
return false;
}
$chars=array(
'a','b','c','d','e','f','g','h','k','m','n','p','x','y',
'A','B','C','D','E','F','G','H','K','M','N','P','X','Y',
1,2,3,4,5,6,7,8,9
);
$str=join('',array_rand(array_flip($chars),$length));
return $str;
}
//产生随机颜色
private function _getRandColor(){
return imagecolorallocate($this->_image,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));
}
}
