php网页生成验证码实现程序

session_start();
class validimg
{
//背景图片目录
var $backgroundpath = ‘validbg’;
//生成验证码宽度
var $width =’80′;
//生成验证码高度
var $height =’25′;
//背景
var $background;
//验证文本
var $text=’abcd’;
//字体目录
var $fontpath = ‘validbg’;
//字体
var $font=’simhei.ttf’;
//字体宽度
var $font_width = ’20′;

function validimg($text)
{
$this->text = $text;
//随机选取一个背景文件
$bgdir =  @dir($this->backgroundpath);
while(false !== ($image = $bgdir ->read()))
{
if($image != ‘.’ && $image != ‘..’ && $this->checktype($image) != false)
{
$backgroundarr[] = $image;

}
}
$bgdir->close();
//随机选取一个字体文件
$fonts =  @dir($this->fontpath);
while(false !== ($font = $fonts ->read()))
{
if($font != ‘.’ && $font != ‘..’ && $this->checktype($font,’FONT’) != false)
{
$fontsarr[] = $font;
}
}
$fonts->close();
$this->font = $fontsarr[array_rand($fontsarr,1)];
$this->background = $backgroundarr[array_rand($backgroundarr,1)];

$this->output();
}

//创建背景图像handdle
function createbackground()
{
switch ($this->checktype($this->background))
{
case ‘jpg’:
$bghanddle = @imagecreatefromjpeg( $this->backgroundpath.’/’.$this->background);
break;
case ‘gif’:
$bghanddle = @imagecreatefromgif( $this->backgroundpath.’/’.$this->background);
break;
case ‘png’:
$bghanddle = @imagecreatefrompng( $this->backgroundpath.’/’.$this->background);
break;
default:
}
return $bghanddle;
}
//检查文件类型
function checktype( $image,$type = ‘IMAGE’)
{
$ext = substr( $image, strrpos($image,’.')+1);
if($type == ‘IMAGE’)
{
if ($ext == ‘jpg’ || $ext ==’gif’ || $ext ==’png’)
return $ext;
else return false;
}else if($type == ‘FONT’)
{
if ($ext == ‘ttf’)
return $ext;
else return false;
}
}
//输出
function output()
{
header(“content-type:image/png;”);
//生成图像
$img = @imagecreatetruecolor( $this->width,$this->height);
$bghanddle = $this->createbackground();
//从背景图像随机位置载入一块作为背景
if($bghanddle)
{
$randx=rand(0,(imagesx($bghanddle) – $this->width));
$randy=rand(0,(imagesy($bghanddle) – $this->height));
}
imagecopy($img,$bghanddle,0,0,$randx,$randy,$this->width,$this->height);
//随机选择角度 字体大小 坐标输出文字
for($i=0;$i<strlen($this->text);$i++)
{
$angle = rand(-30,30);
$fontsize = rand(15,20);
$x = rand($this->font_width*$i,$this->font_width*$i+10);
$color = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255));
imagettftext($img,$fontsize,$angle,$x,20,$color,$this->fontpath.’/’.$this->font,substr($this->text,$i,1));
}
imagepng($img);
//释放资源
imagedestroy($img);
imagedestroy($bghanddle);
}
}

new validimg($_SESSION['valid']);
?>

//随机生成字符串

function randstr($num=4)
{
$chars = ‘ABDEFGHJKLMNPQRSTVWXYabdefghijkmnpqrstvwxy23456789′;
$randstr=”;
for($i=0;$i<$num;$i++)
{
$randstr.=substr($chars,rand(0,strlen($chars)),1);
}
return $randstr;
}
?>
<img src=”validimg.php” />

生成gif动态验证码

PHP生成GIF动画来实现动态图片验证码，以下是实现过程。

ImageCode函数通过GIFEncoder类实现的GIF动画

/**  
 * ImageCode 生成GIF图片验证  
 * @param $string 字符串  
 * @param $width 宽度  
 * @param $height 高度  
 * */ 
function ImageCode($string = '', $width = 75, $height = 25)  
{  
    $authstr = $string ? $string : ((time() % 2 == 0) ? mt_rand(1000, 9999) : mt_rand(10000, 99999));   
      
    $board_width = $width;  
    $board_height = $height;  
    // 生成一个32帧的GIF动画  
    for($i = 0; $i < 32; $i++)  
    {  
        ob_start();  
        $image = imagecreate($board_width, $board_height);  
        imagecolorallocate($image, 0,0,0);  
        // 设定文字颜色数组   
        $colorList[] = ImageColorAllocate($image, 15,73,210);  
        $colorList[] = ImageColorAllocate($image, 0,64,0);  
        $colorList[] = ImageColorAllocate($image, 0,0,64);  
        $colorList[] = ImageColorAllocate($image, 0,128,128);  
        $colorList[] = ImageColorAllocate($image, 27,52,47);  
        $colorList[] = ImageColorAllocate($image, 51,0,102);  
        $colorList[] = ImageColorAllocate($image, 0,0,145);  
        $colorList[] = ImageColorAllocate($image, 0,0,113);  
        $colorList[] = ImageColorAllocate($image, 0,51,51);  
        $colorList[] = ImageColorAllocate($image, 158,180,35);  
        $colorList[] = ImageColorAllocate($image, 59,59,59);  
        $colorList[] = ImageColorAllocate($image, 0,0,0);  
        $colorList[] = ImageColorAllocate($image, 1,128,180);  
        $colorList[] = ImageColorAllocate($image, 0,153,51);  
        $colorList[] = ImageColorAllocate($image, 60,131,1);  
        $colorList[] = ImageColorAllocate($image, 0,0,0);  
        $fontcolor = ImageColorAllocate($image, 0,0,0);  
        $gray = ImageColorAllocate($image, 245,245,245);   
          
        $color = imagecolorallocate($image, 255,255,255);  
        $color2 = imagecolorallocate($image, 255,0,0);  
          
        imagefill($image, 0, 0, $gray);  
          
        $space = 15;        // 字符间距  
        if($i > 0)          // 屏蔽第一帧  
        {  
            for ($k = 0; $k < strlen($authstr); $k++)   
            {   
                $colorRandom = mt_rand(0,sizeof($colorList)-1);   
                $float_top = rand(0,4);  
                $float_left = rand(0,3);  
                imagestring($image, 6, $space * $k, $top + $float_top, substr($authstr, $k, 1), $colorList[$colorRandom]);  
            }  
        }  
          
        for ($k = 0; $k < 20; $k++)   
        {   
            $colorRandom = mt_rand(0,sizeof($colorList)-1);   
            imagesetpixel($image, rand()%70 , rand()%15 , $colorList[$colorRandom]);   
      
        }  
        // 添加干扰线  
        for($k = 0; $k < 3; $k++)  
        {  
            $colorRandom = mt_rand(0, sizeof($colorList)-1);   
            // $todrawline = rand(0,1);  
            $todrawline = 1;  
            if($todrawline)  
            {  
                imageline($image, mt_rand(0, $board_width), mt_rand(0,$board_height), mt_rand(0,$board_width), mt_rand(0,$board_height), $colorList[$colorRandom]);  
            }  
            else   
            {  
                $w = mt_rand(0,$board_width);  
                $h = mt_rand(0,$board_width);  
                imagearc($image, $board_width - floor($w / 2) , floor($h / 2), $w, $h,  rand(90,180), rand(180,270), $colorList[$colorRandom]);  
            }  
        }  
        imagegif($image);  
        imagedestroy($image);  
        $imagedata[] = ob_get_contents();  
        ob_clean();    
        ++$i;    
    }  
      
    $gif = new GIFEncoder($imagedata);    
    Header ('Content-type:image/gif');    
    echo $gif->GetAnimation();    
} 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script language="javascript">
 function refresh_code()
 {
  form1.imgcode.src="verifycode.php?a="+Math.random();
 }
</script>
</head>
<body>
<form id="form1" name="form1" method="post" action="checkcode.php">
  <label for="code">验证码：</label>
  <input type="text" name="code" id="textfield" />
  <img id="imgcode" src="VerifyCode.php" alt="验证码" />
  <a href="javascript:refresh_code()">看不清？换一个</a>
  <input type="submit" name="button" id="button" value="提交" />
</form>
</body>
</html>