简述php设计验证码的过程

php  /  管理员 发布于 7年前   369

简述php设计验证码的过程

php使用GD库生成验证码

一、绘图步骤:

1.创建画布，分配颜色,使用以下两个函数(可以在php手册GD库函数中找到)：

imagecreatetruecolor()

imagecolorallocate()

2.绘画过程：

imagefill()

imagettftext()

imagesetpixel()

imageline()

3.输出图像：

header(“Content-Type:image/png”);

imagepng();

imagejpeg();

4.销毁图片（释放内存）

imagedestroy();

二、绘图具体步骤

生成验证码字符串

private function getCode(){        $str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";        $t='';        for($i=0;$i<$this->m;$i++){$t.=$str[rand(0,$this->type['letter'])];        }        return $t;    }

画出验证码

function drawCode(){        $code=$this->getCode();//获取验证码字符串        imagefill($this->im, 0, 0, $this->bg);        for ($i=0; $i <200 ; $i++) { imagesetpixel($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,255));        }        imageline($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,$this->width), rand(0,$this->height), rand(0,255));        $c=imagecolorallocate($this->im, rand(0,200), rand(0,200), rand(0,200));        for($i=0;$i<$this->m;$i++){imagettftext($this->im, 18, rand(-40,40), 8+(18*$i), 24, $c, "georgia.ttf",$code[$i] );        }    }

输出图像

function printImage(){        $this->drawCode();        header("Content-Type:image/jpeg");        imagepng($this->im);        $this->destroy();    }    function destroy(){        imagedestroy($this->im);    }

三、代码演示

<?php/*** 验证码画图类*/class Image {    private $width;    private $height;    private $im;    private $bg;    private $m;    private $type=array('num' => 9,'letter' => 61 );    function __construct($width,$height,$m)    {        $this->width=$width;        $this->height=$height;        $this->m=$m;        $this->im=imagecreatetruecolor($this->width, $this->height);        $this->bg=imagecolorallocate($this->im, 220, 220, 220);    }    private function getCode(){        $str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";        $t='';        for($i=0;$i<$this->m;$i++){$t.=$str[rand(0,$this->type['letter'])];        }        return $t;    }    function drawCode(){        $code=$this->getCode();//获取验证码字符串        imagefill($this->im, 0, 0, $this->bg);        //加干扰点        for ($i=0; $i <200 ; $i++) { imagesetpixel($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,255));        }        //加干扰线        imageline($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,$this->width), rand(0,$this->height), rand(0,255));        $c=imagecolorallocate($this->im, rand(0,200), rand(0,200), rand(0,200));        for($i=0;$i<$this->m;$i++){imagettftext($this->im, 18, rand(-40,40), 8+(18*$i), 24, $c, "georgia.ttf",$code[$i] );        }    }    function printImage(){        $this->drawCode();        header("Content-Type:image/jpeg");        imagepng($this->im);        $this->destroy();    }    function destroy(){        imagedestroy($this->im);    }}function unit_test(){    $obj=new Image(20*4,30,4);    $obj->printImage();}unit_test();?>

更多PHP相关知识，请访问！

以上就是简述php设计验证码的过程的详细内容，更多请关注其它相关文章！