簡述php設計驗證碼的過程

簡述php設計驗證碼的過程

php使用GD函式庫產生驗證碼

#一、繪圖步驟:

1.建立畫布，分配顏色,使用以下兩個函數(可以在php手冊GD庫函數中找到)：

imagecreatetruecolor()

imagecolorallocate()

2.繪畫過程：

imagefill()

imagettftext()

imagesetpixel()

imageline ()

3.輸出映像：

header(“Content-Type:image/png”);

imagepng();

imagejpeg( );

4.銷毀圖片（釋放記憶體）

imagedestroy();

二、繪圖具體步驟

產生驗證碼字串

private function getCode(){
        $str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        $t='';
        for($i=0;$i<$this->m;$i++){
            $t.=$str[rand(0,$this->type[&#39;letter&#39;])];
        }
        return $t;
    }

畫出驗證碼

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] );
        }
    }

輸出影像

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

三、程式碼示範

 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[&#39;letter&#39;])];
        }
        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相關知識，請造訪PHP中文網！

以上是簡述php設計驗證碼的過程的詳細內容。更多資訊請關注PHP中文網其他相關文章！