PHP驗證碼功能的實現

/**

*產生驗證碼圖片

*/

public function actionVerfiycode() {

Header ( "Content-type: image/gif" );

$border = 0; //是否要邊框 1要:0不要

$how = 4; //驗證碼位元

$w = $how * 15; //圖片寬度

$h = 20; //圖片高度

$fontsize = 5; //字型大小

$alpha = "abcdefghijkmnopqrstuvwxyz"; //驗證碼內容1:字母

$number = "0123456789"; //驗證碼內容2:數字

$randcode = ""; //驗證碼字串初始化

srand ( ( double ) microtime () * 1000000 ); //初始化隨機數種子

$im = ImageCreate ( $w, $h ); //建立驗證圖片

$bgcolor = ImageColorAllocate ( $im, 255, 255, 255 ); //設定背景顏色

ImageFill ( $im, 0, 0, $bgcolor ); //填充背景色

if ($border) {

$black = ImageColorAllocate ( $im, 0, 0, 0 ); //設定邊框顏色

ImageRectangle ( $im, 0, 0, $w - 1, $h - 1, $black ); //繪製邊框

}

for($i = 0; $i < $how; $i ++) {

$alpha_or_number = mt_rand ( 0, 1 ); //字母還是數字

$str = $alpha_or_number ? $alpha : $number;

$which = mt_rand ( 0, strlen ( $str ) - 1 ); //取哪個字元

$code = substr ( $str, $which, 1 ); //取字元

$j = ! $i ? 4 : $j + 15; //繪字元位置

$color3 = ImageColorAllocate ( $im, mt_rand ( 0, 100 ), mt_rand ( 0, 100 ), mt_rand ( 0, 100 ) ); //字元隨即顏色

ImageChar ( $im, $fontsize, $j, 3, $code, $color3 ); //繪字元

$randcode .= $code; //逐位加入驗證碼字串

}

for($i = 0; $i < 5; $i ++) //繪背景幹擾線

{

$color1 = ImageColorAllocate ( $im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) ); //幹擾線顏色

ImageArc ( $im, mt_rand ( - 5, $w ), mt_rand ( - 5, $h ), mt_rand ( 20, 300 ), mt_rand ( 20, 200 ), 55, 44, $color1 ); //幹擾線

}

for($i = 0; $i < $how * 40; $i ++) //繪背景幹擾點

{

$color2 = ImageColorAllocate ( $im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) ); //幹擾點顏色

ImageSetPixel ( $im, mt_rand ( 0, $w ), mt_rand ( 0, $h ), $color2 ); //幹擾點

}

$session=new CHttpSession;

$session->open();

Yii::app()->session->add('randcode',$randcode);

/*繪圖結束*/

Imagegif ( $im );

ImageDestroy ( $im );

/*繪圖結束*/

}

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