/**
*产生验证码图片
*/
public function actionVerfiycode() {
Header ( "Content-type: image/gif" );
$border = 0; //是否要边框 1要:0不要
$how = 4; //验证码位数
$w = $how * 15; //图片宽度
$h = 20; //图片高度
$fontsize = 5; //字体大小
$alpha = "abcdefghijkmnopqrstuvwxyz"; //验证码内容1:字母
$number = "0123456789"; //验证码内容2:数字
$randcode = ""; //验证码字符串初始化
srand ( ( double ) microtime () * 1000000 ); //初始化随机数种子
$im = ImageCreate ( $w, $h ); //创建验证图片
$bgcolor = ImageColorAllocate ( $im, 255, 255, 255 ); //设置背景颜色
ImageFill ( $im, 0, 0, $bgcolor ); //填充背景色
if ($border) {
$black = ImageColorAllocate ( $im, 0, 0, 0 ); //设置边框颜色
ImageRectangle ( $im, 0, 0, $w - 1, $h - 1, $black ); //绘制边框
}
for($i = 0; $i < $how; $i ++) {
$alpha_or_number = mt_rand ( 0, 1 ); //字母还是数字
$str = $alpha_or_number ? $alpha : $number;
$which = mt_rand ( 0, strlen ( $str ) - 1 ); //取哪个字符
$code = substr ( $str, $which, 1 ); //取字符
$j = ! $i ? 4 : $j + 15; //绘字符位置
$color3 = ImageColorAllocate ( $im, mt_rand ( 0, 100 ), mt_rand ( 0, 100 ), mt_rand ( 0, 100 ) ); //字符随即颜色
ImageChar ( $im, $fontsize, $j, 3, $code, $color3 ); //绘字符
$randcode .= $code; //逐位加入验证码字符串
}
for($i = 0; $i < 5; $i ++) //绘背景干扰线
{
$color1 = ImageColorAllocate ( $im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) ); //干扰线颜色
ImageArc ( $im, mt_rand ( - 5, $w ), mt_rand ( - 5, $h ), mt_rand ( 20, 300 ), mt_rand ( 20, 200 ), 55, 44, $color1 ); //干扰线
}
for($i = 0; $i < $how * 40; $i ++) //绘背景干扰点
{
$color2 = ImageColorAllocate ( $im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) ); //干扰点颜色
ImageSetPixel ( $im, mt_rand ( 0, $w ), mt_rand ( 0, $h ), $color2 ); //干扰点
}
$session=new CHttpSession;
$session->open();
Yii::app()->session->add('randcode',$randcode);
/*绘图结束*/
Imagegif ( $im );
ImageDestroy ( $im );
/*绘图结束*/
}
引自:http://www.admin5.com/article/20080314/75984.shtml