//$waterImage="./Hanweb_shuiyin.gif";//水印图片路径
        //imageWaterMark($uploadfile,0,$waterImage); imageWaterMark($pic,4,"./images/line-move.gif","",5,"#FF0000");
function imageWaterMark($groundImage,$waterPos=0,$waterImage="",$waterText="",$textFont=5,$textColor="#FF0000")
{
    $isWaterImage = FALSE;
    $formatMsg = "暂不支持该文件格式，请用图片处理软件将图片转换为GIF、JPG、PNG格式。";
    //读取水印文件
    if(!empty($waterImage) && file_exists($waterImage))
    {
        $isWaterImage = TRUE;
        $water_info = getimagesize($waterImage);
        $water_w    = $water_info[0];//取得水印图片的宽
        $water_h    = $water_info[1];//取得水印图片的高
        switch($water_info[2])//取得水印图片的格式
        {
            case 1:$water_im = imagecreatefromgif($waterImage);break;
            case 2:$water_im = imagecreatefromjpeg($waterImage);break;
            case 3:$water_im = imagecreatefrompng($waterImage);break;
            default:die($formatMsg);
        }
    }
    //读取背景图片
    if(!empty($groundImage) && file_exists($groundImage))
    {
        $ground_info = getimagesize($groundImage);
        $ground_w    = $ground_info[0];//取得背景图片的宽
        $ground_h    = $ground_info[1];//取得背景图片的高
        switch($ground_info[2])//取得背景图片的格式
        {
            case 1:$ground_im = imagecreatefromgif($groundImage);break;
            case 2:$ground_im = imagecreatefromjpeg($groundImage);break;
            case 3:$ground_im = imagecreatefrompng($groundImage);break;
            default:die($formatMsg);
        }
    }
    else
    {
        die("需要加水印的图片不存在！");
    }
    //水印位置
    if($isWaterImage)//图片水印
    {
        $w = $water_w;
        $h = $water_h;
        $label = "图片的";
    }
    else//文字水印
    {
        $temp = imagettfbbox(ceil($textFont*2.5),0,"c:/windows/fonts/stcaiyun.ttf",$waterText);//取得使用 TrueType 字体的文本的范围
        $w = $temp[2] - $temp[6];
        $h = $temp[3] - $temp[7];
        unset($temp);
        $label = "文字区域";
    }
    if( ($ground_w<$w) || ($ground_h<$h) )
    {
        echo "需要加水印的图片的长度或宽度比水印".$label."还小，无法生成水印！";
        return;
    }
    switch($waterPos)
    {
        case 0://随机
            $posX = rand(0,($ground_w - $w));
            $posY = rand(0,($ground_h - $h));
            break;
        case 1://1为顶端居左
            $posX = 0;
            $posY = 0;
            break;
        case 2://2为顶端居中
            $posX = ($ground_w - $w) / 2;
            $posY = 0;
            break;
        case 3://3为顶端居右
            $posX = $ground_w - $w;
            $posY = 0;
            break;
        case 4://4为中部居左
            $posX = 0;
            $posY = ($ground_h - $h) / 2;
            break;
        case 5://5为中部居中
            $posX = ($ground_w - $w) / 2;
            $posY = ($ground_h - $h) / 2;
            break;
        case 6://6为中部居右
            $posX = $ground_w - $w;
            $posY = ($ground_h - $h) / 2;
            break;
        case 7://7为底端居左
            $posX = 0;
            $posY = $ground_h - $h;
            break;
        case 8://8为底端居中
            $posX = ($ground_w - $w) / 2;
            $posY = $ground_h - $h;
            break;
        case 9://9为底端居右
            $posX = $ground_w - $w;
            $posY = $ground_h - $h;
            break;
        default://随机
            $posX = rand(0,($ground_w - $w));
            $posY = rand(0,($ground_h - $h));
            break;   
    }
    //设定图像的混 {MOD}模式
    imagealphablending($ground_im, true);
    if($isWaterImage)//图片水印
    {
        imagecopy($ground_im, $water_im, $posX, $posY, 0, 0, $water_w,$water_h);//拷贝水印到目标文件       
    }
    else//文字水印
    {
        if( !empty($textColor) && (strlen($textColor)==7) )
        {
            $R = hexdec(substr($textColor,1,2));
            $G = hexdec(substr($textColor,3,2));
            $B = hexdec(substr($textColor,5));
        }
        else
        {
            die("水印文字颜 {MOD}格式不正确！");
        }
        imagestring ( $ground_im, $textFont, $posX, $posY, $waterText, imagecolorallocate($ground_im, $R, $G, $B));       
    }
    //生成水印后的图片
    @unlink($groundImage);
    switch($ground_info[2])//取得背景图片的格式
    {
        case 1:imagegif($ground_im,$groundImage);break;
        case 2:imagejpeg($ground_im,$groundImage);break;
        case 3:imagepng($ground_im,$groundImage);break;
        default:die($errorMsg);
    }
    //释放内存
    if(isset($water_info)) unset($water_info);
    if(isset($water_im)) imagedestroy($water_im);
    unset($ground_info);
    imagedestroy($ground_im);
}