PHP图片添加水印

/*
     * 功能：PHP图片水印 (水印支持图片) 
     * @param   str  $groundImage    背景图片，即需要加水印的图片，暂只支持GIF,JPG,PNG格式； 
     * @param  str    $waterPos        水印位置，有10种状态，0为随机位置； 
     *                        1为顶端居左，2为顶端居中，3为顶端居右； 
     *                        4为中部居左，5为中部居中，6为中部居右； 
     *                        7为底端居左，8为底端居中，9为底端居右； 
     * @param str     $waterImage        图片水印，即作为水印的图片，暂只支持GIF,JPG,PNG格式；
     * return str 加好水印图片路径
     */

    public static function imageWaterMark($groundImage, $waterPos = 0, $waterImage = "") {
        $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:
                    Loger::log(array(
                        'msg' => $formatMsg,
                        'file' => __CLASS__ . ':' . __LINE__,
                            ), CLogger::LEVEL_ERROR);
                    return false;
            }
        }

        //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:echo $formatMsg;
                    return false;
            }
        } else {
            Loger::log(array(
                'msg' => "需要加水印的图片不存在!",
                'file' => __CLASS__ . ':' . __LINE__,
                    ), CLogger::LEVEL_ERROR);
            return false;
        }

        //水印位置 
        if ($isWaterImage) {//图片水印 
            $w = $water_w;
            $h = $water_h;
            $label = "图片的";
        }
        if (($ground_w < $w) || ($ground_h < $h)) {
            Loger::log(array(
                'msg' => "需要加水印的图片的长度或宽度比水印" . $label . "还小，无法生成水印！",
                'file' => __CLASS__ . ':' . __LINE__,
                    ), CLogger::LEVEL_ERROR);
            return;
        }
        switch ($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 - 10;
                $posY = $ground_h - $h - 5;
                break;
            default://随机 
                $posX = rand(0, ($ground_w - $w));
                $posY = rand(0, ($ground_h - $h));
                break;
        }

        //设定图像的混色模式 
        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         
        }
        //生成水印后的图片 
        $arrInfo = pathinfo($groundImage);
        $strNewImage = $arrInfo['dirname'] . '/' . $arrInfo['filename'] . '_shuiyin' . '.' . $arrInfo['extension'];
        //@unlink($groundImage); 
        switch ($ground_info[2]) {//取得背景图片的格式 
            case 1:imagegif($ground_im, $strNewImage);
                break;
            case 2:imagejpeg($ground_im, $strNewImage, 100);
                break;
            case 3:imagepng($ground_im, $strNewImage);
                break;
            default:return false;
        }

        //释放内存 
        if (isset($water_info)) {
            unset($water_info);
        }
        if (isset($water_im)) {
            imagedestroy($water_im);
        }
        unset($ground_info);
        imagedestroy($ground_im);
        return $strNewImage;
    }