PHP image upload class and generate thumbnails

/**
* Upload pictures
*/
class imgUpload{
 static protected $a;
 protected $formName; //Form name
 protected $directory; //File uploaded to directory
 protected $ maxSize; //Maximum file upload size
 protected $canUpload; //Whether it can be uploaded
 protected $doUpFile; //Uploaded file name
 protected $sm_File; //Thumbnail name

 private function __construct($_formName='file ', $_directory='./images/uploads/', $_maxSize=1048576){ //1024*1024=1M
 //Initialization parameters
 $this->formName = $_formName;
 $this->directory = $_directory;
 $this->maxSize = $_maxSize;
 $this->canUpload = true;
 $this->doUpFile = '';
 $this->sm_File = '';
 }

 //Determine whether the image is within the allowed format
 static public function Type($_formName='file'){
 $_type = $_FILES[$_formName]['type'];
 switch ($_type){
 case ' image/gif':
 if (self::$a==NULL)
 self::$a = new imgUpload($_formName);
 break;
 case 'image/pjpeg':
 if (self::$a ==NULL)
 self::$a = new imgUpload($_formName);
 break;
 case 'image/x-png':
 if (self::$a==NULL)
 self::$a = new imgUpload($_formName);
 break;
 default:
 self::$a = false;
 }
 return self::$a;
 }

 //Get the file size
 public function getSize($_format=' K'){
 if ($this->canUpload) {
 if (0 == $_FILES[$this->formName]['size']) {
 $this->canUpload = false;
 return $this->canUpload;
 break;
 }
 switch ($_format){
 case 'B':
 return $_FILES[$this->formName]['size'];
 break;
 case 'K ':
 return round($_FILES[$this->formName]['size'] / 1024);
 break;
 case 'M':
 return round($_FILES[$this->formName][' size'] / (1024*1024),2);
 break;
 }
 }
 }

 //Get the file type
 public function getExt(){
 if ($this->canUpload) {
 $_name = $_FILES[$this->formName]['name'];
 $_nameArr = explode('.',$_name);
 $_count = count($_nameArr)-1;
 }
 return $_nameArr[ $_count];
 }

 //Get the file name
 public function getName(){
 if ($this->canUpload) {
 return $_FILES[$this->formName]['name'];
 }
 }

 //Create a new file name
 public function newName(){
 return date('YmdHis').rand(0,9);
 }

 //Upload a file
 public function upload(){
 if ($this->canUpload)
 {
 $_getSize = $this->getSize('B');
 if (!$_getSize)
 {
 return $_getSize;
 break;
 }
                        else
                        {
                                $_newName = $this->newName();
                                $_ext = $this->getExt();
                                $_doUpload = move_uploaded_file($_FILES[$this->formName]['tmp_name'], $this->directory.$_newName.".".$_ext);
                                if ($_doUpload)
                                {
                                        $this->doUpFile = $_newName;
                                }
                                return $_doUpload;
                        }
                }
        }

        //创建缩略图
        public function thumb($_dstChar='_m', $_max_len=320){                //$_dstChar:_m , _s
                if ($this->canUpload && $this->doUpFile != "") {
                        $_ext = $this->getExt();
                        $_srcImage = $this->directory.$this->doUpFile.".".$_ext;

                        //得到图片信息数组
                        $_date = getimagesize($_srcImage, &$info);

                        $src_w = $_date[0];        //源图片宽
                        $src_h = $_date[1];        //源图片高
                        $src_max_len = max($src_w, $src_h);                //求得长边
                        $src_min_len = min($src_w, $src_h);                //求得短边
                        $dst_w = '';                //目标图片宽
                        $dst_h = '';                //目标图片高

                        //宽高按比例缩放，最长边不大于$_max_len
                        if ($src_max_len>$_max_len)
                        {
                                $percent = $src_min_len / $src_max_len;
                                if ($src_w == $src_max_len)
                                {
                                        $dst_w = $_max_len;
                                        $dst_h = $percent * $dst_w;
                                }
                                else
                                {
                                        $dst_h = $_max_len;
                                        $dst_w = $percent * $dst_h;
                                }
                        }
                        else
                        {
                                $dst_w = $src_w;
                                $dst_h = $src_h;
                        }

                        //建立缩略图时,源图片的位置
                        $src_x = '';
                        $src_y = '';

                        //判断如果缩略图用于logo，将对其进行裁减
                        if ('s_' == $_dstChar) {
                                $src_x = $src_w * 0.10;
                                $src_y = $src_h * 0.10;
                                $src_w *= 0.8;
                                $src_h *= 0.8;
                        }

                        //判断图片类型并创建对应新图片
                        switch ($_date[2]){
                                case 1:
                                        $src_im = imagecreatefromgif($_srcImage);
                                        break;
                                case 2:
                                        $src_im = imagecreatefromjpeg($_srcImage);
                                        break;
                                case 3:
                                        $src_im = imagecreatefrompng($_srcImage);
                                        break;
                                case 8:
                                        $src_im = imagecreatefromwbmp($_srcImage);
                                        break;
                        }

                        //创建一幅新图像
                        if ($_date[2]==1) {                //gif无法应用imagecreatetruecolor
                                $dst_im = imagecreate($dst_w, $dst_h);
                        }else {
                                $dst_im = imagecreatetruecolor($dst_w, $dst_h);
                        }

 //Make a thumbnail copy of this image
// $bg = imagecolorallocate($dst_im,255,255,0);
 imagecopyresized($dst_im,$src_im, 0, 0, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h );
 //Perform anti-aliasing operation on the image
 imageantialias($dst_im, true);

 switch ($_date[2]) {
 case 1:
 $cr = imagegif($ dst_im, $this->directory.$this->doUpFile.$_dstChar.".".$_ext, 100);
 break;
 case 2:
 $cr = imagejpeg($dst_im, $this-> directory.$this->doUpFile.$_dstChar.".".$_ext, 100);
 break;
 There is a problem with case 3://imagepng, so use imagejpg instead here
 $cr = imagejpeg($dst_im, $this->directory.$this->doUpFile.$_dstChar.".".$_ext, 100);
 break;
 }
// $cr = imagejpeg($dst_im, $this->directory. $_dstChar.$this->doUpFile, 90);
 if ($cr) {
 $this->sm_File = $this->directory.$this->doUpFile.$_dstChar.".".$ _ext;

 return $this->sm_File;
 }else {
 return false;
 }
 }
 imagedestroy($dst_im);
 imagedestroy($cr);
 }

 //Get the uploaded file name
 public function getUpFile(){
 if ($this->doUpFile!='') {
 $_ext = $this->getExt();
 return $this->doUpFile.".".$_ext ;
 }else {
 return false;
 }
 }

 //Get the full path of the uploaded file
 public function getFilePatch(){
 if ($this->doUpFile!='') {
 $_ext = $this->getExt();
 return $this->directory.$this->doUpFile.".".$_ext;
 }else {
 return false;
 }
 }

 //Get abbreviation Full path of thumbnail file
 public function getThumb(){
 if ($this->sm_File!='') {
 return $this->sm_File;
 }else {
 return false;
 }
 }
 // Get the path of the uploaded file
 public function getDirectory(){
 if ($this->directory!='') {
 return $this->directory;
 }else {
 return false;
 }
 }
}
?>

Image upload, PHP