Php image upload and preview

If (! Isset ($ _ session) session_start ();

/** 2010-6-22
* $ The data array type contains the following variables:
-------------------------------
* $ Sub_type submit type (upload: upload button delete: delete button), default upload
* $ File the $ _ files ['filename'] array obtained through the form
* $ Img_tag_id id of the preview image
* $ Img_dir directory for uploading images
* $ Max_file_size unit: m (MB); default value: 1 m
* $ Type_array: Supported image types (default: image/pjpeg, image/jpeg, image/gif)
**/
Function upload ($ data ){
If (! $ Data ['file']) {
Echo '<script> alert ("file cannot be blank! "); </Script> '; exit;
    }
If (! $ Data ['IMG _ tag_id ']) {
Echo '<script> alert ("preview image tag id cannot be blank! "); </Script> '; exit;
    }
If (! $ Data ['IMG _ dir']) {
Echo '<script> alert ("the image upload directory cannot be blank! "); </Script> '; exit;
    }
If (! Isset ($ data ['max _ file_size ']) {
$ Data ['max _ file_size '] = 1024*1024;
} Else {
$ Data ['max _ file_size '] = $ data ['max _ file_size'] * 1024*1024;
    }
If (! Isset ($ data ['type _ array']) {
$ Data ['type _ array'] = array ('image/pjpeg ', 'image/jpeg', 'image/GIF ');
    }
If (! Isset ($ data ['sub _ type']) {
$ Data ['sub _ type'] = 'upload ';
    }

$ Imgpath = '';
If (isset ($ data ['sub _ type']) & $ data ['sub _ type'] = 'delete '){
If (isset ($ _ session ['name']) & $ _ session ['name']) {
If (is_file ($ _ session ['imgpath']) {
$ B = unlink ($ _ session ['imgpath']);
            }
Unset ($ _ session ['name'], $ _ session ['imgpath']);
If (! Isset ($ _ session ['name']) {
Echo '<script> alert ("deleted successfully! "); </Script> ';
Echo '<script> parent.doc ument. getelementbyid ("'. $ data ['IMG _ tag_id ']. '"). style. display = "none"; </script> ';
} Else {
Echo '<script> alert ("deletion failed! "); </Script> ';
            }
} Else {
Echo '<script> alert ("no manuscript! "); </Script> ';
} Exit;
    }

If (isset ($ _ session ['imgpath']) & $ _ session ['imgpath']) {
Echo '<script> alert ("The manuscript already exists. To upload it again, delete the original manuscript! "); </Script> '; exit;
    }
If (! In_array ($ data ['file'] ['type'], $ data ['type _ array']) {
Echo '<script> alert ("the source is not matched. Upload The. Jpg).gif and. PNG images! "); </Script> '; exit;
    }
If ($ data ['file'] ['size']> $ data ['max _ file_size ']) {
Echo '<script> alert ("your uploaded manuscript is too large. Please select an image below 2 MB to upload! "); </Script> '; exit;
    }

If (! Is_dir ($ data ['IMG _ dir']) {
@ Mkdir ($ data ['IMG _ dir'], 0777, true );
    }
$ Imgpath = $ data ['IMG _ dir']. '/'. date ('his ', time ()). rand (100,999 ). $ data ['file'] ['name'];
$ Isupload = move_uploaded_file ($ data ['file'] ['tmp _ name'], $ imgpath );
If (! $ Isupload ){
Echo '<script> alert ("An error occurred while uploading the manuscript. Please upload it again! "); </Script> '; exit;
} Else {
Echo '<script> alert ("The manuscript is uploaded successfully! "); </Script> ';
    }
$ _ Session ['name'] = $ data ['file'] ['name'];
$ _ Session ['imgpath'] = $ imgpath;

Return $ imgpath;
}

/* Test_start */
$ Sub_type = '';
If (isset ($ _ post ['submit _ upload']) $ sub_type = 'upload ';
If (isset ($ _ post ['submit _ delete']) $ sub_type = 'delete ';
If ($ sub_type) {// echo '<script> alert ("'. $ sub_type. '"); </script>'; exit;
$ Data = array ('sub _ type' => $ sub_type,
'File' => $ _ files ['file'],
'IMG _ tag_id '=> 'picview ',
'IMG _ dir' => 'upload _ img ',
);
$ Imgpath = upload ($ data );
} Else {
$ Imgpath = isset ($ _ session ['imgpath'])? $ _ Session ['imgpath']: '';
}
?>

<Form action = "ad. php" method = "post" enctype = "multipart/form-data" target = "frame">
<Input type = "file" name = "file" class = "input">
<Input type = "submit" name = "submit_upload" value = "upload">
<Input type = "submit" name = "submit_delete" value = "delete">
<Iframe id = "frame" name = "frame" width = "0" height = "0" marginwidth = "0" frameborder = "0" src = "about: blank "> </iframe>
</Form>

<Script>
If ("<? Php echo $ imgpath;?> "){
Parent.doc ument. getelementbyid ("picview"). src = "<? Php echo $ imgpath;?> ";
Parent.doc ument. getelementbyid ("picview"). style. display = "block ";
}
</Script>