Upload image by Resize both side and display center of content

<?php
function fnCreatBigThumbnail($strSourcePath,$strFilename,$strDestinationPath,$intGetWidth,$intGetHeight)
{
    $strSourcePath = $strSourcePath.$strFilename;
    $info = pathinfo($strSourcePath);
    if (strtolower($info['extension']) == 'jpg') {$img = imagecreatefromjpeg( "{$strSourcePath}");}
    elseif(strtolower($info['extension']) == 'gif'){$img = imagecreatefromgif( "{$strSourcePath}");}
    elseif(strtolower($info['extension']) == 'png'){$img = imagecreatefrompng( "{$strSourcePath}");}
   
    $intNewWidth = $intOrigionalWidth = imagesx( $img );
    $intNewHeight = $intOrigionalHeight = imagesy( $img );
   
    if($intOrigionalWidth > $intGetWidth)
    {
        $intNewWidth = $intGetWidth;
        $intNewHeight = (($intOrigionalHeight * $intGetWidth)/$intOrigionalWidth);
    }
    if($intNewHeight > $intGetHeight)
    {
        $intNewHeight = $intGetHeight;
        $intNewWidth = (($intOrigionalWidth * $intGetHeight)/$intOrigionalHeight);
    }

    $tmp_img = imagecreatetruecolor($intGetWidth,$intGetHeight);
    $strWhiteBackground = imagecolorallocate($tmp_img, 255, 255, 255);
    imagefill($tmp_img, 0, 0, $strWhiteBackground);
   
    $floatWhiteWidth = (($intGetWidth - $intNewWidth)/2);
    $floatWhiteHeight = (($intGetHeight - $intNewHeight)/2);
   
    imagecopyresized( $tmp_img, $img, $floatWhiteWidth, $floatWhiteHeight, 0, 0, $intNewWidth, $intNewHeight, $intOrigionalWidth, $intOrigionalHeight );
   
    if(strtolower($info['extension']) == 'jpg'){imagejpeg($tmp_img,"{$strDestinationPath}{$strFilename}");}
    elseif(strtolower($info['extension']) == 'gif'){imagegif( $tmp_img, "{$strDestinationPath}{$strFilename}");}
    elseif(strtolower($info['extension']) == 'png'){imagepng( $tmp_img, "{$strDestinationPath}{$strFilename}");}
}
if(isset($_REQUEST["submit"]))
{
    $type = strtolower($_FILES['file']['type']);
    if(($type=="image/gif")||($type=="image/jpeg") ||($type=="image/png") ||($type=="image/jpeg"))
    {
        move_uploaded_file($_FILES['file']['tmp_name'],'upload/'.$_FILES['file']['name']);
        $strSourcePath = "upload/";
        $strFilename = $_FILES['file']['name'];
        $strDestinationPath = "resize/";
        fnCreatBigThumbnail($strSourcePath,$strFilename,$strDestinationPath,935,440);
    }
    else
    {
        echo "Invalid value";
    }
}   
?>
<form name="frm" action="index.php" method="post" enctype="multipart/form-data">
    <input type="file" name="file"  />
    <input type="submit" name="submit" value="Save" />
</form>