PHP临时文件上传无效图片资源

Hi I have a class for resizing images (resizeManager.php):

        Class ResizeManager
    {
        // *** Class variables
        private $image;
        private $width;
        private $height;
        private $imageResized;

        function __construct($fileName)
        {
            // *** Open up the file
            $this->image = $this->openImage($fileName);

            // *** Get width and height
            $this->width  = imagesx($this->image);
            $this->height = imagesy($this->image);
        }

        ## --------------------------------------------------------

        private function openImage($file)
        {
            // *** Get extension
            $extension = strtolower(strrchr($file, '.'));

            switch($extension)
            {
                case '.jpg':
                case '.jpeg':
                    $img = @imagecreatefromjpeg($file);
                    break;
                case '.gif':
                    $img = @imagecreatefromgif($file);
                    break;
                case '.png':
                    $img = @imagecreatefrompng($file);
                    break;
                default:
                    $img = false;
                    break;
            }
            return $img;
        }

        ## --------------------------------------------------------

        public function resizeImage($newWidth, $newHeight, $option="auto")
        {
            // *** Get optimal width and height - based on $option
            $optionArray = $this->getDimensions($newWidth, $newHeight, $option);

            $optimalWidth  = $optionArray['optimalWidth'];
            $optimalHeight = $optionArray['optimalHeight'];


            // *** Resample - create image canvas of x, y size
            $this->imageResized = imagecreatetruecolor($optimalWidth, $optimalHeight);
            imagecopyresampled($this->imageResized, $this->image, 0, 0, 0, 0, $optimalWidth, $optimalHeight, $this->width, $this->height);


            // *** if option is 'crop', then crop too
            if ($option == 'crop') {
                $this->crop($optimalWidth, $optimalHeight, $newWidth, $newHeight);
            }
        }

        ## --------------------------------------------------------

        private function getDimensions($newWidth, $newHeight, $option)
        {

           switch ($option)
            {
                case 'exact':
                    $optimalWidth = $newWidth;
                    $optimalHeight= $newHeight;
                    break;
                case 'portrait':
                    $optimalWidth = $this->getSizeByFixedHeight($newHeight);
                    $optimalHeight= $newHeight;
                    break;
                case 'landscape':
                    $optimalWidth = $newWidth;
                    $optimalHeight= $this->getSizeByFixedWidth($newWidth);
                    break;
                case 'auto':
                    $optionArray = $this->getSizeByAuto($newWidth, $newHeight);
                    $optimalWidth = $optionArray['optimalWidth'];
                    $optimalHeight = $optionArray['optimalHeight'];
                    break;
                case 'crop':
                    $optionArray = $this->getOptimalCrop($newWidth, $newHeight);
                    $optimalWidth = $optionArray['optimalWidth'];
                    $optimalHeight = $optionArray['optimalHeight'];
                    break;
            }
            return array('optimalWidth' => $optimalWidth, 'optimalHeight' => $optimalHeight);
        }

        ## --------------------------------------------------------

        private function getSizeByFixedHeight($newHeight)
        {
            $ratio = $this->width / $this->height;
            $newWidth = $newHeight * $ratio;
            return $newWidth;
        }

        private function getSizeByFixedWidth($newWidth)
        {
            $ratio = $this->height / $this->width;
            $newHeight = $newWidth * $ratio;
            return $newHeight;
        }

        private function getSizeByAuto($newWidth, $newHeight)
        {
            if ($this->height < $this->width)
            // *** Image to be resized is wider (landscape)
            {
                $optimalWidth = $newWidth;
                $optimalHeight= $this->getSizeByFixedWidth($newWidth);
            }
            elseif ($this->height > $this->width)
            // *** Image to be resized is taller (portrait)
            {
                $optimalWidth = $this->getSizeByFixedHeight($newHeight);
                $optimalHeight= $newHeight;
            }
            else
            // *** Image to be resizerd is a square
            {
                if ($newHeight < $newWidth) {
                    $optimalWidth = $newWidth;
                    $optimalHeight= $this->getSizeByFixedWidth($newWidth);
                } else if ($newHeight > $newWidth) {
                    $optimalWidth = $this->getSizeByFixedHeight($newHeight);
                    $optimalHeight= $newHeight;
                } else {
                    // *** Sqaure being resized to a square
                    $optimalWidth = $newWidth;
                    $optimalHeight= $newHeight;
                }
            }

            return array('optimalWidth' => $optimalWidth, 'optimalHeight' => $optimalHeight);
        }

        ## --------------------------------------------------------

        private function getOptimalCrop($newWidth, $newHeight)
        {

            $heightRatio = $this->height / $newHeight;
            $widthRatio  = $this->width /  $newWidth;

            if ($heightRatio < $widthRatio) {
                $optimalRatio = $heightRatio;
            } else {
                $optimalRatio = $widthRatio;
            }

            $optimalHeight = $this->height / $optimalRatio;
            $optimalWidth  = $this->width  / $optimalRatio;

            return array('optimalWidth' => $optimalWidth, 'optimalHeight' => $optimalHeight);
        }

        ## --------------------------------------------------------

        private function crop($optimalWidth, $optimalHeight, $newWidth, $newHeight)
        {
            // *** Find center - this will be used for the crop
            $cropStartX = ( $optimalWidth / 2) - ( $newWidth /2 );
            $cropStartY = ( $optimalHeight/ 2) - ( $newHeight/2 );

            $crop = $this->imageResized;
            //imagedestroy($this->imageResized);

            // *** Now crop from center to exact requested size
            $this->imageResized = imagecreatetruecolor($newWidth , $newHeight);
            imagecopyresampled($this->imageResized, $crop , 0, 0, $cropStartX, $cropStartY, $newWidth, $newHeight , $newWidth, $newHeight);
        }

        ## --------------------------------------------------------

        public function saveImage($savePath, $imageQuality="100")
        {
            // *** Get extension
            $extension = strrchr($savePath, '.');
            $extension = strtolower($extension);

            switch($extension)
            {
                case '.jpg':
                case '.jpeg':
                    if (imagetypes() & IMG_JPG) {
                        imagejpeg($this->imageResized, $savePath, $imageQuality);
                    }
                    break;

                case '.gif':
                    if (imagetypes() & IMG_GIF) {
                        imagegif($this->imageResized, $savePath);
                    }
                    break;

                case '.png':
                    // *** Scale quality from 0-100 to 0-9
                    $scaleQuality = round(($imageQuality/100) * 9);

                    // *** Invert quality setting as 0 is best, not 9
                    $invertScaleQuality = 9 - $scaleQuality;

                    if (imagetypes() & IMG_PNG) {
                         imagepng($this->imageResized, $savePath, $invertScaleQuality);
                    }
                    break;

                // ... etc

                default:
                    // *** No extension - No save.
                    break;
            }

            imagedestroy($this->imageResized);
        }




    }

在我的页面 (mypage.php) 中，我想仅在其宽度>800 像素或高度>600 像素时调整我上传的图像的大小.

list($width, $height, $type, $attr) = getimagesize($_FILES['pictures']['tmp_name'][$number]); 

if($width>800 || $height>600)
{
 $resizemgr = new ResizeManager($_FILES['pictures']['tmp_name'][$number]);
    //then the actual resizing                      
    [...]
}
else

$ret=@move_uploaded_file($_FILES['pictures']['tmp_name'][$number],$destinationFile); 

Warning: imagesx(): supplied argument is not a valid Image resource in resizeManager.php 

Warning: imagesy(): supplied argument is not a valid Image resource in resizeManager.php 

<form method="post" enctype="multipart/form-data" action="">
<input type="file" name="file" />
<div class="td" style="width: 100%; text-align: left;"><button type="submit">OK</button></div>
</form>
<?php
if( isset( $_FILES['file'] ) )
{
    $img = file_get_contents( $_FILES['file']['tmp_name'] );
    $image = imagecreatefromstring( $img );
    echo imagesx( $image );
}
?>