如何制作GIF图像的动画缩略图？

Question

我已尝试过所有内容以获取缩略图的动画GIF，但我失败了。如果原始图像是动画GIF，我如何使缩略图也动画？我正在使用PHP和GD库。

这是我的缩略图PHP代码：

function upload_thumb($photo_dest, $file_maxdim = "60") {
      // SET DESIRED WIDTH AND HEIGHT
    $x = 0;
    $y = 0;
      $width = $this->file_width;
      $height = $this->file_height;
      if($width > $height)
    { 
        $x = ceil(($width - $height) / 2);
        $width = $height;
      }
    elseif($width < $height)
    {
        $y = ceil(($height - $width) / 2);
        $height = $width;
      }

      // RESIZE IMAGE AND PUT IN USER DIRECTORY
      switch($this->file_ext)
    {
        case "gif":
        case "x-gif";
          $file = imagecreatetruecolor($file_maxdim, $file_maxdim);
          $new = imagecreatefromgif($this->file_tempname);
          $kek=imagecolorallocate($file, 255, 255, 255);
          imagefill($file,0,0,$kek);
          imagecopyresampled($file, $new, 0, 0, $x, $y, $file_maxdim, $file_maxdim, $width, $height);
          imagegif($file, $photo_dest, 100);
          ImageDestroy($new);
          ImageDestroy($file);
          break;

        case "bmp":
          $file = imagecreatetruecolor($file_maxdim, $file_maxdim);
          $new = $this->imagecreatefrombmp($this->file_tempname);
          for($i=0; $i<256; $i++) { imagecolorallocate($file, $i, $i, $i); }
          imagecopyresampled($file, $new, 0, 0, $x, $y, $file_maxdim, $file_maxdim, $width, $height); 
          imagejpeg($file, $photo_dest, 100);
          ImageDestroy($new);
          ImageDestroy($file);
          break;

        case "jpeg":
        case "jpg":
          $file = imagecreatetruecolor($file_maxdim, $file_maxdim);
          $new = imagecreatefromjpeg($this->file_tempname);
          for($i=0; $i<256; $i++) { imagecolorallocate($file, $i, $i, $i); }
          imagecopyresampled($file, $new, 0, 0, $x, $y, $file_maxdim, $file_maxdim, $width, $height);
          imagejpeg($file, $photo_dest, 100);
          ImageDestroy($new);
          ImageDestroy($file);
          break;

        case "png":
        case "apng";
        case "x-png";
        $photo_dest=strtolower($photo_dest);
        $photo_dest=str_replace("jpg","png",$photo_dest);
        $file = imagecreatetruecolor($width, $height);
        $new = imagecreatefrompng($this->file_tempname);
        imagealphablending($file,false);
        imagesavealpha($file,true);
        $transparent = imagecolorallocatealpha($file, 255, 255, 255, 127);
        imagefilledrectangle($file, 0, 0, $width, $height, $transparent);
        imagecopyresampled($file, $new, 0, 0, 0, 0, $width, $height, $this->file_width, $this->file_height);
        imagepng($file, $photo_dest);
        ImageDestroy($new);
        ImageDestroy($file);
        break;
      } 

      chmod($photo_dest, 0777);

      return true;
    }