Usage analysis of CI framework file upload class and image processing class, ci file upload_PHP tutorial

//列表页banner图片
public function edit_list_page_banner($category_id=""){
  $category_id= empty($category_id)?$_POST["category_id"]:$category_id;
  //上传图片
  if(isset($_POST["key"]) && $_POST["key"] == "upload"){
   /*
   1.set_upload_path
   */
   $config['upload_path']="./upload/source/".date("Y/m/d");//文件上传目录
   if(!file_exists("./upload/source/".date("Y/m/d"))){
    mkdir("./upload/source/".date("Y/m/d"),0777,true);//原图路径
   }
   if(!file_exists("./upload/big_thumb/".date("Y/m/d"))){
    mkdir("./upload/big_thumb/".date("Y/m/d"),0777,true);//大缩略图路径
   }
   if(!file_exists("./upload/small_thumb/".date("Y/m/d"))){
    mkdir("./upload/small_thumb/".date("Y/m/d"),0777,true);//小缩略图路径
   }
   $config['allowed_types']="gif|jpg|png|txt";//文件类型
   $config['max_size']="20000";//最大上传大小
   $this->load->library("upload",$config);
   if($this->upload->do_upload('userfile'))//表单中name="userfile"
   {
    //上传成功之后，生成两张缩略图
    $data=$this->upload->data();//返回上传图片的信息
    $this->load->library("image_lib");//载入图像处理类库
    //第一种方式：大缩略图的配置参数
    /*
    $config_big_thumb['image_library'] = 'gd2';//gd2图库
    $config_big_thumb['source_image'] = $data['full_path'];//原图
    $config_big_thumb['new_image'] = "./upload/big_thumb/".date("Y/m/d")."/".$data['file_name'];//大缩略图
    $config_big_thumb['create_thumb'] = true;//是否创建缩略图
    $config_big_thumb['maintain_ratio'] = true;
    $config_big_thumb['width'] = 300;//缩略图宽度
    $config_big_thumb['height'] = 300;//缩略图的高度
    $config_big_thumb['thumb_marker']="_300_300";//缩略图名字后加上 "_300_300",可以代表是一个300*300的缩略图
    */
    //第二种：大缩略图的配置参数
    /*
    $config_big_thumb=array(
     'image_library' => 'gd2',//gd2图库
     'source_image' => $data['full_path'],//原图
     'new_image' => "./upload/big_thumb/".date("Y/m/d")."/".$data['file_name'],//大缩略图
     'create_thumb' => true,//是否创建缩略图
     'maintain_ratio' => true,
     'width' => 300,//缩略图宽度
     'height' => 300,//缩略图的高度
     'thumb_marker'=>"_300_300"//缩略图名字后加上 "_300_300",可以代表是一个300*300的缩略图
    );
    */
    //第三种方式：将部分配置信息放到了config.php文件中
    $config_big_thumb=$this->config->item("config_big_thumb");
    $config_big_thumb['source_image']=$data['full_path'];
    $config_big_thumb['new_image']="./upload/big_thumb/".date("Y/m/d")."/".$data['file_name'];
    //小缩略图的配置参数
    /*
    $config_small_thumb['image_library'] = 'gd2';//gd2图库
    $config_small_thumb['source_image'] = $data['full_path'];//原图
    $config_small_thumb['new_image'] = "./upload/small_thumb/".date("Y/m/d")."/".$data['file_name'];//大缩略图
    $config_small_thumb['create_thumb'] = true;//是否创建缩略图
    $config_small_thumb['maintain_ratio'] = true;
    $config_small_thumb['width'] = 100;//缩略图宽度
    $config_small_thumb['height'] = 100;//缩略图的高度
    $config_small_thumb['thumb_marker']="_100_100";//缩略图名字后加上 "_100_100",可以代表是一个100*100的缩略图
    */
    //小缩略图的配置参数
    $config_small_thumb=array(
     'image_library' => 'gd2',//gd2图库
     'source_image' => $data['full_path'],//原图
     'new_image' => "./upload/small_thumb/".date("Y/m/d")."/".$data['file_name'],//大缩略图
     'create_thumb' => true,//是否创建缩略图
     'maintain_ratio' => true,
     'width' => 100,//缩略图宽度
     'height' => 100,//缩略图的高度
     'thumb_marker'=>"_100_100"//缩略图名字后加上 "_300_300",可以代表是一个300*300的缩略图
    );
    //$this->load->library("image_lib",$config_thumb);
    $this->image_lib->initialize($config_big_thumb);
    $this->image_lib->resize();//生成big缩略图
    $this->image_lib->initialize($config_small_thumb);
    $this->image_lib->resize();//生成small缩略图
    //插入数据库
    $data_array = array(
     'category_id' => $category_id,
     'pic_url' => "./upload/source/".date("Y/m/d")."/".$data['file_name'],
     'addtime' => time(),
     'is_stop' => 1,
     'sort'=>0,
     'gender' => $_POST["gender"],
     'link_url'=>$_POST["link_url"],
     'user_id' => intval($this->cur_user ['user_id'])
    );
    $this->category_model->add_category_banner($data_array);
   }
  }
  $con_arr[] = " category_id= '{$category_id}'";
  if ($gender=='' ) {
   $gender=0;
  }
  $con_arr[] = " gender= '{$gender}'";
  $condition = implode( ' and ', $con_arr);
  $banner_list = $this->category_model->get_banner_all($condition);
  $this->tp->assign('banner_list', $banner_list);
  $this->tp->assign('base_url', base_url());
  $this->tp->assign('gender', $gender);
  $this->tp->assign('category_id', $category_id);
  $this->tp->display("category/edit_list_page_banner.php");
}

//大缩略图的配置参数
$config_big_thumb=array(
 'image_library' => 'gd2',//gd2图库
 'create_thumb' => true,//是否创建缩略图
 'maintain_ratio' => true,
 'width' => 300,//缩略图宽度
 'height' => 300,//缩略图的高度
 'thumb_marker'=>"_300_300"//缩略图名字后加上 "_300_300",可以代表是一个300*300的缩略图
);