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一、 External Interface

          1.   给其他模块使用的接口函数                    作用          mmi_fmgr_init                   initialize file manager context          mmi_fmgr_select_path_and_entry  entry point to file manager for other applications          mmi_fmgr_reset_app_select       reset selection from other application          GetFileSystemErrorString        convert file system return error code to error messgae pop up          2.   分析mmi_fmgr_select_path_and_entry, mmi_fmgr_reset_app_selec          函数原型: void  mmi_fmgr_select_path_and_entry(U8 app_id, U8 sel_type, U32 filter, PS8 start_path, PsFuncPtr callback) ;          (1) 主要分析callback函数              A.    excute mmi_fmgr_select_path_and_entry(......)              start_path              --->  callback(.....)              --->  callback内部检查:  N                    start_path=NULL?  ---> the selection is completed                          |                          | Y                 the selection is aborted              B.  FMGR_SELECT_REPEAT对于callback函数的影响以及                  使用FMGR_SELECT_REPEAT可以多次选择文件/文件夹                  a. Each Select                     select target                start_path                   ---> callback(......)                 ---> callback内部检查  N                      start_path=NULL? ---> user abort ( the selection is aborted )                            |                            | Y                       Y                      reach applications condition? ---> application abort ( the selection is aborted )                            |                            |                      the selection is completed                  b. 两种abort                     user abort:                     will cause a callback with NULL parameter and File Manager will automatically reset ;                     application abort:                     needs to call the mmi_fmgr_reset_app_select( ) to terminate the process          (2) FMGR_SELECT_BROWSE参数              drive option              folder option              file option          3.   Utility Functions          BOOL  mmi_fmgr_get_default_folder_path(S8 * folder,S8 * path,U16 length);          void  mmi_fmgr_remove_last_dir(S8 * path);          S8 *  mmi_fmgr_extract_file_name(S8 * path );          S8 *  mmi_fmgr_extract_ext_file_name(S8 * path);          void  mmi_fmgr_hide_ext_name(S8 * path);                mmi_fmgr_check_file_present                  二、 Cache          1.  First Time Enter a Floder     A.  一般流程         first time enter a floder      --> call fmgr_kenmel: init the cache     --> load file frome FS until the cache is filled     --> 不管是否有sort选项, file manager都会获取 file list     B.  关于 sort API         当目录项内文件数超过255, file manager cant use sort API to get file list from file system     but linear find first/find next instead.     C.  filter        2.  Request for File Info    A.  Function:  fmgr_kernel_get_file_info    B.      call fmgr_kernel_get_file_info with a index         --> get a structe of data filled with useful file information    --> this funciton will use the passed in index to see      Y        if the desired file info is already in chached or not ---> from cache                               |                               | N                               |                 reload cache and return file info

    3.  Image Cache

    A. File Manger模块的预览图Cache    B. 一般流程        Draw Thumb Image                       Y    --> Is in cache? -----> Draw it from cache            |            | N            |                 Decord Image -----> Decord Done -----> Cache the Image -----> Draw it from cache   

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