Specification

• File selection box implemented with M2_STRLIST
• Extended (left) column for directory and file icons
• Limited to (about) 250 items per directory (restriction of M2_STRLIST)
• Selected file is returned as current element in the mass storage API

File selection box without icons:

File selection box with icons:

Code Pattern

Software Structure

The code pattern will use the M2_STRLIST element. All important tasks are done inside the callback procedure of the M2_STRLIST element:

• Calculate and assign the total number of entries for M2_STRLIST element. This is done at startup of M2_STRLIST and for any directory change (M2_STRLIST_MSG_NEW_DIALOG message).
• Return the string and optional icon for each line line of the M2_STRLIST element (M2_STRLIST_MSG_GET_STR and M2_STRLIST_MSG_GET_EXTENDED_STR message).
• Change directory or return the selected file (M2_STRLIST_MSG_SELECT message)

The mass storage subsystem can be used by the M2_STRLIST callback procedure. The mass storage subsystem is an interface to a mass storage library:

Code

/* Show selected file */

const char *fs_show_file_label_cb(m2_rom_void_p element)
{
  return mas_GetFilename();
}

M2_LABEL(el_show_file_label, NULL, "Selected file:");
M2_LABELFN(el_show_filename, NULL, fs_show_file_label_cb);
M2_ROOT(el_show_file_ok, NULL, "ok", &top_el_tlsm);
M2_LIST(list_show_file) = { &el_show_file_label, &el_show_filename, &el_show_file_ok };
M2_VLIST(el_show_file_Vlist, NULL, list_show_file);
M2_ALIGN(top_el_show_file, "-1|1W64H64", &el_show_file_Vlist);

/* File selection dialog */

/* defines the number of additional buttons at the beginning of the STRLIST lines */
#define FS_EXTRA_MENUES 1

/* helper variables for the strlist element */
uint8_t fs_m2tk_first = 0;
uint8_t fs_m2tk_cnt = 0;

const char *fs_strlist_getstr(uint8_t idx, uint8_t msg)  {
  if (msg == M2_STRLIST_MSG_GET_STR)  {
    /* Check for the extra button: Return string for this extra button */
    if ( idx == 0 )
      return "..";
    /* Not the extra button: Return file/directory name */
    mas_GetDirEntry(idx - FS_EXTRA_MENUES);
    return mas_GetFilename();
  } else if ( msg == M2_STRLIST_MSG_GET_EXTENDED_STR ) {
    /* Check for the extra button: Return icon for this extra button */
    if ( idx == 0 )
      return "a";       /* arrow left of the m2icon font */
    /* Not the extra button: Return file or directory icon */
    mas_GetDirEntry(idx - FS_EXTRA_MENUES);
    if ( mas_IsDir() )
      return "A";       /* folder icon of the m2icon font */
    return "B";         /* file icon of the m2icon font */
  } else if ( msg == M2_STRLIST_MSG_SELECT ) {
    /* Check for the extra button: Execute button action */
    if ( idx == 0 ) {
      if ( mas_GetPath()[0] == '\0' )
        m2_SetRoot(&top_el_tlsm);      
      else {
        mas_ChDirUp();
        m2_SetRoot(m2_GetRoot());  /* reset menu to first element, send NEW_DIALOG and force recount */
      }
    /* Not the extra button: Goto subdir or return (with selected file) */
    } else {
      mas_GetDirEntry(idx - FS_EXTRA_MENUES);
      if ( mas_IsDir() ) {
        mas_ChDir(mas_GetFilename());
        m2_SetRoot(m2_GetRoot());  /* reset menu to first element, send NEW_DIALOG and force recount */
      } else {
	/* File has been selected. Here: Show the file to the user */
        m2_SetRoot(&top_el_show_file);  
      }
    }
  } else if ( msg == M2_STRLIST_MSG_NEW_DIALOG ) {
    /* (re-) calculate number of entries, limit no of entries to 250 */
    if ( mas_GetDirEntryCnt() < 250-FS_EXTRA_MENUES )
      fs_m2tk_cnt = mas_GetDirEntryCnt()+FS_EXTRA_MENUES;
    else
      fs_m2tk_cnt = 250;
  }
  return NULL;
}

M2_STRLIST(el_fs_strlist, "l5F3e15W47", &fs_m2tk_first, &fs_m2tk_cnt, fs_strlist_getstr);
M2_SPACE(el_fs_space, "W1h1");
M2_VSB(el_fs_strlist_vsb, "l5W4r1", &fs_m2tk_first, &fs_m2tk_cnt);
M2_LIST(list_fs_strlist) = { &el_fs_strlist, &el_fs_space, &el_fs_strlist_vsb };
M2_HLIST(el_top_fs, NULL, list_fs_strlist);

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