TreeView control starter code

[Charles Dietz]

I thought that this code might be useful as starter code to anyone new to the Treeview control. I know in my case, I like to see very simple code to begin with when dealing with an unfamiliar common control.

I hope this code displays ok on this new forum.

#COMPILE EXE
#DIM ALL
#INCLUDE "win32api.inc"
#INCLUDE "Commctrl.inc"

'Include file statements 
'========================================================================
%ID_TREE = 100

TYPE itemRef_UDT 
   hItem   AS LONG
   parent  AS LONG
   subDirs AS BYTE
   done    AS BYTE
END TYPE

GLOBAL hTree AS LONG
GLOBAL numItems AS LONG
GLOBAL maxDim AS LONG
GLOBAL item() AS STRING
GLOBAL itemRef() AS itemRef_UDT

DECLARE FUNCTION TVInsertItem(LONG, LONG, STRING, BYTE) AS LONG
DECLARE FUNCTION getItemNo(LONG) AS LONG
DECLARE FUNCTION subDirsExist(STRING) AS BYTE
DECLARE SUB getNextDirs(LONG)
'========================================================================

FUNCTION PBMAIN()
   LOCAL hMain AS LONG
   DIALOG NEW PIXELS, 0, "my TreeView", , , 400, 300,%WS_SYSMENU OR %WS_MINIMIZEBOX TO hMain
    'add treeview common control
   CONTROL ADD "SysTreeView32", hMain, %ID_TREE, "", 0, 0, 400, 300, _
              %WS_CHILD OR %WS_VISIBLE OR %TVS_HASBUTTONS OR %TVS_HASLINES OR _
              %TVS_LINESATROOT OR %TVS_SHOWSELALWAYS, %WS_EX_CLIENTEDGE
   DIALOG SHOW MODAL hMain CALL mainProc
   END FUNCTION

CALLBACK FUNCTION mainProc()
   LOCAL i, m, n, hTreeItem, hItem, hParent, hChild AS LONG
   LOCAL s AS STRING, szTxt AS ASCIIZ*64
   LOCAL lpNmh AS NMHDR PTR
   LOCAL lpTV AS NM_TREEVIEW PTR
   LOCAL treeItem AS TV_ITEM
   LOCAL TVdi AS TV_DISPINFO
   SELECT CASE CBMSG
      CASE %WM_INITDIALOG
         maxDim = 2000
         DIM item(maxDim)
         DIM itemRef(maxDim)
         
         'find the first level children of C:\ 
         item(0) = "C:": getNextDirs 0
         
         'display the folders and files 
         CONTROL HANDLE CBHNDL, %ID_TREE TO hTree
         itemRef(0).hItem = TVInsertItem(hTree, 0, "C:\", 1)
         FOR i = 1 TO numItems
            s = PARSE$(item(i), "\", -1)
            hParent = itemRef(itemRef(i).parent).hItem
            hChild = TVInsertItem(hTree, hParent, s, itemRef(i).subDirs)
            itemRef(i).hItem = hChild
         NEXT i
         
         'open with first level folders... the children of C:\
         SendMessage hTree, %TVM_EXPAND, %TVE_EXPAND, itemRef(0).hItem   
      CASE %WM_PAINT
      CASE %WM_COMMAND
         SELECT CASE CBCTL
         END SELECT
      CASE %WM_NOTIFY
         lpNmh = CBLPARAM
         SELECT CASE @lpNmh.Code
            CASE %TVN_ITEMEXPANDING
               'expand or collapse the treeview node hTreeItem
               lpTV = CBLPARAM
               hTreeItem = @lpTV.ItemNew.hItem 
               m = numItems: n = getItemNo(hTreeItem)
               IF itemRef(n).done THEN EXIT FUNCTION
               getNextDirs n
               FOR i = m + 1 TO numItems
                  s = PARSE$(item(i), "\", -1)
                  hParent = itemRef(itemRef(i).parent).hItem
                  hChild = TVInsertItem(hTree, hParent, s, itemRef(i).subDirs)
                  itemRef(i).hItem = hChild
               NEXT i
         END SELECT   
      CASE %WM_SYSCOMMAND
      CASE %WM_DESTROY
   END SELECT
END FUNCTION

FUNCTION getItemNo(hTreeItem AS LONG) AS LONG
   'get itemNo corresponding to item's handle
   'hTreeItem  = item handle
   'numItems   = number of items defined (nodes of treeview)
   '===================================================================
   LOCAL i, n AS LONG
   FOR i = 1 TO numItems
      IF itemRef(i).hItem = hTreeItem THEN n = i: EXIT FOR
   NEXT i
   FUNCTION = n
END FUNCTION

FUNCTION TVInsertItem(hTree AS LONG, hParent AS LONG, sTxt AS STRING, b AS BYTE) AS LONG
   'insert item into treeview control
   '--------------------------------------------------------------------------------
   'hTree   = handle of treeview control
   'hParent = handle of parent to item
   'sTxt    = string label identifying item
   'b       = set if children exist for this item
   '================================================================================
   LOCAL tv_insert AS TV_INSERTSTRUCT
   tv_insert.hParent              = hParent
   tv_insert.Item.Item.mask       = %TVIF_TEXT OR %TVIF_CHILDREN
   tv_insert.Item.Item.pszText    = STRPTR(sTxt)
   tv_insert.Item.Item.cchTextMax = LEN(sTxt)
   IF b THEN tv_insert.Item.Item.cChildren = 1
   FUNCTION = TreeView_InsertItem(hTree, tv_insert)
END FUNCTION

SUB getNextDirs(itemNo AS LONG)
   'find next first level children of itemNo
   'update global item(), itemRef(), and numItems
   '-------------------------------------------------------------------
   'item()    = array of folder names
   'itemRef() = array of folder info UDTs 
   'numItems  = number of nodes identified so far
   '===================================================================
   LOCAL s, sParent AS STRING
   LOCAL attr, i, k, n, nDim AS LONG
   DIM sTemp(maxDim) AS STRING
   sParent = RTRIM$(item(itemNo), "\") + "\"
   attr = %SUBDIR 'OR %READONLY OR %HIDDEN OR %SYSTEM 
   s = DIR$(sParent, attr)
   IF LEN(s) THEN 
      k = GETATTR(sParent + s) AND %SUBDIR
      IF k THEN INCR n: sTemp(n) = s
      DO 
         s = DIR$: k = 0: IF LEN(s) = 0 THEN EXIT DO
         k = GETATTR(sParent + s) AND %SUBDIR
         IF k THEN INCR n: sTemp(n) = s
      LOOP
   END IF
   itemRef(numItems).done = 1
   'found n subdirectories of itemNo
   '... now update numItems, item(), and itemRef() 
   IF n = 0 THEN EXIT SUB
   numItems = numItems + n
   nDim = UBOUND(item)
   IF nDim < numItems THEN 'redim arrays if necessary
      nDim = numItems + 1000
      REDIM PRESERVE item(nDim)
      REDIM PRESERVE itemRef(nDim)
   END IF 
   FOR i = 1 TO n
      s = sParent + sTemp(i)
      item(numItems - n + i) = s
      itemRef(numItems - n + i).parent = itemNo
      itemRef(numItems - n + i).subDirs = subDirsExist(s)
   NEXT i
END SUB

FUNCTION subDirsExist(sItem AS STRING) AS BYTE
   'return 1 if any children exist for this node
   'this function is needed to determine if node needs a [+] button
   '----------------------------------------------------------------
   'sItem  = name of node
   '================================================================
   LOCAL attr, k AS LONG
   LOCAL s, sParent AS STRING
   sParent = RTRIM$(sItem, "\") + "\"
   attr = %SUBDIR 'OR %READONLY OR %HIDDEN OR %SYSTEM 
   s = DIR$(sParent, attr)
   IF LEN(s) THEN 
      k = GETATTR(sParent + s) AND %SUBDIR
      DO WHILE LEN(s) AND k = 0
         s = DIR$: IF LEN(s) = 0 THEN EXIT DO
         k = GETATTR(sParent + s) AND %SUBDIR
      LOOP 
   END IF
   FUNCTION = SGN(k)
END FUNCTION