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TreeView Control
The treeview control displays information in a hierarchical form - showing parent-child relationships between data items. Parent structures can be closed or expanded to minimize the space needed to display and entire "tree", as the structure is called.

• Syntax:
  

  Control Add TreeView, hDlg, id&, txt$, x, y, xx, yy, _
                                       style&, extsytle& CALL callback
  TreeView Insert Item hDlg, id&, hPrnt, hIafter, _
                                      image&, selimage&, txt$ TO hItem
  

  The Control Add TreeView statement simply creates an empty treeview control. The TreeView Insert Item statement must be used to add items (as root or as children items).

  An imagelist is required if images are to be included on the treeview. Imagelists are discussed further down the page.

• Source Code Example:
  This short example creates a complete application with a single treeview, three levels of items. When an item is clicked, the treeview responds with a message. This tutorial page discusses most of the statements used, however the DDT, Controls, Messages, and Callback tutorials provide background information that may be helpful in understanding the example.

   #Compile Exe
   #Resource "pb-test.pbr"
   Global hDlg As Dword, hLst As Dword, hItem As Dword, hTmp As Dword
   Function PBMain() As Long
      Dialog New Pixels, 0, "TreeView",200,200,155,150, _
                                      %WS_SysMenu, 0 To hDlg
      'create control
      Control Add Treeview, hDlg, 100, "", 10,10,130,125
  
      'create imagelist  w,h,depth,size
      ImageList New Icon 16,16,32,3 To hLst
      ImageList Add Icon hLst, "x"
      ImageList Add Icon hLst, "y"
      ImageList Add Icon hLst, "z"
      ImageList Add Icon hLst, "check"
  
      'attach imagelist
      Treeview Set ImageList hdlg, 100, hLst
  
      'add items  hdlg,id&,hPrnt,hIAftr,image&,selimage&,txt$ To hItem
      Treeview Insert Item hDlg,100,0,%TVI_Last,1,1,"One" To hItem
      Treeview Insert Item hDlg,100,hItem,%TVI_Last,1,4,"One-1" To hTmp
      Treeview Insert Item hDlg,100,hItem,%TVI_Last,2,4,"One-2" To hTmp
  
      Treeview Insert Item hDlg,100,0,%TVI_Last,2,2,"Two" To hItem
      Treeview Insert Item hDlg,100,hItem,%TVI_Last,1,4,"Two-1" To hTmp
      Treeview Insert Item hDlg,100,hItem,%TVI_Last,2,4,"Two-2" To hTmp
  
      Treeview Insert Item hDlg,100,0,%TVI_Last,3,3,"Three" To hItem
      Treeview Insert Item hDlg,100,hItem,%TVI_Last,1,4,"Three-1" To hTmp
      Treeview Insert Item hDlg,100,hItem,%TVI_Last,2,4,"Three-2" To hTmp
  
      Treeview Set Bold hDlg, 100, hItem, -1
          
      Dialog Show Modal hDlg Call DlgProc
   End Function
  
   CallBack Function DlgProc() As Long
      If Cb.Msg = %WM_Notify And Cb.NmId = 100 And _
                        Cb.NmCode = %TVN_SelChanged Then
         MsgBox "Selected!"
      End If
   End Function
  

  In this example, the treeview images are stored in a resource file, available from here.

  An additional example of a callback function is provided further down this page.

• Visual Examples:
  And here are a few examples of what you can do with the treeview control in PowerBASIC. Variations on the Control Add TreeView statement were used to create the examples. In some cases, other Control statements or TreeView-specific statements were used to modify the results.

     

  There are a wide variety of options - lines, edit-in-place, images, checkboxes, fonts, scrolling, and more.

Arguments
The Control Add statement is used to create all new controls. Here are the statement's arguments and any special significance to the treeview control.

• hDlg
  The dialog handle to which the treeview control is to be added. The value was returned by the DIALOG NEW statement.

• id&
  The id& argument is a control identifier assigned by the programmer. It must be a value of 1-65535. Values of 100+ are suggested, as PowerBASIC pre-assigns identifiers with special meaning. Numeric equates are suggested over the use of literal values.

• txt$
  An ampersand can also be included in txt$, such as "&Stop", to specify a hot key Alt-S.

  The treeview control does not display the txt$ value, so it is usually set to "". However, any entered txt$ value can be accessed using the GET/SET TEXT statements. This provides the application with a control-specific property that can used for any purpose the programmer chooses.

• x,y and xx,yy
  The integer x,y and xx,yy dimensions use the same units as the parent dialog. (x,y) is the upper/left coordinates of the control. (xx,yy) is the width/height of the control.

  When the control is aligned to an edge of the dialog using one of the style& options, the x,y and xx,yy values are ignored.

• style& and extstyle&
  The style& and extstyle& arguments (listed below) are optional. If not supplied, default values are used (see the table below). If values are supplied, they completely replace default values (i.e., the entered values are not in addition to the default values).

• CALL
  The "CALL callback" section is optional. If not supplied, the callback function of the parent dialog is used. An example callback function for treeview controls is provided further down this page. The #MESSAGE COMMAND compiler directive can be used to prevent sending %WS_NOTIFY messages to the callback function. By default, both %WS_NOTIFY and %WS_COMMAND messages are sent.

Usage Notes
Some of these comments refer to the TreeView-specific statement in the next section below.

Indexing is starts at 1 for all Control and listview statements.

TreeView-Specific PowerBASIC Statements
PowerBASIC provides several statements specific to the treeview control. These allow the application to manage the content and display of the control.

Here's a summary of the TreeView statements, categorized by the capability they provide.

Insert/Delete	Delete, Insert Item, Reset, Select, Unselect
Get Properties	Bold, Check, Child, Count, Expanded, Next, Parent, Previous, Root, Select, Text, User
Set Properties	Bold, Check, Expanded, ImageList, Text, User

And here's a description and syntax for each of the TreeView statements, along with some additional usage information.

TreeView Delete	Delete an item
	hDlg, id&, hItem
TreeView Get Bold	Get bold attribute of an item
	hDlg, id&, hItem TO datav&
TreeView Get Check	Get checkmark attribute of an item
	hDlg, id&, hItem TO datav&
TreeView Get Child	Get handle of first child. 0 if none.
	hDlg, id&, hItem TO datav&
TreeView Get Count	Get total number of items
	hDlg, id&, hItem TO datav&
TreeView Get Expanded	Get expanded attribute of an item
	hDlg, id&, hItem TO datav&
TreeView Get Next	Get handle of next sibling. 0 is none.
	hDlg, id&, hItem TO datav&
TreeView Get Parent	Get handle of parent. 0 if none.
	hDlg, id&, hItem TO datav&
TreeView Get Previous	Get handle of previous sibling
	hDlg, id&, hItem TO datav&
TreeView Get Root	Get handle of topmost data item (root)
	hDlg, id&, hItem TO datav&
TreeView Get Select	Get handle of currently selected item
	hDlg, id&, hItem TO datav&
TreeView Get Text	Get text of specified item
	hDlg, id&, hItem TO datav&
TreeView Get User	Get user value of specified item
	hDlg, id&, hItem TO datav&
TreeView Insert Item	Add new item
	hDlg, id&, hPrnt, hIAftr, image&, selimage&, txt$ TO hItem
TreeView Reset	Delete all items
	hDlg, id&
TreeView Select	Select specified item
	hDlg, id&, hItem
TreeView Set Bold	Set bold attribute of specified item
	hDlg, id&, hItem, flag& 0-false, non-zero=true
TreeView Set Check	Set checkmark attribute of specified item
	hDlg, id&, hItem, flag& 0-false, non-zero=true
TreeView Set Expanded	Set expanded attribute of specified item
	hDlg, id&, hItem, flag& 0-false, non-zero-true
TreeView Set ImageList	Attach imagelist to treeview control
	hDlg, id&, hLst
TreeView Set Text	Set text of specific item
	hDlg, id&, hItem, txt$
TreeView Set User	Set user value of specified item
	hDlg, id&, hItem, NumExpr
TreeView Unselect	Unselect all items
	hDlg, id&

And here is a short description of the arguments used in the TREEVIEW statements.

hDlg	Handle of the dialog that owns the Treeview.
id&	The control identifier assigned with CONTROL ADD TREEVIEW.
hItem	Handle of a Treeview item, used to uniquely identify the item
datav&	A long integer variable to which result data is assigned.
txtv$	A string variable to which result data is assigned.
hPrnt	Handle of the parent item to insert the new item under.
hIAftr	Handle of the item to insert the new item after.
image&	Image index of the new item
selimage&	Selected image index of the new item
txt$	Text to be displayed for the Treeview item
flag&	A long integer value to define specific attributes
hLst	Handle of the ImageList to be used for graphical items

See the Usage section above for information on how to use the values made available by these statements.

Messages, Notifications, Styles, and ExtSstyles
There are four types of named constants in the following table. All are pulled from the MSDN web site.

• Notifications - event notifications a control receives
• Messages - controls may send these
• Styles - affect the visual look of a control
• ExtStyles - additional values that affect the visual look

The first column contains control-specific named constants and the second column contains generic window named constants (treeview controls are windows).

Also, if the PowerBASIC Help file has an entry on the value, it is highlighted in yellow. If the value was noted in PowerBASIC Help as a default value, it is also shown in bold text.

In the values for notifications, descriptions starting with -n and -c refer to events received through the %wm_notify and %wm_command messages. By default, PowerBASIC controls can receive both of these messages.

And here is a short description of many of the named constants corresponding to notifications, styles, and extstyle - particularly those discussed in the PowerBASIC Help topics.

Callback Function
A control can have its own callback function, or use the parent dialog callback function.

A control callback function should return TRUE to indicate it has processed the message. This prevents unnecessarily calling the dialog callback function, which will process the message if no control callback function is available, or if the control callback function returns FALSE.

By default, both %WM_COMMAND and %WM_NOTIFY messages are received. However, if the #MESSAGE COMMAND compiler directive is invoked, the %WM_NOTIFY messages will not be available.

Here's a sample treeview control callback function.

   CallBack Function cbTreeView()
      Select Case CB.MSG
         Case %WM_COMMAND
            Select Case CB.CTLMSG
               Case %nm_click
               Case %nm_dblclk
               Case %nm_killfocus
               Case %nm_rclick
               Case %nm_rdblclk
               Case %nm_return
               Case %nm_setfocus
               Case %tvn_beginlabeledit
               Case %tvn_deleteitem
               Case %tvn_endlabeledit
               Case %tvn_itemchanged
               Case %tvn_itemchanging
               Case %tvn_itemexpanded
               Case %tvn_itemexpanding
               Case %tvn_keydown
               Case %tvn_selchanged
               Case %tvn_selchanging
               Case %tvn_singleexpand
         End Select
      End Select
   End Function

In each Case section, add the statements the application needs to respond to the event. Also, be sure to add "Function=1" as appropriate to indicate that the event was handled by the callback function.

Issues
The TreeView Insert Item statement does not recognize the command to show no images (value 0 for image&).

I'll update this page as more information becomes available.

CONTROL Statement Syntax
The following table lists the various Control statements (except the ADD statements). Most, but not all, can be used with the treeview control. A one-line description of the statement and then its syntax are presented.

CONTROL DISABLE	disable
	hDlg, id&
CONTROL ENABLE	enable	hDlg, id&
CONTROL GET CHECK	check state	hDlg, id& TO iResult1&
CONTROL GET CLIENT	top/left location	hDlg, id& TO wide&, high&
CONTROL GET LOC	top/left location	hDlg, id& TO x&, y&
CONTROL GET SIZE	width/height	hDlg, id& TO width&, height&
CONTROL GET TEXT	text	hDlg, id& TO txt$
CONTROL GET USER	get user data	hDlg, id&, index& TO retvar&
CONTROL HANDLE	window handle for control id	hDlg, id& TO hCtl&
CONTROL KILL	remove control	hDlg, id&
CONTROL POST	put message in queue (non-blocking)	hDlg, id&, Msg&, wParam&, lParam&
CONTROL REDRAW	schedule redraw of control	hDlg, id&
CONTROL SEND	send message to control, wait for processing	hDlg, id&, Msg&, wParam&, lParam& TO iResult2&
CONTROL SET CHECK	set check for 3state or checkbox	hDlg, id&, checkstate&
CONTROL SET CLIENT	change size to specific client area size	hDlg, id&, wide&, high&
CONTROL SET COLOR	set fg/bg color	hDlg, id&, fgcolor&, bgcolor&
CONTROL SET FOCUS	set focus	hDlg, id&
CONTROL SET FONT	select font for a control	hDlg, id&, fonthandle&
CONTROL SET LOC	relocate control within dialog	hDlg, id&, x&, y&
CONTROL SET OPTION	set check state of option control	hDlg, id&, minid&, maxid&
CONTROL SET SIZE	change control size	hDlg, id&, width&, height&
CONTROL SET TEXT	change control text	hDlg, id&, text$
CONTROL SET USER	set user data	hDlg, id&, index&, uservalue&
CONTROL SHOW STATE	toggle visibility	hDlg, id&, showstate& TO iResult3&

If you have any suggestions or corrections, please let me know.