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Posted 9 Dec 2003


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Tree Editor

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4.93/5 (40 votes)
14 Dec 200315 min read
A fully-editable Tree Editor

Image 1


The Tree control is one of the most useful windows controls. Using a single control, it's possible to display any structured information. However, modifying a complex tree programmatically is not straightforward.

This Tree Editor attempts to help programmers to develop Tree Control based applications. Apart from this, it can be used as a stand-alone application to create, modify, load and save any data for which the tree structure applies. Sometimes, people use graphic tools for such purpose. These tools are rather inappropriate. They require complex manipulations to define a node and draw lines between nodes. This Tree Editor provides the user with simple commands (add child, add sibling) to edit a tree quickly. The possibility of importing/exporting trees (using a file or the clipboard) to other programs such as Notepad, as a sheet in Microsoft Excel ® or a table in Microsoft WORD permits alternatively to use these software to enter data to the tree, and to turn then to Tree Editor to modify it, and/or to integrate it to an application based on the Tree Control.


Aside from the MSDN samples and some VISUAL C++ books, I used (and modified to my needs) code from several articles published in "The Code Project". I am mostly thankful to the code authors. These articles are:

More information on subjects developed in this article can be found in:

How to use TREE EDITOR

Cursor Functions      
  Scan the tree (Up/Down Arrow)    
  Scroll (Ctrl +Up/Down Arrow)    
  Scan the tree while expanding/collapsing nodes (Right/Left Arrow)    
Edit Nodes F2    
Move/Copy Branches      
  Using Drag and Drop    
    Allow scrolling while dragging For big trees
  Using Keyboard    
    Copy selected item (Ctrl+C)  
    Cut selected item (Ctrl+X)  
    Paste as a son of selected item (Ctrl+V) or as a new root (Ctrl+Shift+V) Multiple Ctrl+V (or Ctrl+Shift+V) can be done for a single Ctrl+C or Ctrl+X
    Paste above selected item (Ctrl+A) Multiple Ctrl+V (or Ctrl+Shift+V) can be done for a single Ctrl+C or Ctrl+X
Add items      
  Add Child (Insert)    
  Add Sibling (= brother or sister) (Space bar or Return)    
  Delete Selected item (Del)    
  Delete Entire Tree (Ctrl+Del)    
Multi Formats supported      
  Comma Separated Values   Recommended to import/export to other programs
    Example See reference for more details about CSV Format
    Separation character may be:  
      Comma (default when dragging a CSV file from Explorer)
      Tab (Used to copy/paste from the Clipboard - See Ctrl+Ins, Shift+Ins)
      Any printable character. (Ctrl+D for instance: Load tree directory uses the Left Slash ('/') character as a delimiter character. Paths such as: d:/dir/subdir1/subdir2 are "almost" CSV records. With a slight modification inside the program, they become "totally" so)
  Indent format (Input only) To input from Mind Manager ®. To export to Mind Manager, use the clipboard
    1. 1  
    1.1 2  
    1.1.1 3  
    1.2 4  
    1.2.1 5  
    1.3 6  
    1.3.1 7  
    1.3.2 8  
  Tre Format Main Format of Tree Editor See details below
Allow Export/Import to/from      
  Microsoft Excel ® Sheet Use Clipboard (Ctrl+Ins/ Shift+Ins recommended) or CSV format  
  Microsoft WORD ®, Workpad, Notepad or any other software that recognized CSV format Use Clipboard (Ctrl+Ins/ Shift+Ins recommended) or CSV format. Inside Word, use Table > Convert Text to table/Table to Text  
  Allow Copy/Paste from Clipboard    
    Copy Entire Tree to Clipboard (Ctrl+Ins)  
    Paste Entire Tree from Clipboard (Shift+Ins)  
  Open File    
    Using Open Menu or Open recent files  
    Can drag files from Explorer  
    Can add the file name as an Command-line argument  
    Support defining of File associations for tre, csv, idt  
    Build a directory tree (Ctrl+D)  
      Displays the tree only
      Useful to test the program on big trees
  Save file (Ctrl+S)    
    Save as  
  Sort Entire Tree    
    Alphabetic (Ctrl+T)  
    Numeric (Ctrl+Shift+T)  
  Calculate the level of a node (Ctrl+L)    
  Popup Menu    
    Expand all items  
    Collapse all items  
    All functions seen so far are also accessible through Popup Menu  

Note about Edit Mode

When a node is being edited:

  • ESC Exits Edit Mode with no change
  • END Validates the changes and exits Edit Mode
  • INS Validates the changes, add a new sibling, and stays in Edit Mode. Thus, it's possible to press a first time INS and then to insert several children to the same parent, pressing INS after each child has been entered, and this without having to exit edit mode.
  • Dropping an item to a node in the dragged item SubTree is not allowed. However, we do allow this if the user uses the keyboard functions instead.

Note about Drag and Drop

When drag and drop is used to move/copy and paste items (not to be confused with dragging a file from Explorer to open it):

  • If the F3 key function is pressed (no matter where the mouse pointer is), then the cursor turns to an arrow with the letter "R", (A cursor indicating COPY if Ctrl is pressed ("+"), or MOVE else. If the mouse is released then, the item will be copied or moved accordingly as a new root, no matter where the mouse pointer was at dropping time.
  • If the mouse pointer is on the right of an item, the cursor turns to a Right Arrow (A cursor indicating COPY if Ctrl is pressed, or MOVE else. If the mouse is released then, the item will be copied or moved accordingly as a son of the dropped item.
  • If the mouse pointer is on an item or at its left, the cursor turns to an UP Arrow (A cursor indicating COPY if Ctrl is pressed, or MOVE else. If the mouse is released then, the item will be copied or moved accordingly as a sibling above the dropped item.

Programming notes


The application was written in MFC, using a single document architecture (SDI), and the Document / View concept. However, we preferred the classic C file functions (fopen(), fclose(), fread(), fwrite(), fgets(), fputs(), fprintf()) to the serialization mechanism.

Main classes

  • CTreeEditorApp

  • The InitInstance() member was modified to allow dragging files from Explorer, as well as to parse the command line.
  • CAboutDlg

  • No changes from what the application wizard has generated.
  • CTreeEditorDoc

  • Handles the process of opening or saving a file or a directory.

    In response to the menu commands (Open, Save, Save as...), it calls the common dialogs for opening or saving a file.

    • The open and the save common dialogs have been customized with a dialog template and a hook procedure, to allow adding special controls, related to the CSV format. I used the traditional Win API. I guess I could write these functions in a more elegant manner, using the MFC classes.
    • To let the user select a path rather than a directory, (in response to Ctrl+D), I used, SHBrowseForFolder() and SHGetPathFromIDList().
    • To summarize, the proper customized common dialog is called in response to a menu command. When it returns the user selection, it calls: UpdateAllViews(NULL, lHint). The "lHint" parameter tells the CTreeEditorView class what operation to perform (New? Open/Save? Which file? In which format?)
  • CTreeEditorView

  • The view class is based on CView, with an embedded CEditTreeCtrl member. (Using CTreeView has other advantages but makes it harder _ if possible at all? _ to subclass the CTreeCtrl class).
    • OnCreate() and OnInitialUpdate() initialize the tree control
    • OnUpdate() transforms the request from the document class, to instructions to the CEditTreeCtrl class.
  • CTreeType

  • Handles the "tre" format (see below).
    • We must call the member function AllocateTree(count) before using a CTreeType structure. "count" is the maximum number of nodes that can contain the CtreeType structure. As we need also one node for the "imaginary root" (See explanations about the "tre" format below), count+1 nodes of type NODE_TYPE are allocated.
    • DeallocateTree() can be called to deallocate the CTreeType structure, when it's not needed anymore.
  • CMainFrame

  • The initial handling of the copy/paste functions (if called from the edit menu) and the processing of files dropped from Explorer must be done in the CMainFrame class. These handlers merely give the hand to the suitable class.
  • CEditTreeCtrl

  • It makes the bulk of the work. This class is derived from CTreeCtrl.
    The details of these functions are not given here in order not to make this article too long, but it should be understandable from the source code comments.

    Note about Exceptions:

    We prefer to use the try/catch mechanism over using flags and goto to ensure the clearance work (delete pointers, close functions, and so forth) was done on exit from functions whether or not the function ended successfully. As a result, the message: "First-chance exception in TreeEditor.exe (MSVCRTD.DLL): 0xE06D7363: Microsoft C++ Exception." may shown up in the debugger. It is NOT an error if the exception was thrown by the program.

    The "tre" format

  • This is the format that we defined for this application.
  • The definition of this format can be found in class CTreeType (see TreeType.h)
  • It contains the number of items in the whole tree, followed by a structure of NODE_TYPE format (also defined in TreeType.h) for each node.
  • The nodes are defined in DFS (Depth First Search) order.
  • For each node, the NODE_TYPE defines:
  • WORD wNbItems; The number of children
  • WORD wBufSize; The size of buf
  • char *buf; The text of the node
  • HTREEITEM hti; A reference to HTREEITEM in the tree control
  • UINT uState; The state of the node (Expanded/Collapsed)

Below is an example of a tree along with its representation in the "tre" format (excluding hti, wBufSize and uState).

Image 2

Index Number of Children Text
0 2 NULL
1 2 "1"
2 0 "2"
3 0 "3"
4 2 "4"
5 2 "5"
6 0 "6"
7 0 "7"
8 0 "8"


"1" and "4" are both at the root level. Formally, a root cannot have siblings. But we can see this forest (set of trees) as a tree, if we consider all the "roots" as sons of an imaginary root. That is exactly what we do in the "tre" format. In our case, the imaginary root has 2 children ("1" and "4"). If the root of the Tree Control had only one root, then our imaginary root would had had only one children.

As we said previously, the text of the buffer is in the field *buf, its size is given by wBufSize.
This has two advantages over allocating a fixed size (say 256 bytes) to each node:

  • Saving disk space
  • Allowing to extend this format for more complex application, in which *buf will be a pointer to a structure, containing other information than the text displayed in the node.

  • The drawback is the necessity of dealing with pointers all the way.

The two most important functions are:

  • BOOL LoadTreeDataR(CTreeType &tt, HTREEITEM hti, OUTSIDE_PARAM op)
  • BOOL SaveTreeData(CTreeType &tt, HTREEITEM hti,
        OUTSIDE_PARAM op)</li>

    As their names suggest, LoadTreeDataR (actually a wrapper to LoadTreeData to add some pre-processing and post-processing) loads a tree from a CTreeType structure to a tree control, while SaveTreeData saves a tree from the Tree Control to a CTreeType structure.

The "CSV" format

The description of this format can be found in the reference given at the beginning of this article. (Not all the characteristics of the CSV format are implemented, for example we don't handle leading and trailing blanks and we don't consider separator characters enclosed by brackets). In addition to the comma separator, we allow using of the TAB character (0x09), and of any printable characters as separator characters.

Following is the tree given in the previous example, in CSV format, using comma as the separator character.

  • 1,,
  • ,2,
  • ,3,
  • 4,,
  • ,5,
  • ,,6
  • ,,7
  • ,8,
  • To Import a file from Microsoft Excel ® in CSV format
      Using the clipboard: Press Ctrl+Ins in TreeEditor, then Ctrl+V in Excel
    • Using the Save menu: Save file in TreeEditor with extension CSV, using comma as the delimiter. Select Open File in Excel. Option "delimited with comma"
  • To Export a file from Microsoft Excel ® in CSV format
    • Using the clipboard: Select the columns containing the tree in Excel, then press Ctrl+C. In TreeEditor, press Shift+Ins.

      The file is exported in CSV format using TAB as the delimiter. To make it work, the cells in Excel must represent a valid tree. A valid tree is one in which the level can decrease, remain the same or increase by 1.

      Using the save menu: Select "Save as" in Excel, giving the CSV extension. Answer "Yes" to any warning. Open the file in TreeEditor with the CSV extension.
  • To Import/Export a file from Notepad in CSV format
      The simplest way is to use the clipboard
  • To Import/Export a file from Microsoft Word ® in CSV format
  • Use the clipboard or build a WORD table, select it and then use Convert Table to/from text using comma as the delimiter character.

    The IDT format

    This format is used by Mind Manager (More about Mind Manager can be found below and in the link given in reference)
    In this format, the tree are prefixed by their indentation level, followed by the TAB character.

    Following is the tree given in the previous example, in IDT format.

    • 1. 1
    • 1.1 2
    • 1.2 3
    • 2. 4
    • 2.1 5
    • 2.1.1 6
    • 2.1.2 7
    • 2.2 8

    Note: Record which do not contain an indentation level are ignored.

    To import a file from Mind Manager

    • In MindManager:
      • Select: Format>Text Output
      • Select Text Outline Tab
      • Clear check box "Display notes"
      • Clear check box "Use bullets"
      • Display until level: 40
      • Number until level: 40
      • Indent until level: 40
      • Press OK
    • Then:
      • Select File>Export>File
      • Select Text Outline
      • Select a path
      • Press OK
    • Change the extension from txt to idt


    Trees are used in a variety of applications. This Tree Editor can be used for example in the following cases:

    • To load/save/edit Hierarchies, classifications, decision trees (by the way a genealogical tree is not a tree in the sense we use it)
    • To organize ideas. It's amazing how summarizing a book, an article or a memorandum can make things much clearer. A text contains many connection words and connection sentences, that mask the main ideas. For instead: words, words, words So, to make our purpose clearer, words, words, words, and as we said previously (What on earth did they say previously, I was sleeping when I read it!). Using a tree, we can see at a glance what the main ideas are.


      Moreover, trees can be used as creative brain-storming tools to find new ideas. A possible feature, which can be added to this Tree Editor is to make it work in "Brainstorm Mode". (Maybe, I will do in in a future release, meanwhile, you can do this manually. By the way, I intend to add also printing features. The examples in "The Code Project" are a good base, but there is some work to do to integrate them to my program. For the time being, you can export the tree to one of the software indicated, and print from there)

      It is based on a classic but great idea on how to find new ideas?

      In "Brainstorm mode", the software asks part or all the basic questions (The option menu let us defining our precise needs), along with the basic relational operators for the current branch.
      The nine basic questions are:

      • When? (Position in time)
      • Where? (Position in space)
      • How much / How many? (Quantification)
      • Which? (To select one out of many)
      • What? (The object)
      • Who? (The subject)
      • How? (The means)
      • Why? (=> The reasons)
      • What for? (The consequences =>)
      The basic relation operators are:
      • AND
      • OR
      • NOT
      • (XOR can be added eventually)

      The idea is to ask these questions recursively.

      Example: I plan a meeting. The questions asked by the software suggest me to ask:

      WHAT is the main object of this meeting?
      AND WHAT ELSE...
      AND WHAT ELSE...

      WHEN will be the meeting?

      Let's ask the basic questions RECURSIVELY on the ANSWER to that question:
      WHY to choose that date?
      And WHY NOT to choose it? (pros/cons),
      and WHAT OTHER (= OR) date is possible? (Choose alternatives)
      WHO will be the guests?

      Let's detail:
      WHY this guest?
      and WHY NOT this one?, etc, etc.

      I have used this method for years and it helps me a lot. Using this method, you can make the switch from "no idea at all!" to "too many ideas!".

      Mind Maps

      In general, Trees (along with images) are very useful to represent ideas. The classic book in this domain was written by Tony Buzan (See reference). Professional tools were develop, following Tony Buzan theory. The best one I know is Mind Manager ® of Mindjet (See reference)

    Computer Tree-oriented applications

    The tree is a very useful data type in computing. For organizing files in directories, for sorting and searching (especially binary trees), for organizing Data Bases, and to design general-purpose data entry (as in Outlook, Explorer, and Visual Studio).


    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here


    About the Author

    Yossi Patt
    Israel Israel
    No Biography provided

    Comments and Discussions

    QuestionComma Bug, No utf-8 Pin
    Sunny Saini1-May-19 7:21
    MemberSunny Saini1-May-19 7:21 
    QuestionWin10 New files do not persist on machine after close of app. Pin
    lenny haacker7-Jun-18 5:51
    Memberlenny haacker7-Jun-18 5:51 
    Generalhande Unicode Pin
    mapharo18-Aug-10 7:13
    Membermapharo18-Aug-10 7:13 
    GeneralRe: hande Unicode Pin
    shuren8831-May-12 16:06
    Membershuren8831-May-12 16:06 
    GeneralProblem with the copy instruction Pin
    mapharo23-Aug-08 12:20
    Membermapharo23-Aug-08 12:20 
    GeneralAuto jump bug fix Pin
    JetDraft20-Jul-07 2:27
    MemberJetDraft20-Jul-07 2:27 
    GeneralBug report Pin
    Arris7430-Dec-06 10:56
    MemberArris7430-Dec-06 10:56 
    GeneralThank you for good job! Pin
    egor710-Apr-05 11:06
    Memberegor710-Apr-05 11:06 
    Generalbug report Pin
    regale19-Jan-05 15:48
    Memberregale19-Jan-05 15:48 
    GeneralVery nice, and a request Pin
    TheGlynn15-Sep-04 4:05
    MemberTheGlynn15-Sep-04 4:05 
    GeneralPrinting Tree Pin
    anonymous20018-Sep-04 3:42
    Memberanonymous20018-Sep-04 3:42 
    GeneralMulti-Column in Tree Editor Pin
    abogani6-Jul-04 6:16
    Memberabogani6-Jul-04 6:16 
    GeneralRe: Multi-Column in Tree Editor Pin
    df49430-Aug-06 21:22
    Memberdf49430-Aug-06 21:22 
    GeneralNice work ... a little bug Pin
    Member 112044410-Jun-04 5:34
    MemberMember 112044410-Jun-04 5:34 
    GeneralRe: It's not a bug. The Tab character was missing Pin
    Michigan185413-Jun-04 3:08
    MemberMichigan185413-Jun-04 3:08 
    GeneralRe: It's not a bug. The Tab character was missing Pin
    Member 112044423-Jun-04 3:10
    MemberMember 112044423-Jun-04 3:10 
    GeneralRe: It's not a bug. The Tab character was missing Pin
    Michigan185423-Jun-04 20:31
    MemberMichigan185423-Jun-04 20:31 
    GeneralRe: It's not a bug. The Tab character was missing Pin
    luo315-Jul-05 17:24
    Memberluo315-Jul-05 17:24 
    GeneralWonderful Job Pin
    OvermindDL114-Dec-03 19:43
    MemberOvermindDL114-Dec-03 19:43 
    GeneralRe: Wonderful Job Pin
    Michigan185415-Dec-03 20:34
    MemberMichigan185415-Dec-03 20:34 
    GeneralRe: Wonderful Job Pin
    OvermindDL115-Dec-03 22:41
    MemberOvermindDL115-Dec-03 22:41 
    GeneralRe: Wonderful Job Pin
    Michigan185416-Dec-03 1:30
    MemberMichigan185416-Dec-03 1:30 
    GeneralRe: Wonderful Job Pin
    OvermindDL19-Mar-04 15:14
    MemberOvermindDL19-Mar-04 15:14 
    GeneralRe: Wonderful Job Pin
    hewat9-Mar-04 23:37
    Memberhewat9-Mar-04 23:37 
    GeneralRe: Wonderful Job Pin
    OvermindDL122-May-04 20:52
    MemberOvermindDL122-May-04 20:52 

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