Expanding a path to a node

How to expand a path to a node without expaning unnecessary nodes.

Contributor: CHRISTIAN FEICHTNER



{

        How to expand a path to a TOutlineNode referenced by Index



This is a routine from my forthcoming application Information Manager V1.0. I thought that it might be interesting to others, so I'm contributing it to the public.



The purpose I wrote this routine was, that I had an index from a TOutlineNode (which was the result of search) and wanted to expand a path to the node without expanding unnecessary trees.



The following routine accepts an index as a parameter and expands the path to the TOutlineNode with this index.



The routine assumes a TOutline object named Outline.

}



var

  Outline: TOutline;



procedure TSearchDlg.ExpandPathToFoundItem(const FoundItemIndex: Longint);

{------------------------------------------------------------------------------

 Expands a path to a given item (item is specified by the index number). Only the parents needed to get to the specified item will be expanded.

 -----------------------------------------------------------------------------}

var

  ItemIndex: Longint;

  Found: Boolean;

  LastCh: Longint;

  Path: String;

  ItemText: String;

  SepPos: Integer;

  OldSep: String;

begin

  {Save the old ItemSpearator}

  OldSep:=Outline.ItemSeparator;

  {Set the new ItemSeparator}

  Outline.ItemSeparator:='\';

  {Get the full path to the TOutlineNode and add a '\'. This is done, because it


   simplifies the whole algorithm}

  Path:=Outline.Items[FoundItemIndex].FullPath+'\';

  {As long as the end of the path has not been reached}

  while Length(Path) > 0 do begin

    {Determine the position of the first '\' in the path}

    SepPos:=Pos('\',Path);

    {Isolate the TOutlineNode item}

    ItemText:=Copy(Path,1,SepPos-1);

    {Determine the index of the TOutlineNode}

    ItemIndex:=Outline.GetTextItem(ItemText);

    {Expand it}

    Outline.Items[ItemIndex].Expand;

    {Cut the expanded TOutlineNode from the string}

    Path:=Copy(Path,SepPos+1,Length(Path)-SepPos+1);

  end;

  {Restore original ItemSeparator}

  Outline.ItemSeparator:=OldSep;

end;





DETAILS



Let's assume the full path to the desired item is:



        "My Computer\Hardware\SoundCard\Base Adress"



The first step returns the above path. Then the substring "My Computer" is isolated. Then the index of the TOutlineNode "My Computer" is determined by using the "GetTextItem" method. The "Expand" method expands this tree. Afterwards "My Computer" is cut from the path resulting in the new path "Hardware\SoundCard\Base Adress".



Then the index of "Hardware" is determined, expanded and again, cut away. This procedure repeats until there is no path left to expand. Then the path to the given TOutlineNode will be expanded.



If you have any questions or comments, you can reach me by e-mail at

Christian.Feichtner@jk.uni-linz.ac.at or you might want to have a look

at my homepage: http://www.cam.org/~psarena/cfeichtner

 

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