Microsoft KB Archive/161735

= How To Save the Viewing Order of Nodes in a TreeView =

Article ID: 161735

Article Last Modified on 7/13/2004

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APPLIES TO


 * Microsoft Visual FoxPro 5.0 Standard Edition
 * Microsoft Visual FoxPro 6.0 Professional Edition

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This article was previously published under Q161735



SUMMARY
The sample BldTree.scx, located in the Vfp\Samples\Solution\Ole folder, is an example of how to use the TreeView Control. It allows you to add nodes to the TreeView and then save and restore the Nodes from a table. The algorithm that the sample uses saves all of the Nodes by index order. Because of this, it does not restore the Nodes in the same order if you added nodes using "Previous" for the Relationship. This article shows an algorithm that lets you save the Nodes in viewing order so that they can be restored in the same order.



MORE INFORMATION
This article uses the BldTree.scx as a starting point. It will have you add two new command buttons to the form: one to add Nodes to the TreeView Control and a second to save the Nodes in viewing order to a table.

The BldTree.scx can be found in the Vfp\Samples\Solution\Ole folder in Visual FoxPro 5.0. In Visual FoxPro 6.0, BldTree.scx can be found in home(2)+'solution\ole'.

For this article, set the above folder as the default by typing the following command in the Command window in Visual FoxPro 5.0:

SET DEFAULT TO SYS(2004)+'SAMPLES\SOLUTION\OLE'

In Visual FoxPro 6.0, type the following command in the Command window:

SET DEFAULT TO HOME(2)+'SOLUTION\OLE'

 Open the BldTree.scx in the Form Designer. Add two new command buttons to the form. (You may have to change the size of the form to do this.) Change the caption of the first new command button to "Add Previous" (without the quotes). Place the following code in the Click event:

o = THISFORM.oleTree IF !ISNULL(o.SelectedItem) o.Nodes.Add(o.SelectedItem.Key, 3, THISFORM.NewKey, "previous",0) ENDIF

 Change the caption of the second new command button to "Save by View Order" (without the quotes). Place the following code in the Click event:

LOCAL loNodes, lcParent, lcDBFName, lcOldAlias, lcOldSafety, liIndex LOCAL liTmp #DEFINE WARNING_LOC "Continuing will destroy all data in the " + ; "table and create a new table with three fields." + CHR(13) + ; "Do you want to continue?" #DEFINE WARN_LOC "Warning"

lcOldAlias = ALIAS lcOldSafety = SET("SAFETY") lcDBFName = GETFILE("dbf")

IF EMPTY(lcDBFName) && User chose Cancel RETURN ENDIF

IF FILE(lcDBFName) IF THISFORM.OpenDBF(lcDBFName, .T.) AND ; THISFORM.VerifyTableStructure AND ; MESSAGEBOX(WARNING_LOC,48+256+4,WARN_LOC) = 6 SET SAFETY OFF ZAP SET SAFETY &lcOldSafety ELSE RETURN ENDIF ELSE CREATE TABLE (lcDBFName) ; (Key c(4), Parent c(4), Text c(60)) ENDIF

loNodes = THISFORM.oleTree.Nodes FOR i = 1 to loNodes.Count IF ISNULL(loNodes.Item(i).Parent) liIndex = loNodes.Item(i).FirstSibling.Index liTmp = liIndex EXIT ENDIF NEXT

lcParent = "0_" &&Root INSERT INTO (lcDBFName) VALUES ; (loNodes.Item(liIndex).key, ;          lcParent, ;           loNodes.Item(liIndex).Text)

DO WHILE liIndex <> loNodes.Item(liTmp).LastSibling.Index INSERT INTO (lcDBFName) VALUES ; (loNodes.Item(liIndex).Next.key, ;            lcParent, ;             loNodes.Item(liIndex).Next.Text) liIndex = loNodes.Item(liIndex).Next.Index ENDDO

FOR i = 1 TO loNodes.Count IF loNodes.Item(i).Children > 0 liIndex = loNodes.Item(i).Child.Index liTmp = liIndex INSERT INTO (lcDBFName) VALUES ; (loNodes.Item(liIndex).key, ;               loNodes.Item(liIndex).Parent.Key, ;                loNodes.Item(liIndex).Text) DO WHILE liIndex <> loNodes.Item(liTmp).LastSibling.Index INSERT INTO (lcDBFName) VALUES ; (loNodes.Item(liIndex).Next.key, ;                  loNodes.Item(liIndex).Next.Parent.Key, ;                   loNodes.Item(liIndex).Next.Text) liIndex = loNodes.Item(liIndex).Next.Index ENDDO ENDIF NEXT

USE

 Save the form as Vfp\Samples\Solution\Ole\Treebld2.scx</li> Run the Form and create a tree by clicking New Root twice. Select the last node in the TreeView control, and then click Add Previous.</li> Click Save DBF to save a table named OldSave.dbf. Then click Save By View Order to save a table named NewSave.dbf.</li> Click Clear, and then click Load DBF to load OldSave.dbf.</li> Repeat step 10 using NewSave.dbf.</li></ol>

You will see that the OldSave.dbf loaded the Node added with the Add Previous button to the bottom of the TreeView Control. But the NewSave.dbf had the Node added with the Add Previous button in the correct position.

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Brian Combs, Microsoft Corporation

Keywords: kbhowto kbctrl kbcode KB161735

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