FreeTreeviewNode() ???????????????

BlitzMax Forums/MaxGUI Module/FreeTreeviewNode() ???????????????

Pipes

(Posted 2010) [#1]

Hello All,

What's wrong with FreeTreeviewNode or maybe what's wrong with me? Every which way I try to use it I get... "Unhandled Exception:Attempt to access field or method of Null object" Even when I just used the Node:TGadget in the line before it. I just don't get it. Here is an example:

Import MaxGui.Drivers

Strict 

Local window:TGadget=CreateWindow("My Window",50,50,240,240,Null,WINDOW_TITLEBAR|WINDOW_CLIENTCOORDS)
Local treeview:TGadget=CreateTreeView(5,5,ClientWidth(window)-10,ClientHeight(window)-10,window)

SetGadgetLayout treeview, EDGE_ALIGNED, EDGE_ALIGNED, EDGE_ALIGNED, EDGE_ALIGNED

Local root:TGadget=TreeViewRoot(treeview)

Local help:TGadget=AddTreeViewNode("Help",root)
AddTreeViewNode "Topic 1",help
AddTreeViewNode "Topic 2",help
AddTreeViewNode "Topic 3",help

Local projects:TGadget=AddTreeViewNode("Projects",root)
AddTreeViewNode("Sub Project",AddTreeViewNode("Project 1",projects))
AddTreeViewNode("Project 2",projects)
AddTreeViewNode("Project 3",projects)

While WaitEvent()
    Print CurrentEvent.ToString()
    Select EventID()
	Case EVENT_GADGETSELECT
		Select EventSource()
			Case treeview
				Local TRV_NODE:TGadget = SelectedTreeViewNode(treeview)
				Local sTemp$ = GadgetText(TRV_NODE); Print sTemp
					
				If sTemp = "Topic 3" Then FreeTreeViewNode(TRV_NODE)
 '*****Unhandled Exception:Attempt to access field or method of Null object*****
					
				Default
					
			End Select	
		Case EVENT_WINDOWCLOSE
			End
	End Select
Wend

Thanks for the help in advance.

jsp	(Posted 2010) [#2]

Hi,
there is nothing wrong with the FreeTreeViewNode, at least not directly.
The problem you got is a NULL node, which is not taken care about and thus the GadgetText sends the exception.

Import MaxGui.Drivers

Strict 

Local window:TGadget=CreateWindow("My Window",50,50,240,240,Null,WINDOW_TITLEBAR|WINDOW_CLIENTCOORDS)
Local treeview:TGadget=CreateTreeView(5,5,ClientWidth(window)-10,ClientHeight(window)-10,window)

SetGadgetLayout treeview, EDGE_ALIGNED, EDGE_ALIGNED, EDGE_ALIGNED, EDGE_ALIGNED

Local root:TGadget=TreeViewRoot(treeview)

Local help:TGadget=AddTreeViewNode("Help",root)
AddTreeViewNode "Topic 1",help
AddTreeViewNode "Topic 2",help
AddTreeViewNode "Topic 3",help

Local projects:TGadget=AddTreeViewNode("Projects",root)
AddTreeViewNode("Sub Project",AddTreeViewNode("Project 1",projects))
AddTreeViewNode("Project 2",projects)
AddTreeViewNode("Project 3",projects)

While WaitEvent()
    Print CurrentEvent.ToString()
    Select EventID()
	Case EVENT_GADGETSELECT
		Select EventSource()
			Case treeview
				Local TRV_NODE:TGadget = SelectedTreeViewNode(treeview)
				If TRV_NODE
					Local sTemp$ = GadgetText(TRV_NODE); Print sTemp
					
					If sTemp = "Topic 3" Then FreeGadget(TRV_NODE)
 '*****Unhandled Exception:Attempt to access field or method of Null object*****
				End If	
				Default
					
			End Select	
		Case EVENT_WINDOWCLOSE
			End
	End Select
Wend

Pipes

(Posted 2010) [#3]

Hi jsp,
I didn't really think something was wrong with FreeTreeviewNode. I suspected that it was something right in front of me that I couldn't see. It turns out that was a correct suspicion. Thanks for the help it worked.