Populating a tree view from another thread

[Luis Alonso Ramos]

Hello, I've tried filling a tree view with a large database on a worker thread (so my main window keeps responding.) I get an InvalidOperationException saying that I'm doing it from the wrong thread. If I do it from the main thread, it is very slow, and can take up to 30 seconds. Any ideas? Thanks, -- LuisR ___________   Luis Alonso Ramos   Chihuahua, Mexico   www.luisalonsoramos.com

[Colin Angus Mackay]

DISCLAIMER: I've never tried this so I don't know if it will work. Would you be able to generate the tree structure first and then when your data loading thread is finished it fires an event to tell the main thread it is finished. The event handler then takes the nodes and attaches them to the tree control. This would mean that for 30 seconds you have an empty tree control - but at least the application is responsive.

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[Luis Alonso Ramos]

Mmm interesting idea... I'll give it a try! thanks! During thos 30 seconds, I could fill the tree with a "Populating tree control, please wait..." node. -- LuisR ___________   Luis Alonso Ramos   Chihuahua, Mexico   www.luisalonsoramos.com

[Baris Kurtlutepe]

If you want to modify a control from a thread other than the thread that created it, you should use the Invoke method of the Control (in that case the TreeView) to invoke the function that adds the node to the tree. A simple example for adding a node which takes a string parameter for the node could be: private void AddNode(string nodeText) { myTreeView.Nodes.Add(nodeText); } then you can declare a delegate to call this function: private delegate void AddNodeDelegate(string nodeText); and then from any thread, you can safely do this: string nodeText = "This is my safe node text"; AddNodeDelegate myAdd = new AddNodeDelegate(AddNode); myTreeView.Invoke(myAdd, new object[] { nodeText } );