Question

I have a custom control that inherits from TreeView. In this CustomTreeView, I handle the OnNodeMouseClick event to perform some process before changing the node.Checked state as the user would expect it:

public class CustomTreeView : TreeView {
    // Constructor...

    protected override void OnNodeMouseClick(TreeNodeMouseClickEventArgs e) {
       base.OnNodeMouseClick(e);

       // Do something...

       e.Node.Checked = !e.Node.Checked;
    }
}

My problem is when the developer subscribes to the AfterCheck event on a CustomTreeView, the value of e.Action is always TreeViewAction.Unknown (because the checked state of the node is changed in the code), whereas the developer is waiting for TreeViewAction.ByMouse:

public partial class Form1: Form {
    private void customTreeView1_AfterCheck(object sender, TreeViewEventArgs e) {
        // e.Action == TreeViewAction.Unknown
        // [developer] The user clicked on the node, it should be 
        //             TreeViewAction.ByMouse!?
    }
}

What I would like to do is disable the AfterCheck event from firing and call it myself in my CustomTreeView class, that way I would be able to pass parameters with TreeViewAction equal to ByMouse. Something like that:

public class CustomTreeView : TreeView {
    // Constructor...

    protected override void OnNodeMouseClick(TreeNodeMouseClickEventArgs e) {
       base.OnNodeMouseClick(e);

       // Do something...

       // Prevent all AfterCheck events from firing, just for a moment
       // ??

       e.Node.Checked = !e.Node.Checked;

       // Allow AfterCheck events to fire
       // ??

       // Call myself the AfterCheck event
       base.OnAfterCheck(new TreeViewEventArgs(e.Node, TreeViewAction.ByMouse));
    }
}

Is this possible?

Answer 1

Sure, just override OnAfterCheck in CustomTreeView and it will work like you intend.

public class CustomTreeView : TreeView {

    protected override void OnNodeMouseClick(TreeNodeMouseClickEventArgs e) {
       base.OnNodeMouseClick(e);

       // your stuff

       // Call myself the AfterCheck event
       base.OnAfterCheck(new TreeViewEventArgs(e.Node, TreeViewAction.ByMouse));
    }

    protected override void OnAfterCheck(TreeViewEventArgs e)
    {
       // do nothing   
    }
}

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