Method, Delegate and Event Subscription Help in Autodesk Inventor Add-In

Question

I'm creating an add-in for Autodesk Inventor. Basically, you define the buttons you want to add, and tell the app to add the button definitions. The problem I'm having is that when I define the 'OnExecute' method for the button definition, the button doesn't execute. I think the way I'm trying to organize the code is what's creating the problem.

I have a CustomButton class that has a delegate property that looks like this (the signature is void with an input of a NameValueMap Interface)

public class CustomButton
{
    // … properties and methods that don't matter here
    public ButtonDefinitionSink_OnExecuteEventHandler Execute { get; set; }
}

In the main Activate() method (what's called when Inventor starts) I create an instance of the following class to set all the button definitions and the methods that fire when they are clicked. That class looks like this:

public class CustomButtonDefinitions
{
    public CustomButtonDefinitions(ref Application app)
    {
        _inventorApp = app;
        InitializeButtonDefinitions();
    }

    public List<CustomButton> CustomButtons { get; set; } = new List<CustomButton>();

    private void InitializeButtonDefinitions()
    {
        AddTestButton();
    }
    private void AddTestButton()
    {
        var testButton = new CustomButton
        {
            DisplayName = "test",
            InternalName = "testCommand1",
            Ribbon = "Assembly",
            RibbonPanel = "Simplification",
            IconSource = "./Assets/test.jpg",
            Classification = CommandTypesEnum.kFileOperationsCmdType,
            ShowText = true,
            UseLargeIcon = true,
        };

        testButton.Execute = TestButton_Execute;
        CustomButtons.Add(testButton);
    }
    private void TestButton_Execute(NameValueMap Context)
    {
        // This is where the logic of the button would go.
        // For now, just something that gives me an indication it worked.
        System.Windows.Forms.MessageBox.Show("Hello");
        _inventorApp.ActiveDocument.Close();
    }
}

Where I think the source of the error comes from is the next code (this is in the Activate():

CustomButtonDefinitions customButtonDefinitions = new CustomButtonDefinitions(ref _InventorApp);
foreach (var button in customButtonDefinitions.CustomButtons)
{
            // this creates the button in Inventor
    var buttonDef = button.CreateButtonDefinition(ref controlDefs);
    // and this subscribes the button click event to my method  
    buttonDef.OnExecute += button.Execute;
}

There must be something un-subscribing my method from the button click event.

I'll be posting this in the Inventor forums as well, but wanted to check here too since I'm new to delegates and event handlers. I'm either not understanding something about delegates/events or it's something Inventor specific that I'll need some other help with.

Hopefully this is enough to give some context. Thanks in advance.

Answer 1

The problem was the fact that I wasn't creating the button definition in a high enough scope. I needed to create a variable above the scope of the Activate() method so the app could see it when needed.