Load a form without showing it

Question

Short version: I want to trigger the Form_Load() event without making the form visible. This doesn\'t work because Show() ignores the current value of the Visible property:<

Answer 1

Perhaps it should be noted here that you can cause the form's window to be created without showing the form. I think there could be legitimate situations for wanting to do this.

Anyway, good design or not, you can do that like this:

MyForm f = new MyForm();
IntPtr dummy = f.Handle; // forces the form Control to be created

I don't think this will cause Form_Load() to be called, but you will be able to call f.Invoke() at this point (which is what I was trying to do when I stumbled upon this SO question).

Answer 2

It sounds to me like you need to sit down and re-think your approach here. I cannot imagine a single reason your public methods need to be in a form if you are not going to show it. Just make a new class.

Answer 3

I totally agree with Rich B, you need to look at where you are placing your application logic rather than trying to cludge the WinForms mechanisms. All of those operations and data that your Tasks form is exposing should really be in a separate class say some kind of Application Controller or something held by your main form and then used by your tasks form to read and display data when needed but doesn't need a form to be instantiated to exist.

It probably seems a pain to rework it, but you'll be improving the structure of the app and making it more maintainable etc.

Answer 4

Sometimes this would be useful without it being bad design. Sometimes it could be the start of a migration from native to managed.

If you were migrating a c++ app to .NET for example, you may simply make yourwhole app a child window of the .NET form or panel, and gradually migrate over to the .NET by getting rid of your c++ app menu, status bar, toolbar and mapping teh .NEt ones to your app using platform invoke etc...

Your C++ app may take a while to load, but the .NET form doesn't..in which you may like to hide the .NEt form until your c++ app has initialised itself.

I'd set opacity=0 and visible=false to false after calling show, then when your c++ app loads, then reverse.

Answer 5

None of the answers solved the original question, so, add the below, call .Show() to load the form without showing it, then call .ShowForm() to allow it to be visible if you want to after:

private volatile bool _formVisible;
protected override void SetVisibleCore(bool value)
{
    base.SetVisibleCore(_formVisible);
}
public void ShowForm()
{
    _formVisible = true;
    if (InvokeRequired)
    {
        Invoke((Action) Show);
    }
    else
    {
        Show();
    }
}

Answer 6

If you make the method public, then you could access it directly.... however, there could be some unexpected side effects when you call it. But making it public and calling it directly will not draw the screen or open the form.