How can i customize the button if it set a AcceptButton of the form?

Question

I have implemented the custom button control with some additional options. And added my custom button into the form. When i set the Form.Acception is the added custom button, then I want to do some customization in the Button. I want to customize the button appearance in the Custom button class implementation, when it marked as AcceptButton of the Form.

Anyone suggest how can i know the button is marked as AcceptButton of the form in Button class?

Answer 1

WRONG:

protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (((Form)this.TopLevelControl).AcceptButton == this) .... }

UPD:

public class MyButton : Button
    {
        public override void NotifyDefault(bool value)
        {
            if (this.IsDefault != value)
            {
                this.IsDefault = value;
            }

            if (IsDefault)
            {
                this.BackColor = Color.Red;
            }
            else
            {
                this.BackColor = Color.Green;
            }
        }
    }

Answer 2

You could traverse the parents to find the form via the parent property of its base class Control:

public partial class MyButton : Button
{
    public MyButton()
    {
        InitializeComponent();
    }

    private Form CheckParentForm(Control current)
    {
        // if the current is a form, return it.
        if (current is Form)
            return (Form)current;

        // if the parent of the current not is null, 
        if (current.Parent != null)
            // check his parent.
            return CheckParentForm(current.Parent);

        // there is no parent found and we didn't find a Form.
        return null;
    }

    protected override void OnCreateControl()
    {
        base.OnCreateControl();

        // find the parent form.
        var form = CheckParentForm(this);

        // if a form was found, 
        if (form != null)
            // check if this is set as accept button
            if (this == form.AcceptButton)
                // for example, change the background color (i used for testing)
                this.BackColor = Color.RosyBrown;
    }
}

Because of the recursion, it also works when the Button is placed on a Panel.

Note: The accept button must be set before OnCreateControl is called (for example in the form's constructor)

---

After some googling I found a standard implementation:

You can also use: this.FindForm();

public partial class MyButton : Button
{
    public MyButton()
    {
        InitializeComponent();

    }

    protected override void OnCreateControl()
    {
        base.OnCreateControl();

        var form = FindForm();

        if (form != null)
            if (this == form.AcceptButton)
                this.BackColor = Color.RosyBrown;

    }
}

---

Event shorter in C# 6.0:

public partial class MyButton : Button
{
    public MyButton()
    {
        InitializeComponent();

    }

    protected override void OnCreateControl()
    {
        base.OnCreateControl();

        if (this == FindForm()?.AcceptButton)
            this.BackColor = Color.RosyBrown;
    }
}

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