Question

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            {
                if (keyData == Keys.Escape) this.Close();
                return base.ProcessCmdKey(ref msg, keyData);
            }
        }

I discovered this snippet to close windows form by esc. I really want to implement this to every windows form. I try to create a new abstract class which inherit from Form and another windows form will inherit from this one . But it doesn’t work this way .

abstract class AbsForm: Form {
        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            {
                if (keyData == Keys.Escape) this.Close();
                return base.ProcessCmdKey(ref msg, keyData);
            }
        }
    }
    public partial class HoaDonBanSach : AbsForm
    {
        public HoaDonBanSach()
        {
            InitializeComponent();
        }

Thanks for reading this 🙂

Answer 1

I would suggest not doing this in the Form but instead implement an IMessageFilter and add it using Application.AddMessageFilter. Something like the following:

public class CloseWindowBehavior : IMessageFilter {

    const int WM_KEYDOWN = 0x100;
    const int VK_ESCAPE = 0x1B;

    bool IMessageFilter.PreFilterMessage(ref Message m) {
        if (m.Msg == WM_KEYDOWN && (int)m.WParam == VK_ESCAPE) {
            if (Form.ActiveForm != null) {
                Form.ActiveForm.Close();
            }
            return true;
        }
        return false;
    }

}

Application.AddMessageFilter(new CloseWindowBehavior());