How to increase cell quantity using keyboard up and down arrows ?

Question

How to increase cell quantity using keyboard up and down arrows ?

I work on windows form desktop application using csharp

I face issue I can't increase quantity or decrease using press on key up or down
on datagridview control
when have quantity 1 value then when press up arrow then will be 2
when have quantity 2 then when press down arrow will be 1

private void GridTrxInvF_KeyPress(object sender, KeyPressEventArgs e)    
    {    
        int currentNumber = Utilities.ObjectConverter.ConvertToInteger(GridTrxInvF.Rows[GridTrxInvF.CurrentCell.RowIndex].Cells["Quantity"].Value);    
    
        if (e.KeyChar ==(char) Keys.Down)    
        {    
    
            GridTrxInvF.Rows[GridTrxInvF.CurrentCell.RowIndex].Cells["Quantity"].Value = (currentNumber - 1).ToString();    
        }    
        else if (e.KeyChar == (char)Keys.Up)    
        {    
            GridTrxInvF.Rows[GridTrxInvF.CurrentCell.RowIndex].Cells["Quantity"].Value = (currentNumber + 1).ToString();    
        }    
    
    }    

when press up arrow or down
it moving to quanityt previous row when press down keyboard button
or moving to quantity Next rows when press up keyboard button
so what i do to solve issue please ?

Answer 1

namespace WindowsFormsApp1
{
    using System;
    using System.Windows.Forms;


    public partial class Form1 : Form
    {
        //private DataGridViewEx GridTrxInvF;

        public Form1()
        {
            InitializeComponent();

            this.GridTrxInvF.UpDownKeyPress += GridTrxInvF_UpDownKeyPress;
        }

        private void GridTrxInvF_UpDownKeyPress(object sender, KeyEventArgs e)
        {
            if (GridTrxInvF.CurrentCell.OwningColumn.Name != "Quantity")
            {
                return;
            }

            int currentNumber = 0;
            var v = GridTrxInvF.Rows[GridTrxInvF.CurrentCell.RowIndex].Cells["Quantity"].Value;
            if (v != DBNull.Value && v != null)
            {
                int.TryParse(v.ToString(), out currentNumber);
            }

            if (e.KeyData == Keys.Down)
            {
                GridTrxInvF.Rows[GridTrxInvF.CurrentCell.RowIndex].Cells["Quantity"].Value = (currentNumber - 1).ToString();
                e.Handled = true;
            }
            else if (e.KeyData == Keys.Up)
            {
                GridTrxInvF.Rows[GridTrxInvF.CurrentCell.RowIndex].Cells["Quantity"].Value = (currentNumber + 1).ToString();
                e.Handled = true;
            }

        }
    }

    class DataGridViewEx : DataGridView
    {
        protected override bool ProcessDataGridViewKey(KeyEventArgs e)
        {
            switch (e.KeyCode)
            {
            case Keys.Down:
            case Keys.Up:
                UpDownKeyPress?.Invoke(this, e);
                if (e.Handled)
                {
                    return true;
                }
                break;

            }
            return base.ProcessDataGridViewKey(e);
        }

        public event KeyEventHandler UpDownKeyPress;
    }
}