private void btnAdd_Click(object sender, EventArgs e)
        {
            btnEdit.Visible = false;
            frmSPPAddItem frm = new frmSPPAddItem
            {
                StartPosition = FormStartPosition.CenterScreen
            };


            frm.ShowDialog();

            if (frmSPPAddItem.itemAdded)
            {
                //add data to datarow
                //add datarow to table

                DataRow dt_Row = dt_Source.NewRow();

                dt_Row[header_Size]       = frmSPPAddItem.item_Size;
                dt_Row[header_Unit]       = "MM";
                dt_Row[header_Type]       = frmSPPAddItem.item_Type;
                dt_Row[header_Code]       = frmSPPAddItem.item_Code;
                dt_Row[header_Target_Pcs] = frmSPPAddItem.item_Target_Pcs;
                dt_Row[header_Target_Bag] = frmSPPAddItem.item_Target_Bags;

                dt_Source.Rows.Add(dt_Row);

                //add data to target list
                ShowTargetList();
                //calculate material qty
                ShowMaterialList();
                frmSPPAddItem.itemAdded = false;
            }
        }
        private void dgvTargetItem_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
        {
            //get item info
            DataTable dt       = (DataTable)dgvTargetItem.DataSource;
            int       rowIndex = dgvTargetItem.CurrentRow.Index;

            //string code, string type, string size, string unit

            string code      = dt.Rows[rowIndex][header_Code].ToString();
            string type      = dt.Rows[rowIndex][header_Type].ToString();
            string size      = dt.Rows[rowIndex][header_Size].ToString();
            string unit      = dt.Rows[rowIndex][header_Unit].ToString();
            string targetPcs = dt_Source.Rows[rowIndex][header_Target_Pcs].ToString();

            if (rowIndex >= 0)
            {
                frmSPPAddItem frm = new frmSPPAddItem(code, type, size, unit, targetPcs)
                {
                    StartPosition = FormStartPosition.CenterScreen
                };



                frm.ShowDialog();

                if (frmSPPAddItem.itemEdited)
                {
                    btnEdit.Visible = false;
                    //add data to datarow
                    //add datarow to table
                    dt_Source.Rows.RemoveAt(rowIndex);
                    DataRow dt_Row = dt_Source.NewRow();

                    dt_Row[header_Size]       = frmSPPAddItem.item_Size;
                    dt_Row[header_Unit]       = "MM";
                    dt_Row[header_Type]       = frmSPPAddItem.item_Type;
                    dt_Row[header_Code]       = frmSPPAddItem.item_Code;
                    dt_Row[header_Target_Pcs] = frmSPPAddItem.item_Target_Pcs;
                    dt_Row[header_Target_Bag] = frmSPPAddItem.item_Target_Bags;

                    dt_Source.Rows.Add(dt_Row);

                    //add data to target list
                    ShowTargetList();
                    //calculate material qty
                    ShowMaterialList();
                    frmSPPAddItem.itemEdited = false;
                }
                else if (frmSPPAddItem.itemRemoved)
                {
                    btnEdit.Visible = false;
                    dt_Source.Rows.RemoveAt(rowIndex);
                    dgvTargetItem.DataSource = dt_Source;



                    //add data to target list
                    ShowTargetList();
                    //calculate material qty
                    ShowMaterialList();
                    frmSPPAddItem.itemRemoved = false;
                }
            }
            else
            {
                MessageBox.Show("Please select a row!");
            }
        }