สอบถามเรื่องการเขียนโปรแกรมสื่อการเรียนการสอนหน่อยครับ โดยใช้ Visual Basic

private void SetChart()
        {
           
            if (txtMean.Text == "" && txtSD.Text == "") { return; }

            PictureBox1.Top = 5; PictureBox1.Left = 10;
            PictureBox1.Width = ((aLS_F_711DataGridView.Rows.Count + 5) * SizeColumn > Panel1.Width) ? (aLS_F_711DataGridView.Rows.Count + 5) * SizeColumn : Panel1.Width;
            PictureBox1.Height = Panel1.Height - 30;

            // Set value 
            double _SD = double.Parse(txtSD.Text);
            double vMain = double.Parse(txtMean.Text);
            double vUp3SD = vMain + (3 * _SD);
            double vUp2SD = vMain + (2 * _SD);
            double vDwn2SD = vMain - (2 * _SD);
            double vDwn3SD = vMain - (3 * _SD);
            
            int lntMain = Convert.ToInt32(PictureBox1.Height / 2);
            int lntUp3SD = lntMain - Convert.ToInt32(lntMain / 1.2);
            int lntUp2SD = lntMain - Convert.ToInt32(lntMain / 2);
            int lntDwn2SD = lntMain + Convert.ToInt32(lntMain / 2);
            int lntDwn3SD = lntMain + Convert.ToInt32(lntMain / 1.2);
            double ddd = (lntDwn3SD - lntUp3SD) / (vUp3SD - vDwn3SD);
            b = new Bitmap((aLS_F_711DataGridView.RowCount + 5) * SizeColumn > Panel1.Width ? (aLS_F_711DataGridView.RowCount + 5) * SizeColumn : Panel1.Width, Panel1.Size.Height);
            using (Graphics g = Graphics.FromImage(b))
            {
                g.Clear(PictureBox1.BackColor);
                g.FillRectangle(Brushes.Black, new Rectangle(0, 0, b.Width, b.Height));
                // PanelPicResize();
                System.Drawing.Pen p;

                // Set line Main
                p = new System.Drawing.Pen(Brushes.Pink, 3);
                g.DrawLine(p, SizeColumn, lntMain, b.Width, lntMain);
                g.DrawString(string.Format("{0:0.0000}", vMain), this.Font, Brushes.Azure, 5, lntMain - 5);

                p = new System.Drawing.Pen(Brushes.Yellow, 2);
                //set line down 2SD
                g.DrawLine(p, SizeColumn, lntDwn2SD, b.Width, lntDwn2SD);
                g.DrawString(string.Format("{0:0.0000}", vDwn2SD), this.Font, Brushes.Azure, 5, lntDwn2SD - 5);
                //set line Up 2SD
                g.DrawLine(p, SizeColumn, lntUp2SD, b.Width, lntUp2SD);
                g.DrawString(string.Format("{0:0.0000}", vUp2SD), this.Font, Brushes.Azure, 5, lntUp2SD - 5);

                p = new System.Drawing.Pen(Brushes.Red, 2);
                //set line down 3SD
                g.DrawLine(p, SizeColumn, lntDwn3SD, b.Width, lntDwn3SD);
                g.DrawString(string.Format("{0:0.0000}", vDwn3SD), this.Font, Brushes.Azure, 5, lntDwn3SD - 5);
                //set line Up 3SD
                g.DrawLine(p, SizeColumn, lntUp3SD, b.Width, lntUp3SD);
                g.DrawString(string.Format("{0:0.0000}", vUp3SD), this.Font, Brushes.Azure, 5, lntUp3SD - 5);

                int x1 = 0;
                int y1 = 0;
                int x2 = 0;
                int y2 = 0;
                x1 = SizeColumn;
                x2 = SizeColumn + Convert.ToInt32(SizeColumn / 2.2);
                y1 = lntMain;
                y2 = 0;
                p = new System.Drawing.Pen(Brushes.Blue, 5);
                p.EndCap = System.Drawing.Drawing2D.LineCap.RoundAnchor;
                p.StartCap = System.Drawing.Drawing2D.LineCap.RoundAnchor;
                double c = (lntDwn3SD - lntUp3SD) / (vUp3SD - vDwn3SD);
                if (aLS_F_711DataGridView.RowCount < 1) { return; }
                for (int i = 0; i <= aLS_F_711DataGridView.RowCount - 1; i++)
                {
                    if (i > 0)
                    {
                        x2 = x2 + SizeColumn;
                    }
                    if (aLS_F_711DataGridView[1, i].Value != null)
                    {
                        try
                        {
                            y2 = (int)((ddd * (vUp3SD - (double)aLS_F_711DataGridView[3, i].Value)) + lntUp3SD);
                        }
                        catch { }
                        //y2 = ((int)(ddd * ((vUp3SD - (double)aLS_F_711DataGridView[1, i].Value)) + lntUp3SD));
                      
                        g.DrawLine(p, x1, y1, x2, y2);
                        g.DrawString(string.Format("{0:0.0000}", (double)aLS_F_711DataGridView[3, i].Value) + Environment.NewLine + string.Format("{0:dd/MM/yyyy}", (DateTime)aLS_F_711DataGridView[2, i].Value), this.Font, Brushes.White, x2 + 5, y2);
                        x1 = x2;
                        y1 = y2;
                    }

                }
            }
            PictureBox1.BackgroundImage = b;
            PictureBox1.Size = b.Size;
            // MessageBox.Show("dgdfhgfh");
        }