Enkelt histogram

List<int> data=null;
public Form1()
{
    InitializeComponent();
    data = new List<int>(100);
}
private void buttonDaw_Click(object sender, EventArgs e)
{
    String[] lines = textBox1.Text.Split('\r');
    data=new List<int>(lines.Length);
    try
    {
        foreach (string line in lines)
            if (line.Trim().Length > 0)
                data.Add(Convert.ToInt32(line.Trim()));
    }
    catch (Exception ex)
    {
        labelMsg.Text = "feil format";
    }
    // force a redraw
    panel1.Invalidate();
}

private void panel1_Resize(object sender, EventArgs e)
{
    // we force a redraw when panel is sized
    panel1.Invalidate();
}

private void panel1_Paint(object sender, PaintEventArgs e)
{
    // we draw on the panel and copy it to a bitmap
    // then we save it
    Rectangle Rec = new Rectangle(0, 0, panel1.Width, panel1.Height);
    
    drawData(e.Graphics, Rec, data);
    // copy the drawing to a bitmap
    Bitmap canvas = new Bitmap(Rec.Width, Rec.Height);
    Graphics bg = Graphics.FromImage(canvas);
    // copy from screen, in screen coordinates
    Rectangle screenR = panel1.RectangleToScreen(Rec);
    bg.CopyFromScreen(new Point(screenR.X, screenR.Y), 
        new Point(0, 0), 
        new Size(screenR.Width,screenR.Height));
    // save the drawing
   canvas.Save(Path.Combine(Application.StartupPath, "bildetest.gif"));
}

private void panel1_Paint(object sender, PaintEventArgs e)
{
    // we draw on a bitmap and copies this bitmap to the panel
    // then we save it
    Rectangle Rec = new Rectangle(0, 0, panel1.Width, panel1.Height);
    Bitmap canvas = new Bitmap(Rec.Width, Rec.Height);
    Graphics cg = Graphics.FromImage(canvas);
    // set white background
    cg.FillRectangle(Brushes.White,Rec);
    
    drawData(cg, Rec,data);
  
    // copy the drawing to the panel
    e.Graphics.DrawImage(canvas,new Point(0,0));
    
    // save the drawing
    canvas.Save(Path.Combine(Application.StartupPath, "bildetest.gif"));
}

// draw data within Rec on g
private void drawData(Graphics g,Rectangle Rec,List<int>data)
{
    Font tFont = new Font("Arial", 16);
    SolidBrush blueBrush = new SolidBrush(Color.Blue);
    // any data to display
    if (data.Count == 0)
    {
        g.DrawString(" Ingen data ",
            tFont,
            blueBrush,
            new Point(10, 4));
    }
    else
    {
        // find max value
        float max = 0.0F;
        foreach (int number in data)
            max = Math.Max((float)number, max);
        
        // Width of each column, with some margins
        int w = 
            (Rec.Width - 10 * data.Count - 20) / data.Count;
         // flip round top and leave some room at top for text
        int txtheight = 20;
        g.ResetTransform();
        g.TranslateTransform(0.0F, Rec.Height);
        g.ScaleTransform(1.0F,
            -1.0F * ((Rec.Height - txtheight) / (max + 1)));
        for (int ix = 0; ix < data.Count; ix++)
        {
            g.FillRectangle(Brushes.Red,
                new Rectangle(10 + ix * (w + 10), 0, w, data[ix]));
        }
        
        // text it 
        g.ResetTransform();
        g.DrawString("Resultater", tFont, blueBrush, new Point(10, 4));
    }
    g.Flush();
}