Barchart in GraphicsContainer (rotate)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace grafika_oszlopdiagram
{
    public partial class Form1 : Form
    {
        Random rand;
        Graphics g;
        int[] ertekek;
        GraphicsContainer container;
        LinearGradientBrush linearBrush;
        Rectangle area;
        int height;
        int width;
        int distance;
        int bar_width;
        int bar_height;

        public Form1()
        {
            InitializeComponent();
            rand = new Random();
            g = CreateGraphics();
            ertekek = new int[5];
            g.SmoothingMode = SmoothingMode.AntiAlias;
            for (int i = 0; i < ertekek.Length; i++)
            {
                ertekek[i] = rand.Next(2, 10);
            }
            container = g.BeginContainer();
        }

        private void trackBar1_Scroll(object sender, EventArgs e)
        {
            Invalidate();
            Update();

            // Trackbar maximum = 300;
            height = trackBar1.Value;
            width = trackBar1.Value;
            distance = 10;
            bar_height = ((area.Height / ertekek.Length - 1) - distance) < 50 ?
                ((area.Height / ertekek.Length - 1) - distance) : 50;
            area = new Rectangle(20, 20, width, height);

            // Area
            g.DrawRectangle(new Pen(Color.Chocolate, 4), area);


            for (int i = 0; i < ertekek.Length; i++)
            {
                float sum = ertekek.Sum();
                bar_width = (int)((ertekek[i] / sum) * area.Width) * ertekek.Length / 2;

                if (bar_height == 0)
                {
                    bar_height = 1;
                }
                if (bar_width == 0)
                {
                    bar_width = 1;
                }
                Rectangle rect = new Rectangle(area.X + 10, area.Y + (int)distance, bar_width, bar_height);

                linearBrush = new LinearGradientBrush(rect, Color.Tan, Color.Peru, LinearGradientMode.ForwardDiagonal);

                distance += bar_height + 8;
                g.FillRectangle(linearBrush, rect);
                g.DrawRectangle(Pens.Brown, rect);
            }

            g.EndContainer(container);
        }

        private void trackBar2_Scroll(object sender, EventArgs e)
        {
            Invalidate();
            Update();
            g.RotateTransform(trackBar2.Value);
            g.Save();
            trackBar1_Scroll(this, e);
        }
    }
}