1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:
51:
52:
53:
54:
55:
56:
57:
58:

using System;
using System.Drawing;
using System.Drawing.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form2 : Form
    {
        private Bitmap schaltplan;
        private Graphics schaltplanGraphics;

        public Form2()
        {
            InitializeComponent();
            schaltplan = new Bitmap(1000,1000);
            schaltplanGraphics = Graphics.FromImage(schaltplan);
        }

        private void Form2_Paint(object sender, PaintEventArgs e)
        {
            schaltplanGraphics.Clear(Color.White);
            schaltplanGraphics.FillEllipse(new SolidBrush(Color.Green), 100, 100, 50, 100);
            schaltplanGraphics.FillRectangle(new SolidBrush(Color.Red), 150, 150, 100, 100);
            DrawText(textBox1.Text, new Font("Comic Sans Ms", 24), schaltplan, new Point(90, 145));
            e.Graphics.DrawImage(schaltplan, 0, 0);
        }

        static void DrawText(string text, Font font, Bitmap targetImage, Point position)
        {
            if (String.IsNullOrEmpty(text.Trim())) return;
            
            Size size = Graphics.FromImage(targetImage).MeasureString(text, font).ToSize();

            Bitmap bmp = new Bitmap(size.Width, size.Height);
            Graphics gfx = Graphics.FromImage(bmp);

            gfx.DrawString(text, font, new SolidBrush(Color.White), 0, 0);

            for (int y = 0; y < bmp.Height; y++)
            {
                for (int x = 0; x < bmp.Width; x++)
                {
                    Color c1 = bmp.GetPixel(x, y);
                    if (c1 == Color.FromArgb(0, 0, 0, 0)) continue;
                    Color c2 = targetImage.GetPixel(position.X + x, position.Y + y);

                    targetImage.SetPixel(position.X + x, position.Y + y, Color.FromArgb(255 - c2.R, 255 - c2.G, 255 - c2.B));
                }
            }
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            Invalidate();
        }
    }
}