Draw text lines by OpenTk in the OpenGL Window with C# and Windows Forms

C#, Windows Forms, Open TK

   public void statistics()
        {

            if (statisticsOnOff)
            {
                //Generate the plane containing the statistics
                GL.Begin(PrimitiveType.Quads);
                GL.TexCoord2(0f, 1f); GL.Vertex2(0f, 0f);
                GL.TexCoord2(1f, 1f); GL.Vertex2(glControl1.Width, 0f);
                GL.TexCoord2(1f, 0f); GL.Vertex2(glControl1.Width, glControl1.Height);
                GL.TexCoord2(0f, 0f); GL.Vertex2(0f, glControl1.Height);
                GL.End();

                if (drawStatistics)
                {
                    // Upload the Bitmap to OpenGL.
                    // Do this only when text changes.
                    BitmapData data = text_bmp.LockBits(new Rectangle(0, 0, text_bmp.Width, text_bmp.Height), ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
                    GL.TexImage2D(TextureTarget.Texture2D, 0, OpenTK.Graphics.OpenGL.PixelInternalFormat.Rgba, data.Width, data.Height, 0,
                    OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0);
                    text_bmp.UnlockBits(data);

                    //Text rendering in th OpenGL Controller
                    // Render text using System.Drawing.
                    // Do this only when text changes.

                    if (displayStatistics)
                    {
                        fpsToGeometry = "fps " + idleCounter.ToString();
                    }
                    else
                    {
                        fpsToGeometry = "";
                        statisticsOnOff = false;
                        glControl1_Resized = true;
                    }

                    using (Graphics gfx = Graphics.FromImage(text_bmp))
                    {
                        gfx.Clear(Color.Transparent);
                        gfx.DrawString(fpsToGeometry, drawFont, drawBrush, drawPoint); // Draw as many strings as you need
                    }

                    drawStatistics = false;
                }

                if (setUpViewPort)
                {
                    //Enabling the use of the textures in the OpenGL controller 
                    GL.Enable(EnableCap.Texture2D);
                    GL.Enable(EnableCap.Blend);
                    GL.BlendFunc(BlendingFactorSrc.One, BlendingFactorDest.OneMinusSrcAlpha);
                }

                if (!statisticsTextureCreated)
                {
                    //Text rendering in the OpenGL Controller
                    // Create Bitmap and OpenGL texture
                    text_bmp = new Bitmap(glControl1.Width, glControl1.Height); // match glControl1 size
                    text_texture = GL.GenTexture();
                    GL.BindTexture(TextureTarget.Texture2D, text_texture);
                    GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)All.Linear);
                    GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)All.Linear);
                    GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, text_bmp.Width, text_bmp.Height, 0,
                    OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, IntPtr.Zero); // just allocate me

                    statisticsTextureCreated = true;
                };

                if (glControl1_Resized)
                {
                    // Ensure Bitmap and texture match window size
                    text_bmp.Dispose();
                    text_bmp = new Bitmap(glControl1.Width, glControl1.Height);
                    GL.BindTexture(TextureTarget.Texture2D, text_texture);
                    GL.TexImage2D(TextureTarget.Texture2D, 0, 0, 0, text_bmp.Width, text_bmp.Height,
                    OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, IntPtr.Zero);

                    glControl1_Resized = false;
                }   
            }
            
           
        }