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


namespace WindowsFormsApplication1
{
    public partial class FormOverlay : Form
    {



        public struct RECT
        {
            public int left, top, right, bottom;
        }

        RECT rect;

        Graphics g;





        Pen myPen = new Pen(Color.Red);

        public const string WINDOW_NAME = "Battlefield 3™";
        IntPtr handle = FindWindow(null, WINDOW_NAME);

        [DllImport("user32.dll")]
        static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

        [DllImport("user32.dll", SetLastError = true)]
        static extern int GetWindowLong(IntPtr hWnd, int nIndex);

        [DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool GetWindowRect(IntPtr hwnd, out RECT lpRect);

        public FormOverlay()
        {
            InitializeComponent();
        }

        private void FormOverlay_Load(object sender, EventArgs e)
        {

            this.BackColor = Color.Wheat;
            this.TransparencyKey = Color.Wheat;
            this.TopMost = true;
            this.FormBorderStyle = FormBorderStyle.None;

            int initialStyle = GetWindowLong(this.Handle, -20);
            SetWindowLong(this.Handle, -20, initialStyle | 0x80000 | 0x20);

            GetWindowRect(handle, out rect);
            this.Size = new Size(rect.right - rect.left, rect.bottom - rect.top);
            this.Top = rect.top;
            this.Left = rect.left;
        }


        private void FormOverlay_Paint(object sender, PaintEventArgs e)
        {
            g = e.Graphics;
            g.DrawRectangle(myPen, 100, 100, 200, 200);
            g.DrawString("All your base are belong to us", this.Font, Brushes.Red, new PointF(500f, 500f));

        }



        private void update_Tick(object sender, EventArgs e)
        {
            FormOverlay_Load(null, null);
        }
    }
}