Spy.cs

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

namespace MLSpyware
{
    internal class Spy
    {
        public Image CaptureScreen()
        {
            return CaptureWindow(User32.GetDesktopWindow());
        }
        public Image CaptureWindow(IntPtr handle)
        {
            IntPtr hdcSrc = User32.GetWindowDC(handle);
            User32.RECT windowRect = new User32.RECT();
            User32.GetWindowRect(handle, ref windowRect);
            int width = windowRect.right - windowRect.left;
            int height = windowRect.bottom - windowRect.top;
            IntPtr hdcDest = GDI32.CreateCompatibleDC(hdcSrc);
            IntPtr hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc, width, height);
            IntPtr hOld = GDI32.SelectObject(hdcDest, hBitmap);
            GDI32.BitBlt(hdcDest, 0, 0, width, height, hdcSrc, 0, 0, GDI32.SRCCOPY);
            GDI32.SelectObject(hdcDest, hOld);
            GDI32.DeleteDC(hdcDest);
            User32.ReleaseDC(handle, hdcSrc);

            Image img = Image.FromHbitmap(hBitmap);
            GDI32.DeleteObject(hBitmap);

            return img;
        }

        public void CaptureWindowToFile(IntPtr handle, string filename, ImageFormat format)
        {
            Image img = CaptureWindow(handle);
            img.Save(filename, format);
        }
        public void CaptureScreenToFile(string filename, ImageFormat format)
        {
            CaptureScreen().Save(filename, format);
        }

        private class GDI32
        {

            public const int SRCCOPY = 0x00CC0020; // BitBlt dwRop parameter

            [DllImport("gdi32.dll")]
            public static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest,
                int nWidth, int nHeight, IntPtr hObjectSource,
                int nXSrc, int nYSrc, int dwRop);
            //The BitBlt function performs a bit-block transfer of the color data corresponding to
            //a rectangle of pixels from the specified source device context into a destination device context.

            [DllImport("gdi32.dll")]
            public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC, int nWidth,int nHeight);
            //The CreateCompatibleBitmap function creates a bitmap compatible with the device that is associated with the specified device context.

            [DllImport("gdi32.dll")]
            public static extern IntPtr CreateCompatibleDC(IntPtr hDC);
            //The CreateCompatibleDC function creates a memory device context (DC) compatible with the specified device.

            [DllImport("gdi32.dll")]
            public static extern bool DeleteDC(IntPtr hDC);

            [DllImport("gdi32.dll")]
            public static extern bool DeleteObject(IntPtr hObject);

            [DllImport("gdi32.dll")]
            public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
            //The SelectObject function selects an object into the specified device context (DC). The new object replaces the previous object of the same type.
        }

        private class User32
        {
            [StructLayout(LayoutKind.Sequential)]
            public struct RECT
            {
                public int left;
                public int top;
                public int right;
                public int bottom;
            }

            [DllImport("user32.dll")]
            public static extern IntPtr GetDesktopWindow();
            //Retrieves a handle to the desktop window. The desktop window covers the entire screen.
            //The desktop window is the area on top of which other windows are painted.

            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowDC(IntPtr hWnd);
            //The GetWindowDC function retrieves the device context (DC)
            //for the entire window, including title bar, menus, and scroll bars.
            //A window device context permits painting anywhere in a window,
            //because the origin of the device context is the upper-left corner of the window instead of the client area.

            [DllImport("user32.dll")]
            public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDC);

            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowRect(IntPtr hWnd, ref RECT rect);
            //Retrieves the dimensions of the bounding rectangle of the specified window.
            //The dimensions are given in screen coordinates that are relative to the upper-left corner of the screen.
        }
    }

}