#region

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

#endregion

namespace CSFrameworkV5.UserCustom
{
    public class ScreenCapture
    {
        /// <summary>
        ///     指定窗口截图
        /// </summary>
        /// <param name="handle">窗口句柄. (在windows应用程序中, 从Handle属性获得)</param>
        /// <returns></returns>
        public static Image CaptureWindow(IntPtr handle)
        {
            var hdcSrc = User32.GetWindowDC(handle);
            var windowRect = new User32.RECT();
            User32.GetWindowRect(handle, ref windowRect);
            var width = windowRect.right - windowRect.left;
            var height = windowRect.bottom - windowRect.top;
            var hdcDest = GDI32.CreateCompatibleDC(hdcSrc);
            var hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc, width, height);
            var 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;
        }

        /// <summary>
        ///     辅助类 定义 Gdi32 API 函数
        /// </summary>
        private class GDI32
        {
            public const int SRCCOPY = 0x00CC0020;

            [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);

            [DllImport("gdi32.dll")]
            public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC,
                int nWidth,
                int nHeight);

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

            [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);
        }

        /// <summary>
        ///     辅助类 定义User32 API函数
        /// </summary>
        private class User32
        {
            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowDC(IntPtr hWnd);

            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowRect(IntPtr hWnd,
                ref RECT rect);

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

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