几个常用的API在c#中的定义

最近一个项目中用到的一些API，在解决一些实际的问题上（特别是和外部程序打交道）的时候还是蛮有用的。具体的参数什么的网上都有！

    public class API
    {
        #region 窗口函数

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

        [DllImport("user32.dll", EntryPoint = "FindWindowEx", SetLastError = true)]
        public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

        [DllImport("user32.dll", EntryPoint = "SetForegroundWindow", SetLastError = true)]
        public static extern void SetForegroundWindow(IntPtr hwnd);

        [DllImport("user32.dll", EntryPoint = "GetWindow", SetLastError = true)]
        public static extern IntPtr GetWindow(IntPtr hWnd, uint wCmd);

        [DllImport("user32.dll", EntryPoint = "GetClassName", CharSet = CharSet.Unicode, SetLastError = true)]
        internal static extern int GetClassName(IntPtr hWnd, StringBuilder buf, int nMaxCount);

        [DllImport("user32.dll", EntryPoint = "SetWindowPos", CharSet = CharSet.Unicode, SetLastError = true)]
        public static extern bool SetWindowPos(IntPtr hWnd, int hwndinsertAfter, int x, int y, int cx, int cy, int wFlags);

        //显示窗体（包括使得窗体最小化，最大化等等操作）
        [DllImport("user32.dll ")]
        public static extern bool ShowWindow(IntPtr hwnd, int cmdshow);

        /// <summary>
        /// 设置窗体标题
        /// </summary>
        /// <param name="hwnd">窗体句柄</param>
        /// <param name="lpStrjng">要设置的标题</param>
        /// <returns></returns>
        [DllImport("user32.dll ")]
        public static extern bool SetWindowText(IntPtr hwnd, string lpStrjng);

        /// <summary>
        /// 获得窗体的位置（相对于整个屏幕)
        /// </summary>
        /// <param name="hwnd">窗体句柄</param>
        /// <param name="rc">自定义的矩形结构，请调用该类中的RectangleEx</param>
        /// <returns></returns>
        [DllImport("user32.dll")]
        public static extern int GetWindowRect(IntPtr hwnd, ref RectangleEx rc);
        public struct RectangleEx
        {
            public int leftTopX;
            public int leftTopY;
            public int rightBottomX;
            public int rightBottomY;

            public int Width
            {
                get { return rightBottomX - leftTopX; }
            }

            public int Height
            {
                get { return rightBottomY - leftTopY; }
            }

        }

        /// <summary>
        /// 获得包含指定点的窗口的句柄
        /// </summary>
        /// <param name="p">一个被检测的点的POINT结构</param>
        /// <returns></returns>
        [DllImport("user32.dll ")]
        public static extern IntPtr WindowFromPoint(Point p);

        /// <summary>
        /// 获得窗口文字
        /// </summary>
        /// <param name="hWnd"></param>
        /// <param name="lpString">用来保存文字的stringBuilder</param>
        /// <param name="nMaxCount">stringBuilder的容量</param>
        /// <returns></returns>
        [DllImport("user32.dll")]
        public static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString,
            int nMaxCount);


        public delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);

        /// <summary>
        /// 枚举所有控件
        /// </summary>
        /// <param name="lpEnumFunc"></param>
        /// <param name="lParam"></param>
        /// <returns></returns>
        [DllImport("user32.dll")]
        public static extern int EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);


        #endregion

        #region 消息函数

        //发送消息的类型（第二个参数）
        public const int WM_KEYDOWN = 0X100;
        public const int WM_KEYUP = 0X101;
        public const int WM_CHAR = 0X102;
        /// <summary>
        /// 发送消息，等待返回
        /// </summary>
        /// <param name="hWnd">窗体句柄</param>
        /// <param name="wMsg">被发送的消息类型(如键盘按下消息，字符消息等等)</param>
        /// <param name="wParam">附加的消息指定信息</param>
        /// <param name="lParam">附加的消息指定信息</param>
        /// <returns></returns>
        [DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern IntPtr SendMessage(IntPtr hWnd, int wMsg, int wParam, int lParam);

        [DllImport("user32.dll", EntryPoint = "PostMessage", SetLastError = true)]
        public static extern IntPtr PostMessage(IntPtr hWnd, int wMsg, int wParam, int lParam);

        #endregion

        #region 鼠标函数

        [DllImport("user32.dll", EntryPoint = "SetCursorPos")]
        internal extern static int SetCursorPos(int x, int y);

        /// 使用范例：   API.mouse_event(0x2 | 0x4, x,y, 0, 0); 在（x,y）处单击一下
        public readonly int MOUSEEVENTF_LEFTDOWN = 0x2;
        public readonly int MOUSEEVENTF_LEFTUP = 0x4;
        [DllImport("user32.dll")]
        public static extern void mouse_event(int dwFlags, int dx, int dy, int dwData, int dwExtraInfo);


        #endregion

        #region 键盘函数


        public static int KEYEVENTF_EXTENDEDKEY = 0x0001;
        public static int KEYEVENTF_KEYUP = 0x0002;
        public static byte VK_LWIN = 0x5B;
        [DllImport("user32.dll", EntryPoint = "keybd_event")]
        public static extern void keybd_event(
            byte bVk,
            byte bScan,
            int dwFlags,
            int dwExtraInfo
        );


        #endregion

        #region 自绘函数

        /// <summary>
        /// 获得窗口指定点处的句柄
        /// </summary>
        /// <param name="hwnd">主窗体句柄</param>
        /// <param name="top">该点相对于主窗体上边框的距离</param>
        /// <param name="left">该点相对于主窗体左边框的距离</param>
        /// <returns></returns>
        public static IntPtr GetWinPartFromPoint(IntPtr hwnd, int top, int left)
        {
            RectangleEx r = new RectangleEx();
            GetWindowRect(hwnd, ref r);
            //转化为整个屏幕的坐标
            int topScreen = top + r.leftTopY;
            int leftScreen = left + r.leftTopX;
            return WindowFromPoint(new Point(topScreen, leftScreen));
        }

        /// <summary>
        /// 到某处单击一下返回
        /// </summary>
        /// <param name="ox">原来的鼠标地点x</param>
        /// <param name="oy"></param>
        /// <param name="x">目标地点x</param>
        /// <param name="y"></param>
        public static void ClickPosition(int ox,int oy,int x, int y)
        {
            SetCursorPos(x, y);
            mouse_event(0x2 | 0x4, x, y, 0, 0);
            SetCursorPos(ox, oy);
        }

        #endregion
    }