c# 窗體常用的dll

1.查找窗口

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

lpClassName：要找的窗口類，一般null

lpWindowName：要找的窗口標題

2.發送消息到一個或多個窗口

[DllImport("User32.dll", EntryPoint = "SendMessage", SetLastError = true, CharSet = CharSet.Auto)]
        private static extern int SendMessage(IntPtr hwnd, uint wMsg, int wParam, int lParam);

hwnd：窗口句柄（類似FindWindow返回值）

wMsg：區別於其他消息的常量值,16進制數

wParam：通常是一個與消息有關的常量值，也可能是窗口或控件的句柄  0

lParam：一個指向內存中數據的指針  0

3.查找子窗體

[DllImport("User32.dll", EntryPoint = "FindWindowEx", SetLastError = true)]
        private static extern IntPtr FindWindowEx(IntPtr hwndParent, uint hwndChildAfter, string lpszClass, string lpszWindow);

hwndParent：查找子窗體的父窗體句柄，若爲null則以桌面爲父窗體

hwndChildAfter：子窗體句柄

lpszClass：只想一個指定了類名的空結束字符串，或標識一個類名字符串成員的指針

lpszWindow：指向一個指定了窗體名（窗體標題）的空結束字符串

4.獲取進程接口ID

[DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern int GetWindowThreadProcessId(IntPtr hwnd, out int ID);

hwnd：窗口句柄，由FindWindow獲取

ID:存放進程ID的變量

5.減少內存佔用

[DllImport("KERNEL32.DLL", EntryPoint = "SetProcessWorkingSetSize", SetLastError = true, CallingConvention = CallingConvention.StdCall)]
        internal static extern bool SetProcessWorkingSetSize(IntPtr pProcess, int dwMinimumWorkingSetSize, int dwMaximumWorkingSetSize);
        [DllImport("KERNEL32.DLL", EntryPoint = "GetCurrentProcess", SetLastError = true, CallingConvention = CallingConvention.StdCall)]
        internal static extern IntPtr GetCurrentProcess();

調用：IntPtr pHandle = GetCurrentProcess();

           SetProcessWorkingSetSize(pHandle,-1,-1);