C#获取进程的主窗口句柄

原文http://blog.csdn.net/debugconsole/article/details/8333921

 

通过调用Win32 API实现。
public class User32API
{
    private static Hashtable processWnd = null;

    public delegate bool WNDENUMPROC(IntPtr hwnd, uint lParam);

    static User32API()
    {
        if (processWnd == null)
       {
            processWnd = new Hashtable();
        }
    }

    [DllImport("user32.dll", EntryPoint = "EnumWindows", SetLastError = true)]
    public static extern bool EnumWindows(WNDENUMPROC lpEnumFunc, uint lParam);

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

    [DllImport("user32.dll", EntryPoint = "GetWindowThreadProcessId")]
    public static extern uint GetWindowThreadProcessId(IntPtr hWnd, ref uint lpdwProcessId);

    [DllImport("user32.dll", EntryPoint = "IsWindow")]
    public static extern bool IsWindow(IntPtr hWnd);

    [DllImport("kernel32.dll", EntryPoint = "SetLastError")]
    public static extern void SetLastError(uint dwErrCode);

    public static IntPtr GetCurrentWindowHandle()
    {
        IntPtr ptrWnd = IntPtr.Zero;
        uint uiPid = (uint)Process.GetCurrentProcess().Id;  // 当前进程 ID
        object objWnd = processWnd[uiPid];

        if (objWnd != null)
        {
            ptrWnd = (IntPtr)objWnd;
            if (ptrWnd != IntPtr.Zero && IsWindow(ptrWnd))  // 从缓存中获取句柄
            {
                return ptrWnd;
            }
            else
            {
                ptrWnd = IntPtr.Zero;
            }
        }

        bool bResult = EnumWindows(new WNDENUMPROC(EnumWindowsProc), uiPid);
        // 枚举窗口返回 false 并且没有错误号时表明获取成功
        if (!bResult && Marshal.GetLastWin32Error() == 0)
        {
            objWnd = processWnd[uiPid];
            if (objWnd != null)
            {
                ptrWnd = (IntPtr)objWnd;
            }
        }

        return ptrWnd;
    }

    private static bool EnumWindowsProc(IntPtr hwnd, uint lParam)
    {
        uint uiPid = 0;

        if (GetParent(hwnd) == IntPtr.Zero)
        {
            GetWindowThreadProcessId(hwnd, ref uiPid);
            if (uiPid == lParam)    // 找到进程对应的主窗口句柄
            {
                processWnd[uiPid] = hwnd;   // 把句柄缓存起来
                SetLastError(0);    // 设置无错误
                return false;   // 返回 false 以终止枚举窗口
            }
        }

        return true;
    }
}
 
调用User32API.GetCurrentWindowHandle()即可返回当前进程的主窗口句柄，如果获取失败则返回IntPtr.Zero。
--EOF--
 
2008年10月7日补充：微软实现的获取进程主窗口句柄代码
Code
public class MyProcess
{
    private bool haveMainWindow = false;
    private IntPtr mainWindowHandle = IntPtr.Zero;
    private int processId = 0;

    private delegate bool EnumThreadWindowsCallback(IntPtr hWnd, IntPtr lParam);

    public IntPtr GetMainWindowHandle(int processId)
    {
        if (!this.haveMainWindow)
        {
            this.mainWindowHandle = IntPtr.Zero;
            this.processId = processId;
            EnumThreadWindowsCallback callback = new EnumThreadWindowsCallback(this.EnumWindowsCallback);
            EnumWindows(callback, IntPtr.Zero);
            GC.KeepAlive(callback);

            this.haveMainWindow = true;
        }
        return this.mainWindowHandle;
    }

    private bool EnumWindowsCallback(IntPtr handle, IntPtr extraParameter)
    {
        int num;
        GetWindowThreadProcessId(new HandleRef(this, handle), out num);
        if ((num == this.processId) && this.IsMainWindow(handle))
        {
            this.mainWindowHandle = handle;
            return false;
        }
        return true;
    }

    private bool IsMainWindow(IntPtr handle)
    {
        return (!(GetWindow(new HandleRef(this, handle), 4) != IntPtr.Zero) && IsWindowVisible(new HandleRef(this, handle)));
    }

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern bool EnumWindows(EnumThreadWindowsCallback callback, IntPtr extraData);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern int GetWindowThreadProcessId(HandleRef handle, out int processId);

    [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
    public static extern IntPtr GetWindow(HandleRef hWnd, int uCmd);

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    public static extern bool IsWindowVisible(HandleRef hWnd);
}