c# - 从控件子类化 ParentForm WndProc

Question

我正在将自定义的 MenuStrip 控件集成到另一个 .NET 应用程序中。除了焦点问题外，MenuStrip 工作正常。如果承载 MenuStrip 的窗体未获得焦点，则用户需要单击两次 - 一次激活窗体，另一次选择菜单项。主机表单是我无法修改的独立 .NET 应用程序的一部分。我只能修改我的控件的源代码。

我找到了一个 solution at the WinForm level它覆盖了 Form WndProc 方法，除了我没有 WinForm 的源代码访问权限，也不能重新编译主机应用程序和表单。

有没有办法子类化控件的 ParentForm，以便在未获得焦点时自动激活 ParentForm？

Answer 1

我能够使用 ContainerControl.ParentForm 获取对宿主窗体的引用，但是在生产环境中 ParentForm 返回 null，我仍然需要找到解决方案。我将 NewWndProc 处理程序放在 try/catch 中，以防它抛出任何异常，尽管我不确定它会抛出什么(如果有的话)。我可能不得不只使用 Win32 函数而不使用 Form.Focused 和 Form.Activate() .NET 方法。无论如何，这是代码:

public class FocusFormWrapper
{
    #region DllImport
    public const int GWL_WNDPROC = (-4);
    public const UInt32 WM_CLOSE = 0x0010;
    public const UInt32 WM_PARENTNOTIFY = 0x0210; 

    public delegate IntPtr WndProcDelegate(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool IsWindow(IntPtr hWnd);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr GetWindowLong(IntPtr hWnd, int nIndex);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr newWndProc);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr CallWindowProc(IntPtr lpPrevWndFunc, IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern IntPtr FindWindow(string _ClassName, string _WindowName);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern int SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool SetForegroundWindow(IntPtr hWnd);
    #endregion DllImport

    private Form myForm = null;
    private IntPtr hWndTarget = IntPtr.Zero;
    private IntPtr oldWndProc = IntPtr.Zero;
    private WndProcDelegate newWndProc;

    private FocusFormWrapper()
    {
    }

    public FocusFormWrapper(Form sourceForm)
    {
        if (sourceForm == null)
            throw new ArgumentNullException("sourceForm");
        if (!IsWindow(sourceForm.Handle))
            throw new ArgumentException("sourceForm IsWindow failed");

        myForm = sourceForm;
        hWndTarget = myForm.Handle;
        AddSubclass();
    }

    ~FocusFormWrapper()
    {
        RemoveSubclass();
        myForm = null;
        newWndProc = null;
    }

    private int AddSubclass()
    {
        int result = -1;
        if (myForm != null && newWndProc == null)
        {
            newWndProc = new WndProcDelegate(NewWndProc);
            oldWndProc = GetWindowLong(hWndTarget, GWL_WNDPROC);
            result = SetWindowLong(hWndTarget, GWL_WNDPROC, Marshal.GetFunctionPointerForDelegate(newWndProc));
        }
        return result;
    }

    public int RemoveSubclass()
    {
        int result = -1;
        if (myForm != null && newWndProc != null)
        {
            result = SetWindowLong(hWndTarget, GWL_WNDPROC, oldWndProc);
            newWndProc = null;
        }
        return result;
    }

    public IntPtr NewWndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
    {
        try
        {
            if (msg == WM_PARENTNOTIFY && !myForm.Focused)
            {
                // Make this form auto-grab the focus when menu/controls are clicked 
                myForm.Activate();
            }
            if (msg == WM_CLOSE)
            {
                RemoveSubclass();
            }
        }
        catch
        {
        }

        return CallWindowProc(oldWndProc, hWnd, msg, wParam, lParam);
    }
}