如何从Windows窗体创建仅消息窗口？ [英] How do I create a message-only window from windows forms?

问题描述

我试图在Winforms应用程序中创建一个仅消息窗口，以从MFC库类接收窗口消息。

I'm trying to create a message-only window to receive window messages from an MFC library class, within a winforms application.

我尝试了子类化 NativeWindow ，并在构造函数中请求这样的窗口句柄：

I've tried subclassing NativeWindow, and in the constructor requesting a window handle like this:

CreateParams cp = new CreateParams();
cp.Parent = (IntPtr)HWND_MESSAGE;
this.CreateHandle(cp);

但是我收到一条Win32Exception消息错误创建窗口句柄。如何从Windows窗体创建仅消息窗口？是使用 NativeWindow 正确的方法吗？

but I get a Win32Exception thrown with the message "Error creating window handle". How do I create a message-only window from windows forms? Is using NativeWindow the right approach?

推荐答案

我知道这是7.5岁，但万一有人发现这个，我想我会回应。我使用了Microsoft的 TimerNativeWindow代码，并删除了计时器功能。我最终使用了这种方法：

I know this is 7.5 years old, but just in case anyone finds this, I thought I would respond. I used Microsoft's TimerNativeWindow code and removed the timer functionality. I ended up using this approach:

    public class MyNativeWindow : NativeWindow
    {
        private readonly string _caption;
        private const int WmClose = 0x0010;

        [SuppressMessage("Microsoft.Reliability", "CA2006:UseSafeHandleToEncapsulateNativeResources")]
        private static readonly HandleRef HwndMessage = new HandleRef(null, new IntPtr(-3));

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        [ResourceExposure(ResourceScope.None)]
        private static extern IntPtr PostMessage(HandleRef hwnd, int msg, int wparam, int lparam);

        [DllImport("user32.dll", ExactSpelling = true, CharSet = CharSet.Auto)]
        [ResourceExposure(ResourceScope.Process)]
        private static extern int GetWindowThreadProcessId(HandleRef hWnd, out int lpdwProcessId);

        [DllImport("kernel32.dll", ExactSpelling = true, CharSet = CharSet.Auto)]
        [ResourceExposure(ResourceScope.Process)]
        private static extern int GetCurrentThreadId();

        public MyNativeWindow(string caption)
        {
            _caption = caption;
        }

        public bool CreateWindow()
        {
            if (Handle == IntPtr.Zero)
            {
                CreateHandle(new CreateParams
                {
                    Style = 0,
                    ExStyle = 0,
                    ClassStyle = 0,
                    Caption = _caption,
                    Parent = (IntPtr)HwndMessage
                });
            }
            return Handle != IntPtr.Zero;
        }


        public void DestroyWindow()
        {
            DestroyWindow(true, IntPtr.Zero);
        }

        private bool GetInvokeRequired(IntPtr hWnd)
        {
            if (hWnd == IntPtr.Zero) return false;
            int pid;
            var hwndThread = GetWindowThreadProcessId(new HandleRef(this, hWnd), out pid);
            var currentThread = GetCurrentThreadId();
            return (hwndThread != currentThread);
        }

        private void DestroyWindow(bool destroyHwnd, IntPtr hWnd)
        {
            if (hWnd == IntPtr.Zero)
            {
                hWnd = Handle;
            }

            if (GetInvokeRequired(hWnd))
            {
                PostMessage(new HandleRef(this, hWnd), WmClose, 0, 0);
                return;
            }

            lock (this)
            {
                if (destroyHwnd)
                {
                    base.DestroyHandle();
                }
            }
        }

        public override void DestroyHandle()
        {
            DestroyWindow(false, IntPtr.Zero);
            base.DestroyHandle();
        }
    }

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