全局热键的问题

Question

为什么，this.Hide()后，热键就不响应了呢 ？

Answer 1

没有消息到来using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Collections;
using System.Windows.Forms;public class C_全局热键 : IMessageFilter
{
    public event Action<int> OnHotkey;
    public enum KeyFlags
    {
        MOD_ALT = 0x1,
        MOD_CONTROL = 0x2,
        MOD_SHIFT = 0x4,
        MOD_WIN = 0x8
    }    class NativeMethods
    {
        private NativeMethods() { }        #region WIN32 API        [DllImport("user32.dll")]
        public static extern UInt32 RegisterHotKey(IntPtr hWnd, UInt32 id, UInt32 fsModifiers, UInt32 vk);        [DllImport("user32.dll")]
        public static extern UInt32 UnregisterHotKey(IntPtr hWnd, UInt32 id);        [DllImport("kernel32.dll")]
        public static extern UInt32 GlobalAddAtom(String lpString);        [DllImport("kernel32.dll")]
        public static extern UInt32 GlobalDeleteAtom(UInt32 nAtom);        #endregion
    }    Hashtable keyIDs = new Hashtable();
    IntPtr hWnd;    public C_全局热键(IntPtr hWnd)
    {
        this.hWnd = hWnd;
        Application.AddMessageFilter(this);
    }    public int RegisterHotkey(Keys Key, KeyFlags keyflags)
    {
        UInt32 hotkeyid = NativeMethods.GlobalAddAtom(System.Guid.NewGuid().ToString());
        NativeMethods.RegisterHotKey((IntPtr)hWnd, hotkeyid, (UInt32)keyflags, (UInt32)Key);
        keyIDs.Add(hotkeyid, hotkeyid);
        return (int)hotkeyid;
    }    public void UnregisterHotkeys()
    {
        Application.RemoveMessageFilter(this);
        foreach (UInt32 key in keyIDs.Values)
        {
            NativeMethods.UnregisterHotKey(hWnd, key);
            NativeMethods.GlobalDeleteAtom(key);
        }
    }
    public bool PreFilterMessage(ref Message m)
    {
        if (m.Msg ==  0x0312)
        {                            //这里断点没有到
            if (OnHotkey != null)
            {
                foreach (UInt32 key in keyIDs.Values)
                {
                    if ((UInt32)m.WParam == key)
                    {
                        OnHotkey((int)m.WParam);
                        return true;
                    }
                }
            }
        }        return false;
    }
}

Answer 2

隐藏窗体：
 this.WindowState = FormWindowState.Minimized;
            this.ShowInTaskbar = false;

Answer 3

        protected override void WndProc(ref Message m)
        {
            const int WM_HOTKEY = 0x0312;
            //按快捷键 
            switch (m.Msg)
            {
                case WM_HOTKEY:
                    switch (m.WParam.ToInt32())
                    {
                        case 100:    //按下的是F7
                            CopyPosition();
                            break;                        default:
                            break;
                    }
                    break;
            }            base.WndProc(ref m);
        }

Answer 4

this.Hide() 在Net的源码中只是一个
  public void Hide()
        {
            this.Visible = false;
        }
可能隐藏了后，对于P/Invoke的某些方法不起作用了。

Answer 5

问题的正解是:
 //这里因为 this.ShowInTaskbar=false 会改变窗体句柄值，因此需要再次注册热键,不信？Debug this.Handle
因为句柄改变要重新注册一下热键