WndProcに送信されるメッセージを監視するために、スレッド固有のWindowsフックをインストールしました。最初はうまくいきました。ただし、Tabキーを約19回押してフォーム内でフォーカスを移動した後、フックコールバックは呼び出されなくなりました。これは、Tabキーをすばやく押すかゆっくり押すかに関係なく発生しました。誰かが実際に何が起こっているのか説明できますか？
以下は私が書いたコードです。Windows764ビットでテストしました。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace HookTest
{
static class Program
{
private const int WH_CALLWNDPROC = 4;
private delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);
private class MainForm : Form
{
private Button button1;
private TextBox textBox1;
public MainForm()
{
this.button1 = new System.Windows.Forms.Button();
this.textBox1 = new System.Windows.Forms.TextBox();
this.SuspendLayout();
//
// button1
//
this.button1.Location = new System.Drawing.Point(12, 38);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(75, 23);
this.button1.TabIndex = 0;
this.button1.Text = "Button 1";
this.button1.UseVisualStyleBackColor = true;
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(12, 12);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(100, 20);
this.textBox1.TabIndex = 1;
//
// MainForm
//
this.Controls.Add(this.textBox1);
this.Controls.Add(this.button1);
this.Name = "MainForm";
this.Text = "Main Form";
this.ResumeLayout(false);
this.PerformLayout();
}
}
private static IntPtr hWndProcHook = IntPtr.Zero;
private static int messageCount = 0;
[DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr GetModuleHandle(string lpModuleName);
[DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
public static extern uint GetCurrentThreadId();
[DllImport("User32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr SetWindowsHookEx(int idHook,
HookProc lpfn, IntPtr hMod, uint dwThreadId);
[DllImport("User32.dll", CharSet = CharSet.Auto)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool UnhookWindowsHookEx(IntPtr hhk);
[DllImport("User32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode,
IntPtr wParam, IntPtr lParam);
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
InstallHook();
Application.Run(new MainForm());
UninstallHook();
}
private static void InstallHook()
{
if (Program.hWndProcHook == IntPtr.Zero)
{
Console.WriteLine("Hooking...");
Program.hWndProcHook = SetWindowsHookEx(
WH_CALLWNDPROC,
WndProcHookCallback,
GetModuleHandle(null),
GetCurrentThreadId());
if(Program.hWndProcHook != IntPtr.Zero)
Console.WriteLine("Hooked successfully.");
else
Console.WriteLine("Failed to hook.");
}
}
private static void UninstallHook()
{
if (Program.hWndProcHook != IntPtr.Zero)
{
Console.WriteLine("Unhooking...");
if (UnhookWindowsHookEx(Program.hWndProcHook))
Console.WriteLine("Unhooked successfully.");
else
Console.WriteLine("Failed to unhook.");
Program.hWndProcHook = IntPtr.Zero;
}
}
private static IntPtr WndProcHookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
Console.WriteLine("WndProcHookCallback {0}", Program.messageCount++);
return CallNextHookEx(Program.hWndProcHook, nCode, wParam, lParam);
}
}
}