一、WndProc:
主要用在拦截并处理系统消息和自定义消息
比如:
windows程序会产生很多消息,比如你单击鼠标,移动窗口都会产生消息。这个函数就是默认的消息处理函数。你可以重载这个函数来制定自己的消息处理流程.
在Winform程序中,可以重写WndProc函数,来捕捉所有发生的窗口消息。
这样,我们就可以"篡改"传入的消息,而人为的让窗口改变行为。
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Runtime.InteropServices; namespace ControlTest { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private Demo demo = null; private void Form1_Load(object sender, EventArgs e) { //demo = new Demo(this.Handle.ToInt32()); } private void button1_Click(object sender, EventArgs e) { demo = new Demo(this.Handle.ToInt32()); demo.Test(); } protected override void WndProc(ref Message m) { if (m.Msg == Demo.MY_MSG_BEGIN) { MessageBox.Show("类Demo for循环开始."); } else if (m.Msg == Demo.MY_MSG_END) { MessageBox.Show("类Demo for循环结束."); } base.WndProc(ref m); } } public class Demo { private int m_hWnd = 0; public Demo(int hWnd) { m_hWnd = hWnd; } private const int WM_USER = 0x0400; public static int MY_MSG_BEGIN = WM_USER + 100; public static int MY_MSG_END = WM_USER + 101; [DllImport("User32.DLL")] public static extern int SendMessage(int hWnd, int Msg, int wParam, int lParam); public void Test() { SendMessage(m_hWnd, MY_MSG_BEGIN, 0, 0); for (int i = 0; i < 100000; i++) { Application.DoEvents(); } SendMessage(m_hWnd, MY_MSG_END, 0, 0); } } }
二、SendMessage:
该函数将指定的消息发送到一个或多个窗口。此函数为指定的窗口调用窗口程序,直到窗口程序处理完消息再返回。而函数PostMessage不同,将一个消息寄送到一个线程的消息队列后立即返回。
函数原型:LRESULT SendMessage(HWND hWnd,UINT Msg,WPARAM wParam,LPARAM IParam);
参数:
hWnd:其窗口程序将接收消息的窗口的句柄。如果此参数为HWND_BROADCAST,则消息将被发送到系统中所有顶层窗口,包括无效或不可见的非自身拥有的窗口、被覆盖的窗口和弹出式窗口,但消息不被发送到子窗口。
Msg:指定被发送的消息。
wParam:指定附加的消息指定信息。
IParam:指定附加的消息指定信息。
返回值:返回值指定消息处理的结果,依赖于所发送的消息。
备注:需要用HWND_BROADCAST通信的应用程序应当使用函数RegisterWindowMessage来为应用程序间的通信取得一个唯一的消息。
如果指定的窗口是由调用线程创建的,则窗口程序立即作为子程序调用。如果指定的窗口是由不同线程创建的,则系统切换到该线程并调用恰当的窗口程序。线程间的消息只有在线程执行消息检索代码时才被处理。发送线程被阻塞直到接收线程处理完消息为止。
SendMessage是一个在user32.dll中声明的API函数,在C#中导入如下:
using System.Runtime.InteropServices; [DllImport("user32.dll", EntryPoint="SendMessageA")] public static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);
本文描述其参数 lParam 的用法,主要是数据类型之间的转化。
● 一种最简单的处理方式是声明多个SendMessage函数(overload),用所需的数据类型直接替换IntPtr。例如:
//声明: [DllImport("user32.dll", EntryPoint="SendMessageA")] private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, string lParam); [DllImport("user32.dll", EntryPoint="SendMessageA")] private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, ref Rectangle lParam); //调用: string s = "hello, floodzhu"; SendMessage(this.textBox1.Handle, WM_SETTEXT, IntPtr.Zero, s); Rectangle rect = new Rectangle(); SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, ref rect);
● 对要求返回字符串的类型(out string)可以用 StringBuilder 代替,此时不需要 out/ref。例如:
[DllImport("user32.dll", EntryPoint="SendMessageA")] private static extern int SendMessage (IntPtr hwnd, int wMsg, int wParam, StringBuilder lParam); private void button1_Click(object sender, System.EventArgs e) { const int buffer_size = 1024; StringBuilder buffer = new StringBuilder(buffer_size); SendMessage(this.textBox1.Handle, WM_GETTEXT, buffer_size, buffer); //MessageBox.Show(buffer.ToString()); }
● 如果想用 InPtr 类型统一处理的话,可以借助于 Marshal 或者 GCHandle 的相关方法。例如:
[DllImport("user32.dll", EntryPoint="SendMessageA")] private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam); private void button2_Click(object sender, System.EventArgs e) { Rectangle rect = new Rectangle(); IntPtr buffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Rectangle))); Marshal.StructureToPtr(rect, buffer ,true); SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, buffer); rect = (Rectangle)Marshal.PtrToStructure(buffer, typeof(Rectangle)); Marshal.FreeHGlobal(buffer); }
或者
private void button2_Click(object sender, System.EventArgs e) { Rectangle rect = new Rectangle(); GCHandle gch = GCHandle.Alloc(rect); SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, (IntPtr)gch); rect = (Rectangle)Marshal.PtrToStructure((IntPtr)gch, typeof(Rectangle)); gch.Free(); }
● 模拟按钮点击。第三个参数是可选参数,有时需要有时不需要,比如该例中就不需要。
const int BM_CLICK = 0xF5; IntPtr maindHwnd = FindWindow(null, "QQ用户登录"); //获得QQ登陆框的句柄 if (maindHwnd != IntPtr.Zero) { IntPtr childHwnd = FindWindowEx(maindHwnd, IntPtr.Zero, null, "登录"); //获得按钮的句柄 if (childHwnd != IntPtr.Zero) { SendMessage(childHwnd, BM_CLICK, 0, 0); //发送点击按钮的消息 } else { MessageBox.Show("没有找到子窗口"); } } else { MessageBox.Show("没有找到窗口"); }
三、PostMessage:
用 PostMessage、SendNotifyMessage、SendMessageCallback 等异步函数发送系统消息时,参数里不可以使用指针,因为发送者并不等待消息的处理就返回,接受者还没处理指针就已经被释放了。
PostMessage只负责将消息放到消息队列中,不确定何时及是否处理 SendMessage要等到受到消息处理的返回码(DWord类型)后才继续 PostMessage执行后马上返回 SendMessage必须等到消息被处理后才会返回。 下面通过一个小例子来说明下这2个方法进行参数传递的不同点:
//Win32 API 类 using System; using System.Runtime.InteropServices; namespace TestHwnd { public class Win32API { [DllImport("User32.dll", EntryPoint = "FindWindow")] public static extern IntPtr FindWindow(string lpClassName, string lpWindowName); [DllImport("User32.dll", EntryPoint = "FindWindowEx")] public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpClassName, string lpWindowName); /// <summary> /// 自定义的结构 /// </summary> public struct My_lParam { public int i; public string s; } /// <summary> /// 使用COPYDATASTRUCT来传递字符串 /// </summary> [StructLayout(LayoutKind.Sequential)] public struct COPYDATASTRUCT { public IntPtr dwData; public int cbData; [MarshalAs(UnmanagedType.LPStr)] public string lpData; } //消息发送API [DllImport("User32.dll", EntryPoint = "SendMessage")] public static extern int SendMessage( IntPtr hWnd, // 信息发往的窗口的句柄 int Msg, // 消息ID int wParam, // 参数1 int lParam //参数2 ); //消息发送API [DllImport("User32.dll", EntryPoint = "SendMessage")] public static extern int SendMessage( IntPtr hWnd, // 信息发往的窗口的句柄 int Msg, // 消息ID int wParam, // 参数1 ref My_lParam lParam //参数2 ); //消息发送API [DllImport("User32.dll", EntryPoint = "SendMessage")] public static extern int SendMessage( IntPtr hWnd, // 信息发往的窗口的句柄 int Msg, // 消息ID int wParam, // 参数1 ref COPYDATASTRUCT lParam //参数2 ); //消息发送API [DllImport("User32.dll", EntryPoint = "PostMessage")] public static extern int PostMessage( IntPtr hWnd, // 信息发往的窗口的句柄 int Msg, // 消息ID int wParam, // 参数1 int lParam // 参数2 ); //消息发送API [DllImport("User32.dll", EntryPoint = "PostMessage")] public static extern int PostMessage( IntPtr hWnd, // 信息发往的窗口的句柄 int Msg, // 消息ID int wParam, // 参数1 ref My_lParam lParam //参数2 ); //异步消息发送API [DllImport("User32.dll", EntryPoint = "PostMessage")] public static extern int PostMessage( IntPtr hWnd, // 信息发往的窗口的句柄 int Msg, // 消息ID int wParam, // 参数1 ref COPYDATASTRUCT lParam // 参数2 ); } } //主窗体,发送消息 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Runtime.InteropServices; namespace TestHwnd { public partial class Main : Form { public IntPtr hwndTest; public int IwndTest; public IntPtr hwndfrmTest; public Main() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { Test test = new Test(); test.Show(this); } private void timer1_Tick(object sender, EventArgs e) { string strTest = "25425"; Win32API.COPYDATASTRUCT cds; cds.dwData = (IntPtr)100; cds.lpData = strTest; byte[] sarr = System.Text.Encoding.UTF8.GetBytes(strTest); int len = sarr.Length; cds.cbData = len + 1; Win32API.My_lParam lp=new Win32API.My_lParam(); lp.i=3; lp.s="test"; if(hwndTest!=(IntPtr)0) { if (DateTime.Now.Second % 2 == 0) { Win32API.SendMessage(hwndTest, 0x60, 1, 3);//传递2个整型参数成功 } if(DateTime.Now.Second % 3 == 0) { Win32API.SendMessage(hwndTest, 0x61, 5, ref lp);//传递整型参数和结构类型成功,这个方法加以改变后可以传递对象 } if(DateTime.Now.Second % 5 == 0) { Win32API.SendMessage(hwndTest, 0x62, 5, ref cds);//传递整型参数和不定长的字符串成功 } if(DateTime.Now.Second % 7 == 0) { Win32API.PostMessage(hwndTest, 0x63, 5, 6);//传递2个整型参数成功 } if(DateTime.Now.Second % 9 == 0) { Win32API.PostMessage(hwndTest, 0x64, 3, ref lp);//传递整型参数成功,但是传递参数lp失败,3可以传递成功。 } if(DateTime.Now.Second % 11 == 0) { Win32API.PostMessage(hwndTest, 0x65, 3, ref cds);//传递整型参数成功,传递参数cds失败,3可以传递成功。 } } } } } //子窗体接收消息以及参数 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Runtime.InteropServices; namespace TestHwnd { public partial class Test : Form { Main main; public Test() { InitializeComponent(); } private void Test_Load(object sender, EventArgs e) { main = this.Owner as Main; main.hwndTest = this.Handle; } ///重写窗体的消息处理函数DefWndProc,从中加入自己定义消息的检测的处理入口 protected override void DefWndProc(ref Message m) { switch (m.Msg) { //接收自定义消息MYMESSAGE,并显示其参数 case 0x60: { label1.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + m.LParam.ToInt32().ToString(); } break; case 0x61: { Win32API.My_lParam ml = new Win32API.My_lParam(); Type t = ml.GetType(); ml = (Win32API.My_lParam)m.GetLParam(t); label2.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + ml.i.ToString()+":"+ml.s; } break; case 0x62: { Win32API.COPYDATASTRUCT mystr = new Win32API.COPYDATASTRUCT(); Type mytype = mystr.GetType(); mystr = (Win32API.COPYDATASTRUCT)m.GetLParam(mytype); string str2 = mystr.lpData; label3.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + str2; } break; case 0x63: { label4.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + m.LParam.ToInt32().ToString(); } break; case 0x64: { Win32API.My_lParam ml = new Win32API.My_lParam(); Type t = ml.GetType(); ml = (Win32API.My_lParam)m.GetLParam(t); label5.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + ml.i.ToString()+":"+ml.s; } break; case 0x65: { Win32API.COPYDATASTRUCT mystr = new Win32API.COPYDATASTRUCT(); Type mytype = mystr.GetType(); mystr = (Win32API.COPYDATASTRUCT)m.GetLParam(mytype); string str2 = mystr.lpData; label6.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + str2; } break; default: base.DefWndProc(ref m); break; } } private void button1_Click(object sender, EventArgs e) { main.hwndTest = (IntPtr) (0); this.Close(); } } }