如何使用c#控制windows自带计算器？

用c#控制windows自带计算器实例
代码出自http://www.codeproject.com/csharp/WindowsAPIsFromCS.asp
我只是将英文“计算器”标题改为了中文的，本来目的是为了将工作中常扫描程序加三个快捷键，因为家里没有扫描仪，以至装了ocr工具，还是不能打开扫描介面。只得将此文先发到博客上，一是方便大家学习，二是可以容易找到，在公司再作这未完成的东东。

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Runtime.InteropServices;

namespace TestWinAPI
{
/// <summary>
/// Summary description for Form1.
/// </summary>
public class MainForm : System.Windows.Forms.Form
{
private System.Windows.Forms.Button btnGetWindows;
private const int WM_CLOSE = 16;
private const int BN_CLICKED = 245;
private System.Windows.Forms.Button btnCloseCalc;
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container components = null;
/// <summary>
/// The FindWindow API
/// </summary>
/// <param name="lpClassName">the class name for the window to search for</param>
/// <param name="lpWindowName">the name of the window to search for</param>
/// <returns></returns>
[DllImport("User32.dll")]
public static extern Int32 FindWindow(String lpClassName,String lpWindowName);

/// <summary>
/// The SendMessage API
/// </summary>
/// <param name="hWnd">handle to the required window</param>
/// <param name="msg">the system/Custom message to send</param>
/// <param name="wParam">first message parameter</param>
/// <param name="lParam">second message parameter</param>
/// <returns></returns>
[DllImport("user32.dll", CharSet=CharSet.Auto)]
public static extern int SendMessage(int hWnd, int msg, int wParam, IntPtr lParam);

/// <summary>
/// The FindWindowEx API
/// </summary>
/// <param name="parentHandle">a handle to the parent window </param>
/// <param name="childAfter">a handle to the child window to start search after</param>
/// <param name="className">the class name for the window to search for</param>
/// <param name="windowTitle">the name of the window to search for</param>
/// <returns></returns>
[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className, string windowTitle);

public MainForm()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

//
// TODO: Add any constructor code after InitializeComponent call
//
}

/// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.btnGetWindows = new System.Windows.Forms.Button();
this.btnCloseCalc = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// btnGetWindows
//
this.btnGetWindows.Location = new System.Drawing.Point(16, 24);
this.btnGetWindows.Name = "btnGetWindows";
this.btnGetWindows.Size = new System.Drawing.Size(120, 23);
this.btnGetWindows.TabIndex = 0;
this.btnGetWindows.Text = "Use Calculator";
this.btnGetWindows.Click += new System.EventHandler(this.btnGetWindows_Click);
//
// btnCloseCalc
//
this.btnCloseCalc.Location = new System.Drawing.Point(16, 72);
this.btnCloseCalc.Name = "btnCloseCalc";
this.btnCloseCalc.Size = new System.Drawing.Size(120, 23);
this.btnCloseCalc.TabIndex = 2;
this.btnCloseCalc.Text = "Close the Calculator";
this.btnCloseCalc.Click += new System.EventHandler(this.btnCloseCalc_Click);
//
// MainForm
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(234, 119);
this.Controls.Add(this.btnCloseCalc);
this.Controls.Add(this.btnGetWindows);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.MaximizeBox = false;
this.Name = "MainForm";
this.Text = "Test Windows API";
this.ResumeLayout(false);

}
#endregion

/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.Run(new MainForm());
}

private void btnGetWindows_Click(object sender, System.EventArgs e)
{
int hwnd=0;
IntPtr hwndChild=IntPtr.Zero;

//Get a handle for the Calculator Application main window
hwnd=FindWindow(null,"计算器");
if(hwnd == 0)
{
if(MessageBox.Show("Couldn't find the calculator application. Do you want to start it?","TestWinAPI",MessageBoxButtons.YesNo)== DialogResult.Yes)
{
System.Diagnostics.Process.Start("Calc");
}
}
else
{

//Get a handle for the "1" button
hwndChild = FindWindowEx((IntPtr)hwnd,IntPtr.Zero,"Button","2");

//send BN_CLICKED message
SendMessage((int)hwndChild,BN_CLICKED,0,IntPtr.Zero);

//Get a handle for the "+" button
hwndChild = FindWindowEx((IntPtr)hwnd,IntPtr.Zero,"Button","+");

//send BN_CLICKED message
SendMessage((int)hwndChild,BN_CLICKED,0,IntPtr.Zero);

//Get a handle for the "2" button
hwndChild = FindWindowEx((IntPtr)hwnd,IntPtr.Zero,"Button","3");

//send BN_CLICKED message
SendMessage((int)hwndChild,BN_CLICKED,0,IntPtr.Zero);

//Get a handle for the "=" button
hwndChild = FindWindowEx((IntPtr)hwnd,IntPtr.Zero,"Button","=");

//send BN_CLICKED message
SendMessage((int)hwndChild,BN_CLICKED,0,IntPtr.Zero);

}//花纯春改写，http://ike.126.com

}

private void btnCloseCalc_Click(object sender, System.EventArgs e)
{
int hwnd=0;

//Get a handle for the Calculator Application main window
hwnd=FindWindow(null,"计算器");

//send WM_CLOSE system message
if(hwnd!=0)
SendMessage(hwnd,WM_CLOSE,0,IntPtr.Zero);
}
}
}