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如何在对话框程序中让对话框捕获WM_KEYDOWN消息 ---- zt

如何在对话框程序中让对话框捕获WM_KEYDOWN消息

作者:孙鑫                  日期:2003-9-4

在对话框程序中,我们经常是利用对话框上的子控件进行命令响应来处理一些事件。如果我们想要让对话框(子控件的父窗口)类来响应我们的按键消息,我们可以通过ClassWizardWM_KEYDOWN消息进行响应,当程序运行后,我们按下键盘上的按键,但对话框不会有任何的反应。这是因为在对话框程序中,某些特定的消息,例如按键消息,它们被Windows内部的对话框过程处理了(即在基类中完成了处理,有兴趣的读者可以查看MFC的源代码),或者被发送给子控件进行处理,所以我们在对话框类中就捕获不到按键的消息了。

既然我们知道了这个处理的过程,我们就可以找到底层处理按键消息的函数,然后在子类中重载它,就可以在对话框程序中处理按键消息了。在MFC中,是利用BOOL ProcessMessageFilter(int code, LPMSG lpMsg)这个虚函数来过滤或响应菜单和对话框的特定Windows消息。下面我们通过程序给大家演示基于对话框的应用程序对WM_KEYDOWN消息的捕获。

第一步:新建一个工程,选择MFC AppWizard (exe),工程名为WinSun,点击ok,进入下一步,选择Dialog based,点击Finish

第二步:在CWinSunApp类上点击右键,选择Add Member Varialbe,增加一个类型为HWND,变量名m_hwndDlgpublic的变量。代码如下:

WinSun.h

class CWinSunApp : public CWinApp

{

public:

       HWND m_hwndDlg;

       CWinSunApp();

 

// Overrides

       // ClassWizard generated virtual function overrides

       //{{AFX_VIRTUAL(CWinSunApp)

       public:

       virtual BOOL InitInstance();

       //}}AFX_VIRTUAL

 

// Implementation

 

       //{{AFX_MSG(CWinSunApp)

              // NOTE - the ClassWizard will add and remove member functions here.

              //    DO NOT EDIT what you see in these blocks of generated code !

       //}}AFX_MSG

       DECLARE_MESSAGE_MAP()

};

 

第三步:在WinSun.cppCWinSunApp类)文件中的InitInstance()函数中添加如下代码:

WinSun.cpp

BOOL CWinSunApp::InitInstance()

{

       AfxEnableControlContainer();

 

       // Standard initialization

       // If you are not using these features and wish to reduce the size

       // of your final executable, you should remove from the following

       // the specific initialization routines you do not need.

 

#ifdef _AFXDLL

       Enable3dControls();                     // Call this when using MFC in a shared DLL

#else

       Enable3dControlsStatic();      // Call this when linking to MFC statically

#endif

 

       CWinSunDlg dlg;

       m_pMainWnd = &dlg;

       int nResponse = dlg.DoModal();

       if (nResponse == IDOK)

       {

              // TODO: Place code here to handle when the dialog is

              // dismissed with OK

       }

       else if (nResponse == IDCANCEL)

       {

              // TODO: Place code here to handle when the dialog is

              // dismissed with Cancel

       }

 

       // Since the dialog has been closed, return FALSE so that we exit the

       // application, rather than start the application's message pump.

       m_hwndDlg=NULL;

       return FALSE;

}

 

第四步:CWinSunApp类上点击右键,选择Add Virtual Function,在左边一栏里,选择ProcessMessageFilter,在右边按钮上选择Add and Edit,然后加入以下代码:

WinSun.cpp

BOOL CWinSunApp::ProcessMessageFilter(int code, LPMSG lpMsg)

{

       // TODO: Add your specialized code here and/or call the base class

       if(m_hwndDlg!=NULL)

       {

              //判断消息,如果消息是从对话框发出的或者其子控件发出的,我们就进行处理。sunxin

              if((lpMsg->hwnd==m_hwndDlg) || ::IsChild(m_hwndDlg,lpMsg->hwnd))

              {

                     //如果消息是WM_KEYDOWN,我们就弹出一个消息框。sunxin

                     if(lpMsg->message==WM_KEYDOWN)

                     {

                            AfxMessageBox("捕获WM_KEYDOWN消息成功!");

                     }

              }

       }

       return CWinApp::ProcessMessageFilter(code, lpMsg);

}

 

第五步:在WinSunDlg.cppCWinSunDlg类)中的OnInitialDialog()函数中加入以下代码:

WinSunDlg.cpp

BOOL CWinSunDlg::OnInitDialog()

{

       CDialog::OnInitDialog();

 

       // Add "About..." menu item to system menu.

 

       // IDM_ABOUTBOX must be in the system command range.

       ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);

       ASSERT(IDM_ABOUTBOX < 0xF000);

 

       CMenu* pSysMenu = GetSystemMenu(FALSE);

       if (pSysMenu != NULL)

       {

              CString strAboutMenu;

              strAboutMenu.LoadString(IDS_ABOUTBOX);

              if (!strAboutMenu.IsEmpty())

              {

                     pSysMenu->AppendMenu(MF_SEPARATOR);

                     pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);

              }

       }

 

       // Set the icon for this dialog. The framework does this automatically

       // when the application's main window is not a dialog

       SetIcon(m_hIcon, TRUE);                  // Set big icon

       SetIcon(m_hIcon, FALSE);          // Set small icon

      

       // TODO: Add extra initialization here

//将对话框的句柄传递到CWinSunApp类中。sunxin

       ((CWinSunApp*)AfxGetApp())->m_hwndDlg=m_hWnd;

       return TRUE; // return TRUE unless you set the focus to a control

}

 

第六步:在对话框窗口销毁后,将CWinSunApp类中的变量m_hwndDlg置为NULL,为此我们CWinSunDlg类上点击右键,选择Add Windows Message Handler,在左边一栏中选择WM_DESTROY,在右边按钮上选择Add and Edit,然后加入以下代码:

WinSunDlg.cpp

void CWinSunDlg::OnDestroy()

{

       CDialog::OnDestroy();

      

       // TODO: Add your message handler code here

       ((CWinSunApp*)AfxGetApp())->m_hwndDlg=NULL;

}

 

至此,我们的工作就做完了,现在我们可以按Ctrl+F5运行程序,看到我们想要的结果。当然,如果我们想捕获WM_KEYUPWM_CHAR消息,也是类似,这就交给读者下来自行完成了。想要浏览更多技术文章,请登录网站:http://www.sunxin.org

posted on 2007-08-29 11:35 大龙 阅读(664) 评论(0)  编辑 收藏 引用


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