MFC：在SDI应用程序中禁用新文件和保存文件功能

Question

在代码中使用命令以编程方式禁用应用程序中的这两个功能最简单的方法是什么？提前致谢。

Answer 1

你可以处理更新UI消息：

ON_UPDATE_COMMAND_UI(ID_FILE_NEW, OnUpdateFileNew) 
ON_UPDATE_COMMAND_UI(ID_FILE_SAVE, OnUpdateFileSave) 

... 

void CMainFrame::OnUpdateFileNew(CCmdUI *pCmdUI) 
{ 
    pCmdUI->Enable(FALSE); 
} 

void CMainFrame::OnUpdateFileSave(CCmdUI *pCmdUI) 
{ 
    pCmdUI->Enable(FALSE); 
} 

Answer 2

请拨打CMenu::EnableMenuItem并附上相应的菜单项，MF_DISABLED作为第二个参数。这是documentation。

Answer 3

覆盖CWinApp::OnFileNew用自己的功能，如下图所示。

BEGIN_MESSAGE_MAP(CMyApp, CWinApp) 
    ON_COMMAND(ID_APP_ABOUT, &CMyApp::OnAppAbout) 
    // Standard file based document commands 
    **//ON_COMMAND(ID_FILE_NEW, &CWinApp::OnFileNew)** 
    ON_COMMAND(ID_FILE_NEW, &CMyApp::OnFileNew) 
    ON_COMMAND(ID_FILE_OPEN, &CWinApp::OnFileOpen) 
    // Standard print setup command 
    ON_COMMAND(ID_FILE_PRINT_SETUP, &CWinApp::OnFilePrintSetup) 
END_MESSAGE_MAP() 


void CMyApp::OnFileNew() 
{ 
     //Create a static member variable to hold the state. For the first time create a docment. From next time avoid calling CWinApp::OnFileNew(); 
    if(m_bDocCreated == FALSE) 
    { 
     CString strMsg; 
     strMsg.Format(L"Create New DOC"); 
     AfxMessageBox(strMsg); 

     CWinApp::OnFileNew(); 
     m_bDocCreated = TRUE; 
    } 
    else 
    { 
     CFrameWnd* pFrame = (CFrameWnd*)AfxGetMainWnd(); 
     CMyDoc* pDoc = (CMyDoc*)pFrame->GetActiveDocument(); 
     CString strMsg; 
     strMsg.Format(L"Doc ID = %ld",pDoc->m_lIndex); 
     AfxMessageBox(strMsg); 

    } 


}