Chapter 4 Menu and Chapter 6 File I/O

Back to MENU – Chapter 4

Chapter 4-3: Menu Magic 2 Ways for creating a menu: Use the Resource view Use CMenu class and create it manually

Create a menu using CMenu class Design a popup menu Add(attach) the popup menu to the main menu 2. Add it to the main menu 1. Design a popup menu

Procedure Design a popup menu Attach it to the main menu Create a new PopupMenu: CreatePopupMenu() Adding menu items to the menu: AppendMenu() Attach it to the main menu Get the main menu: GetMenu() Attach a menu to the existing menu: AppendMenu()

Coding practice In the CMainFrame::OnCreate function int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct) { // … ... CMenu Popup; Popup.CreatePopupMenu(); Popup.AppendMenu(MF_STRING, 201, “Red(&R)"); Popup.AppendMenu(MF_STRING, 202, “Green(&G)"); Popup.AppendMenu(MF_STRING, 203, “Blue(&B)"); CMenu * pMenuMain = GetMenu(); pMenuMain->AppendMenu(MF_POPUP, (UINT_PTR) Popup.Detatch(), “Color(&C)”); }

Modifying menus by using CMenu Function Description AppendMenu Adds an item to the end of a menu InsertMenu Inserts an item into a menu at a specified location ModifyMenu Changes the command ID, text, or other characteristics of a menu item DeleteMenu Deletes a menu item and the submenu associated with it, if any RemoveMenu Deletes a menu item Example of deleting menu CMenu* pMenu = GetMenu ()->GetSubMenu (1); pMenu->DeleteMenu (2, MF_BYPOSITION); // Delete by position pMenu->DeleteMenu (ID_SHAPE_CIRCLE, MF_BYCOMMAND); // Delete by ID

Summary CMenu class: store the menu properties AppendMenu() member function Flag: MF_STRING (when adding a normal menu item) MF_POPUP (when attaching a popup menu) MF_SEPARATOR ID: In case of MF_STRING : Command ID In case of MF_POPUP : Pointer to the popup menu (use CMenu::Detatch() function) bool CMenu::AppendMenu( Flag, ID, Caption )

Context menu Context menu

Context menu message handler 1. When click the mouse right button or key 2. Windows sends WM_CONTEXTMENU message 3. Add the message handler

Prototype of the handler WM_CONTEXTMENU message handler pWnd – window where the mouse cursor is located pos – the position of the mouse cursor afx_msg void OnContextMenu (CWnd* pWnd, CPoint pos) ;

Coding Practice Add the WM_CONTEXTMENU handler AfxMessageBox(_T(“Context Menu”));

Show the menu in the handler Use CMenu::TrackPopupMenu() function nFlags TPM_LEFTALIGN, TPM_CENTERALIGN, TPM_RIGHTALIGN TPM_LEFTBUTTON, TPM_RIGHTBUTTON BOOL TrackPopupMenu (UINT nFlags, int x, int y, CWnd* pWnd, LPCRECT lpRect = 0) ;

Show the menu in the handler Use CMenu::TrackPopupMenu() function x, y Position where the menu will be located(스크린 좌표) pWnd Window which will get the WM_COMMAND message Usually use AfxGetMainWnd() function to get the CMainFrame lpRect The rectangle region of the menu. Give 0 usually. BOOL TrackPopupMenu (UINT nFlags, int x, int y, CWnd* pWnd, LPCRECT lpRect = 0) ;

An example to show the context menu Create a menu and show it: void CChildView::OnContextMenu(CWnd* pWnd, CPoint point) { CMenu menuPopup; menuPopup.CreatePopupMenu(); menuPopup.AppendMenu(MF_STRING, 201, "Red (&R)"); menuPopup.AppendMenu(MF_STRING, 202, "Green (&G)"); menuPopup.AppendMenu(MF_STRING, 203, "Blue (&B)"); menuPopup.TrackPopupMenu( TPM_LEFTALIGN|TPM_LEFTBUTTON, point.x, point.y, AfxGetMainWnd()); }

More example Using existing menu as a context menu void CChildView::OnContextMenu(CWnd* pWnd, CPoint point) { CMenu menu; menu.LoadMenu(IDR_MAINFRAME); CMenu* pMenu = menu.GetSubMenu(4); pMenu->TrackPopupMenu( TPM_LEFTALIGN|TPM_RIGHTBUTTON, point.x, point.y, AfxGetMainWnd()); }

Chapter 6: FILE I/O and Serialize CFile class

Introduction (1/2) How to read/write a file Usual way of File I/O Use CFile class Use member functions: CFile::Read() and CFile::Write() Universal use. Low level file I/O Serialize Use CArchive class Use operators: << and >> Easy to use Limited functionality

Introduction (2/2) MFC Class Hierarchy Basic File I/O Derived Classes for specific purposes

CFile class Basic functionality Open or create a file(Open). Read data at the file pointer(Read). Write data at the file pointer(Write). Change the file pointer (Seek). Close the file(Close).

CFile: Two ways to Open a file Use CFile::Open member function Use a constructor CFile file; file.Open( filename, mode, error ); CFile file ( filename, mode );

CFile class (1/6) CFile file; file.Open( filename, mode, error ); Open and Create: Use CFile::Open(..) CFile file; file.Open( filename, mode, error ); CFile file; if( file.Open("mytest.txt", CFile::modeRead) == false) AfxMessageBox(_T(“Error”));

CFile class (1/6) CFile file; file.Open( filename, mode, error ); Open and Create: Use CFile::Open(..) Get errors and related information CFile file; file.Open( filename, mode, error ); CFile file; CFileException e; if(!file.Open("mytest.txt", CFile::modeReadWrite, &e)) e.ReportError();

CFile class (1/6) CFile file ( filename, mode ); Open and Create : Use the constructor CFile file ( filename, mode ); try { CFile file("mytest.txt", CFile::modeReadWrite); } catch (CFileException* e) e->ReportError(); e->Delete();

CFile class (2/6) Access modes of CFile flags meaning CFile::modeCreate Directs the constructor to create a new file. If the file exists already, it is truncated to 0 length CFile::modeNoTruncate Combine this value with modeCreate. If the file being created already exists, it is not truncated to 0 length. CFile::modeRead Requests read access only CFile::modeReadWrite Requests read and write access CFile::modeWrite Requests write access only CFile::shareDenyNone Opens the file nonexclusively CFile::shareDenyRead Denies read access to other parties. CFile::shareDenyWrite Denies write access to other parties. CFile::shareDenyExclusive Denies both read and write access to other parties (default).

CFile class(3/6) Close a file: Destructor closes it automatically void CExFileView::OnLButtonDblClk(UINT nFlags, CPoint point) { CFile file; CFileException e; if(!file.Open("mytest.txt", CFile::modeReadWrite|CFile::modeCreate, &e)) e.ReportError(); return; } // skip ... } // -> CFile::~CFile() is called and close the file automatically.

CFile class (4/6) Close a file: CFile::Close member function When opening a multiple files void CExFileView::OnLButtonDblClk(UINT nFlags, CPoint point) { CFile file; CFileException e; if(!file.Open("mytest.txt“, CFile::modeReadWrite|CFile::modeCreate| CFile::modeNoTruncate, &e)) e.ReportError(); return; } file.Close();

CFile class (5/6) Read and Write Change the file pointer UINT CFile::Read (void* lpBuf, UINT nCount) ; void CFile::Write (const void* lpBuf, UINT nCount) ; ULONGLONG CFile::Seek (LONGLONG lOff, UINT nFrom) ; nFrom meaning CFile::begin Move the file pointer by lOff bytes from the beginning CFile::current Move the file pointer by lOff bytes from the current position CFile::end Move the file pointer by lOff bytes from the end

CFile class: Write Data void CFile::Write (const void* lpBuf, UINT nCount) ; CFile file(_T(“test.txt“), CFile::modeCreate|CFile::modeWrite); int a = 30; int b = 20; file.Write(&a, sizeof(a)); file.Write(&b, sizeof(b));

CFile class: Read Data UINT CFile::Read (void* lpBuf, UINT nCount) ; CFile file; CFileException e; if(!file.Open(_T("test.txt“), CFile::modeRead, &e)) { e.ReportError(); return; }; int a,b; file.Read(&a, sizeof(a)); file.Read(&b, sizeof(b));

CFile class: Read Data UINT CFile::Read (void* lpBuf, UINT nCount) ; CFile file; CFileException e; if(!file.Open(_T("test.txt“), CFile::modeRead, &e)){ e.ReportError(); return; }; int a,b; file.Read(&a, sizeof(a)); file.Read(&b, sizeof(b)); CString str; str.Format(_T("a=%d b=%d"), a, b); AfxMessageBox(str);

Coding Practice Create variables “a” and “b” When clicking mouse left button, create “test.txt” file, and store the values of “a” and “b” variables When clicking mouse right button, read “test.txt” file, and read the values of “a” and “b” variables Show the data by using AfxMessageBox function

CFile class (6/6) Miscellaneous functions CFile::GetLength(), CFile::SetLength() Get or change the file size. CFile::GetPosition() Get the file position. CFile::LockRange(), CFile::UnlockRange() Lock or Unlock the file. If lock a file, other process can not access the file. CFile::GetFilePath(), CFile::GetFileName() Get full path or file name as a CString