CS351 Systems Programming

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CS351 Systems Programming

• Menus
• Sockets
• Programming Assignment

Ondrej Hrebicek Mudit Tandon
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Introduction to Menus

• An integral part of a Windows application
• Easy to create using Visual Studios Resource
  Editor
• Each selectable menu item is assigned a unique ID
  number
• The unique ID is passed together with a
  WM_COMMAND message whenever a user chooses a menu
  item

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Menu Structure

• Main menu or Top-level menu located
  immediately below the caption bar
• Submenus or Drop-down menus invoked by items
  in the main menu can be nested
• Menu items can be enabled, disabled, grayed
  out, checked, or unchecked

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Creating a Menu

• Insert ? Resource ? Menu
• Declare each menu items text and unique ID in
  the Menu Item Properties dialog box
• Add an in front of the character youd like
  underlined (Alt key shortcut)
• ID numbers are sent in the low word of wParam of
  a WM_COMMAND message
• lParam is 0

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case WM_COMMAND // Process all of our button
and menu commands switch (LOWORD
(wParam)) case ID_PUZZLE_OPEN
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Integrating Menus with your Application

• 1) Specify the menu name within your window class
• wndclass.lpszMenuName TEXT (MyMenu)
• 2) Use LoadMenu () to obtain a menu handle
• hMenu LoadMenu (hInstance, TEXT (MyMenu))
• hMenu LoadMenu (hInstance, MAKEINTRESOURCE
  (ID_MENU))
• Pass hMenu to CreateWindow (...) or to SetMenu
  (hwnd, hMenu)

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Menu Operations

• Obtaining a windows menu handle hMenu GetMenu
  (hwnd)
• Check or uncheck a menu item
• CheckMenuItem (hMenu, iID, MF_CHECKED)
• CheckMenuItem (hMenu, iID, MF_UNCHECKED)
• Enable, disable, gray out a menu item
• EnableMenuItem (hMenu, iID, MF_GRAYED)
• EnableMenuItem (hMenu, iID, MF_ENABLED)
• EnableMenuItem (hMenu, iID, MF_DISABLED)

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Floating Popup Menus

• Independent or main menus submenus
• To display a popup menu in your client area
• Capture the WM_RBUTTONUP message
• Get the x and y coordinates of the mouse click
  (low and high word of lParam, respectively)
• Convert x and y to screen coordinates
• Call TrackPopupMenu (hMenu, uFlags, x, y, 0,
  hWnd, NULL)

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Sockets
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Sockets

• Concept developed at UC Berkeley to add network
  support to UNIX
• Used primarily over TCP/IP
• Raw sockets for handmade packets
• On Win32, the Windows Sockets API is used
• Slightly modifies original socket interface

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Socket Initialization

• 1) Initialize windows networking
• if (iError WSAStartup (MAKEWORD(2,0),
  WSAData))
• MessageBox (hWnd, "Error in WSAStartup.",
  "Socket Error", MB_ICONERROR)
• return FALSE
• 2) Create an internet TCP socket stream
• if ((sock socket (AF_INET, SOCK_STREAM,
  IPPROTO_TCP)) INVALID_SOCKET)
• MessageBox (hWnd, "Error in socket.", "Socket
  Error", MB_ICONERROR)
• WSACleanup ()
• return FALSE

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Socket Initialization (contd)

• 3) Fill out the required address information
• sa.sin_family AF_INET
• sa.sin_port htons (80)
• sa.sin_addr.S_un.S_addr inet_addr (szServer)
• Host to Network function needed because MSB of
  port number needs to be first on Intel machines
  it is last
• 4) Connect to the server
• if (connect (sock, (SOCKADDR ) sa, sizeof
  (sa)) SOCKET_ERROR)
• MessageBox (hWnd, "Error in socket.", "Socket
  Error", MB_ICONERROR)
• WSACleanup ()
• return FALSE

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Sending and Receiving Data

• send (sock, buffer, strlen (buffer), 0)
• iBytesDownloaded recv (sock, (CHAR ) data,
  sizeof (data), 0)
• Once data downloaded, recv () returns 0
• closesocket (sock)
• WSACleanup ()