WINDOWS PROGRAMMING

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WINDOWS PROGRAMMING

• Where
• the fun
• starts

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WINDOWS PROGRAMMING LANGUAGES

• C C
• BASIC VISUAL BASIC

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Encapsulation

• Combining data and the functions that process the
  data into a single entity.
• Data refers to the members of a structure or
  CLASS that hold data.
• Functions refer to pointers to functions
  included as members of a structure or CLASS
• Window and Dialog Classes Provided by C are
  Actually Structures Set up this Way.

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Writing a Windows Program
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STEP BY STEP APPROACH
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STEP 1

• Initialize the Application . . .
• Write a function that does the following
• declare a variable of the WNDCLASS type
• fill the members of that variable with values
  that customize your window
• call the RegisterClass function, passing your
  class
• return TRUE or FALSE (BOOL) to the main function,
  based upon whether RegisterClass was successful
  or not

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BOOL InitApplication ( HANDLE hInstance )
WNDCLASS wc wc.style
CS_HREDRAW CS_VREDRAW wc.lpfnWndProc
MainWndProc wc.cbClsExtra
0 wc.cbWndExtra 0 wc.hInstance
hInstance wc.hIcon LoadIcon (
hInstance, IDI_APPLICATION ) wc.hCursor
LoadCursor ( NULL, IDC_ARROW
) wc.hbrBackground GetStockObject (
WHITE_BRUSH
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BOOL InitApplication ( HANDLE hInstance )

• wc.lpszMenuName NULL
• wc.lpszClassName szAppName
• if ( !RegisterClass ( wc ) )
• return ( FALSE )
• return ( TRUE )

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STEP 2

• Initialize an Instance of the Application
• Write a function to do the following
• Assign the current instance to a global variable
  for use by other windows and dialog boxes in the
  program.
• Call the CreateWindow function, passing the App
  Name as specified in your class, the windows
  position and size, handles to parent and child
  windows and the handle to the current instance.
• If the window could not be created, return FALSE,
  otherwise call the ShowWindow function to display
  the window.

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BOOL InitInstance ( HANDLE hInstance, int
nCmdShow )

• hInst hInstance / assign instance to
  global variable /
• hWnd CreateWindow ( szAppName, / ClassName
  /
• My Window", / window title /
• WS_OVERLAPPEDWINDOW, / window style flag/
• 70, / horizontal position
  /
• 70, / vertical position
  /
• 500, / window width /
• 350, / window height /
• NULL, / handle of parent
  window /
• NULL, / handle of child or
  menu /
• hInstance, / handle of app
  instance /
• NULL ) / window creation
  data /
• if ( !hWnd ) / If window could not be created,
  return "failure /
• return ( FALSE )
• ShowWindow ( hWnd, nCmdShow ) / Show the
  window /
• return ( TRUE ) / Returns the
  value from PostQuitMessage /

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BACK IN MAIN

• Make Calls to Your InitApplication and
  InitInstance Functions.
• Write a Windows Message Loop that Continuously
  Checks for New Messages (such as the click of a
  mouse button or press of a key on the keyboard)
• When a Message is Received, the WNDCLASS Window
  you Created will Call the Window Procedure it
  points to (MainWndProc).

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STEP 3

• Handle the Windows Messages Received
• Write MainWndProc, which does the following
• Use nested switch constructs to handle valid
  windows messages expected by the main window.
• Makes calls to other procedures such as Dialog
  Box procedures, when necessary for handling
  messages to other resources.

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LRESULT CALLBACK MainWndProc ( HWND hWnd,
UINT message,WPARAM wParam, LPARAM
lParam )

• switch ( message )
• case WM_COMMAND / Menu Selection or Dialog
  Box Control /
• switch (wParam)
• case CM_EXIT / ID of the EXIT
  menu item /
• DestroyWindow ( hWnd )
• case CM_MESSAGE_TO_SCREEN / another menu
  item /
• MessageBox( hWnd, "Message Text",
  Message Title", MB_OK)
• default
• return ( DefWindowProc ( hWnd, message,
  wParam, lParam ) )
• default
• return ( DefWindowProc ( hWnd, message, wParam,
  lParam ) )

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WINDOWS MESSAGES

• WM_COMMAND - Sent as the result of a mouse click
  or key press.
• Carries as part of its structure, IDs of Menu
  Items, Buttons or Dialog Box Controls selected by
  the mouse or keyboard.
• Other messages can be sent to a window or dialog
  box by a call to a function inside the program
  telling the object to behave a certain way.

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FLAGS

• Determine Window Style or Behavior
• Can Be Grouped in a Single Call to a Creation
  Function in Order to Add Functionality to a
  Window
• hWnd CreateWindow ( szAppName, / ClassName
  /
• My Window", / window title /
• WS_OVERLAPPEDWINDOW, / window style flag/
• 70, / horizontal position
  /
• 70, / vertical position
  /
• 500, / window width /
  etc...
• Flags are Names for an Underlying Number
  Created with define in windows.h

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New Data Types

• MSG
• BOOL
• HWND
• HANDLE
• WNDCLASS

• LRESULT
• WPARAM
• LPARAM
• CALLBACK
• UINT

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New Files

• include ltwindows.hgt
• Resource Files .rc
• Custom Header Files .h

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New Classes

• WNDCLASS
• structure declaration (data type) in windows.h
• contains members and pointers to functions for a
  basic window.