Function Prototypes

1
Function Prototypes

• include ltwindows.hgt
• LRESULT CALLBACK WndProc (HWND, UINT, WPARAM,
  
  LPARAM)
• Int WinAPI WinMain(HINSTANCE hInstance,
• HINSTANCE hPrevInstance,
• PSTR szCmdLine,
• int iCmdShow)

2
Variable Declarations

• static TCHAR szAppName TEXT(HelloWin)
• HWND hwnd
• MSG msg
• WNDCLASS wndclass

3
Fill in Class Characteristics

• wndclass.style CS_HREDRAW CS_VREDRAW
• wndclass.lpfnWndProc WndProc
• .
• wndclass.hInstance hInstance
• wndclass.hIcon LoadIcon(NULL,
  IDI_APPLICATION)
• wndclass.hCursor LoadCursor(NULL, ID_ARROW)
• wndclass.hbrBackground (HBRUSH)
• GetStockObject(WHITE_BRUSH)
• wndclass.lpszClassName szAppName //class name

4
Register Class

• if (!RegisterClass (wndclass))
• MessageBox (..)
• return 0

5
Create Window

• hwnd CreateWindow(szAppName, //set above
• TEXT(The Hello Program), //caption
• WS_OVERLAPPEDWINDOW, //style
• CW_USEDEFAULT, // initial x
  
• CW_USEDEFAULT, // initial y
• CW_USEDEFAULT, // initial x size
• CW_USEDEFAULT, // initial y size
• NULL, //parent window handle
• NULL, // window menu handle
• hInstance, // program instance
  handle
• NULL // creation parameters)

6
Display Window on Screen

• ShowWindow(hwnd, icmdShow) // normal,
  min, max
• UpdateWindow(hwnd) //Paint yourself.

7
Message Loop

• while (GetMessage (msg, NULL, 0, 0,)
• TranslateMessage(msg)
• DispatchMessage(msg)
• return (msg.wParam)
• // end of WinMain

8
Message Data Structure
typedef struct tagMSG HWND hwnd UINT
message WPARAM wParam LPARAM
lParam DWORD time POINT pt
MSG
9
Message Processing Function

• //Associated with window class.
• LRESULT CALLBACK WndProc(
• HWND hwnd,
• UINT message,
• WPARAM wParam,
• LPARAM lParam)

10
Variables in WndProc

• HDC hdc // window to receive msg.
• PAINTSTRUCT ps // Used by OS
• RECT rect // top, bottom, right, left
• // Determine if care about msg.

11
Message Handlers

• switch(message)
• case WM_CREATE
• PlaySound(TEXT(hellowin.wav),
• NULL, SND_FILENAME SND_ASYNC)
• return 0

12
WM_PAINT

• case WM_PAINT
• hdc BeginPaint(hwnd, ps)
• GetClientRect(hwnd, rect)
• DrawText(hdc, TEXT(Hello), -1, rect,
• DT_SINGLELINE DT_CENTER DT_VCENTER)
  
• EndPaint(hwnd, ps)
• return 0

13
Default Processing

• case WM_DESTROY //generated when user exits
• PostQuitMessage (0)
• return 0
• // END OF SWITCH
• return DefWindowProc(hwnd, message, wParam,
  lParam) // catches all messages not //
  processed in WndProc.