Windows Programming Basics

Notations

• b: BOOL, int
• by: byte
• c:char
• dw:DWORD, unsigned long
• fn:function
• h:handle, int
• i:int
• l:long
• lp:long pointer
• n:int
• p:pointer
• s:string
• sz:a zero terminated string
• w:WORD, unsigned short

WinMain()

• Function signature:
int WINAPI WinMain (HINSTANCE hInstance,
HINSTANCE hPreInstance, // Always NULL
LPSTR lpCmdLine,
int nCmdShow // e.g. SW_SHOWNORMAL, SW_SHOWHIDE );

• WINAPI specifier 
  • Required by Windows
• Need to include window.h

Create a simple Window

• Specifying a program window with WNDCLASS struct (or WNDCLASSEX)
  struct WNDCLASS{
UINT style; // Window style
WNDPROC lpfnWndProc; // Pointer to message processing fxn
int cbClsExtra; // Extra byte after window class
int cbWndExtra; // Extra byte after win instance
HINSTANCE hInstance; // App handle
HICON hIcon; // App icon when minimized
HCURSOR hCursor; // Win cursor
HBRUSH hbrBackground; // Background color
LPCTSTR lpszMenuName; // Pointer to menu resource name. 0 if none
LPCTSTR lpszClassName; // Pointer to class name
};

• Register WNDCLASS
  RegisterClass(&WinClass);
// Or RegisterClassEx(&WindClassEx);
• Create window with CreateWindow():
  HWND hWnd; // Window handle...hWnd = CreateWindow(
szAppName, // the window class name
"A Basic Window the Hard Way", // The window title
WS_OVERLAPPEDWINDOW, // Window style as overlapped
CW_USEDEFAULT, // Default screen position of upper left
CW_USEDEFAULT, // corner of our window as x,y...
CW_USEDEFAULT, // Default window size, width...
CW_USEDEFAULT, // ...and height
0, // No parent window
0, // No menu
hInstance, // Program Instance handle
0 // No window creation data
);
• Show window:ShowWindow(hWnd, nCmdShow);
• Update window:UpdateWindow(hWnd);
• Handle messages
  MSG msg; // Windows message structure
while(GetMessage(&msg, 0, 0, 0) == TRUE) // Get any messages
{
TranslateMessage(&msg); // Translate the message
DispatchMessage(&msg); // Dispatch the message to WindowProc()
}
• Message processing function:
  long CALLBACK WindowProc(
HWND hWnd, // Window handle where message originated fromUINT msg, // message id
WPARAM wParam, // 32 bit value with addtional info
LPARAM lParam // another 32 bit value
);

  • Decoding windows message
    switch(message)
{
case WM_PAINT:
// Code to deal with drawing the client area
break;case WM_LBUTTONDOWN:
// Code to deal with the left mouse button being pressed
break;
case WM_LBUTTONUP:
// Code to deal with the left mouse button being released
break;
case WM_DESTROY:
// Code to deal with a window being destroyed
break;
default:
// Code to handle any other messages
}
    • Default message processing 
      default:
  return DefWindowProc(hWnd, message, wParam, lParam);
    • End program case WM_DESTROY: // Window is being destroyed  PostQuitMessage(0);  return 0;

Example:
// OFWIN.CPP Native windows program to display text in a window
#include long CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);// Listing OFWIN_1
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
  LPSTR lpCmdLine, int nCmdShow)
{
  WNDCLASS WindowClass; // Structure to hold our window's attributesstatic char szAppName[] = "OFWin"; // Define window class name
  HWND hWnd; // Window handle
  MSG msg; // Windows message structure// Redraw the window if the size changes
  WindowClass.style = CS_HREDRAW | CS_VREDRAW;// Define our procedure for message handling
  WindowClass.lpfnWndProc = WindowProc;WindowClass.cbClsExtra = 0; // No extra bytes after the window class
  WindowClass.cbWndExtra = 0; // structure or the window instanceWindowClass.hInstance = hInstance; // Application instance handle