/*-------------------------------------------------
   CHECKER3.C -- Mouse Hit-Test Demo Program No. 3
                 (c) Charles Petzold, 1998
  -------------------------------------------------*/

#include <windows.h>

#define DIVISIONS 5

LRESULT CALLBACK WndProc   (HWND, UINT, WPARAM, LPARAM) ;
LRESULT CALLBACK ChildWndProc (HWND, UINT, WPARAM, LPARAM) ;

TCHAR szChildClass[] = TEXT ("Checker3_Child") ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("Checker3") ;
     HWND         hwnd ;
     MSG          msg ;
     WNDCLASS     wndclass ;
     
     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;
     
     if (!RegisterClass (&wndclass))
     {
          MessageBox (NULL, TEXT ("Program requires Windows NT!"), 
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     wndclass.lpfnWndProc   = ChildWndProc ;
     wndclass.cbWndExtra    = sizeof (long) ;
     wndclass.hIcon         = NULL ;
     wndclass.lpszClassName = szChildClass ;
     
     RegisterClass (&wndclass) ;
     
     hwnd = CreateWindow (szAppName, TEXT ("Checker3 Mouse Hit-Test Demo"),
                          WS_OVERLAPPEDWINDOW,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;
     
     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;
     
     while (GetMessage (&msg, NULL, 0, 0))
     {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
     }
     return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     static HWND hwndChild[DIVISIONS][DIVISIONS] ;
     int         cxBlock, cyBlock, x, y ;
     
     switch (message)
     {
     case WM_CREATE :
          for (x = 0 ; x < DIVISIONS ; x++)
               for (y = 0 ; y < DIVISIONS ; y++)
                    hwndChild[x][y] = CreateWindow (szChildClass, NULL,
                              WS_CHILDWINDOW | WS_VISIBLE,
                              0, 0, 0, 0,
                              hwnd, (HMENU) (y << 8 | x),
                              (HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE),
                              NULL) ;
          return 0 ;
               
     case WM_SIZE :
          cxBlock = LOWORD (lParam) / DIVISIONS ;
          cyBlock = HIWORD (lParam) / DIVISIONS ;
          
          for (x = 0 ; x < DIVISIONS ; x++)
                for (y = 0 ; y < DIVISIONS ; y++)
                    MoveWindow (hwndChild[x][y],
                                x * cxBlock, y * cyBlock,
                                cxBlock, cyBlock, TRUE) ;
          return 0 ;
               
     case WM_LBUTTONDOWN :
          MessageBeep (0) ;
          return 0 ;
          
     case WM_DESTROY :
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}

LRESULT CALLBACK ChildWndProc (HWND hwnd, UINT message, 
                               WPARAM wParam, LPARAM lParam)
{
     HDC         hdc ;
     PAINTSTRUCT ps ;
     RECT        rect ;
     
     switch (message)
     {
     case WM_CREATE :
          SetWindowLong (hwnd, 0, 0) ;       // on/off flag
          return 0 ;
          
     case WM_LBUTTONDOWN :
          SetWindowLong (hwnd, 0, 1 ^ GetWindowLong (hwnd, 0)) ;
          InvalidateRect (hwnd, NULL, FALSE) ;
          return 0 ;
          
     case WM_PAINT :
          hdc = BeginPaint (hwnd, &ps) ;
          
          GetClientRect (hwnd, &rect) ;
          Rectangle (hdc, 0, 0, rect.right, rect.bottom) ;
          
          if (GetWindowLong (hwnd, 0))
          {
               MoveToEx (hdc, 0,          0, NULL) ;
               LineTo   (hdc, rect.right, rect.bottom) ;
               MoveToEx (hdc, 0,          rect.bottom, NULL) ;
               LineTo   (hdc, rect.right, 0) ;
          }
          
          EndPaint (hwnd, &ps) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}