/*------------------------------------------
   RNDRCTMT.C -- Displays Random Rectangles
                 (c) Charles Petzold, 1998
  ------------------------------------------*/

#include <windows.h>
#include <process.h>

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

HWND hwnd ;
int  cxClient, cyClient ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("RndRctMT") ;
     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 ("This program requires Windows NT!"),
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName, TEXT ("Random Rectangles"),
                          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 ;
}

VOID Thread (PVOID pvoid)
{
     HBRUSH hBrush ;
     HDC    hdc ;
     int    xLeft, xRight, yTop, yBottom, iRed, iGreen, iBlue ;
     
     while (TRUE)
     {
          if (cxClient != 0 || cyClient != 0)
          {
               xLeft   = rand () % cxClient ;
               xRight  = rand () % cxClient ;
               yTop    = rand () % cyClient ;
               yBottom = rand () % cyClient ;
               iRed    = rand () & 255 ;
               iGreen  = rand () & 255 ;
               iBlue   = rand () & 255 ;
               
               hdc = GetDC (hwnd) ;
               hBrush = CreateSolidBrush (RGB (iRed, iGreen, iBlue)) ;
               SelectObject (hdc, hBrush) ;
               
               Rectangle (hdc, min (xLeft, xRight), min (yTop, yBottom),
                               max (xLeft, xRight), max (yTop, yBottom)) ;
               
               ReleaseDC (hwnd, hdc) ;
               DeleteObject (hBrush) ;
          }
     }
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     switch (message)
     {
     case WM_CREATE:
          _beginthread (Thread, 0, NULL) ;
          return 0 ;
          
     case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          cyClient = HIWORD (lParam) ;
          return 0 ;
          
     case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}