/*----------------------------------------
   SYSPAL2.C -- Displays system palette
                (c) Charles Petzold, 1998
  ----------------------------------------*/

#include <windows.h>

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

TCHAR szAppName [] = TEXT ("SysPal2") ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     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 ("This program requires Windows NT!"),
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName, TEXT ("System Palette #2"), 
                          WS_OVERLAPPEDWINDOW, 
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;

     if (!hwnd)
          return 0 ;

     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;

     while (GetMessage (&msg, NULL, 0, 0))
     {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
     }
     return msg.wParam ;
}

BOOL CheckDisplay (HWND hwnd)
{
     HDC hdc ;
     int iPalSize ;

     hdc = GetDC (hwnd) ;
     iPalSize = GetDeviceCaps (hdc, SIZEPALETTE) ;
     ReleaseDC (hwnd, hdc) ;

     if (iPalSize != 256)
     {
          MessageBox (hwnd, TEXT ("This program requires that the video ")
                            TEXT ("display mode have a 256-color palette."),
                      szAppName, MB_ICONERROR) ;
          return FALSE ;
     }
     return TRUE ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     static HPALETTE hPalette ;
     static int      cxClient, cyClient ;
     HBRUSH          hBrush ;
     HDC             hdc ;
     int             i, x, y ;
     LOGPALETTE    * plp ;
     PAINTSTRUCT     ps ;
     RECT            rect ;

     switch (message)
     {
     case WM_CREATE:
          if (!CheckDisplay (hwnd))
               return -1 ;

          plp = malloc (sizeof (LOGPALETTE) + 255 * sizeof (PALETTEENTRY)) ;

          plp->palVersion    = 0x0300 ;
          plp->palNumEntries = 256 ;

          for (i = 0 ; i < 256 ; i++)
          {
               plp->palPalEntry[i].peRed   = i ;
               plp->palPalEntry[i].peGreen = 0 ;
               plp->palPalEntry[i].peBlue  = 0 ;
               plp->palPalEntry[i].peFlags = PC_EXPLICIT ;
          }
          
          hPalette = CreatePalette (plp) ;
          free (plp) ;          
          return 0 ;
     
     case WM_DISPLAYCHANGE:
          if (!CheckDisplay (hwnd))
               DestroyWindow (hwnd) ;

          return 0 ;

     case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          cyClient = HIWORD (lParam) ;
          return 0 ;

     case WM_PAINT:
          hdc = BeginPaint (hwnd, &ps) ;

          SelectPalette (hdc, hPalette, FALSE) ;
          RealizePalette (hdc) ;

          for (y = 0 ; y < 16 ; y++)
          for (x = 0 ; x < 16 ; x++)
          {
               hBrush = CreateSolidBrush (PALETTEINDEX (16 * y + x)) ;
               SetRect (&rect, x      * cxClient / 16,  y      * cyClient / 16,
                              (x + 1) * cxClient / 16, (y + 1) * cyClient / 16);
               FillRect (hdc, &rect, hBrush) ;
               DeleteObject (hBrush) ;
          }
          EndPaint (hwnd, &ps) ;
          return 0 ;

     case WM_PALETTECHANGED:
          if ((HWND) wParam != hwnd)
               InvalidateRect (hwnd, NULL, FALSE) ;

          return 0 ;

     case WM_DESTROY:
          DeleteObject (hPalette) ;
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}