showbit.c

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/*-----------------------------------------------------------
   SHOWBIT.C -- Shows bitmaps in BITLIB dynamic-link library
                (c) Charles Petzold, 1998
  -----------------------------------------------------------*/

#include <windows.h>

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

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

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 ("Show Bitmaps from BITLIB (Press Key)"),
                          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 ;
}

void DrawBitmap (HDC hdc, int xStart, int yStart, HBITMAP hBitmap)
{
     BITMAP bm ;
     HDC    hMemDC ;
     POINT  pt ;
     
     hMemDC = CreateCompatibleDC (hdc) ;
     SelectObject (hMemDC, hBitmap) ;
     GetObject (hBitmap, sizeof (BITMAP), &bm) ;
     pt.x = bm.bmWidth ;
     pt.y = bm.bmHeight ;
     
     BitBlt (hdc, xStart, yStart, pt.x, pt.y, hMemDC, 0, 0, SRCCOPY) ;
     
     DeleteDC (hMemDC) ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     static HINSTANCE hLibrary ;
     static int       iCurrent = 1 ;
     HBITMAP          hBitmap ;
     HDC              hdc ;
     PAINTSTRUCT      ps ;
     
     switch (message)
     {
     case WM_CREATE:
          if ((hLibrary = LoadLibrary (TEXT ("BITLIB.DLL"))) == NULL)
          {
               MessageBox (hwnd, TEXT ("Can't load BITLIB.DLL."),
                           szAppName, 0) ;
               return -1 ;
          }
          return 0 ;
          
     case WM_CHAR:
          if (hLibrary)
          {
               iCurrent ++ ;
               InvalidateRect (hwnd, NULL, TRUE) ;
          }
          return 0 ;
          
     case WM_PAINT:
          hdc = BeginPaint (hwnd, &ps) ;
          
          if (hLibrary)
          {
               hBitmap = LoadBitmap (hLibrary, MAKEINTRESOURCE (iCurrent)) ;

               if (!hBitmap) 
               {
                    iCurrent = 1 ;
                    hBitmap = LoadBitmap (hLibrary, 
                                          MAKEINTRESOURCE (iCurrent)) ;
               }
               if (hBitmap)
               {
                    DrawBitmap (hdc, 0, 0, hBitmap) ;
                    DeleteObject (hBitmap) ;
               }
          }
          EndPaint (hwnd, &ps) ;
          return 0 ;
          
     case WM_DESTROY:
          if (hLibrary)
               FreeLibrary (hLibrary) ;
          
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}