VBdemo: C/C++ Version

Note how the Paste item on the top-level menu is enabled through the IDM_CUT menu handler with the EnableMenuItem() and DrawMenuBar() Windows API functions. We've already seen the EnableMenuItem() function in action, but DrawMenuBar() is new. When we change the top-level menu, Windows does not immediately redraw the menu bar, so we must call DrawMenuBar() to do this. If we didn't, the Paste menu item would be enabled but would still appear grayed out.

/****************************************************************************\
*                                                                            *
*  VBdemo.c                                                                  *
*                                                                            *
*  This program demonstrates how to copy the contents of one virtual buffer  *
*  to another, with and without transparent colors.                          *
*                                                                            *
\****************************************************************************/
#include <fgwin.h>
#include "VBdemo.h"
#define vbWidth  640
#define vbHeight 480
LRESULT CALLBACK WindowProc(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdParam, int iCmdShow)
{
   static char szAppName[] = "FGvbdemo";
   HWND        hWnd;
   MSG         msg;
   WNDCLASSEX  wndclass;
   wndclass.cbSize        = sizeof(wndclass);
   wndclass.style         = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
   wndclass.lpfnWndProc   = WindowProc;
   wndclass.cbClsExtra    = 0;
   wndclass.cbWndExtra    = 0;
   wndclass.hInstance     = hInstance;
   wndclass.hIcon         = LoadIcon(NULL,IDI_APPLICATION);
   wndclass.hCursor       = LoadCursor(NULL,IDC_ARROW);
   wndclass.hbrBackground = NULL;
   wndclass.lpszMenuName  = szAppName;
   wndclass.lpszClassName = szAppName;
   wndclass.hIconSm       = LoadIcon(NULL,IDI_APPLICATION);
   RegisterClassEx(&wndclass);
   hWnd = CreateWindow(szAppName, // window class name
      "Virtual Buffer Copy Demo", // window caption
      WS_OVERLAPPEDWINDOW,     // window style
      CW_USEDEFAULT,           // initial x position
      CW_USEDEFAULT,           // initial y position
      CW_USEDEFAULT,           // initial x size
      CW_USEDEFAULT,           // initial y size
      NULL,                    // parent window handle
      NULL,                    // window menu handle
      hInstance,               // program instance handle
      NULL);                   // creation parameters
   ShowWindow(hWnd,iCmdShow);
   UpdateWindow(hWnd);
   while (GetMessage(&msg,NULL,0,0))
   {
      TranslateMessage(&msg);
      DispatchMessage(&msg);
   }
   return msg.wParam;
}
/****************************************************************************\
*                                                                            *
*  WindowProc()                                                              *
*                                                                            *
\****************************************************************************/
HDC      hDC;
HMENU    hMenu;
HPALETTE hPal;
int      hVB1, hVB2;
UINT     cxClient, cyClient;
LRESULT CALLBACK WindowProc(HWND hWnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
   PAINTSTRUCT ps;
   switch (iMsg)
   {
      case WM_CREATE:
         hDC = GetDC(hWnd);
         fg_setdc(hDC);
         hPal = fg_defpal();
         fg_realize(hPal);
         fg_vbinit();
         hVB2 = fg_vballoc(vbWidth,vbHeight);
         fg_vbopen(hVB2);
         fg_vbcolors();
         hVB1 = fg_vballoc(vbWidth,vbHeight);
         fg_vbopen(hVB1);
         fg_vbcolors();
         fg_setcolor(25);
         fg_fillpage();
         fg_setcolor(20);
         fg_rect(vbWidth/4,vbWidth*3/4,vbHeight/4,vbHeight*3/4);
         hMenu = GetMenu(hWnd);
         return 0;
      case WM_COMMAND:
         switch (wParam)
         {
            case IDM_Cut:
               fg_vbcopy(0,vbWidth-1,0,vbHeight-1,0,vbHeight-1,hVB1,hVB2);
               fg_erase();
               fg_vbscale(0,vbWidth-1,0,vbHeight-1,0,cxClient-1,0,cyClient-1);
               EnableMenuItem(hMenu,IDM_Paste,MF_ENABLED);
               DrawMenuBar(hWnd);
               return 0;
            case IDM_Paste:
               fg_tcdefine(25,1);
               fg_vbtccopy(0,vbWidth-1,0,vbHeight-1,0,vbHeight-1,hVB2,hVB1);
               fg_vbscale(0,vbWidth-1,0,vbHeight-1,0,cxClient-1,0,cyClient-1);
               return 0;
            case IDM_Exit:
               DestroyWindow(hWnd);
               return 0;
         }
         break;
      case WM_PAINT:
         BeginPaint(hWnd,&ps);
         fg_vbscale(0,vbWidth-1,0,vbHeight-1,0,cxClient-1,0,cyClient-1);
         EndPaint(hWnd,&ps);
         return 0;
      case WM_SETFOCUS:
         fg_realize(hPal);
         InvalidateRect(hWnd,NULL,TRUE);
         return 0;
      case WM_SIZE:
         cxClient = LOWORD(lParam);
         cyClient = HIWORD(lParam);
         return 0;
      case WM_DESTROY:
         fg_vbclose();
         fg_vbfree(hVB1);
         fg_vbfree(hVB2);
         fg_vbfin();
         DeleteObject(hPal);
         ReleaseDC(hWnd,hDC);
         PostQuitMessage(0);
         return 0;
   }
   return DefWindowProc(hWnd,iMsg,wParam,lParam);
}