windows程序設計POEMOEM.c解析與錯誤修改

/*-------------------------------------------
   POEPOEM.C -- Demonstrates Custom Resource
                (c) Charles Petzold, 1998
  -------------------------------------------*/

#include <windows.h>
#include "resource.h"
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

HINSTANCE hInst ;  //定義一個全局的實例句柄

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     TCHAR    szAppName [16], szCaption [64], szErrMsg [64] ;
     HWND     hwnd ;
     MSG      msg ;
     WNDCLASS wndclass ;
    

     LoadString (hInstance, IDS_APPNAME, szAppName,
                            sizeof (szAppName) / sizeof (TCHAR)) ;   //加載字符串

     LoadString (hInstance, IDS_CAPTION, szCaption,
                            sizeof (szCaption) / sizeof (TCHAR)) ;

  hInst = hInstance;  //給全局實例句柄賦值
       
     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (hInstance, POEPOEM) ;  //加載圖標
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;
    
     if (!RegisterClass (&wndclass))
     {
          LoadStringA (hInstance, IDS_APPNAME, (char *) szAppName,
                                  sizeof (szAppName)) ;

          LoadStringA (hInstance, IDS_ERRMSG, (char *) szErrMsg,
                                   sizeof (szErrMsg)) ;

          MessageBoxA (NULL, (char *) szErrMsg,
                             (char *) szAppName, MB_ICONERROR) ;
          return 0 ;
     }
    

     hwnd = CreateWindow (szAppName, szCaption,
                          WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN,  //WS_CLIPCHILDREN與父窗口有關
                          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 char  * pText ;
     static HGLOBAL hResource ;
     static HWND    hScroll ;
     static int     iPosition, cxChar, cyChar, cyClient, iNumLines, xScroll ;
     HDC            hdc ;
     PAINTSTRUCT    ps ;
     RECT           rect ;
     TEXTMETRIC     tm ;

     switch (message)
     {
     case WM_CREATE :
          hdc = GetDC (hwnd) ;
          GetTextMetrics (hdc, &tm) ;
          cxChar = tm.tmAveCharWidth ;
          cyChar = tm.tmHeight + tm.tmExternalLeading ;
          ReleaseDC (hwnd, hdc) ;
         
          xScroll = GetSystemMetrics (SM_CXVSCROLL) ;
          //創建一個垂直滾動條
          hScroll = CreateWindow (TEXT ("scrollbar"), NULL,
                                  WS_CHILD | WS_VISIBLE | SBS_VERT,
                                  0, 0, 0, 0,
                                  hwnd, (HMENU) 1, hInst, NULL) ;
          //加載自定義的資源，該資源內容由定義
          hResource = LoadResource (hInst,   
     FindResource (hInst, MAKEINTRESOURCE(ANNABELLEE),
                                           TEXT("TEXT"))
             ) ;          //加載自定義資源

         
          pText = (char *) LockResource (hResource) ;  //鎖定自定義資源
          iNumLines = 0 ;       //行數
         
          while (*pText != '\\' && *pText != '\0')
          {
               if (*pText == '\n')
                    iNumLines ++ ;
               pText = AnsiNext (pText) ;
          }
          *pText = '\0' ;
         
          SetScrollRange (hScroll, SB_CTL, 0, iNumLines, FALSE) ;
          SetScrollPos   (hScroll, SB_CTL, 0, FALSE) ;
          return 0 ;
         
     case WM_SIZE :

//指定子窗口（滾動條的位置）
          MoveWindow (hScroll, LOWORD (lParam) - xScroll, 0,
                      xScroll, cyClient = HIWORD (lParam), TRUE) ;
          SetFocus (hwnd) ;
          return 0 ;
         
     case WM_SETFOCUS :
          SetFocus (hScroll) ;
          return 0 ;
         
     case WM_VSCROLL :

//處理滾動條消息
          switch (LOWORD(wParam))
          {
          case SB_TOP :
               iPosition = 0 ;
               break ;
          case SB_BOTTOM :
               iPosition = iNumLines ;
               break ;
          case SB_LINEUP :
               iPosition -= 1 ;
               break ;
          case SB_LINEDOWN :
               iPosition += 1 ;
               break ;
          case SB_PAGEUP :
               iPosition -= cyClient / cyChar ;
               break ;
          case SB_PAGEDOWN :
               iPosition += cyClient / cyChar ;
               break ;
          case SB_THUMBPOSITION :
               iPosition = HIWORD (wParam) ;
               break ;
          }
          iPosition = max (0, min (iPosition, iNumLines)) ;
         
          if (iPosition != GetScrollPos (hScroll, SB_CTL))
          {
               SetScrollPos (hScroll, SB_CTL, iPosition, TRUE) ;
               InvalidateRect (hwnd, NULL, TRUE) ;
          }
          return 0 ;
         
     case WM_PAINT :
          hdc = BeginPaint (hwnd, &ps) ;
              
          pText = (char *) LockResource (hResource) ;   //鎖定資源
   
          GetClientRect (hwnd, &rect) ;
          rect.left += cxChar ;
          rect.top  += cyChar * (1 - iPosition) ;
          DrawTextA (hdc, pText, -1, &rect, DT_EXTERNALLEADING); //pttext爲執行該資源的指針，DT_EXTERNALLEADING可加入外部字體的高度

          EndPaint (hwnd, &ps) ;
          return 0 ;
              
     case WM_DESTROY :
          FreeResource (hResource) ;
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}