windows 程序设计 System Metrics Display Program No. 3

/*----------------------------------------------------
   SYSMETS3.C -- System Metrics Display Program No. 3
                 (c) Charles Petzold, 1998
  ----------------------------------------------------*/

#define WINVER 0x0500
#include <windows.h>
#include "sysmets.h"

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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("SysMets3") ;
     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 ("Program requires Windows NT!"), 
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName, TEXT ("Get System Metrics No. 3"),
                          WS_OVERLAPPEDWINDOW | WS_VSCROLL | WS_HSCROLL,
                          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 int  cxChar, cxCaps, cyChar, cxClient, cyClient, iMaxWidth ;
     HDC         hdc ;
     int         i, x, y, iVertPos, iHorzPos, iPaintBeg, iPaintEnd ;
     PAINTSTRUCT ps ;
     SCROLLINFO  si ;
     TCHAR       szBuffer[10] ;
     TEXTMETRIC  tm ;
     
     switch (message)
     {
     case WM_CREATE:
          hdc = GetDC (hwnd) ;
          
          GetTextMetrics (hdc, &tm) ;
          cxChar = tm.tmAveCharWidth ;
          cxCaps = (tm.tmPitchAndFamily & 1 ? 3 : 2) * cxChar / 2 ;
          cyChar = tm.tmHeight + tm.tmExternalLeading ;
          
          ReleaseDC (hwnd, hdc) ;

               // Save the width of the three columns
          
          iMaxWidth = 40 * cxChar + 22 * cxCaps ;
          return 0 ;
          
     case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          cyClient = HIWORD (lParam) ;

               // Set vertical scroll bar range and page size

          si.cbSize = sizeof (si) ;
          si.fMask  = SIF_RANGE | SIF_PAGE ;
          si.nMin   = 0 ;
          si.nMax   = NUMLINES - 1 ;
          si.nPage  = cyClient / cyChar ;
          SetScrollInfo (hwnd, SB_VERT, &si, TRUE) ;

               // Set horizontal scroll bar range and page size

          si.cbSize = sizeof (si) ;
          si.fMask  = SIF_RANGE | SIF_PAGE ;
          si.nMin   = 0 ;
          si.nMax   = 2 + iMaxWidth / cxChar ;
          si.nPage  = cxClient / cxChar ;
          SetScrollInfo (hwnd, SB_HORZ, &si, TRUE) ;
          return 0 ;
          
     case WM_VSCROLL:
               // Get all the vertial scroll bar information

          si.cbSize = sizeof (si) ;
          si.fMask  = SIF_ALL ;
          GetScrollInfo (hwnd, SB_VERT, &si) ;

               // Save the position for comparison later on

          iVertPos = si.nPos ;

          switch (LOWORD (wParam))
          {
          case SB_TOP:
               si.nPos = si.nMin ;
               break ;
               
          case SB_BOTTOM:
               si.nPos = si.nMax ;
               break ;
               
          case SB_LINEUP:
               si.nPos -= 1 ;
               break ;
               
          case SB_LINEDOWN:
               si.nPos += 1 ;
               break ;
               
          case SB_PAGEUP:
               si.nPos -= si.nPage ;
               break ;
               
          case SB_PAGEDOWN:
               si.nPos += si.nPage ;
               break ;
               
          case SB_THUMBTRACK:
               si.nPos = si.nTrackPos ;
               break ;
               
          default:
               break ;         
          }
               // Set the position and then retrieve it.  Due to adjustments
               //   by Windows it may not be the same as the value set.

          si.fMask = SIF_POS ;
          SetScrollInfo (hwnd, SB_VERT, &si, TRUE) ;
          GetScrollInfo (hwnd, SB_VERT, &si) ;

               // If the position has changed, scroll the window and update it

          if (si.nPos != iVertPos)
          {                    
               ScrollWindow (hwnd, 0, cyChar * (iVertPos - si.nPos), 
                                   NULL, NULL) ;
               UpdateWindow (hwnd) ;
          }
          return 0 ;
          
     case WM_HSCROLL:
               // Get all the vertial scroll bar information

          si.cbSize = sizeof (si) ;
          si.fMask  = SIF_ALL ;

               // Save the position for comparison later on

          GetScrollInfo (hwnd, SB_HORZ, &si) ;
          iHorzPos = si.nPos ;

          switch (LOWORD (wParam))
          {
          case SB_LINELEFT:
               si.nPos -= 1 ;
               break ;
               
          case SB_LINERIGHT:
               si.nPos += 1 ;
               break ;
               
          case SB_PAGELEFT:
               si.nPos -= si.nPage ;
               break ;
               
          case SB_PAGERIGHT:
               si.nPos += si.nPage ;
               break ;
               
          case SB_THUMBPOSITION:
               si.nPos = si.nTrackPos ;
               break ;
               
          default :
               break ;
          }
               // Set the position and then retrieve it.  Due to adjustments
               //   by Windows it may not be the same as the value set.

          si.fMask = SIF_POS ;
          SetScrollInfo (hwnd, SB_HORZ, &si, TRUE) ;
          GetScrollInfo (hwnd, SB_HORZ, &si) ;
          
               // If the position has changed, scroll the window 

          if (si.nPos != iHorzPos)
          {
               ScrollWindow (hwnd, cxChar * (iHorzPos - si.nPos), 0, 
                             NULL, NULL) ;
          }
          return 0 ;

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

               // Get vertical scroll bar position

          si.cbSize = sizeof (si) ;
          si.fMask  = SIF_POS ;
          GetScrollInfo (hwnd, SB_VERT, &si) ;
          iVertPos = si.nPos ;

               // Get horizontal scroll bar position

          GetScrollInfo (hwnd, SB_HORZ, &si) ;
          iHorzPos = si.nPos ;

               // Find painting limits

          iPaintBeg = max (0, iVertPos + ps.rcPaint.top / cyChar) ;
          iPaintEnd = min (NUMLINES - 1,
                           iVertPos + ps.rcPaint.bottom / cyChar) ;
          
          for (i = iPaintBeg ; i <= iPaintEnd ; i++)
          {
               x = cxChar * (1 - iHorzPos) ;
               y = cyChar * (i - iVertPos) ;
               
               TextOut (hdc, x, y,
                        sysmetrics[i].szLabel,
                        lstrlen (sysmetrics[i].szLabel)) ;
               
               TextOut (hdc, x + 22 * cxCaps, y,
                        sysmetrics[i].szDesc,
                        lstrlen (sysmetrics[i].szDesc)) ;
               
               SetTextAlign (hdc, TA_RIGHT | TA_TOP) ;
               
               TextOut (hdc, x + 22 * cxCaps + 40 * cxChar, y, szBuffer,
                        wsprintf (szBuffer, TEXT ("%5d"),
                             GetSystemMetrics (sysmetrics[i].iIndex))) ;
               
               SetTextAlign (hdc, TA_LEFT | TA_TOP) ;
          }

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