windows程序设计键盘问题 10C

/*--------------------------------------------------------
KEYVIEW1.C -- Displays Keyboard and Character Messages
(c) Charles Petzold, 1998
--------------------------------------------------------*/

#include

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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("KeyView1") ;
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 ("Keyboard Message Viewer #1"),
                      WS_OVERLAPPEDWINDOW,
                      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 cxClientMax, cyClientMax, cxClient, cyClient, cxChar, cyChar ;
static int cLinesMax, cLines ;
static PMSG pmsg ;
static RECT rectScroll ;
static TCHAR szTop[] = TEXT ("Message Key Char ")
TEXT ("Repeat Scan Ext ALT Prev Tran") ;
static TCHAR szUnd[] = TEXT ("_______ ___ ____ ")
TEXT ("______ ____ ___ ___ ____ ____") ;

 static TCHAR * szFormat[2] = { 

           TEXT ("%-13s %3d %-15s%c%6u %4d %3s %3s %4s %4s"),
           TEXT ("%-13s            0x%04X%1s%c %6u %4d %3s %3s %4s %4s") } ;

 static TCHAR * szYes  = TEXT ("Yes") ;
 static TCHAR * szNo   = TEXT ("No") ;
 static TCHAR * szDown = TEXT ("Down") ;
 static TCHAR * szUp   = TEXT ("Up") ;

 static TCHAR * szMessage [] = { 
                     TEXT ("WM_KEYDOWN"),    TEXT ("WM_KEYUP"), 
                     TEXT ("WM_CHAR"),       TEXT ("WM_DEADCHAR"), 
                     TEXT ("WM_SYSKEYDOWN"), TEXT ("WM_SYSKEYUP"), 
                     TEXT ("WM_SYSCHAR"),    TEXT ("WM_SYSDEADCHAR") } ;
 HDC          hdc ;
 int          i, iType ;
 PAINTSTRUCT  ps ;
 TCHAR        szBuffer[128], szKeyName [32] ;
 TEXTMETRIC   tm ;

 switch (message)
 {
 case WM_CREATE:
 case WM_DISPLAYCHANGE:

           // Get maximum size of client area

      cxClientMax = GetSystemMetrics (SM_CXMAXIMIZED) ;
      cyClientMax = GetSystemMetrics (SM_CYMAXIMIZED) ;

          // Get character size for fixed-pitch font

      hdc = GetDC (hwnd) ;

      SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ;
      GetTextMetrics (hdc, &tm) ;
      cxChar = tm.tmAveCharWidth ;
      cyChar = tm.tmHeight ;

      ReleaseDC (hwnd, hdc) ;

           // Allocate memory for display lines

      if (pmsg)
           free (pmsg) ;

      cLinesMax = cyClientMax / cyChar ;
      pmsg = malloc (cLinesMax * sizeof (MSG)) ;
      cLines = 0 ;
                               // fall through
 case WM_SIZE:
      if (message == WM_SIZE)
      {
           cxClient = LOWORD (lParam) ;
           cyClient = HIWORD (lParam) ;
      }
           // Calculate scrolling rectangle

      rectScroll.left   = 0 ;
      rectScroll.right  = cxClient ;
      rectScroll.top    = cyChar ;
      rectScroll.bottom = cyChar * (cyClient / cyChar) ;

      InvalidateRect (hwnd, NULL, TRUE) ;
      return 0 ;

 case WM_KEYDOWN:
 case WM_KEYUP:
 case WM_CHAR:
 case WM_DEADCHAR:
 case WM_SYSKEYDOWN:
 case WM_SYSKEYUP:
 case WM_SYSCHAR:
 case WM_SYSDEADCHAR: 

           // Rearrange storage array

      for (i = cLinesMax - 1 ; i > 0 ; i--)
      {
           pmsg[i] = pmsg[i - 1] ;
      }
           // Store new message

      pmsg[0].hwnd = hwnd ;
      pmsg[0].message = message ;
      pmsg[0].wParam = wParam ;
      pmsg[0].lParam = lParam ;

      cLines = min (cLines + 1, cLinesMax) ;

           // Scroll up the display

      ScrollWindow (hwnd, 0, -cyChar, &rectScroll, &rectScroll) ;

      break ;        // ie, call DefWindowProc so Sys messages work

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

      SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ;
      SetBkMode (hdc, TRANSPARENT) ;
      TextOut (hdc, 0, 0, szTop, lstrlen (szTop)) ;
      TextOut (hdc, 0, 0, szUnd, lstrlen (szUnd)) ;

      for (i = 0 ; i < min (cLines, cyClient / cyChar - 1) ; i++)
      {
           iType = pmsg[i].message == WM_CHAR ||
                   pmsg[i].message == WM_SYSCHAR ||
                   pmsg[i].message == WM_DEADCHAR ||
                   pmsg[i].message == WM_SYSDEADCHAR ;

           GetKeyNameText (pmsg[i].lParam, szKeyName, 
                           sizeof (szKeyName) / sizeof (TCHAR)) ;

           TextOut (hdc, 0, (cyClient / cyChar - 1 - i) * cyChar, szBuffer,
                    wsprintf (szBuffer, szFormat [iType],
                         szMessage [pmsg[i].message - WM_KEYFIRST],                   
                         pmsg[i].wParam,
                         (PTSTR) (iType ? TEXT (" ") : szKeyName),
                         (TCHAR) (iType ? pmsg[i].wParam : ' '),
                         LOWORD (pmsg[i].lParam),
                         HIWORD (pmsg[i].lParam) & 0xFF,
                         0x01000000 & pmsg[i].lParam ? szYes  : szNo,
                         0x20000000 & pmsg[i].lParam ? szYes  : szNo,
                         0x40000000 & pmsg[i].lParam ? szDown : szUp,
                         0x80000000 & pmsg[i].lParam ? szUp   : szDown)) ;
      }
      EndPaint (hwnd, &ps) ;
      return 0 ;

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

}
以上的代码是windows程序设计第六章KEYVIEW1的代码,在网上查过资料后发现scrollwindow函数实际上是根据参数的滚动范围 算出 不会滚出显示区域的矩形,对这部分像素直接BitBlt到新的合适位置,对于滚动出现的矩形,擦除背景,设该矩形为无效区域,那么我觉得因为这里滚动的值是-cychar,也就是滚动一行,那么我认为无效区域就是最下面的一行,于是我将源程序修改了下,将wm_paint函数下 for (i = 0 ; i < min (cLines, cyClient / cyChar - 1) ; i++)去掉,(当然括弧也去掉)将所有pmsg【i】修改为pmsg[0], TextOut (hdc, 0, (cyClient / cyChar - 1 - i) * cyChar, szBuffer,修改为TextOut (hdc, 0, (cyClient / cyChar - 1) * cyChar, szBuffer,然后运行,发现发送消息时,比如按a,消息排序应该是wm_keydown,wm_char,wm_keyup,但是显示出来的没有wm_keydown,那一行是空白,如图,我按得是q、e、r和F1,效果就是这样,请知道的告诉下为什么,谢谢了图片说明

2个回答

这里要说明一下,显示区域是相对于屏幕的,一个矩形的显示区域内容向上或向下滚动一行,实际上是整个矩形内的所有内容都需要重绘的。
向上滚动一行,上边一行隐藏了,下边一行显示了,但相对于屏幕而言矩形内的所有内容的位置都变了。

但现在的问题是,如果我按下的字符产生的消息是2个的话,比如按下F1,就只是发送keydown和keyup的消息显示是正常的,如果是三个消息,比如按下a,keydown那一行就是空白,只有char和keyup能显示,如果忽略char消息,keydown消息就又能显示出来,这是什么原因呢

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