windows程序设计 之 「KeyView1」范例算法分析 笔记

程序源代码如下:

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

#include <windows.h>

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 ;  //窗口最大化时显示字符行
          pmsg = (PMSG)malloc (cLinesMax * sizeof (MSG)) ;
          cLines = 0 ;
                                   // fall through  连续执行下面一个标签
     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) ;  // 取(cyClient / cyChar)整数

 

          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--)
          {
                // 丢弃最后一个结构中的数据，预留第一个结构。
                // 可以这样理解，把全部结构数据向后顺移一位。
               pmsg[i] = pmsg[i - 1] ;
          }

               // Store new message

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

 

              //有按键消息来时，cLines加1，最大不超过窗口最大化时显示字符行
          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)) ;

 

             //因为两个字符串绘画坐标一样，必须设定透明模式以防止第二个字符串擦除第一个字符串
          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++)
          {

                    //如果是字符消息则标记 1 ，如果是按键消息则标记 0
               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],

               //计算得出消息类型，并索引。
                             szMessage [pmsg[i].message - WM_KEYFIRST],

               //如果是按键消息就输出虚拟键代码，显示为十进制有符号整数，宽度为3个字符。
               //如果是字符消息就输出ANSI或Unicode字符代码，显示为大写十六进制数，宽度为4个字符，空白处用 0 填充。
                             pmsg[i].wParam,

               //如果是按键消息就输出键名(szKeyName),并采用左对齐，宽度为15个字符。
               //如果是字符消息就输出空格，宽度为1个字符。
                             (PTSTR) (iType ? TEXT (" ") : szKeyName),

              // 如果是按键消息就输出空格。
              // 如果是字符消息就输出该字符。pmsg[i].wParam = wParam （字符的对应编码，使用强制类型转换得到相应字符）
                             (TCHAR) (iType ? pmsg[i].wParam : ' '),

             //低十六位记录着按键的重复计数次数。用十进制方式显示为无符号整数，宽度为6个字符。
                             LOWORD (pmsg[i].lParam),

            //取高十六位中的低八位，解释为键盘扫描码(OEM),显示为十进制有符号整数，宽度为4个字符。
                             HIWORD (pmsg[i].lParam) & 0xFF,

            // 0000 0001 0000 0000 0000 0000 0000 0000 读取 扩充键旗标(Extended Key Flag) 状态。
                             0x01000000 & pmsg[i].lParam ? szYes  : szNo,

            // 0010 0000 0000 0000 0000 0000 0000 0000 读取 内容代码(Context Code) 状态。
                             0x20000000 & pmsg[i].lParam ? szYes  : szNo,

           // 0100 0000 0000 0000 0000 0000 0000 0000 读取 键的先前状态(Previous Key State)
                             0x40000000 & pmsg[i].lParam ? szDown : szUp,

           // 1000 0000 0000 0000 0000 0000 0000 0000 读取 转换状态(Transition State)
                             0x80000000 & pmsg[i].lParam ? szUp   : szDown)) ;
          }
          EndPaint (hwnd, &ps) ;
          return 0 ;

 

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