keyview1.c

键盘 键盘 键盘 键盘 键盘 键盘 键盘 键盘 键盘 键盘 键盘 键盘

/*--------------------------------------------------------
   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") } ;
	       //这是输出格式控制.

     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://屏幕的显示分辨率改变时会产生该消息,相关参数:wParam(颜色位数)
			   //LOWORD(lParam)水平分辨率
			   //HIWORD(lParam)垂直分辨率
     //显示分辨率被调整的信息,在分辨率被改变的情况下重新释放消息内存数组,并为消息数组重新分配内存空间.
               // Get maximum size of client area

          cxClientMax = GetSystemMetrics (SM_CXMAXIMIZED) ;
          cyClientMax = GetSystemMetrics (SM_CYMAXIMIZED) ;
	  //在windows环境下,各种显示分辨率可能导致屏幕超出比例显示,GetSystemMetrics
	  //可获得窗口显示各种元素的宽度和高度.

              // Get character size for fixed-pitch font

          hdc = GetDC (hwnd) ;

          SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ;
	  //得到等宽字体的句柄,并将等宽字体选入设备描述表.
          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 = (PMSG)malloc(cLinesMax * sizeof (MSG)) ;
	  //让pmsg指向一个能存放最大字符行数个的消息的内存空间
	  /*malloc:allocate memory blocks.
	  void * malloc(
		size_t size
	  );
	  size:Bytes to allocate.给被分配的空间返回一个void指针,当没有足够内存能用使返回NULL.
	  */
          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
	  //如果cLinesMax为9,即pms消息数组可以存放9条消息
          //将原来数组前下标0到7的8条消息重新存放至1到8下标的储存区内
	  //新消息放至0下标处,模拟了一个队列
	  //FIFO--先进先出的队列模型
          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) ;
	  //第2个参数是横向滚动的单位.第三个是纵向的.第四个指向要滚动的客户区的RECT结构体的那一部分.
          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], //消息
			     //[]中表示的是消息的下标.右键查看WM_KEYFIRST会有定义它的值.

			     //WM_KEYFIRST:键盘消息的消息过滤.同WM_KEYLAST
			     //这两个消息的wParam和lParam参数全是0.
                             pmsg[i].wParam, //虚拟键代码
                             (PTSTR) (iType ? TEXT (" ") : szKeyName),  
                             (TCHAR) (iType ? pmsg[i].wParam : ' '),    //显示字符值
                             LOWORD (pmsg[i].lParam),                   //重复次数
                             HIWORD (pmsg[i].lParam) & 0xFF,		//OEM键盘扫描码

                             0x01000000 & pmsg[i].lParam ? szYes  : szNo,//判断是否为增强键盘的扩展键

                             0x20000000 & pmsg[i].lParam ? szYes  : szNo,//判断是否同时使用了ALT键

                             0x40000000 & pmsg[i].lParam ? szDown : szUp,//判断前一次击键状

                             0x80000000 & pmsg[i].lParam ? szUp   : szDown)) ;//判断转换状态
          }
          EndPaint (hwnd, &ps) ;
          return 0 ;
                                                                                                                           
     case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}