三、Windows键盘消息和字符集
本章剩下的范例程序有缺陷。它们不能在所有版本的Windows下都正常执行。这些缺陷不是特意引过程序代码中的；事实上，您也许永远不会遇到这些缺陷。只有在不同的键盘语言和键盘布局间切换，以及在多字节字符集的远东版Windows下执行程序时，这些问题才会出现－所以我不愿将它们称为「错误」。
不过，如果程序使用Unicode编译并在Windows NT下执行，那么程序会执行得更好。我在第二章提到过这个问题，并且展示了Unicode对简化棘手的国际化问题的重要性。
KEYVIEW1程序
了解键盘国际化问题的第一步，就是检查Windows传递给窗口消息处理程序的键盘内容和字符消息。程序6-2所示的KEYVIEW1会对此有所帮助。该程序在显示区域显示Windows向窗口消息处理程序发送的8种不同键盘消息的全部信息。
程序6-2 KEYVIEW1
KEYVIEW1.C
/*---------------------------------------------------------------------
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 ;
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 ; // i.e., 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) ;
}
KEYVIEW1显示窗口消息处理程序接收到的每次按键和字符消息的内容，并将这些消息储存在一个MSG结构的数组中。该数组的大小依据最大化窗口的大小和等宽的系统字体。如果使用者在程序执行时调整了视讯显示的大小（在这种情况下KEYVIEW1接收WM_DISPLAYCHANGE消息），将重新分配此数组。KEYVIEW1使用标准C的malloc函数为数组配置内存。
图6-2给出了在键入「Windows」之后KEYVIEW1的屏幕显示。第一列显示了键盘消息；第二列在键名称的前面显示了按键消息的虚拟键代码，此代码是经由GetKeyNameText函数取得的；第三列（标注为「Char」）在字符本身的后面显示字符消息的十六进制字符代码。其余六列显示了lParam消息参数中六个字段的状态。
为便于以分行的方式显示此信息，KEYVIEW1使用了等宽字体。与前一章所讨论的一样，这需要呼叫GetStockObject和SelectObject：
SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ;
SetBkMode (hdc, TRANSPARENT) ;
