《programming windows》中的一个错误
这是WINDOWS程序设计里第6章鼠标测试里的一段代码，我想测试一下WM_SETFOCUS消息的触发条件，就在父窗口的消息处理函数里的WM_SETFOCUS后面加了几行代码，结果确在弹出一个窗口后点确定又会弹出，如此一共会弹出16个，这是什么意思啊，难道父窗口里产生了16个WM_SETFOCUS消息？或者是我对窗口的某些操作导致它又产生了WM_SETFOCUS消息？还有就是为什么子窗口创建后再点击子窗口，父窗口没有接收到WM_SETFOCUS消息?
我记得programming windows上的原话是"实际上当你在子窗口上单击的时候,情况有些复杂,这是是父窗口而不是自窗口获取焦点"难道说这句话有问题？
#include <windows.h>
#define DIVISIONS 5
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
LRESULT CALLBACK ChildWndProc (HWND, UINT, WPARAM, LPARAM) ;
int idFocus = 0 ;
TCHAR szChildClass[] = TEXT ("Checker4_Child") ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("Checker4") ;
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 ;
}
wndclass.lpfnWndProc = ChildWndProc ;
wndclass.cbWndExtra = sizeof (long) ;
wndclass.hIcon = NULL ;
wndclass.lpszClassName = szChildClass ;
RegisterClass (&wndclass) ;
hwnd = CreateWindow (szAppName, TEXT ("Checker4 Mouse Hit-Test Demo"),
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 HWND hwndChild[DIVISIONS][DIVISIONS] ;
int cxBlock, cyBlock, x, y ;
HWND hwnd1;
switch (message)
{
case WM_CREATE :
for (x = 0 ; x < DIVISIONS ; x++)
for (y = 0 ; y < DIVISIONS ; y++)
hwndChild[x][y] = CreateWindow (szChildClass, NULL,
WS_CHILDWINDOW | WS_VISIBLE,
0, 0, 0, 0,
hwnd, (HMENU) (y << 8 | x),
HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE),
NULL) ;
return 0 ;
case WM_SIZE :
cxBlock = LOWORD (lParam) / DIVISIONS ;
cyBlock = HIWORD (lParam) / DIVISIONS ;
for (x = 0 ; x < DIVISIONS ; x++)
for (y = 0 ; y < DIVISIONS ; y++)
MoveWindow ( hwndChild[x][y],
x * cxBlock, y * cyBlock,
cxBlock, cyBlock, TRUE) ;
return 0 ;
case WM_LBUTTONDOWN :
MessageBeep (0) ;
return 0 ;
// On set-focus message, set focus to child window
case WM_SETFOCUS:
hwnd1=SetFocus (GetDlgItem (hwnd, idFocus)) ;
wsprintf((LPWSTR)buffer,L"%d",hwnd1)
MessageBox(hwnd,(LPCWSTR)buffer,(LPCWSTR)"",NULL);
return 0 ;
// On key-down message, possibly change the focus window
case WM_KEYDOWN:
x = idFocus & 0xFF ;
y = idFocus >> 8 ;
switch (wParam)
{
case VK_UP: y-- ; break ;
case VK_DOWN: y++ ; break ;
case VK_LEFT: x-- ; break ;
case VK_RIGHT: x++ ; break ;
case VK_HOME: x = y = 0 ; break ;
case VK_END: x = y = DIVISIONS - 1 ; break ;
default: return 0 ;
}
x = (x + DIVISIONS) % DIVISIONS ;
y = (y + DIVISIONS) % DIVISIONS ;
idFocus = y << 8 | x ;
SetFocus (GetDlgItem (hwnd, idFocus)) ;
return 0 ;
case WM_DESTROY :
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}
LRESULT CALLBACK ChildWndProc (HWND hwnd, UINT message,
WPARAM wParam, LPARAM lParam)
{
HDC hdc ;
PAINTSTRUCT ps ;
RECT rect ;
switch (message)
{
case WM_CREATE :
SetWindowLong (hwnd, 0, 0) ; // on/off flag
return 0 ;
case WM_KEYDOWN:
// Send most key presses to the parent window
if (wParam != VK_RETURN && wParam != VK_SPACE)
{
SendMessage (GetParent (hwnd), message, wParam, lParam) ;
return 0 ;
}
// For Return and Space, fall through to toggle the square
case WM_LBUTTONDOWN :
SetWindowLong (hwnd, 0, 1 ^ GetWindowLong (hwnd, 0)) ;
SetFocus (hwnd) ;
InvalidateRect (hwnd, NULL, FALSE) ;
return 0 ;
// For focus messages, invalidate the window for repaint
case WM_SETFOCUS:
idFocus = GetWindowLong (hwnd, GWL_ID) ;
// Fall through
case WM_KILLFOCUS:
InvalidateRect (hwnd, NULL, TRUE) ;
return 0 ;
case WM_PAINT :
hdc = BeginPaint (hwnd, &ps) ;
GetClientRect (hwnd, &rect) ;
Rectangle (hdc, 0, 0, rect.right, rect.bottom) ;
// Draw the "x" mark
if (GetWindowLong (hwnd, 0))
{
MoveToEx (hdc, 0, 0, NULL) ;
LineTo (hdc, rect.right, rect.bottom) ;
MoveToEx (hdc, 0, rect.bottom, NULL) ;
LineTo (hdc, rect.right, 0) ;
}
// Draw the "focus" rectangle
if (hwnd == GetFocus ())
{
rect.left += rect.right / 10 ;
rect.right -= rect.left ;
rect.top += rect.bottom / 10 ;
rect.bottom -= rect.top ;
SelectObject (hdc, GetStockObject (NULL_BRUSH)) ;
SelectObject (hdc, CreatePen (PS_DASH, 0, 0)) ;
Rectangle (hdc, rect.left, rect.top, rect.right, rect.bottom) ;
DeleteObject (SelectObject (hdc, GetStockObject (BLACK_PEN))) ;
}
EndPaint (hwnd, &ps) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}
[解决办法]
我没有测试你的代码，但我看了一下，你在窗口的某个控件获得焦点时就会弹出一个信息框。这样做会使原来的对话框上的控件失去焦点，当你点信息框的确定关闭信息框后，焦点又重回到了原来的那个控件，那样应该再次触发WM_SETFOCUS才对，以此推理，在弹出这个信息框后应该进入一个死循环而不是16个才对。
我建一个win32工程试一下你的代码。
[解决办法]
在VC6.0里有一个小工具叫SPY++,你用他看窗口收到了多少SETFOCUS不就行了吗!
