windows窗口消息内部处理机制

LRESULT WINAPI
RealDefWindowProcA(HWND hWnd,
                   UINT Msg,
                   WPARAM wParam,
                   LPARAM lParam)
{
    LRESULT Result = 0;
    PWND Wnd;

    //    spy++的入口
    SPY_EnterMessage(SPY_DEFWNDPROC, hWnd, Msg, wParam, lParam);

    switch (Msg)
    {
        case WM_NCCREATE:
        {
            if (lParam)
            {
                LPCREATESTRUCTA cs = (LPCREATESTRUCTA)lParam;
                /* check for string, as static icons, bitmaps (SS_ICON, SS_BITMAP)
                 * may have child window IDs instead of window name */
                if (HIWORD(cs->lpszName))
                {
                    //    这个和setwindowtext是一样的, 只是将cs中的名字拷贝到窗口对象中的windowname而已
                    DefSetText(hWnd, (PCWSTR)cs->lpszName, TRUE);
                }
                Result = 1;
            }
            break;
        }

        case WM_GETTEXTLENGTH:
        {
            PWSTR buf;
            ULONG len;

            Wnd = ValidateHwnd(hWnd);
            if (Wnd != NULL && Wnd->strName.Length != 0)
            {
                buf = DesktopPtrToUser(Wnd->strName.Buffer);
                if (buf != NULL &&
                    NT_SUCCESS(RtlUnicodeToMultiByteSize(&len,
                                                         buf,
                                                         Wnd->strName.Length)))
                {
                    Result = (LRESULT) len;
                }
            }
            else Result = 0L;

            break;
        }

        case WM_GETTEXT:
        {
            PWSTR buf = NULL;
            PSTR outbuf = (PSTR)lParam;
            UINT copy;

            Wnd = ValidateHwnd(hWnd);
            if (Wnd != NULL && wParam != 0)
            {
                if (Wnd->strName.Buffer != NULL)
                    buf = DesktopPtrToUser(Wnd->strName.Buffer);
                else
                    outbuf[0] = L'\0';

                if (buf != NULL)
                {
                    if (Wnd->strName.Length != 0)
                    {
                        copy = min(Wnd->strName.Length / sizeof(WCHAR), wParam - 1);
                        Result = WideCharToMultiByte(CP_ACP,
                                                     0,
                                                     buf,
                                                     copy,
                                                     outbuf,
                                                     wParam,
                                                     NULL,
                                                     NULL);
                        outbuf[Result] = '\0';
                    }
                    else
                        outbuf[0] = '\0';
                }
            }
            break;
        }

        case WM_SETTEXT:
        {
            DefSetText(hWnd, (PCWSTR)lParam, TRUE);

            if ((GetWindowLongPtrW(hWnd, GWL_STYLE) & WS_CAPTION) == WS_CAPTION)
            {
                DefWndNCPaint(hWnd, HRGN_WINDOW, -1);
            }
            Result = 1;
            break;
        }

        case WM_IME_KEYDOWN:
        {
            Result = PostMessageA(hWnd, WM_KEYDOWN, wParam, lParam);
            break;
        }

        case WM_IME_KEYUP:
        {
            Result = PostMessageA(hWnd, WM_KEYUP, wParam, lParam);
            break;
        }

        case WM_IME_CHAR:
        {
            if (HIBYTE(wParam))
                PostMessageA(hWnd, WM_CHAR, HIBYTE(wParam), lParam);
            PostMessageA(hWnd, WM_CHAR, LOBYTE(wParam), lParam);
            break;
        }

        case WM_IME_STARTCOMPOSITION:
        case WM_IME_COMPOSITION:
        case WM_IME_ENDCOMPOSITION:
        case WM_IME_SELECT:
        case WM_IME_NOTIFY:
        {
            HWND hwndIME;

            hwndIME = DefWndImmGetDefaultIMEWnd(hWnd);
            if (hwndIME)
                Result = SendMessageA(hwndIME, Msg, wParam, lParam);
            break;
        }

        case WM_IME_SETCONTEXT:
        {
            HWND hwndIME;

            hwndIME = DefWndImmGetDefaultIMEWnd(hWnd);
            if (hwndIME)
                Result = DefWndImmIsUIMessageA(hwndIME, Msg, wParam, lParam);
            break;
        }

        /* fall through */
        default:
            Result = User32DefWindowProc(hWnd, Msg, wParam, lParam, FALSE);
    }

    SPY_ExitMessage(SPY_RESULT_DEFWND, hWnd, Msg, Result, wParam, lParam);
    return Result;
}

只要一深入到用户对象， 就进入了win32k子系统层

windows消息定义 win32k层

static MSGMEMORY MsgMemory[] =
{
    { WM_CREATE, MMS_SIZE_SPECIAL, MMS_FLAG_READWRITE },
    { WM_DDE_ACK, sizeof(KMDDELPARAM), MMS_FLAG_READ },
    { WM_DDE_EXECUTE, MMS_SIZE_WPARAM, MMS_FLAG_READ },
    { WM_GETMINMAXINFO, sizeof(MINMAXINFO), MMS_FLAG_READWRITE },
    { WM_GETTEXT, MMS_SIZE_WPARAMWCHAR, MMS_FLAG_WRITE },
    { WM_NCCALCSIZE, MMS_SIZE_SPECIAL, MMS_FLAG_READWRITE },
    { WM_NCCREATE, MMS_SIZE_SPECIAL, MMS_FLAG_READWRITE },
    { WM_SETTEXT, MMS_SIZE_LPARAMSZ, MMS_FLAG_READ },
    { WM_STYLECHANGED, sizeof(STYLESTRUCT), MMS_FLAG_READ },
    { WM_STYLECHANGING, sizeof(STYLESTRUCT), MMS_FLAG_READWRITE },
    { WM_COPYDATA, MMS_SIZE_SPECIAL, MMS_FLAG_READ },
    { WM_COPYGLOBALDATA, MMS_SIZE_WPARAM, MMS_FLAG_READ },
    { WM_WINDOWPOSCHANGED, sizeof(WINDOWPOS), MMS_FLAG_READ },
    { WM_WINDOWPOSCHANGING, sizeof(WINDOWPOS), MMS_FLAG_READWRITE },
};