vc入门知识介绍

消息

何志丹

PreTranslateMessage函数顾名思义,就是在消息被翻译之前,做的一些事.我们可以屏蔽一个键或一个命令.
下面是一些常用消息的相关信息.这些信息放pMsg中.
WM_KEYDOWN
nVirtKey = (int) wParam; /*虚键值,和ascll码有许多相同的地方*/
lKeyData = lParam; /*和硬件有关*/
WM_CHAR
chCharCode = (TCHAR) wParam;
lKeyData = lParam;
WM_COMMAND
wNotifyCode = HIWORD(wParam);
wID = LOWORD(wParam);
hwndCtl = (HWND) lParam;
WM_LBUTTONDOWN
fwKeys = wParam; //
xPos = LOWORD(lParam); // 鼠标横坐标
yPos = HIWORD(lParam); // 鼠标纵坐标
fwKeys
MK_CONTROL MK_LBUTTON MK_MBUTTON MK_RBUTTON MK_SHIFT
WM_MOUSEMOVE
fwKeys = wParam;
xPos = LOWORD(lParam);
yPos = HIWORD(lParam);

下面这个例子演示了,PreTranslateMessage的常用用法.
BOOL CPreTranslateDlg::PreTranslateMessage(MSG* pMsg)
{
if(WM_KEYDOWN == pMsg->message )
if(0x30 == (int) pMsg->wParam)
{
return true; /*禁止在编辑框中输入0(ascll 0x30)*/
}

if(WM_CHAR == pMsg->message )
if('A' == (TCHAR) pMsg->wParam)
{
return true; /*禁止在编辑框中输入'A'*/
}

if(WM_MOUSEMOVE == pMsg->message)
if(MK_CONTROL & pMsg->wParam) /*当ctrl被按下鼠标移动时,显示相关信息*/
{
int xPos = LOWORD(pMsg->lParam);
int yPos = HIWORD(pMsg->lParam);
CString str ;
str.Format("鼠标的坐标%d %d",xPos,yPos);
AfxMessageBox(str);
}

if(WM_COMMAND == pMsg->message)
if(ID_1 == LOWORD(pMsg->wParam))//禁止菜单项ID_1,注意按钮发送的是BN_CLICKED
{
return true;
}
return CDialog::PreTranslateMessage(pMsg);
}