CODEWITHSUNDEEP
mfc
Mr. Boy
Mr. Boy

Reputation: 63816

EN_MSGFILTER, can't prevent message propogation

I have a dialog with a rich-text control. The dialog wants to intercept right-click events on the control; in some cases the dialog should do its own functionality and block the message reaching the control, in other cases it should let the control receive the message.

So I have:

ON_NOTIFY(EN_MSGFILTER, IDC_RICHTEXT, OnRichTextMsgfilter)

void CMyDialog::OnRichTextMsgfilter(NMHDR *pNMHDR, LRESULT *pResult)
{
    MSGFILTER *pMsgFilter = reinterpret_cast<MSGFILTER *>(pNMHDR);
    *pResult = 0;
    if (pMsgFilter->msg == WM_RBUTTONUP)
    {
        if(...)
         *pResult=1;
    }
}

I step through the code and pResult is set when it should be, but the control still gets the message. Looking at MSDN it says:

If the control should process the event, the message returns a zero value. If the control should ignore the event, the message returns a nonzero value.

But the defined message handler signature has no return... I am assuming that's what *pResult is for. Is that not true? If so how do I achieve this?

Upvotes: 0

Views: 452

Answers (2)

Goz
Goz

Reputation: 62333

The WM_RBUTTONDOWN is stil getting through...

Upvotes: 0

Ruddy
Ruddy

Reputation: 1754

So i've tried to reproduce this behavior in a simple dialog based app and i really can't -- however, i'm not sure what it is that intercepting the right button message is trying to solve.

That said the following code completely blocks the Left button mouse clicks in my testing (If this returns TRUE the control does not respond to left clicks - however focus will get set to the control on the initial click down and that is more a window manager issue than the control itself)

void CTestDlg::OnMsgfilterRichedit1(NMHDR* pNMHDR, LRESULT* pResult) 
{
    MSGFILTER *pMsgFilter = reinterpret_cast<MSGFILTER *>(pNMHDR);

    if (pMsgFilter->msg == WM_LBUTTONUP || pMsgFilter->msg == WM_LBUTTONDOWN)
    {
        *pResult = TRUE;
        return;
    }

    *pResult = FALSE;
}

If i change *pResult = TRUE to *pResult = FALSE then the left clicks start working again.

It could be that you want to catch and filter out the WM_RBUTTONDOWN rather than WM_RBUTTONUP to do what you intend, but since i'm unsure what functionality you are trying to filter out i can't say for sure.

Upvotes: 1

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