Dynamically disabling message system of a window

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Hi,

is there a chance to disable the messaging system for a particular window dynamically during runtime? Looking at my application, I have got a CEdit control (lets say Edit1) and a handler routine which will be called on EN_CHANGE notification.

The message handler now invokes SetWindowTextW (or SetDlgItemTextW [both tried]) which issues WM_SETTEXT message to other CEdit controls (lets say Edit2). This is part of the functionality and has to be implemented as mentioned.

The EN_CHANGE message handler for the Edit2 is the same as in the clause above due to objective oriented design. SetWindowTextW/SetDlgItemTextW is called which invokes the (same) message handler for Edit1 and so on and so on .... stack overflow.

Thats why my question to disable the message handling for an CEdit control before calling SetWindowTextW/SetDlgItemTextW and enabling the message handling afterwards. This would achieve that only the Text of the CEdit control will be set, but not issuing another WM_SETTEXT message.

Thanks for your help in advance.

koni

Posted 21-Jun-11 3:25am

derkoni87

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వేంకటనారాయణ(venkatmakam) · Answer 1 · 2011-06-21T04:07:00

I did not completely understood your question.But upto my understanding you are doing this.

VB

ON_EN_CHANGE(IDC_EDIT1, &CTestCEdit1Dlg::OnEnChangeEdit1)
ON_EN_CHANGE(IDC_EDIT2, &CTestCEdit1Dlg::OnEnChangeEdit2)

in OnEnChangeEdit1 you are changing the text of EDIT2 and in OnEnChangeEdit2 you are changing the text of EDIT1.if it is then,
Declare a Bool variable m_bool and initialise it to true in dialog constructor.after

C#

void CTestCEdit1Dlg::OnEnChangeEdit1()
{
    // TODO:  If this is a RICHEDIT control, the control will not
    // send this notification unless you override the CDialog::OnInitDialog()
    // function and call CRichEditCtrl().SetEventMask()
    // with the ENM_CHANGE flag ORed into the mask.
    if(m_bool == TRUE)
    {
        m_bool = FALSE;
        m_Edit2.SetWindowTextW(_T("Hi2"));
    }
     else
    {
        m_bool = TRUE;
    }
    // TODO:  Add your control notification handler code here
}

and

C#

void CTestCEdit1Dlg::OnEnChangeEdit2()
{
    // TODO:  If this is a RICHEDIT control, the control will not
    // send this notification unless you override the CDialog::OnInitDialog()
    // function and call CRichEditCtrl().SetEventMask()
    // with the ENM_CHANGE flag ORed into the mask.
    if(m_bool == TRUE)
    {
        m_bool = FALSE;
        m_Edit1.SetWindowTextW(_T("Hi1"));
    }
    else
    {
        m_bool = TRUE;
    }
    // TODO:  Add your control notification handler code here
}
}

Albert Holguin · Answer 2 · 2011-06-21T03:41:00

Solution 1

Well, one quick way of doing this is to just derive your classes from the same base but don't include the SetWindowText() to the secondary CEdit in one.

With a derivation sort of like this (where CEdit is whatever common base you want):

class CEditSetTxt : public CEdit
class CEditFinal  : public CEdit

Posted 21-Jun-11 3:41am

Albert Holguin

Comments

derkoni87 21-Jun-11 9:51am

Well, as I understood your solution you dont want to implement SetWindowText of the CEdit derived class (CEditFinal). But this wont work as SetWindowTextW is not declared as virtual method in CWnd base class of CEdit.

Or are you pointing at a solution which refuses a WM_SETTEXT message in the message handler of CEditFinal class?

Albert Holguin 21-Jun-11 10:00am

Where are you calling SetWindowText() from? Just exclude that from one of the CEdit derived classes... unless I'm misunderstanding what you're doing...

KarstenK · Answer 3 · 2011-06-21T04:01:00

Solution 2

overwrite PreTranslateMessage and handle the messages your way.

Tip: best is to call the default PreTranslateMessage at the end

Posted 21-Jun-11 4:01am

KarstenK

Comments

derkoni87 21-Jun-11 10:55am

I tried out your solution and wrote a class which is derived from CEdit. The following code (btw. whats the tag to highlight sourcecode):

void LockEnChange(BOOL value = TRUE)
{
m_LockEnChange = value;
}

BOOL PreTranslateMessage(MSG* pMsg)
{
BOOL returnValue = TRUE;

switch (pMsg->message)
{
case WM_SETTEXT:
{
if (m_LockEnChange == FALSE)
{
returnValue = CEdit::PreTranslateMessage(pMsg);
}
break;
}
default:
{
returnValue = CEdit::PreTranslateMessage(pMsg);
break;
}
}

return returnValue;
}

(with BOOLEAN m_LockEnChange variable declared respectively)

But there is no WM_SETTEXT message when stepping over SetWindowTextW. As I understood, SetWindowTextW uses SendMessageW to invoke the message handler in direct way? So there has to be an WM_SETTEXT event during that time?!

KarstenK 22-Jun-11 2:42am

why arent your function i a class scope of your derived class?

derkoni87 22-Jun-11 3:03am

They are. I have just quickly implemented these functions in the header file of the derived class, so you dont see the function's scope.