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Hi to all,



I created a class that enherits from CEdit and overrode its OnChar() message

handler to intercept the entered keys and filter only those that are lower

case. It also verifies if an entered key is upper case to convert it to lower

case and filter it.



Everything works good except the conversion from upper to lower case. The

problem is that even if the OnChar() handler does convert the character to

lower case, the character is still displayed in the edit box as it was

entered, i.e. in upper case.



Please note that if I remove the line: "nChar = tolower(nChar);", the upper

case characters will be rejected and this is not what I want. I want the same

behaviour than the edit control's Lowercase property, which will convert all

characters to lowercase as they are typed into the edit box. However, this

property allows all other character types to be output.



Here's the code of the OnChar() message handler:



#define BACK_SPACE 8



void CEditLoCase::OnChar(UINT nChar, UINT nRepCnt, UINT nFlags)

{

TRACE("OnChar(): %c ; %d\n", nChar, nFlags);



// Filter all the characters in 'm_pFilter' to be processed.

nChar = tolower(nChar);

if ((nChar>= 'a' && nChar <= 'z') ||

nChar == BACK_SPACE)

{

CEdit::OnChar(nChar, nRepCnt, nFlags);

}

else

{

MessageBeep(MB_OK);

}

}





I appreciate any help and thank you in advance.



Geo


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Geo,



Why not just create the control with the ES_LOWERCASE style?



Dave

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Geo schrieb:



To "hook" into the default behaviour of a Non-MFC windows control, you need

"Window"-subclassing instead of "C++ MFC" subclassing. If you step into the

CEdit::OnChar function above with your debugger, you will notice that the

handler will probably do nothing (I have not checked), at least it will not

forward the message to the windows edit control.



Have a look at CWnd::SubclassWindow.



Norbert

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This problem arises because Microsoft totally screwed up the MFC implementation on day 1.

You can't change ANY of the parameters that are coming in; the superclass call simply

takes the incoming parameters and reuses them, instead of doing something intelligent,

such as using your parameters! (That paragraph at the end of every MFC call is there

because I collarred the MFC guys at an MVP conference and told them they had to fix MFC to

be right. They didn't, but they at least notified us that every call is screwed up.

Apparently they never *actually* understood object-oriented programming and subclassing,

and kludged up something that sort-of-worked most of the time.)



However, as already pointed out, using the ES_LOWERCASE flag will solve your problem, so

your approach is needlessly complicated. You don't even need subclassing to implement it,

just a ModifyStyle call (ES_LOWERCASE and ES_UPPERCASE are two style bits that can be

freely modified after the control is created)

joe



On Sat, 21 Oct 2006 06:10:02 -0700, Geo <Geo@discussions.microsoft.com>wrote:



Why 8? Why not _T('\b')?

****

This ignores your change to nChar and simply reuses the original nChar value, which it has

hidden away!

****

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