Change char inserted using Alt+Unicode in CRichEdit - c++

Question

I want to change a unicode char inserted using Alt+Unicode code from the keyboard.
I used PretranslateMessage for changing the chars inserted directly from the keyboard and it worked. But with the Alt+Unicode code method it does not.
Here is the code:
Microsoft Word has this functionality when enabling show/hide paragraph marks.
BOOL CEmphasizeEdit::PreTranslateMessage(MSG* msg)
{
if (msg->hwnd == m_hWnd)
{
if (msg->message == WM_CHAR)
{
if (TheApp.Options.m_bShowWSpaceChars)
{
if (msg->wParam == ' ') // This works in both cases Space key pressed or Alt + 3 + 2 in inserted
{
msg->wParam = '·';
}
else if (msg->wParam == (unsigned char)' ') // this does not work
{
msg->wParam = (unsigned char)'°';
}
}
}
}
return CRichEditCtrl::PreTranslateMessage(msg);
}
If I insert from the keyboard Alt + 0 + 1 + 6 + 0 which is ' '(No-Break Space), I want the CRichEditCtrl to display '°' or another char that I specify.
How can I handle this to make it work?

Answer 1

Alt+Space is reserved for program's close menu.
You should use another sequence like Ctrl+Space or Alt+Ctrl+Space
' ' and (unsigned char)' ' are the same thing, therefore the code never reaches else if (msg->wParam == (unsigned char)' '). You should remove that.
Use GetAsyncKeyState to see if Alt or Ctrl key is pressed down.
BOOL IsKeyDown(int vkCode)
{
return GetAsyncKeyState(vkCode) & 0x8000;
}
...
if (msg->wParam == ' ')
{
if (IsKeyDown(VK_CONTROL))
msg->wParam = L'°';
else
msg->wParam = L'+';
}
...

Answer 2

I had to get the cursor position send an append string to the control and then set the selection after the inserted character. When this happens I have to skip CRichEditCtrl::PreTranslateMessage(msg);
BOOL CEmphasizeEdit::PreTranslateMessage(MSG* msg)
{
if (msg->hwnd == m_hWnd)
{
if (msg->message == WM_CHAR)
{
TCHAR text[2];
text[1] = 0x00;
BOOL found = 1;
switch (msg->wParam)
{
case 0x20: text[0] = _C('·'); break;
case 0xA0: text[0] = 0xB0; break;
}
CHARRANGE cr;
GetSel(cr);
cr.cpMax++;
cr.cpMin++;
ReplaceSel(text);
SetSel(cr);
return 1;
}
}
return CRichEditCtrl::PreTranslateMessage(msg);
}