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CRichEditView and last char removed from file

Posted on 2003-11-30
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Last Modified: 2013-11-20
I hav a CRichEditView and would like to get the last removed (or about to be removed) character when the user presses the backspace or delete key.

Any ideas?
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Question by:boodabelly
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Accepted Solution

by:
Roshan Davis earned 500 total points
ID: 9848191
Map WM_KEYDOWN do use the code

void CMyRichEditView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{

      long lStartPos, lEndPos;
      CString csTextToBeDeleted;

      GetRichEditCtrl().GetSel(lStartPos, lEndPos);

      if ( VK_BACK == nChar ||
             VK_DELETE == nChar )
      {
        if (lEndPos - lStartPos > 0)
        {
                  csTextToBeDeleted = GetRichEditCtrl().GetSelText();
        }
            else
            {
                  if ( VK_BACK == nChar )
                  {
                        GetRichEditCtrl().SetSel(lStartPos-1, lStartPos);
                  }
                  else
                  {
                        GetRichEditCtrl().SetSel(lStartPos, lStartPos+1);
                  }

                  csTextToBeDeleted = GetRichEditCtrl().GetSelText();

                  GetRichEditCtrl().SetSel(lStartPos, lEndPos);
            }

            csTextToBeDeleted;   <----------------------- THIS WILL BE THE TEXT THAT TO BE DELETED
      }
      
      

      CRichEditView::OnKeyDown(nChar, nRepCnt, nFlags);
}

Good Luck
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Author Comment

by:boodabelly
ID: 9848430
thanks man, works like a champ! =)
0
 
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Author Comment

by:boodabelly
ID: 9848470
ugh, well, appearantly I accepted a little in haste and excitement.  I am trying to detect when a new line character is removed from the screen, can you answer that still or do I need to post another question?
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Expert Comment

by:Roshan Davis
ID: 9848480
I will check that....
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Expert Comment

by:Roshan Davis
ID: 9848495
In that case that text (csTextToBeDeleted) will give you the character 13.

char cChar = 13;

you can compare that text with cChar.

Rosh :)
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Author Comment

by:boodabelly
ID: 9848665
ok, what am I doing wrong here?

// from constants file
#define BYY_NEW_LINE                  13

void Cbyy_view::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{

      long start_pos;
      long end_pos;

      if(!can_edit())
      {
            return;
      }

      GetRichEditCtrl().GetSel(start_pos, end_pos);

      if(nChar == VK_BACK || nChar == VK_DELETE)
      {
            if(end_pos - start_pos > 0)
            {
                  m_last_deleted_text = GetRichEditCtrl().GetSelText();
            }
            else
            {
                  if(nChar == VK_BACK)
                  {
                        GetRichEditCtrl().SetSel(start_pos - 1, start_pos);
                  }
                  else
                  {
                        GetRichEditCtrl().SetSel(start_pos, start_pos + 1);
                  }

                  m_last_deleted_text = GetRichEditCtrl().GetSelText();
                  GetRichEditCtrl().SetSel(start_pos, end_pos);
            }

            if(m_last_deleted_text == BYY_NEW_LINE)
            {
                  update_edit_areas(-1);
            }
      }

      CRichEditView::OnKeyDown(nChar, nRepCnt, nFlags);
}
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LVL 23

Expert Comment

by:Roshan Davis
ID: 9848704
This will work, I modified that string comparison like "GetAt" check the below code

// from constants file
#define BYY_NEW_LINE               13

void Cbyy_view::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{

    long start_pos;
    long end_pos;

    if(!can_edit())
    {
         return;
    }

    GetRichEditCtrl().GetSel(start_pos, end_pos);

    if(nChar == VK_BACK || nChar == VK_DELETE)
    {
         if(end_pos - start_pos > 0)
         {
              m_last_deleted_text = GetRichEditCtrl().GetSelText();
         }
         else
         {
              if(nChar == VK_BACK)
              {
                   GetRichEditCtrl().SetSel(start_pos - 1, start_pos);
              }
              else
              {
                   GetRichEditCtrl().SetSel(start_pos, start_pos + 1);
              }

              m_last_deleted_text = GetRichEditCtrl().GetSelText();
              GetRichEditCtrl().SetSel(start_pos, end_pos);
         }

         if(m_last_deleted_text.GetAt(0) == BYY_NEW_LINE)
         {
              update_edit_areas(-1);
         }
    }

    CRichEditView::OnKeyDown(nChar, nRepCnt, nFlags);
}
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LVL 1

Author Comment

by:boodabelly
ID: 9848774
hmmm, well the .GetAt(0) crashes because the strlen is < 0.  m_last_deleted_text = "" when I remove a new line char.  I am thinking I might have to get the current line, move the cursor the appropriate direction and check the line number again.  I will try that and report back
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LVL 23

Expert Comment

by:Roshan Davis
ID: 9848779
Okay,
Good Luck
0
 
LVL 1

Author Comment

by:boodabelly
ID: 9848908
roshmon, cool man, this is what I got to work from the help you gave me, guess I need to get more used to this MFC stuff (I'm too old skool C), have to start thinking in MFC and getting comfortable with what functions do what, logic for MFC is pretty simple, just need to get more comfortable with it, ok, its 3am and I am rambling, BTW,this is what I got to work

void Cbyy_view::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{

      long start_pos;
      long end_pos;
      int line_num;


      line_num = m_curr_line;
      GetRichEditCtrl().GetSel(start_pos, end_pos);

      if(nChar == VK_BACK || nChar == VK_DELETE)
      {
            if(!can_edit())
            {
                  return;
            }

            if(nChar == VK_BACK)
            {
                  GetRichEditCtrl().SetSel(start_pos - 1, start_pos - 1);
            }
            else
            {
                  // increment two positions to go past the '\n'
                  GetRichEditCtrl().SetSel(start_pos + 2, start_pos + 2);
            }

            line_num = GetRichEditCtrl().LineFromChar(-1) + 1;

            if(line_num != m_curr_line)
            {
                  update_edit_areas(-1);
            }

            GetRichEditCtrl().SetSel(start_pos, end_pos);
      }

      CRichEditView::OnKeyDown(nChar, nRepCnt, nFlags);
}

thanks again man!
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LVL 23

Expert Comment

by:Roshan Davis
ID: 9848928
Welcome :0)
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