Re: CRichEditCtrl nTrackPos not working

Sorry, I didn't feel that information was relevant. That could easily be my
problem, I'm fairly new to MFC and don't know all that is required for the
setup process.

I'm trying to make a program for monitoring data. The richtext field
displays various data, so I'm just trying to append text to the field (the
user isn't allowed to enter text in the field). I wrote a function called
AppendToRichText:

void AppendToRichText(CRichEditCtrl &richText, CHARFORMAT2 cf, std::string
str) {
    int linePos;
    int lineCnt;
    CHARRANGE cursor;
    SCROLLINFO si;
    POINT p = {0, 0};
    int winStatus = richText.IsWindowEnabled();

    // Disable updating the window and any selection editing
    richText.SetRedraw(FALSE);
    richText.EnableWindow(FALSE);

    // Back up the cursor and scroll bar position
    richText.GetSel(cursor);
    linePos = richText.LineFromChar(richText.LineIndex()) + 1;
    lineCnt = richText.GetLineCount();
    si.cbSize = sizeof(SCROLLINFO);
    si.fMask = SIF_POS | SIF_RANGE | SIF_PAGE | SIF_TRACKPOS;
    richText.GetScrollInfo(SB_VERT, &si);

    // Move the cursor to the end of the window
    richText.SetSel(-1, -1);

    // Set up the character formatting
    richText.SetSelectionCharFormat(cf);

    // Append the text
    richText.ReplaceSel(str.c_str());

    // Restore the cursor and scroll bar position
    // Autoscroll according to scrollbar pos - If nMax == nMin, then
    // the scroll bar was grayed out
    if (si.nTrackPos + (int)si.nPage >= si.nMax && si.nMin != si.nMax) {

        // Increment the cursor if it was at the end of the window
        if (linePos + 1 >= lineCnt) {
            cursor.cpMin += richText.GetTextLength();
            cursor.cpMax += richText.GetTextLength();
        }
        richText.SetSel(cursor);
        UpdateScrollPos(richText, -1, BOTTOM);

    }
    else {
        // Maintain the original cursor and scroll bar position
        richText.SetSel(cursor);
        si.cbSize = sizeof(SCROLLINFO);
        si.fMask = SIF_POS;
        p.y = si.nTrackPos;
        richText.SetScrollInfo(SB_VERT, &si);
        richText.SendMessage(EM_SETSCROLLPOS, 0, (LPARAM) &p);
    }

    // Re-Enable the window
    richText.EnableWindow(winStatus);
    richText.SetRedraw(winStatus);
    richText.RedrawWindow();
}

NOTE: The function UpdateScrollPos will update the scroll bar to the bottom
of the richtext field - I want the control to automatically scroll as text is
appended if the scroll bar was previously at the bottom of the text field.

My problem right now is that when the AppendToRichText is called, if the
user is dragging on the scroll bar, the dragging status is lost and the
scroll bar is returned to its position before being dragged. It would also
be nice to keep the status of the user dragging the scroll bar.

"Joseph M. Newcomer" wrote: