Higliting matching brackets in QPlainTextEdit

[Nebelig]

I have implemented the method of highlighting matching brackets in my class

void CodeEditor::cursorPositionChanged()
{
    if (!bracketBeginCursor.isNull() || !bracketEndCursor.isNull()) {
        bracketBeginCursor.setCharFormat(QTextCharFormat());
        bracketEndCursor.setCharFormat(QTextCharFormat());
        bracketBeginCursor = bracketEndCursor = QTextCursor();
    }
 
    QTextCursor cursor = textCursor();
 
    int position = cursor.position();
 
    if ((!cursor.atBlockEnd()   && doc->characterAt(position) == '(') ||
        (!cursor.atBlockStart() && doc->characterAt(position - 1) == ')')) {
 
        bool forward = doc->characterAt(position) == '(';
 
        QTextCursor::MoveOperation move;
 
        QChar c, begin, end;
 
        if (forward) { //bool forward =
            position++;
            move = QTextCursor::NextCharacter;
            begin = '(';
            end   = ')';
 
        } else {
            position -= 2;
            move = QTextCursor::PreviousCharacter;
            begin = ')';
            end   = '(';
        }
 
        bracketBeginCursor = QTextCursor(cursor);
        bracketBeginCursor.movePosition(move, QTextCursor::KeepAnchor);
 
        QTextCharFormat format = bracketMismatchFormat;
 
        int braceDepth = 1;
 
        while (!(c = doc->characterAt(position)).isNull()) {
            if (c == begin) {
                braceDepth++;
            } else if (c == end) {
                braceDepth--;
 
                if (!braceDepth) {
                    bracketEndCursor = QTextCursor(doc);
                    bracketEndCursor.setPosition(position);
                    bracketEndCursor.movePosition(QTextCursor::NextCharacter, QTextCursor::KeepAnchor);
                    bracketEndCursor.setCharFormat(bracketMatchFormat);
 
                    format = bracketMatchFormat;
 
                    break;
                }
            }
            forward ? position++ : position--;
        }
        bracketBeginCursor.setCharFormat(format);
    }
}

void CodeEditor::cursorPositionChanged()
{
    if (!bracketBeginCursor.isNull() || !bracketEndCursor.isNull()) {
        bracketBeginCursor.setCharFormat(QTextCharFormat());
        bracketEndCursor.setCharFormat(QTextCharFormat());
        bracketBeginCursor = bracketEndCursor = QTextCursor();
    }

    QTextCursor cursor = textCursor();

    int position = cursor.position();

    if ((!cursor.atBlockEnd()   && doc->characterAt(position) == '(') ||
        (!cursor.atBlockStart() && doc->characterAt(position - 1) == ')')) {

        bool forward = doc->characterAt(position) == '(';

        QTextCursor::MoveOperation move;

        QChar c, begin, end;

        if (forward) { //bool forward =
            position++;
            move = QTextCursor::NextCharacter;
            begin = '(';
            end   = ')';

        } else {
            position -= 2;
            move = QTextCursor::PreviousCharacter;
            begin = ')';
            end   = '(';
        }

        bracketBeginCursor = QTextCursor(cursor);
        bracketBeginCursor.movePosition(move, QTextCursor::KeepAnchor);

        QTextCharFormat format = bracketMismatchFormat;

        int braceDepth = 1;

        while (!(c = doc->characterAt(position)).isNull()) {
            if (c == begin) {
                braceDepth++;
            } else if (c == end) {
                braceDepth--;
                
                if (!braceDepth) {
                    bracketEndCursor = QTextCursor(doc);
                    bracketEndCursor.setPosition(position);
                    bracketEndCursor.movePosition(QTextCursor::NextCharacter, QTextCursor::KeepAnchor);
                    bracketEndCursor.setCharFormat(bracketMatchFormat);

                    format = bracketMatchFormat;

                    break;
                }
            }
            forward ? position++ : position--;
        }
        bracketBeginCursor.setCharFormat(format);
    }
}

To copy to clipboard, switch view to plain text mode 

everything works fine, but if the bracket is highlighted and is the first in a block, then the text is placed to the left of it will have the same QTextCharFormat...

Perhaps there is a link with

QTextCharFormat QTextCursor::charFormat () const
Returns the format of the character immediately before the cursor position().
If the cursor is positioned at the beginning of a text block that is not empty then the format of the character immediately after the cursor is returned.

Thanks for any advice.

[msr]

(this is an old topic I know)

One issue of this code is that it changes the undo/redo history of the qplaintextedit. Is there any way to disable the undo/redo while changing the qtextcharformat so it isn't added to the undo stack? Thanks

[wysota]

The method described in this thread is outdated. Use QPlainTextEdit::setExtraSelections() instead.