basetexteditor.cpp

            if (d->m_codeFoldingVisible) {

                bool collapseThis = false;
                bool collapseAfter = false;
                bool hasClosingCollapse = false;

                if (TextBlockUserData *userData = static_cast<TextBlockUserData*>(block.userData())) {
                    if (!userData->ifdefedOut()) {
                        collapseAfter = (userData->collapseMode() == TextBlockUserData::CollapseAfter);
                        collapseThis = (userData->collapseMode() == TextBlockUserData::CollapseThis);
                        hasClosingCollapse = userData->hasClosingCollapse() && (previousBraceDepth > 0);
                    }
                }

                int extraAreaHighlightCollapseBlockNumber = -1;
                int extraAreaHighlightCollapseEndBlockNumber = -1;
                bool endIsVisible = false;
                if (!d->m_highlightBlocksInfo.isEmpty()) {
                    extraAreaHighlightCollapseBlockNumber =  d->m_highlightBlocksInfo.open.last();
                    extraAreaHighlightCollapseEndBlockNumber =  d->m_highlightBlocksInfo.close.first();
                    endIsVisible = doc->findBlockByNumber(extraAreaHighlightCollapseEndBlockNumber).isVisible();

                    QTextBlock before = doc->findBlockByNumber(extraAreaHighlightCollapseBlockNumber-1);
                    if (TextBlockUserData::hasCollapseAfter(before)) {
                        extraAreaHighlightCollapseBlockNumber--;
                    }
                }

                TextBlockUserData *nextBlockUserData = TextEditDocumentLayout::testUserData(nextBlock);

                bool collapseNext = nextBlockUserData
                                    && nextBlockUserData->collapseMode() == TextBlockUserData::CollapseThis
                                    && !nextBlockUserData->ifdefedOut();

                bool nextHasClosingCollapse = nextBlockUserData
                                              && nextBlockUserData->hasClosingCollapseInside()
                                              && nextBlockUserData->ifdefedOut();

                bool drawBox = ((collapseAfter || collapseNext) && !nextHasClosingCollapse);
                bool active = blockNumber == extraAreaHighlightCollapseBlockNumber;
                bool drawStart = drawBox && active;
                bool drawEnd = blockNumber == extraAreaHighlightCollapseEndBlockNumber || (drawStart && !endIsVisible);
                bool hovered = blockNumber >= extraAreaHighlightCollapseBlockNumber
                               && blockNumber <= extraAreaHighlightCollapseEndBlockNumber;

                int boxWidth = collapseBoxWidth(fm);
                if (hovered) {
                    QRect box = QRect(extraAreaWidth + 1, top, boxWidth - 2, bottom - top);
                    drawRectBox(&painter, box, drawStart, drawEnd, pal);
                }

                if (drawBox) {
                    bool expanded = nextBlock.isVisible();
                    int size = boxWidth/4;
                    QRect box(extraAreaWidth + size, top + size,
                              2 * (size) + 1, 2 * (size) + 1);
                    drawFoldingMarker(&painter, pal, box, expanded, active, hovered);
                }
            }

            painter.restore();
        }


        if (d->m_revisionsVisible && block.revision() != documentLayout->lastSaveRevision) {
            painter.save();
            painter.setRenderHint(QPainter::Antialiasing, false);
            if (block.revision() < 0)
                painter.setPen(QPen(Qt::darkGreen, 2));
            else
                painter.setPen(QPen(Qt::red, 2));
            painter.drawLine(extraAreaWidth - 1, top, extraAreaWidth - 1, bottom - 1);
            painter.restore();
        }

        if (d->m_lineNumbersVisible) {
            const QString &number = QString::number(blockNumber + 1);
            bool selected = (
                    (selStart < block.position() + block.length()
                    && selEnd > block.position())
                    || (selStart == selEnd && selStart == block.position())
                    );
            if (selected) {
                painter.save();
                QFont f = painter.font();
                f.setBold(d->m_currentLineNumberFormat.font().bold());
                f.setItalic(d->m_currentLineNumberFormat.font().italic());
                painter.setFont(f);
                painter.setPen(d->m_currentLineNumberFormat.foreground().color());
            }
            painter.drawText(markWidth, top, extraAreaWidth - markWidth - 4, fm.height(), Qt::AlignRight, number);
            if (selected)
                painter.restore();
        }

        block = nextVisibleBlock;
        blockNumber = nextVisibleBlockNumber;
    }
}

void BaseTextEditor::drawFoldingMarker(QPainter *painter, const QPalette &pal,
                                       const QRect &rect,
                                       bool expanded,
                                       bool active,
                                       bool hovered) const
{
    Q_UNUSED(active)
    Q_UNUSED(hovered)
    QStyle *s = style();
    if (ManhattanStyle *ms = qobject_cast<ManhattanStyle*>(s))
        s = ms->baseStyle();

    if (!qstrcmp(s->metaObject()->className(), "OxygenStyle")) {
        painter->save();
        painter->setPen(Qt::NoPen);
        int size = rect.size().width();
        int sqsize = 2*(size/2);

        QColor textColor = pal.buttonText().color();
        QColor brushColor = textColor;

        textColor.setAlpha(100);
        brushColor.setAlpha(100);

        QPolygon a;
        if (expanded) {
            // down arrow
            a.setPoints(3, 0, sqsize/3,  sqsize/2, sqsize  - sqsize/3,  sqsize, sqsize/3);
        } else {
            // right arrow
            a.setPoints(3, sqsize - sqsize/3, sqsize/2,  sqsize/2 - sqsize/3, 0,  sqsize/2 - sqsize/3, sqsize);
            painter->setBrush(brushColor);
        }
        painter->translate(0.5, 0.5);
        painter->setRenderHint(QPainter::Antialiasing);
        painter->translate(rect.topLeft());
        painter->setPen(textColor);
        painter->setBrush(textColor);
        painter->drawPolygon(a);
        painter->restore();
    } else {
        QStyleOptionViewItemV2 opt;
        opt.rect = rect;
        opt.state = QStyle::State_Active | QStyle::State_Item | QStyle::State_Children;
        if (expanded)
            opt.state |= QStyle::State_Open;
        if (active)
            opt.state |= QStyle::State_MouseOver | QStyle::State_Enabled | QStyle::State_Selected;
        if (hovered)
            opt.palette.setBrush(QPalette::Window, pal.highlight());

         // QGtkStyle needs a small correction to draw the marker in the right place
        if (!qstrcmp(s->metaObject()->className(), "QGtkStyle"))
           opt.rect.translate(-2, 0);
        else if (!qstrcmp(s->metaObject()->className(), "QMacStyle"))
            opt.rect.translate(-1, 0);

        s->drawPrimitive(QStyle::PE_IndicatorBranch, &opt, painter, this);
    }
}

void BaseTextEditor::slotModificationChanged(bool m)
{
    if (m)
        return;

    QTextDocument *doc = document();
    TextEditDocumentLayout *documentLayout = qobject_cast<TextEditDocumentLayout*>(doc->documentLayout());
    QTC_ASSERT(documentLayout, return);
    int oldLastSaveRevision = documentLayout->lastSaveRevision;
    documentLayout->lastSaveRevision = doc->revision();

    if (oldLastSaveRevision != documentLayout->lastSaveRevision) {
        QTextBlock block = doc->begin();
        while (block.isValid()) {
            if (block.revision() < 0 || block.revision() != oldLastSaveRevision) {
                block.setRevision(-documentLayout->lastSaveRevision - 1);
            } else {
                block.setRevision(documentLayout->lastSaveRevision);
            }
            block = block.next();
        }
    }
    d->m_extraArea->update();
}

void BaseTextEditor::slotUpdateRequest(const QRect &r, int dy)
{
    if (dy)
        d->m_extraArea->scroll(0, dy);
    else if (r.width() > 4) { // wider than cursor width, not just cursor blinking
        d->m_extraArea->update(0, r.y(), d->m_extraArea->width(), r.height());
        if (!d->m_searchExpr.isEmpty()) {
            const int m = d->m_searchResultOverlay->dropShadowWidth();
            viewport()->update(r.adjusted(-m, -m, m, m));
        }
    }

    if (r.contains(viewport()->rect()))
        slotUpdateExtraAreaWidth();
}

void BaseTextEditor::saveCurrentCursorPositionForNavigation()
{
    d->m_lastCursorChangeWasInteresting = true;
    d->m_tempNavigationState = saveState();
}

void BaseTextEditor::updateCurrentLineHighlight()
{
    QList<QTextEdit::ExtraSelection> extraSelections;

    if (d->m_highlightCurrentLine) {
        QTextEdit::ExtraSelection sel;
        sel.format.setBackground(d->m_currentLineFormat.background());
        sel.format.setProperty(QTextFormat::FullWidthSelection, true);
        sel.cursor = textCursor();
        sel.cursor.clearSelection();
        extraSelections.append(sel);
    }

    setExtraSelections(CurrentLineSelection, extraSelections);


    // the extra area shows information for the entire current block, not just the currentline.
    // This is why we must force a bigger update region.
    int cursorBlockNumber = textCursor().blockNumber();
    if (cursorBlockNumber != d->m_cursorBlockNumber) {
        QPointF offset = contentOffset();
        QTextBlock block = document()->findBlockByNumber(d->m_cursorBlockNumber);
        if (block.isValid())
            d->m_extraArea->update(blockBoundingGeometry(block).translated(offset).toAlignedRect());
        block = document()->findBlockByNumber(cursorBlockNumber);
        if (block.isValid())
            d->m_extraArea->update(blockBoundingGeometry(block).translated(offset).toAlignedRect());
        d->m_cursorBlockNumber = cursorBlockNumber;
    }

}

void BaseTextEditor::slotCursorPositionChanged()
{
#if 0
    qDebug() << "block" << textCursor().blockNumber()+1
            << "depth:" << TextEditDocumentLayout::braceDepth(textCursor().block())
            << '/' << TextEditDocumentLayout::braceDepth(document()->lastBlock());
#endif
    if (!d->m_contentsChanged && d->m_lastCursorChangeWasInteresting) {
        Core::EditorManager::instance()->addCurrentPositionToNavigationHistory(editableInterface(), d->m_tempNavigationState);
        d->m_lastCursorChangeWasInteresting = false;
    } else if (d->m_contentsChanged) {
        saveCurrentCursorPositionForNavigation();
    }
    updateHighlights();
}

void BaseTextEditor::updateHighlights()
{
    if (d->m_parenthesesMatchingEnabled && hasFocus()) {
        // Delay update when no matching is displayed yet, to avoid flicker
        if (extraSelections(ParenthesesMatchingSelection).isEmpty()
            && d->m_animator == 0) {
            d->m_parenthesesMatchingTimer->start(50);
        } else {
             // use 0-timer, not direct call, to give the syntax highlighter a chance
            // to update the parantheses information
            d->m_parenthesesMatchingTimer->start(0);
        }
    }

    updateCurrentLineHighlight();

    if (d->m_displaySettings.m_highlightBlocks) {
        QTextCursor cursor = textCursor();
        d->extraAreaHighlightCollapseBlockNumber = cursor.blockNumber();
        d->extraAreaHighlightCollapseColumn = cursor.position() - cursor.block().position();
        d->m_highlightBlocksTimer->start(100);
    }
}

void BaseTextEditor::slotUpdateBlockNotify(const QTextBlock &block)
{
    static bool blockRecursion = false;
    if (blockRecursion)
        return;
    blockRecursion = true;
    if (d->m_overlay->isVisible()) {
        /* an overlay might draw outside the block bounderies, force
           complete viewport update */
        viewport()->update();
    } else {
        if (block.previous().isValid() && block.userState() != block.previous().userState()) {
        /* The syntax highlighting state changes. This opens up for
           the possibility that the paragraph has braces that support
           code folding. In this case, do the save thing and also
           update the previous block, which might contain a collapse
           box which now is invalid.*/
            emit requestBlockUpdate(block.previous());
        }
        if (!d->m_findScope.isNull()) {
            if (block.position() < d->m_findScope.selectionEnd()
                && block.position()+block.length() >= d->m_findScope.selectionStart() ) {
                QTextBlock b = block.document()->findBlock(d->m_findScope.selectionStart());
                do {
                    emit requestBlockUpdate(b);
                    b = b.next();
                } while (b.isValid() && b.position() < d->m_findScope.selectionEnd());
            }
        }
    }
    blockRecursion = false;
}

void BaseTextEditor::timerEvent(QTimerEvent *e)
{
    if (e->timerId() == d->autoScrollTimer.timerId()) {
        const QPoint globalPos = QCursor::pos();
        const QPoint pos = d->m_extraArea->mapFromGlobal(globalPos);
        QRect visible = d->m_extraArea->rect();
        verticalScrollBar()->triggerAction( pos.y() < visible.center().y() ?
                                            QAbstractSlider::SliderSingleStepSub
                                            : QAbstractSlider::SliderSingleStepAdd);
        QMouseEvent ev(QEvent::MouseMove, pos, globalPos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
        extraAreaMouseEvent(&ev);
        int delta = qMax(pos.y() - visible.top(), visible.bottom() - pos.y()) - visible.height();
        if (delta < 7)
            delta = 7;
        int timeout = 4900 / (delta * delta);
        d->autoScrollTimer.start(timeout, this);

    } else if (e->timerId() == d->collapsedBlockTimer.timerId()) {
        d->visibleCollapsedBlockNumber = d->suggestedVisibleCollapsedBlockNumber;
        d->suggestedVisibleCollapsedBlockNumber = -1;
        d->collapsedBlockTimer.stop();
        viewport()->update();
    }
    QPlainTextEdit::timerEvent(e);
}


void BaseTextEditorPrivate::clearVisibleCollapsedBlock()
{
    if (suggestedVisibleCollapsedBlockNumber) {
        suggestedVisibleCollapsedBlockNumber = -1;
        collapsedBlockTimer.stop();
    }
    if (visibleCollapsedBlockNumber >= 0) {
        visibleCollapsedBlockNumber = -1;
        q->viewport()->update();
    }
}

void BaseTextEditor::mouseMoveEvent(QMouseEvent *e)
{
    d->m_lastEventWasBlockSelectionEvent = (e->modifiers() & Qt::AltModifier);

    updateLink(e);

    if (e->buttons() == Qt::NoButton) {
        const QTextBlock collapsedBlock = collapsedBlockAt(e->pos());
        const int blockNumber = collapsedBlock.next().blockNumber();
        if (blockNumber < 0) {
            d->clearVisibleCollapsedBlock();
        } else if (blockNumber != d->visibleCollapsedBlockNumber) {
            d->suggestedVisibleCollapsedBlockNumber = blockNumber;
            d->collapsedBlockTimer.start(40, this);
        }

        // Update the mouse cursor
        if (collapsedBlock.isValid() && !d->m_mouseOnCollapsedMarker) {
            d->m_mouseOnCollapsedMarker = true;
            viewport()->setCursor(Qt::PointingHandCursor);
        } else if (!collapsedBlock.isValid() && d->m_mouseOnCollapsedMarker) {
            d->m_mouseOnCollapsedMarker = false;
            viewport()->setCursor(Qt::IBeamCursor);
        }
    } else {
        QPlainTextEdit::mouseMoveEvent(e);
    }
    if (d->m_lastEventWasBlockSelectionEvent && d->m_inBlockSelectionMode) {
        if (textCursor().atBlockEnd()) {
            d->m_blockSelectionExtraX = qMax(0, e->pos().x() - cursorRect().center().x()) / fontMetrics().averageCharWidth();
        } else {
            d->m_blockSelectionExtraX = 0;
        }
    }
    if (viewport()->cursor().shape() == Qt::BlankCursor)
        viewport()->setCursor(Qt::IBeamCursor);
}

void BaseTextEditor::mousePressEvent(QMouseEvent *e)
{
    if (e->button() == Qt::LeftButton) {
        d->clearBlockSelection(); // just in case, otherwise we might get strange drag and drop

        QTextBlock collapsedBlock = collapsedBlockAt(e->pos());
        if (collapsedBlock.isValid()) {
            toggleBlockVisible(collapsedBlock);
            viewport()->setCursor(Qt::IBeamCursor);
        }

        updateLink(e);

        if (d->m_currentLink.isValid())
            d->m_linkPressed = true;
    }
    QPlainTextEdit::mousePressEvent(e);
}

void BaseTextEditor::mouseReleaseEvent(QMouseEvent *e)
{
    if (mouseNavigationEnabled()
        && d->m_linkPressed
        && e->modifiers() & Qt::ControlModifier
        && !(e->modifiers() & Qt::ShiftModifier)
        && e->button() == Qt::LeftButton
        ) {
        const QTextCursor cursor = cursorForPosition(e->pos());
        if (openLink(findLinkAt(cursor))) {
            clearLink();
            return;
        }
    }

    QPlainTextEdit::mouseReleaseEvent(e);
}

void BaseTextEditor::leaveEvent(QEvent *e)
{
    // Clear link emulation when the mouse leaves the editor
    clearLink();
    QPlainTextEdit::leaveEvent(e);
}

void BaseTextEditor::keyReleaseEvent(QKeyEvent *e)
{
    // Clear link emulation when Ctrl is released
    if (e->key() == Qt::Key_Control)
        clearLink();

    QPlainTextEdit::keyReleaseEvent(e);
}

void BaseTextEditor::dragEnterEvent(QDragEnterEvent *e)
{
    // If the drag event contains URLs, we don't want to insert them as text
    if (e->mimeData()->hasUrls()) {
        e->ignore();
        return;
    }

    QPlainTextEdit::dragEnterEvent(e);
}

void BaseTextEditor::extraAreaLeaveEvent(QEvent *)
{
    // fake missing mouse move event from Qt
    QMouseEvent me(QEvent::MouseMove, QPoint(-1, -1), Qt::NoButton, 0, 0);
    extraAreaMouseEvent(&me);
}

void BaseTextEditor::extraAreaMouseEvent(QMouseEvent *e)
{
    QTextCursor cursor = cursorForPosition(QPoint(0, e->pos().y()));
    cursor.setPosition(cursor.block().position());

    int markWidth;
    extraAreaWidth(&markWidth);

    if (d->m_codeFoldingVisible
        && e->type() == QEvent::MouseMove && e->buttons() == 0) { // mouse tracking
        // Update which folder marker is highlighted
        const int highlightBlockNumber = d->extraAreaHighlightCollapseBlockNumber;
        const int highlightColumn = d->extraAreaHighlightCollapseColumn;
        d->extraAreaHighlightCollapseBlockNumber = -1;
        d->extraAreaHighlightCollapseColumn = -1;

        if (e->pos().x() > extraArea()->width() - collapseBoxWidth(fontMetrics())) {
            d->extraAreaHighlightCollapseBlockNumber = cursor.blockNumber();
            if (TextBlockUserData::canCollapse(cursor.block())
                || !TextBlockUserData::hasClosingCollapse(cursor.block()))
                d->extraAreaHighlightCollapseColumn = cursor.block().length()-1;
            if (TextBlockUserData::hasCollapseAfter(cursor.block())) {
                d->extraAreaHighlightCollapseBlockNumber++;
                d->extraAreaHighlightCollapseColumn = -1;
                if (TextBlockUserData::canCollapse(cursor.block().next())
                    || !TextBlockUserData::hasClosingCollapse(cursor.block().next()))
                    d->extraAreaHighlightCollapseColumn = cursor.block().next().length()-1;
            }
        } else if (d->m_displaySettings.m_highlightBlocks) {
            QTextCursor cursor = textCursor();
            d->extraAreaHighlightCollapseBlockNumber = cursor.blockNumber();
            d->extraAreaHighlightCollapseColumn = cursor.position() - cursor.block().position();
        }

        if (highlightBlockNumber != d->extraAreaHighlightCollapseBlockNumber
            || highlightColumn != d->extraAreaHighlightCollapseColumn) {
            d->m_highlightBlocksTimer->start(d->m_highlightBlocksInfo.isEmpty() ? 120 : 0);
        }
    }

    // Set whether the mouse cursor is a hand or normal arrow
    if (e->type() == QEvent::MouseMove) {
        bool hand = (e->pos().x() <= markWidth);
        if (hand != (d->m_extraArea->cursor().shape() == Qt::PointingHandCursor))
            d->m_extraArea->setCursor(hand ? Qt::PointingHandCursor : Qt::ArrowCursor);
    }

    if (e->type() == QEvent::MouseButtonPress || e->type() == QEvent::MouseButtonDblClick) {
        if (e->button() == Qt::LeftButton) {
            int boxWidth = collapseBoxWidth(fontMetrics());
            if (d->m_codeFoldingVisible && e->pos().x() > extraArea()->width() - boxWidth) {
                if (!cursor.block().next().isVisible()) {
                    toggleBlockVisible(cursor.block());
                    d->moveCursorVisible(false);
                } else if (collapseBox().contains(e->pos())) {
                    cursor.setPosition(
                            document()->findBlockByNumber(d->m_highlightBlocksInfo.open.last()).position()
                            );
                    QTextBlock c = cursor.block();
                    if (TextBlockUserData::hasCollapseAfter(c.previous()))
                        c = c.previous();
                    toggleBlockVisible(c);
                    d->moveCursorVisible(false);
                }
            } else if (d->m_marksVisible && e->pos().x() > markWidth) {
                QTextCursor selection = cursor;
                selection.setVisualNavigation(true);
                d->extraAreaSelectionAnchorBlockNumber = selection.blockNumber();
                selection.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);
                selection.movePosition(QTextCursor::Right, QTextCursor::KeepAnchor);
                setTextCursor(selection);
            } else {
                d->extraAreaToggleMarkBlockNumber = cursor.blockNumber();
            }
        } else if (d->m_marksVisible && e->button() == Qt::RightButton) {
            QMenu * contextMenu = new QMenu(this);
            emit d->m_editable->markContextMenuRequested(editableInterface(), cursor.blockNumber() + 1, contextMenu);
            if (!contextMenu->isEmpty())
                contextMenu->exec(e->globalPos());
            delete contextMenu;
        }
    } else if (d->extraAreaSelectionAnchorBlockNumber >= 0) {
        QTextCursor selection = cursor;
        selection.setVisualNavigation(true);
        if (e->type() == QEvent::MouseMove) {
            QTextBlock anchorBlock = document()->findBlockByNumber(d->extraAreaSelectionAnchorBlockNumber);
            selection.setPosition(anchorBlock.position());
            if (cursor.blockNumber() < d->extraAreaSelectionAnchorBlockNumber) {
                selection.movePosition(QTextCursor::EndOfBlock);
                selection.movePosition(QTextCursor::Right);
            }
            selection.setPosition(cursor.block().position(), QTextCursor::KeepAnchor);
            if (cursor.blockNumber() >= d->extraAreaSelectionAnchorBlockNumber) {
                selection.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);
                selection.movePosition(QTextCursor::Right, QTextCursor::KeepAnchor);
            }

            if (e->pos().y() >= 0 && e->pos().y() <= d->m_extraArea->height())
                d->autoScrollTimer.stop();
            else if (!d->autoScrollTimer.isActive())
                d->autoScrollTimer.start(100, this);

        } else {
            d->autoScrollTimer.stop();
            d->extraAreaSelectionAnchorBlockNumber = -1;
            return;
        }
        setTextCursor(selection);
    } else if (d->extraAreaToggleMarkBlockNumber >= 0 && d->m_marksVisible && d->m_requestMarkEnabled) {
        if (e->type() == QEvent::MouseButtonRelease && e->button() == Qt::LeftButton) {
            int n = d->extraAreaToggleMarkBlockNumber;
            d->extraAreaToggleMarkBlockNumber = -1;
            if (cursor.blockNumber() == n) {
                int line = n + 1;
                emit d->m_editable->markRequested(editableInterface(), line);
            }
        }
    }
}

QTextBlock TextBlockUserData::testCollapse(const QTextBlock& block)
{
    QTextBlock info = block;
    if (block.userData() && static_cast<TextBlockUserData*>(block.userData())->collapseMode() == CollapseAfter)
        ;
    else if (block.next().userData()
             && static_cast<TextBlockUserData*>(block.next().userData())->collapseMode()
             == TextBlockUserData::CollapseThis)
        info = block.next();
    else
        return QTextBlock();
    int pos = static_cast<TextBlockUserData*>(info.userData())->collapseAtPos();
    if (pos < 0)
        return QTextBlock();
    QTextCursor cursor(info);
    cursor.setPosition(cursor.position() + pos);
    matchCursorForward(&cursor);
    return cursor.block();
}

void TextBlockUserData::doCollapse(const QTextBlock& block, bool visible)
{
    QTextBlock info = block;
    if (block.userData() && static_cast<TextBlockUserData*>(block.userData())->collapseMode() == CollapseAfter)
        ;
    else if (block.next().userData()
             && static_cast<TextBlockUserData*>(block.next().userData())->collapseMode()
             == TextBlockUserData::CollapseThis)
        info = block.next();
    else {
        if (visible && !block.next().isVisible()) {
            // no match, at least unfold!
            QTextBlock b = block.next();
            while (b.isValid() && !b.isVisible()) {
                b.setVisible(true);
                b.setLineCount(visible ? qMax(1, b.layout()->lineCount()) : 0);
                b = b.next();
            }
        }
        return;
    }
    int pos = static_cast<TextBlockUserData*>(info.userData())->collapseAtPos();
    if (pos < 0)
        return;
    QTextCursor cursor(info);
    cursor.setPosition(cursor.position() + pos);
    if (matchCursorForward(&cursor) != Match) {
        if (visible) {
            // no match, at least unfold!
            QTextBlock b = block.next();
            while (b.isValid() && !b.isVisible()) {
                b.setVisible(true);
                b.setLineCount(visible ? qMax(1, b.layout()->lineCount()) : 0);
                b = b.next();
            }
        }
        return;
    }

    QTextBlock b = block.next();
    while (b < cursor.block()) {
        b.setVisible(visible);
        b.setLineCount(visible ? qMax(1, b.layout()->lineCount()) : 0);
        if (visible) {
            TextBlockUserData *data = canCollapse(b);
            if (data && data->collapsed()) {
                QTextBlock end =  testCollapse(b);
                if (data->collapseIncludesClosure())
                    end = end.next();
                if (end.isValid()) {
                    b = end;
                    continue;
                }
            }
        }
        b = b.next();
    }

    bool collapseIncludesClosure = hasClosingCollapseAtEnd(b);
    if (collapseIncludesClosure) {
        b.setVisible(visible);
        b.setLineCount(visible ? qMax(1, b.layout()->lineCount()) : 0);
    }
    static_cast<TextBlockUserData*>(info.userData())->setCollapseIncludesClosure(collapseIncludesClosure);
    static_cast<TextBlockUserData*>(info.userData())->setCollapsed(!block.next().isVisible());

}


void BaseTextEditor::ensureCursorVisible()
{
    QTextBlock block = textCursor().block();
    if (!block.isVisible()) {
        while (!block.isVisible() && block.previous().isValid())
            block = block.previous();
        toggleBlockVisible(block);
    }
    QPlainTextEdit::ensureCursorVisible();
}

void BaseTextEditor::toggleBlockVisible(const QTextBlock &block)
{
    TextEditDocumentLayout *documentLayout = qobject_cast<TextEditDocumentLayout*>(document()->documentLayout());
    QTC_ASSERT(documentLayout, return);

    bool visible = block.next().isVisible();
    TextBlockUserData::doCollapse(block, !visible);
    documentLayout->requestUpdate();
    documentLayout->emitDocumentSizeChanged();
}


const TabSettings &BaseTextEditor::tabSettings() const
{
    return d->m_document->tabSettings();
}

const DisplaySettings &BaseTextEditor::displaySettings() const
{
    return d->m_displaySettings;
}


void BaseTextEditor::indentOrUnindent(bool doIndent)
{
    QTextCursor cursor = textCursor();
    cursor.beginEditBlock();

    int pos = cursor.position();
    const TextEditor::TabSettings &tabSettings = d->m_document->tabSettings();

    QTextDocument *doc = document();

    if (!cursor.hasSelection() && doIndent) {
        // Insert tab if there is no selection and indent is requested
        QTextBlock block = cursor.block();
        QString text = block.text();
        int indentPosition = (cursor.position() - block.position());;
        int spaces = tabSettings.spacesLeftFromPosition(text, indentPosition);
        int startColumn = tabSettings.columnAt(text, indentPosition - spaces);
        int targetColumn = tabSettings.indentedColumn(tabSettings.columnAt(text, indentPosition), doIndent);
        cursor.setPosition(block.position() + indentPosition);
        cursor.setPosition(block.position() + indentPosition - spaces, QTextCursor::KeepAnchor);
        cursor.removeSelectedText();
        cursor.insertText(tabSettings.indentationString(startColumn, targetColumn, block));
    } else {
        // Indent or unindent the selected lines
        int anchor = cursor.anchor();
        int start = qMin(anchor, pos);
        int end = qMax(anchor, pos);

        QTextBlock startBlock = doc->findBlock(start);
        QTextBlock endBlock = doc->findBlock(end-1).next();

        for (QTextBlock block = startBlock; block != endBlock; block = block.next()) {
            QString text = block.text();
            int indentPosition = tabSettings.lineIndentPosition(text);
            if (!doIndent && !indentPosition)
                indentPosition = tabSettings.firstNonSpace(text);
            int targetColumn = tabSettings.indentedColumn(tabSettings.columnAt(text, indentPosition), doIndent);
            cursor.setPosition(block.position() + indentPosition);
            cursor.insertText(tabSettings.indentationString(0, targetColumn, block));
            cursor.setPosition(block.position());
            cursor.setPosition(block.position() + indentPosition, QTextCursor::KeepAnchor);
            cursor.removeSelectedText();
        }
    }

    cursor.endEditBlock();
}

void BaseTextEditor::handleHomeKey(bool anchor)
{
    QTextCursor cursor = textCursor();
    QTextCursor::MoveMode mode = QTextCursor::MoveAnchor;

    if (anchor)
        mode = QTextCursor::KeepAnchor;

    const int initpos = cursor.position();
    int pos = cursor.block().position();
    QChar character = characterAt(pos);
    const QLatin1Char tab = QLatin1Char('\t');

    while (character == tab || character.category() == QChar::Separator_Space) {
        ++pos;
        if (pos == initpos)
            break;
        character = characterAt(pos);
    }

    // Go to the start of the block when we're already at the start of the text
    if (pos == initpos)
        pos = cursor.block().position();

    cursor.setPosition(pos, mode);
    setTextCursor(cursor);
}

void BaseTextEditor::handleBackspaceKey()
{
    QTextCursor cursor = textCursor();
    int pos = cursor.position();
    QTC_ASSERT(!cursor.hasSelection(), return);

    if (d->m_snippetOverlay->isVisible()) {
        QTextCursor snippetCursor = cursor;
        snippetCursor.movePosition(QTextCursor::Left);
        d->snippetCheckCursor(snippetCursor);
    }

    const TextEditor::TabSettings &tabSettings = d->m_document->tabSettings();

    if (tabSettings.m_autoIndent && autoBackspace(cursor))
        return;

    if (!tabSettings.m_smartBackspace) {
        cursor.deletePreviousChar();
        return;
    }

    QTextBlock currentBlock = cursor.block();
    int positionInBlock = pos - currentBlock.position();
    const QString blockText = currentBlock.text();
    if (cursor.atBlockStart() || tabSettings.firstNonSpace(blockText) < positionInBlock) {
        cursor.deletePreviousChar();
        return;
    }

    int previousIndent = 0;
    const int indent = tabSettings.columnAt(blockText, positionInBlock);

    for (QTextBlock previousNonEmptyBlock = currentBlock.previous();
         previousNonEmptyBlock.isValid();
         previousNonEmptyBlock = previousNonEmptyBlock.previous()) {
        QString previousNonEmptyBlockText = previousNonEmptyBlock.text();
        if (previousNonEmptyBlockText.trimmed().isEmpty())
            continue;
        previousIndent = tabSettings.columnAt(previousNonEmptyBlockText,
                                              tabSettings.firstNonSpace(previousNonEmptyBlockText));
        if (previousIndent < indent) {
            cursor.beginEditBlock();
            cursor.setPosition(currentBlock.position(), QTextCursor::KeepAnchor);
            cursor.insertText(tabSettings.indentationString(previousNonEmptyBlockText));
            cursor.endEditBlock();
            return;
        }
    }
    cursor.deletePreviousChar();
}

void BaseTextEditor::wheelEvent(QWheelEvent *e)
{
    d->clearVisibleCollapsedBlock();
    if (scrollWheelZoomingEnabled() && e->modifiers() & Qt::ControlModifier) {
        const int delta = e->delta();
        if (delta < 0)
            zoomOut();
        else if (delta > 0)
            zoomIn();
        return;
    }
    QPlainTextEdit::wheelEvent(e);
}

void BaseTextEditor::zoomIn(int range)
{
    d->clearVisibleCollapsedBlock();
    emit requestFontZoom(range*10);
}

void BaseTextEditor::zoomOut(int range)
{
    zoomIn(-range);
}

void BaseTextEditor::zoomReset()
{
    emit requestZoomReset();
}

bool BaseTextEditor::isElectricCharacter(const QChar &) const
{
    return false;
}

void BaseTextEditor::indentInsertedText(const QTextCursor &tc)
{
    indent(tc.document(), tc, QChar::Null);
}

void BaseTextEditor::countBracket(QChar open, QChar close, QChar c, int *errors, int *stillopen)
{
    if (c == open)
        ++*stillopen;
    else if (c == close)
        --*stillopen;

    if (*stillopen < 0) {
        *errors += -1 * (*stillopen);
        *stillopen = 0;
    }
}

void BaseTextEditor::countBrackets(QTextCursor cursor, int from, int end, QChar open, QChar close, int *errors, int *stillopen)
{
    cursor.setPosition(from);
    QTextBlock block = cursor.block();
    while (block.isValid() && block.position() < end) {
        TextEditor::Parentheses parenList = TextEditor::TextEditDocumentLayout::parentheses(block);
        if (!parenList.isEmpty() && !TextEditor::TextEditDocumentLayout::ifdefedOut(block)) {
            for (int i = 0; i < parenList.count(); ++i) {
                TextEditor::Parenthesis paren = parenList.at(i);
                int position = block.position() + paren.pos;
                if (position < from || position >= end)
                    continue;
                countBracket(open, close, paren.chr, errors, stillopen);
            }
        }
        block = block.next();
    }
}

bool BaseTextEditor::contextAllowsAutoParentheses(const QTextCursor &cursor,
                                                  const QString &textToInsert) const
{
    Q_UNUSED(cursor);
    Q_UNUSED(textToInsert);
    return false;
}

bool BaseTextEditor::isInComment(const QTextCursor &cursor) const
{
    Q_UNUSED(cursor);
    return false;
}

QString BaseTextEditor::insertMatchingBrace(const QTextCursor &tc, const QString &text,
                                            const QChar &la, int *skippedChars) const
{
    Q_UNUSED(tc);
    Q_UNUSED(text);
    Q_UNUSED(la);
    Q_UNUSED(skippedChars);
    return QString();
}

QString BaseTextEditor::insertParagraphSeparator(const QTextCursor &tc) const
{
    Q_UNUSED(tc);
    return QString();
}

QString BaseTextEditor::autoComplete(QTextCursor &cursor, const QString &textToInsert) const
{
    const bool checkBlockEnd = d->m_allowSkippingOfBlockEnd;
    d->m_allowSkippingOfBlockEnd = false; // consume blockEnd.

    if (!contextAllowsAutoParentheses(cursor, textToInsert))
        return QString();

    const QString text = textToInsert;
    const QChar lookAhead = characterAt(cursor.selectionEnd());

    QChar character = textToInsert.at(0);
    const QString parentheses = QLatin1String("()");
    const QString brackets = QLatin1String("[]");
    if (parentheses.contains(character) || brackets.contains(character)) {
        QTextCursor tmp= cursor;
        bool foundBlockStart = TextEditor::TextBlockUserData::findPreviousBlockOpenParenthesis(&tmp);
        int blockStart = foundBlockStart ? tmp.position() : 0;
        tmp = cursor;
        bool foundBlockEnd = TextEditor::TextBlockUserData::findNextBlockClosingParenthesis(&tmp);
        int blockEnd = foundBlockEnd ? tmp.position() : (cursor.document()->characterCount() - 1);
        const QChar openChar = parentheses.contains(character) ? QLatin1Char('(') : QLatin1Char('[');
        const QChar closeChar = parentheses.contains(character) ? QLatin1Char(')') : QLatin1Char(']');

        int errors = 0;
        int stillopen = 0;
        countBrackets(cursor, blockStart, blockEnd, openChar, closeChar, &errors, &stillopen);
        int errorsBeforeInsertion = errors + stillopen;
        errors = 0;
        stillopen = 0;
        countBrackets(cursor, blockStart, cursor.position(), openChar, closeChar, &errors, &stillopen);
        countBracket(openChar, closeChar, character, &errors, &stillopen);
        countBrackets(cursor, cursor.position(), blockEnd, openChar, closeChar, &errors, &stillopen);
        int errorsAfterInsertion = errors + stillopen;
        if (errorsAfterInsertion < errorsBeforeInsertion)
            return QString(); // insertion fixes parentheses or bracket errors, do not auto complete
    }

    int skippedChars = 0;
    const QString autoText = insertMatchingBrace(cursor, text, lookAhead, &skippedChars);

    if (checkBlockEnd && textToInsert.at(0) == QLatin1Char('}')) {
        if (textToInsert.length() > 1)
            qWarning() << "*** handle event compression";

        int startPos = cursor.selectionEnd(), pos = startPos;
        while (characterAt(pos).isSpace())
            ++pos;

        if (characterAt(pos) == QLatin1Char('}'))
            skippedChars += (pos - startPos) + 1;
    }

    if (skippedChars) {
        const int pos = cursor.position();
        cursor.setPosition(pos + skippedChars);
        cursor.setPosition(pos, QTextCursor::KeepAnchor);
    }

    return autoText;
}

bool BaseTextEditor::autoBackspace(QTextCursor &cursor)
{
    d->m_allowSkippingOfBlockEnd = false;