Qt拖拽分隔线

void DragBaseBoxLayout::addWidget(QWidget* widget)
{
	this->layout()->addWidget(widget);
}

void DragBaseBoxLayout::hideIndicator(Indicator i)
{
	if (m_indicators[i])
		m_indicators[i]->hide();
}

void DragBaseBoxLayout::showIndicator(Indicator i, const QRect &geometry, const QPalette &p)
{
	if (!m_indicators[i])
		m_indicators[i] = new InvisibleWidget(this);
	QWidget *indicator = m_indicators[i];
	indicator->setAutoFillBackground(true);
	indicator->setPalette(p);
	indicator->setGeometry(geometry);
	indicator->show();
	indicator->raise();
}

void DragBaseBoxLayout::setImageTransparency(QImage &image, int alpha)
{
	const int height = image.height();
	for (int l = 0; l < height; l++) {
		QRgb *line = reinterpret_cast<QRgb *>(image.scanLine(l));
		QRgb *lineEnd = line + image.width();
		for (; line < lineEnd; line++) {
			const QRgb rgba = *line;
			*line = qRgba(qRed(rgba), qGreen(rgba), qBlue(rgba), alpha);
		}
	}
}

int DragBaseBoxLayout::findItemAt(const QPoint &pos) const
{
	if (!layout())
		return -1;

	const QLayout *lt = layout();
	const int count = lt->count();

	if (count == 0)
		return -1;

	int best = -1;
	int bestIndex = -1;

	for (int index = 0; index < count; index++) {
		QLayoutItem *item = lt->itemAt(index);
		bool visible = true;
		if (const QWidget *w = item->widget())
			visible = w->isVisible();
		if (visible) {
			const QRect g = item->geometry();

			const int dist = (g.center() - pos).manhattanLength();
			if (best == -1 || dist < best) {
				best = dist;
				bestIndex = index;
			}
		}
	}
	return bestIndex;
}

bool DragBaseBoxLayout::eventFilter(QObject *watched, QEvent *event)
{
	if (watched == this){
		if (event->type() == QEvent::ChildRemoved && m_isDragout){
			QBoxLayout* layout = dynamic_cast<QBoxLayout*>(this->layout());
			layout->insertWidget(m_srcIndex, m_widget);
			m_widget->show();
		}
	}
	return QWidget::eventFilter(watched, event);
}

void DragBaseBoxLayout::mousePressEvent(QMouseEvent *event)
{
	QWidget *child = static_cast<QWidget*>(childAt(event->pos()));
	m_srcIndex = layout()->indexOf(child);
	if (!child || m_srcIndex == -1)
		return;
	m_widget = child;
	child->hide();
	layout()->removeWidget(child);
	QMimeData *mimeData = new QMimeData;
	mimeData->setData(m_dargItemstr, "");

	QDrag *drag = new QDrag(this);
	QImage& image = child->grab().toImage();
	setImageTransparency(image, 120);
	drag->setMimeData(mimeData);
	drag->setPixmap(QPixmap::fromImage(image));
	drag->setHotSpot(event->pos() - child->pos());
	drag->exec(Qt::MoveAction);
}


QRect DragHBoxLayout::extendedGeometry(int index) const
{
	QLayoutItem *item = layout()->itemAt(index);
	QRect g = item->geometry();

	const QBoxLayout *box = static_cast<const QBoxLayout*>(layout());
	if (index == 0){
		QPoint topLeft = g.topLeft();
		topLeft.rx() = layout()->geometry().left();
		g.setTopLeft(topLeft);
		return g;
	}

	if (index < box->count() - 1)
		return g;

	QPoint bottomRight = g.bottomRight();
	bottomRight.rx() = layout()->geometry().right();
	g.setBottomRight(bottomRight);
	return g;
}

void DragHBoxLayout::adjustIndicator(const QPoint &pos, int index)
{
	if (index == -1) {
		hideIndicator(LeftIndicator);
		hideIndicator(TopIndicator);
		hideIndicator(RightIndicator);
		hideIndicator(BottomIndicator);
		return;
	}
	m_currentIndex = index;
	QLayoutItem *item = layout()->itemAt(index);
	const QRect g = extendedGeometry(index);

	QPalette bluePalette;
	bluePalette.setColor(QPalette::Window, Qt::blue);
	hideIndicator(LeftIndicator);
	hideIndicator(TopIndicator);

	const int fromRight = g.right() - pos.x();
	const int fromLeft = pos.x() - g.x();
	const int fromLeftRight = qMin(fromRight, fromLeft);
	hideIndicator(BottomIndicator);
	const bool closeToLeft = fromLeftRight == fromLeft;
	m_currentIndex = closeToLeft ? m_currentIndex : m_currentIndex + 1;
	showIndicator(RightIndicator, QRect(closeToLeft ? g.x() : g.right() + 1 - indicatorSize, g.y(), indicatorSize, g.height()), bluePalette);
}

void DragHBoxLayout::highlightWidget(QWidget *widget, const QPoint &pos)
{
	const int index = findItemAt(pos);
	adjustIndicator(pos, index);
}

void  DragHBoxLayout::dragEnterEvent(QDragEnterEvent * event)
{
	if (event->mimeData()->hasFormat(m_dargItemstr)) {
		m_isDragout = false;
		highlightWidget(m_widget, event->pos());
		event->setDropAction(Qt::MoveAction);
		event->accept();
	}
	else {
		event->ignore();
	}
}

void  DragHBoxLayout::dragMoveEvent(QDragMoveEvent * event)
{
	if (event->mimeData()->hasFormat(m_dargItemstr)) {
		m_isDragout = false;
		highlightWidget(m_widget, event->pos());
		event->setDropAction(Qt::MoveAction);
		event->accept();
	}
	else {
		event->ignore();
	}
}

void  DragHBoxLayout::dragLeaveEvent(QDragLeaveEvent*/* event*/)
{
	m_isDragout = true;
	adjustIndicator(QPoint(), -1);
}

void  DragHBoxLayout::dropEvent(QDropEvent * event)
{
	if (event->mimeData()->hasFormat(m_dargItemstr)) {
		hideIndicator(RightIndicator);
		QBoxLayout* layout = dynamic_cast<QBoxLayout*>(this->layout());
		m_widget->show();
		layout->insertWidget(m_currentIndex, m_widget);
		event->setDropAction(Qt::MoveAction);
		event->accept();
	}
	else {
		event->ignore();
	}
}


QRect DragVBoxLayout::extendedGeometry(int index) const
{
	QLayoutItem *item = layout()->itemAt(index);
	QRect g = item->geometry();

	const QBoxLayout *box = static_cast<const QBoxLayout*>(layout());
	if (index == 0){
		QPoint topLeft = g.topLeft();
		topLeft.ry() = layout()->geometry().top();
		g.setTopLeft(topLeft);
		return g;
	}

	if (index < box->count() - 1)
		return g;

	QPoint bottomRight = g.bottomRight();
	bottomRight.ry() = layout()->geometry().bottom();
	g.setBottomRight(bottomRight);
	return g;
}

void DragVBoxLayout::adjustIndicator(const QPoint &pos, int index)
{
	if (index == -1) {
		hideIndicator(LeftIndicator);
		hideIndicator(TopIndicator);
		hideIndicator(RightIndicator);
		hideIndicator(BottomIndicator);
		return;
	}
	m_currentIndex = index;
	QLayoutItem *item = layout()->itemAt(index);
	const QRect g = extendedGeometry(index);

	QPalette bluePalette;
	bluePalette.setColor(QPalette::Window, Qt::blue);
	hideIndicator(LeftIndicator);
	hideIndicator(TopIndicator);

	const int fromBottom = g.bottom() - pos.y();
	const int fromTop = pos.y() - g.y();
	const int fromBottomTop = qMin(fromBottom, fromTop);

	hideIndicator(RightIndicator);
	const bool closeToTop = fromBottomTop == fromTop;
	m_currentIndex = closeToTop ? m_currentIndex : m_currentIndex + 1;
	showIndicator(BottomIndicator, QRect(g.x(), closeToTop ? g.y() : g.bottom() + 1 - indicatorSize, g.width(), indicatorSize), bluePalette);

}

void DragVBoxLayout::highlightWidget(QWidget *widget, const QPoint &pos)
{
	const int index = findItemAt(pos);
	adjustIndicator(pos, index);
}

void  DragVBoxLayout::dragEnterEvent(QDragEnterEvent * event)
{
	if (event->mimeData()->hasFormat(m_dargItemstr)) {
		m_isDragout = false;
		highlightWidget(m_widget, event->pos());
		event->setDropAction(Qt::MoveAction);
		event->accept();
	}
	else {
		event->ignore();
	}
}

void  DragVBoxLayout::dragMoveEvent(QDragMoveEvent * event)
{
	if (event->mimeData()->hasFormat(m_dargItemstr)) {
		m_isDragout = false;
		highlightWidget(m_widget, event->pos());
		event->setDropAction(Qt::MoveAction);
		event->accept();
	}
	else {
		event->ignore();
	}
}

void  DragVBoxLayout::dragLeaveEvent(QDragLeaveEvent*/* event*/)
{
	m_isDragout = true;
	adjustIndicator(QPoint(), -1);
}

void  DragVBoxLayout::dropEvent(QDropEvent * event)
{
	if (event->mimeData()->hasFormat(m_dargItemstr)) {
		hideIndicator(BottomIndicator);
		QBoxLayout* layout = dynamic_cast<QBoxLayout*>(this->layout());
		m_widget->show();
		layout->insertWidget(m_currentIndex, m_widget);
		event->setDropAction(Qt::MoveAction);
		event->accept();
	}
	else {
		event->ignore();
	}
}