Some refactoring to improve code clarity, renamed DockWidgetTitleBar into DockWidgetTab because in the GUI it is a tab, created new class CDockAreaTabBar for the tabbar of a dock area

src/DockAreaTabBar.cpp

@@ -0,0 +1,173 @@
+//============================================================================
+/// \file   DockAreaTabBar.cpp
+/// \author Uwe Kindler
+/// \date   24.08.2018
+/// \brief  Implementation of CDockAreaTabBar class
+//============================================================================
+
+//============================================================================
+//                                   INCLUDES
+//============================================================================
+#include "DockAreaTabBar.h"
+
+#include <QMouseEvent>
+#include <QScrollBar>
+#include <QDebug>
+
+#include "FloatingDockContainer.h"
+#include "DockAreaWidget.h"
+#include "DockOverlay.h"
+#include "DockManager.h"
+
+namespace ads
+{
+/**
+ * Private data class of CDockAreaTabBar class (pimpl)
+ */
+struct DockAreaTabBarPrivate
+{
+	CDockAreaTabBar* _this;
+	QPoint DragStartMousePos;
+	CDockAreaWidget* DockArea;
+	CFloatingDockContainer* FloatingWidget = nullptr;
+
+	/**
+	 * Private data constructor
+	 */
+	DockAreaTabBarPrivate(CDockAreaTabBar* _public);
+};
+// struct DockAreaTabBarPrivate
+
+//============================================================================
+DockAreaTabBarPrivate::DockAreaTabBarPrivate(CDockAreaTabBar* _public) :
+	_this(_public)
+{
+
+}
+
+//============================================================================
+CDockAreaTabBar::CDockAreaTabBar(CDockAreaWidget* parent) :
+	QScrollArea(parent),
+	d(new DockAreaTabBarPrivate(this))
+{
+	d->DockArea = parent;
+	setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Ignored);
+	setFrameStyle(QFrame::NoFrame);
+	setWidgetResizable(true);
+	setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+	setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+}
+
+//============================================================================
+CDockAreaTabBar::~CDockAreaTabBar()
+{
+	delete d;
+}
+
+
+//============================================================================
+void CDockAreaTabBar::wheelEvent(QWheelEvent* Event)
+{
+	Event->accept();
+	const int direction = Event->angleDelta().y();
+	if (direction < 0)
+	{
+		horizontalScrollBar()->setValue(horizontalScrollBar()->value() + 20);
+	}
+	else
+	{
+		horizontalScrollBar()->setValue(horizontalScrollBar()->value() - 20);
+	}
+}
+
+
+//============================================================================
+void CDockAreaTabBar::mousePressEvent(QMouseEvent* ev)
+{
+	if (ev->button() == Qt::LeftButton)
+	{
+		ev->accept();
+		d->DragStartMousePos = ev->pos();
+		return;
+	}
+	QScrollArea::mousePressEvent(ev);
+}
+
+
+//============================================================================
+void CDockAreaTabBar::mouseReleaseEvent(QMouseEvent* ev)
+{
+	if (ev->button() == Qt::LeftButton)
+	{
+		qDebug() << "CTabsScrollArea::mouseReleaseEvent";
+		ev->accept();
+		d->FloatingWidget = nullptr;
+		d->DragStartMousePos = QPoint();
+		return;
+	}
+	QScrollArea::mouseReleaseEvent(ev);
+}
+
+
+//============================================================================
+void CDockAreaTabBar::mouseMoveEvent(QMouseEvent* ev)
+{
+	QScrollArea::mouseMoveEvent(ev);
+	if (ev->buttons() != Qt::LeftButton)
+	{
+		return;
+	}
+
+	if (d->FloatingWidget)
+	{
+		d->FloatingWidget->moveFloating();
+		return;
+	}
+
+	// If this is the last dock area in a dock container it does not make
+	// sense to move it to a new floating widget and leave this one
+	// empty
+	if (d->DockArea->dockContainer()->isFloating()
+	 && d->DockArea->dockContainer()->visibleDockAreaCount() == 1)
+	{
+		return;
+	}
+
+	if (!this->geometry().contains(ev->pos()))
+	{
+		qDebug() << "CTabsScrollArea::startFloating";
+		startFloating(d->DragStartMousePos);
+		auto Overlay = d->DockArea->dockManager()->containerOverlay();
+		Overlay->setAllowedAreas(OuterDockAreas);
+	}
+
+	return;
+}
+
+
+//============================================================================
+void CDockAreaTabBar::mouseDoubleClickEvent(QMouseEvent *event)
+{
+	// If this is the last dock area in a dock container it does not make
+	// sense to move it to a new floating widget and leave this one
+	// empty
+	if (d->DockArea->dockContainer()->isFloating() && d->DockArea->dockContainer()->dockAreaCount() == 1)
+	{
+		return;
+	}
+	startFloating(event->pos());
+}
+
+
+//============================================================================
+void CDockAreaTabBar::startFloating(const QPoint& Pos)
+{
+	QSize Size = d->DockArea->size();
+	CFloatingDockContainer* FloatingWidget = new CFloatingDockContainer(d->DockArea);
+	FloatingWidget->startFloating(Pos, Size);
+	d->FloatingWidget = FloatingWidget;
+}
+} // namespace ads
+
+//---------------------------------------------------------------------------
+// EOF DockAreaTabBar.cpp