Fixxed isse #131 - Crash on dropping in same area multiple times

src/DockContainerWidget.cpp

@@ -679,6 +679,23 @@ void DockContainerWidgetPrivate::moveToContainer(QWidget* Widget, DockWidgetArea
 	}
 	else
 	{
+		// We check, if we insert the dropped widget into the same place that
+		// it already has and do nothing, if it is the same place. It would
+		// also work without this check, but it looks nicer with the check
+		// because there will be no layout updates
+		auto Splitter = internal::findParent<CDockSplitter*>(DroppedDockArea);
+		auto InsertParam = internal::dockAreaInsertParameters(area);
+		if (Splitter == RootSplitter && InsertParam.orientation() == Splitter->orientation())
+		{
+			if (InsertParam.append() && Splitter->lastWidget() == DroppedDockArea)
+			{
+				return;
+			}
+			else if (!InsertParam.append() && Splitter->firstWidget() == DroppedDockArea)
+			{
+				return;
+			}
+		}
 		DroppedDockArea->dockContainer()->removeDockArea(DroppedDockArea);
 		NewDockArea = DroppedDockArea;
 	}
@@ -1435,42 +1452,38 @@ void CDockContainerWidget::dropFloatingWidget(CFloatingDockContainer* FloatingWi
 }
 
 
-//============================================================================
-void CDockContainerWidget::dropWidget(QWidget* Widget, const QPoint& TargetPos)
+/**
+ * Returns the dock area for a dropped widget.
+ */
+CDockAreaWidget* droppedDockArea(QWidget* Widget)
 {
-    ADS_PRINT("CDockContainerWidget::dropFloatingWidget");
-    CDockWidget* SingleDockWidget = topLevelDockWidget();
-	CDockAreaWidget* DockArea = dockAreaAt(TargetPos);
-	auto dropArea = InvalidDockWidgetArea;
-	auto ContainerDropArea = d->DockManager->containerOverlay()->dropAreaUnderCursor();
-
-	if (DockArea)
+	auto DroppedArea = qobject_cast<CDockAreaWidget*>(Widget);
+	if (!DroppedArea)
 	{
-		auto dropOverlay = d->DockManager->dockAreaOverlay();
-		dropOverlay->setAllowedAreas(DockArea->allowedAreas());
-		dropArea = dropOverlay->showOverlay(DockArea);
-		if (ContainerDropArea != InvalidDockWidgetArea &&
-			ContainerDropArea != dropArea)
-		{
-			dropArea = InvalidDockWidgetArea;
-		}
-
-		if (dropArea != InvalidDockWidgetArea)
-		{
-            ADS_PRINT("Dock Area Drop Content: " << dropArea);
-            d->moveToNewSection(Widget, DockArea, dropArea);
-		}
+		auto DroppedWidget = qobject_cast<CDockWidget*>(Widget);
+		DroppedArea = DroppedWidget->dockAreaWidget();
 	}
 
-	// mouse is over container
-	if (InvalidDockWidgetArea == dropArea)
+	return DroppedArea;
+}
+
+
+//============================================================================
+void CDockContainerWidget::dropWidget(QWidget* Widget, DockWidgetArea DropArea, CDockAreaWidget* TargetAreaWidget)
+{
+	if (TargetAreaWidget && TargetAreaWidget == droppedDockArea(Widget))
 	{
-		dropArea = ContainerDropArea;
-        ADS_PRINT("Container Drop Content: " << dropArea);
-		if (dropArea != InvalidDockWidgetArea)
-		{
-			d->moveToContainer(Widget, dropArea);
-		}
+		return;
+	}
+
+    CDockWidget* SingleDockWidget = topLevelDockWidget();
+	if (TargetAreaWidget)
+	{
+		d->moveToNewSection(Widget, TargetAreaWidget, DropArea);
+	}
+	else
+	{
+		d->moveToContainer(Widget, DropArea);
 	}
 
 	// If there was a top level widget before the drop, then it is not top

src/DockContainerWidget.h

@@ -96,9 +96,13 @@ protected:
 	void dropFloatingWidget(CFloatingDockContainer* FloatingWidget, const QPoint& TargetPos);
 
 	/**
-	 * Drop a dock area or a dock widget given in widget parameter
+	 * Drop a dock area or a dock widget given in widget parameter.
+	 * If the TargetAreaWidget is a nullptr, then the DropArea indicates
+	 * the drop area for the container. If the given TargetAreaWidget is not
+	 * a nullptr, then the DropArea indicates the drop area in the given
+	 * TargetAreaWidget
 	 */
-	void dropWidget(QWidget* Widget, const QPoint& TargetPos);
+	void dropWidget(QWidget* Widget, DockWidgetArea DropArea, CDockAreaWidget* TargetAreaWidget);
 
 	/**
 	 * Adds the given dock area to this container widget

src/DockOverlay.cpp

@@ -396,6 +396,20 @@ DockWidgetArea CDockOverlay::dropAreaUnderCursor() const
 }
 
 
+//============================================================================
+DockWidgetArea CDockOverlay::visibleDropAreaUnderCursor() const
+{
+	if (isHidden() || !d->DropPreviewEnabled)
+	{
+		return InvalidDockWidgetArea;
+	}
+	else
+	{
+		return dropAreaUnderCursor();
+	}
+}
+
+
 //============================================================================
 DockWidgetArea CDockOverlay::showOverlay(QWidget* target)
 {

src/DockOverlay.h

@@ -81,6 +81,13 @@ public:
 	 */
 	DockWidgetArea dropAreaUnderCursor() const;
 
+	/**
+	 * This function returns the same like dropAreaUnderCursor() if this
+	 * overlay is not hidden and if drop preview is enabled and returns
+	 * InvalidDockWidgetArea if it is hidden or drop preview is disabled.
+	 */
+	DockWidgetArea visibleDropAreaUnderCursor() const;
+
 	/**
 	 * Show the drop overly for the given target widget
 	 */

src/DockSplitter.cpp

@@ -88,6 +88,20 @@ bool CDockSplitter::hasVisibleContent() const
 	return false;
 }
 
+
+//============================================================================
+QWidget* CDockSplitter::firstWidget() const
+{
+	return (count() > 0) ? widget(0) : nullptr;
+}
+
+
+//============================================================================
+QWidget* CDockSplitter::lastWidget() const
+{
+	return (count() > 0) ? widget(count() - 1) : nullptr;
+}
+
 } // namespace ads
 
 //---------------------------------------------------------------------------

src/DockSplitter.h

@@ -61,6 +61,16 @@ public:
 	 * Returns true, if any of the internal widgets is visible
 	 */
 	bool hasVisibleContent() const;
+
+	/**
+	 * Returns first widget or nullptr if splitter is empty
+	 */
+	QWidget* firstWidget() const;
+
+	/**
+	 * Returns last widget of nullptr is splitter is empty
+	 */
+	QWidget* lastWidget() const;
 }; // class CDockSplitter
 
 } // namespace ads

src/FloatingDragPreview.cpp

@@ -286,12 +286,15 @@ void CFloatingDragPreview::moveEvent(QMoveEvent *event)
 void CFloatingDragPreview::finishDragging()
 {
 	ADS_PRINT("CFloatingDragPreview::finishDragging");
-	auto DockDropArea = d->DockManager->dockAreaOverlay()->dropAreaUnderCursor();
-	auto ContainerDropArea = d->DockManager->containerOverlay()->dropAreaUnderCursor();
-	bool DropPossible = (DockDropArea != InvalidDockWidgetArea) || (ContainerDropArea != InvalidDockWidgetArea);
-	if (d->DropContainer && DropPossible)
+	auto DockDropArea = d->DockManager->dockAreaOverlay()->visibleDropAreaUnderCursor();
+	auto ContainerDropArea = d->DockManager->containerOverlay()->visibleDropAreaUnderCursor();
+	if (d->DropContainer && (DockDropArea != InvalidDockWidgetArea))
 	{
-		d->DropContainer->dropWidget(d->Content, QCursor::pos());
+		d->DropContainer->dropWidget(d->Content, DockDropArea, d->DropContainer->dockAreaAt(QCursor::pos()));
+	}
+	else if (d->DropContainer && (ContainerDropArea != InvalidDockWidgetArea))
+	{
+		d->DropContainer->dropWidget(d->Content, ContainerDropArea, nullptr);
 	}
 	else
 	{