Implemented auto-scrolling for ticket 499

src/gui/UBDocumentThumbnailWidget.cpp

@@ -26,9 +26,10 @@ UBDocumentThumbnailWidget::UBDocumentThumbnailWidget(QWidget* parent)
     : UBThumbnailWidget(parent)
     , mDropCaretRectItem(0)
     , mClosestDropItem(0)
-    , mDragEnabled(true)
+	, mDragEnabled(true), mScrollMagnitude(0)
 {
-    // NOOP
+    mScrollTimer = new QTimer(this);
+	connect(mScrollTimer, SIGNAL(timeout()), this, SLOT(autoScroll()));
 }
 
 
@@ -96,13 +97,43 @@ void UBDocumentThumbnailWidget::dragEnterEvent(QDragEnterEvent *event)
 void UBDocumentThumbnailWidget::dragLeaveEvent(QDragLeaveEvent *event)
 {
     Q_UNUSED(event);
+	if (mScrollTimer->isActive())
+	{
+		mScrollMagnitude = 0;
+		mScrollTimer->stop();
+	}
     deleteDropCaret();
 }
 
+void UBDocumentThumbnailWidget::autoScroll()
+{
+	this->verticalScrollBar()->setValue(this->verticalScrollBar()->value() + mScrollMagnitude);
+}
+
 void UBDocumentThumbnailWidget::dragMoveEvent(QDragMoveEvent *event)
 {
-    QList<UBSceneThumbnailPixmap*> pixmapItems;
-    foreach (QGraphicsItem *item, scene()->items(mapToScene(frameRect())))
+	QRect boundingFrame = frameRect();
+	//setting up automatic scrolling
+	const int SCROLL_DISTANCE = 16;
+	int bottomDist = boundingFrame.bottom() - event->pos().y(), topDist = boundingFrame.top() - event->pos().y();
+	if(qAbs(bottomDist) <= SCROLL_DISTANCE)
+	{
+		mScrollMagnitude = (SCROLL_DISTANCE - bottomDist)*4;
+		if(verticalScrollBar()->isVisible() && !mScrollTimer->isActive()) mScrollTimer->start(100);
+	}
+	else if(qAbs(topDist) <= SCROLL_DISTANCE)
+	{
+		mScrollMagnitude = (- SCROLL_DISTANCE - topDist)*4;
+		if(verticalScrollBar()->isVisible() && !mScrollTimer->isActive()) mScrollTimer->start(100);
+	}
+	else
+	{
+		mScrollMagnitude = 0;
+		mScrollTimer->stop();
+	}
+
+	QList<UBSceneThumbnailPixmap*> pixmapItems;
+    foreach (QGraphicsItem *item, scene()->items(mapToScene(boundingFrame)))
     {
         UBSceneThumbnailPixmap* sceneItem = dynamic_cast<UBSceneThumbnailPixmap*>(item);
         if (sceneItem)
@@ -161,9 +192,15 @@ void UBDocumentThumbnailWidget::dragMoveEvent(QDragMoveEvent *event)
     event->acceptProposedAction();
 }
 
+
 void UBDocumentThumbnailWidget::dropEvent(QDropEvent *event)
 {
-    deleteDropCaret();
+	if (mScrollTimer->isActive())
+	{
+		mScrollMagnitude = 0;
+		mScrollTimer->stop();
+	}
+	deleteDropCaret();
 
     if (mClosestDropItem)
     {

src/gui/UBDocumentThumbnailWidget.h

@@ -41,6 +41,9 @@ class UBDocumentThumbnailWidget: public UBThumbnailWidget
     signals:
         void sceneDropped(UBDocumentProxy* proxy, int source, int target);
 
+	private slots:
+		void autoScroll();
+
     protected:
 
         virtual void mouseMoveEvent(QMouseEvent *event);
@@ -57,6 +60,8 @@ class UBDocumentThumbnailWidget: public UBThumbnailWidget
         UBSceneThumbnailPixmap *mClosestDropItem;
         bool mDropIsRight;
         bool mDragEnabled;
+		QTimer* mScrollTimer;
+		int mScrollMagnitude;
 };
 
 #endif /* UBDOCUMENTTHUMBNAILWIDGET_H_ */