Support drag&drop objects into timeline

Implement dragging items from the "Basic Objects" and project assets to
the timeline tree part.

Task-number: QT3DS-1455
Change-Id: Iafb58d647221c63dcaa5ac9cced3ab9ee8de2a68
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

15 files changed, 304 insertions, 199 deletions

diff --git a/src/Authoring/Studio/Controls/Control.h b/src/Authoring/Studio/Controls/Control.h
index 7beccd8e..b0079d31 100644
--- a/src/Authoring/Studio/Controls/Control.h
+++ b/src/Authoring/Studio/Controls/Control.h
@@ -117,7 +117,7 @@ public:
 
     virtual CPt GetSize() const;
     virtual void SetSize(CPt inSize);
-    void SetSize(long inWidth, long inHeight);
+    virtual void SetSize(long inWidth, long inHeight);
     virtual void OnSizeChanged(CPt inSize);
 
     virtual CPt GetMinimumSize();
diff --git a/src/Authoring/Studio/DragAndDrop/DropSource.cpp b/src/Authoring/Studio/DragAndDrop/DropSource.cpp
index bd764dd4..190eb95a 100644
--- a/src/Authoring/Studio/DragAndDrop/DropSource.cpp
+++ b/src/Authoring/Studio/DragAndDrop/DropSource.cpp
@@ -41,6 +41,9 @@
 #include "TimelineDropSource.h"
 #include "BasicObjectDropSource.h"
 #include "ListBoxDropSource.h"
+#include "Views.h"
+#include "MainFrm.h"
+#include "TimelineWidget.h"
 
 CDropSource::CDropSource(long inFlavor, unsigned long inSize)
     : m_Flavor(inFlavor)
@@ -49,10 +52,12 @@ CDropSource::CDropSource(long inFlavor, unsigned long inSize)
     , m_HasValidTarget(false)
     , m_CurrentFlags(0)
 {
+    g_StudioApp.GetViews()->getMainFrame()->getTimelineWidget()->enableDnD();
 }
 
 CDropSource::~CDropSource()
 {
+    g_StudioApp.GetViews()->getMainFrame()->getTimelineWidget()->enableDnD(false);
 }
 
 CDropSource *CDropSourceFactory::Create(long inFlavor, void *inData, unsigned long inSize)
diff --git a/src/Authoring/Studio/MainFrm.cpp b/src/Authoring/Studio/MainFrm.cpp
index 0aace15e..bdca8bc2 100644
--- a/src/Authoring/Studio/MainFrm.cpp
+++ b/src/Authoring/Studio/MainFrm.cpp
@@ -60,6 +60,7 @@
 #include "TimelineWidget.h"
 #include "ProjectView.h"
 #include "RowTree.h"
+#include "WidgetControl.h"
 
 #include <QtGui/qevent.h>
 #include <QtGui/qdesktopservices.h>
@@ -1845,8 +1846,9 @@ void CMainFrame::OnConnectionChanged(bool connected)
 
 TimelineWidget *CMainFrame::getTimelineWidget() const
 {
-    return static_cast<TimelineWidget *>(m_paletteManager->GetControl(
-                                             CPaletteManager::CONTROLTYPE_TIMELINE)->widget());
+    WidgetControl *control = static_cast<WidgetControl *>
+            (m_paletteManager->GetControl(CPaletteManager::CONTROLTYPE_TIMELINE)->widget());
+    return static_cast<TimelineWidget *>(control->getControl());
 }
 
 CRecentItems *CMainFrame::GetRecentItems()
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.cpp b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.cpp
index fbca0934..eb78c31d 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.cpp
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.cpp
@@ -141,7 +141,7 @@ RowTree *RowManager::createRow(EStudioObjectType rowType, RowTree *parentRow, co
         qWarning() << __FUNCTION__ << "Property row cannot have children. No row added.";
     } else {
         // If the row doesnt have a parent, insert it under the scene (first row is the tree header)
-        if (parentRow == nullptr && rowType != OBJTYPE_SCENE && m_layoutTree->count() > 1)
+        if (!parentRow && rowType != OBJTYPE_SCENE && m_layoutTree->count() > 1)
             parentRow = static_cast<RowTree *>(m_layoutTree->itemAt(1));
 
         RowTree *rowTree = nullptr;
@@ -168,18 +168,13 @@ RowTree *RowManager::createRow(EStudioObjectType rowType, RowTree *parentRow, co
     return nullptr;
 }
 
-RowTree *RowManager::getRowAbove(RowTree *row)
+RowTree *RowManager::getNextSiblingRow(RowTree *row) const
 {
-    int rowIndex = getRowIndex(row);
-
-    if (rowIndex > 1) {
-        RowTree *rowAbove = static_cast<RowTree *>(m_layoutTree->itemAt(rowIndex - 1));
-
-        if (rowAbove) {
-            while (rowAbove && rowAbove->depth() > row->depth())
-                rowAbove = rowAbove->parentRow();
-
-            return rowAbove;
+    if (row && m_layoutTree->count() > 1) {
+        for (int i = row->indexInLayout() + 1; i < m_layoutTree->count(); ++i) {
+            RowTree *row_i = static_cast<RowTree *>(m_layoutTree->itemAt(i)->graphicsItem());
+            if (row_i->depth() <= row->depth())
+                return row_i;
         }
     }
 
@@ -209,7 +204,7 @@ RowTimeline *RowManager::rowTimelineAt(int idx)
 // Call this to select/unselect row, affecting bindings
 void RowManager::selectRow(RowTree *row, bool multiSelect)
 {
-    if (row == nullptr)
+    if (!row)
         return;
 
     if (row->isProperty())
@@ -269,7 +264,7 @@ void RowManager::updateRulerDuration()
 
 void RowManager::updateFiltering(RowTree *row)
 {
-    if (row == nullptr) { // update all rows
+    if (!row) { // update all rows
         RowTree *row_i;
         for (int i = 1; i < m_layoutTree->count(); ++i) {
             row_i = static_cast<RowTree *>(m_layoutTree->itemAt(i)->graphicsItem());
@@ -293,7 +288,7 @@ void RowManager::updateRowFilterRecursive(RowTree *row)
 
 void RowManager::updateRowFilter(RowTree *row)
 {
-    bool parentOk = row->parentRow() == nullptr || row->parentRow()->isVisible();
+    bool parentOk = !row->parentRow()|| row->parentRow()->isVisible();
     bool shyOk     = !row->shy()    || !m_scene->treeHeader()->filterShy();
     bool visibleOk = row->visible() || !m_scene->treeHeader()->filterHidden();
     bool lockOk    = !row->locked() || !m_scene->treeHeader()->filterLocked();
@@ -306,10 +301,6 @@ void RowManager::updateRowFilter(RowTree *row)
 void RowManager::deleteRow(RowTree *row)
 {
    if (row && row->rowType() != OBJTYPE_SCENE) {
-       auto rowAbove = getRowAbove(row);
-       if (rowAbove)
-           selectRow(rowAbove);
-
        if (row->parentRow())
            row->parentRow()->removeChild(row);
 
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.h b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.h
index b74207e3..2b0778d2 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.h
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowManager.h
@@ -67,7 +67,7 @@ public:
                        const QString &label = QString(), const QString &propType = QString(),
                        int index = -1);
     RowTree *rowAt(int idx);
-    RowTree *getRowAbove(RowTree *row);
+    RowTree *getNextSiblingRow(RowTree *row) const;
     RowTree *selectedRow() const;
     QVector<RowTree *> selectedRows() const;
     RowTimeline *rowTimelineAt(int idx);
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.cpp b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.cpp
index c63d71fd..ca1ce405 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.cpp
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.cpp
@@ -28,13 +28,18 @@
 
 #include "RowMover.h"
 #include "RowTree.h"
+#include "RowManager.h"
+#include "TimelineGraphicsScene.h"
 #include "TimelineConstants.h"
 
 #include <QtGui/qpainter.h>
 #include <QtWidgets/qapplication.h>
 #include <QtWidgets/qgraphicsitem.h>
+#include <QtWidgets/qgraphicslinearlayout.h>
 
-RowMover::RowMover() : QGraphicsRectItem()
+RowMover::RowMover(TimelineGraphicsScene *scene)
+    : QGraphicsRectItem()
+    , m_scene(scene)
 {
     setZValue(99);
     setRect(0, -5, TimelineConstants::TREE_MAX_W, 10);
@@ -88,21 +93,23 @@ bool RowMover::isActive()
 
 void RowMover::start(RowTree *row)
 {
-    m_sourceRow = row;
     m_active = true;
 
-    m_sourceRow->setMoveSourceRecursive(true);
-
-    qApp->setOverrideCursor(Qt::ClosedHandCursor);
+    if (row) {
+        m_sourceRow = row;
+        m_sourceRow->setMoveSourceRecursive(true);
+        qApp->setOverrideCursor(Qt::ClosedHandCursor);
+    }
 }
 
-void RowMover::end()
+void RowMover::end(bool force)
 {
-    if (m_active) {
-        m_sourceRow->setMoveSourceRecursive(false);
-
+    if (m_active || force) {
         m_active = false;
-        m_sourceRow = nullptr;
+        if (m_sourceRow) {
+            m_sourceRow->setMoveSourceRecursive(false);
+            m_sourceRow = nullptr;
+        }
 
         setVisible(false);
         resetInsertionParent();
@@ -112,7 +119,6 @@ void RowMover::end()
     }
 }
 
-
 void RowMover::updateState(int index, int depth, int rawIndex)
 {
     m_targetIndex = index;
@@ -121,17 +127,125 @@ void RowMover::updateState(int index, int depth, int rawIndex)
     setVisible(true);
 }
 
-// TODO: not used, probably delete
-bool RowMover::isValidMove(int index, RowTree *rowAtIndex)
+void RowMover::updateTargetRow(int mouseX, int mouseY)
+{
+    int indexRaw = qRound((float)mouseY / TimelineConstants::ROW_H) - 1;
+    int indexInLayout = indexRaw;
+    m_scene->rowManager()->correctIndex(indexInLayout);
+    bool valid = indexInLayout != -1;
+
+    RowTree *rowAtIndex;
+    RowTree *nextRowAtIndex;
+
+    if (valid) { // valid row index
+        rowAtIndex = static_cast<RowTree *>(m_scene->layoutTree()->itemAt(indexInLayout)
+                                            ->graphicsItem());
+        nextRowAtIndex = indexInLayout > m_scene->layoutTree()->count() - 2 ? nullptr :
+                     static_cast<RowTree *>(m_scene->layoutTree()->itemAt(indexInLayout + 1)
+                                            ->graphicsItem());
+
+        if (!rowAtIndex->expanded())
+            nextRowAtIndex = m_scene->rowManager()->getNextSiblingRow(rowAtIndex);
+
+                // not moving an ancestor into a decendent
+        valid = (!m_sourceRow || !rowAtIndex->isDecendentOf(m_sourceRow))
+
+                // not inserting as a first child of self
+                && (!m_sourceRow || !(rowAtIndex == m_sourceRow && !rowAtIndex->empty()))
+
+                // not inserting non-layer at root level
+                && !((!m_sourceRow || m_sourceRow->rowType() != OBJTYPE_LAYER)
+                     && rowAtIndex->rowType() == OBJTYPE_SCENE)
+
+                // Layer cases
+                && validLayerMove(rowAtIndex, nextRowAtIndex);
+    }
+
+    if (valid) {
+        // if dragging over a property or a parent of a property, move to the first row
+        // after the property
+        if (rowAtIndex->isProperty())
+            indexRaw = rowAtIndex->parentRow()->childProps().last()->indexInLayout();
+        else if (rowAtIndex->hasPropertyChildren() && rowAtIndex->expanded())
+            indexRaw = rowAtIndex->childProps().last()->indexInLayout();
+
+        // calc insertion depth
+        int depth;
+        if (m_sourceRow && m_sourceRow->rowType() == OBJTYPE_LAYER) {
+            depth = 2; // layers can only be moved on depth 2
+        } else {
+            int depthMin = nextRowAtIndex ? nextRowAtIndex->depth() : 3;
+            int depthMax = rowAtIndex->depth();
+
+            if (rowAtIndex->isContainer() && rowAtIndex->expanded()
+                    && rowAtIndex != m_sourceRow) {
+                depthMax++; // Container: allow insertion as a child
+            } else if (rowAtIndex->isPropertyOrMaterial()
+                      && !rowAtIndex->parentRow()->isContainer()) {
+                 depthMax--; // non-container with properties and/or a material
+            }
+
+            static const int LEFT_MARGIN = 20;
+            static const int STEP = 15;
+            depth = (mouseX - LEFT_MARGIN) / STEP;
+            depth = qBound(depthMin, depth, depthMax);
+        }
+
+        // calc insertion parent
+        RowTree *insertParent = rowAtIndex;
+        for (int i = rowAtIndex->depth(); i >= depth; --i)
+            insertParent = insertParent->parentRow();
+        resetInsertionParent(insertParent);
+
+        if (m_sourceRow && m_sourceRow->rowType() == OBJTYPE_MATERIAL
+                && m_sourceRow->parentRow() != m_insertionParent) {
+            valid = false; // not moving a material row outside its parent
+        }
+
+        if (valid) {
+            // calc insertion index
+            int index = rowAtIndex->index() + 1;
+            if ((rowAtIndex->isProperty() && depth == rowAtIndex->depth())
+                    || rowAtIndex == insertParent) {
+                index = 0;
+            } else if (depth < rowAtIndex->depth()) {
+                RowTree *row = rowAtIndex;
+                for (int i = depth; i < rowAtIndex->depth(); ++i)
+                    row = row->parentRow();
+                index = row->index() + 1;
+            }
+
+            if (m_sourceRow && insertParent == m_sourceRow->parentRow()
+                    && index > m_sourceRow->index()) {
+                index--;
+            }
+
+            updateState(index, depth, indexRaw);
+        }
+    }
+
+    if (!valid) {
+        setVisible(false);
+        resetInsertionParent();
+    }
+}
+
+bool RowMover::validLayerMove(RowTree *rowAtIndex, RowTree *nextRowAtIndex)
 {
-    return
-        // not the same row
-        //index != m_currentIndex &&
+    // we don't care about non-layers in this method
+    if (!m_sourceRow || m_sourceRow->rowType() != OBJTYPE_LAYER)
+        return true;
 
-        // not moving an ancestor into a decendent
-        !rowAtIndex->isDecendentOf(m_sourceRow)
+    if (rowAtIndex->rowType() == OBJTYPE_SCENE)
+        return true;
+
+    if (rowAtIndex->rowType() == OBJTYPE_LAYER)
+       return rowAtIndex->empty() || !rowAtIndex->expanded();
+
+    if (!nextRowAtIndex || (nextRowAtIndex->depth() <= rowAtIndex->depth()
+                            && nextRowAtIndex->depth() == 2)) {
+        return true;
+    }
 
-        // not at the top of an expanded object with property children
-         && (rowAtIndex->childRows().empty() || !rowAtIndex->childRows().first()->isProperty()
-             || !rowAtIndex->expanded());
+    return false;
 }
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.h b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.h
index 23988c93..d9cc1ea8 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.h
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/RowMover.h
@@ -34,27 +34,29 @@
 #include <QtWidgets/qgraphicsitem.h>
 
 class RowTree;
+class TimelineGraphicsScene;
 
 class RowMover : public QGraphicsRectItem
 {
 public:
-    RowMover();
+    RowMover(TimelineGraphicsScene *m_scene);
     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
                QWidget *widget = nullptr) override;
 
-    void start(RowTree *row);
-    void end();
-    void resetInsertionParent(RowTree *newTarget = nullptr);
-    void updateState(int index, int depth, int rawIndex);
-
-    RowTree *insertionParent() const;
-    RowTree *sourceRow() const;
-
+    void start(RowTree *row = nullptr);
+    void end(bool force = false);
+    void updateTargetRow(int mouseX, int mouseY);
     int targetIndex() const;
     bool isActive();
-    bool isValidMove(int index, RowTree *rowAtIndex);
+    bool validLayerMove(RowTree *rowAtIndex, RowTree *nextRowAtIndex);
+    RowTree *insertionParent() const;
+    RowTree *sourceRow() const;
 
 private:
+    void updateState(int index, int depth, int rawIndex);
+    void resetInsertionParent(RowTree *newTarget = nullptr);
+
+    TimelineGraphicsScene *m_scene = nullptr;
     RowTree *m_insertionParent = nullptr; // insertion parent
     RowTree *m_sourceRow = nullptr;       // dragged row
     int m_targetIndex = -1;               // insertion index
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.cpp b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.cpp
index 899be517..6bd995a9 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.cpp
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.cpp
@@ -75,7 +75,7 @@ TimelineGraphicsScene::TimelineGraphicsScene(TimelineWidget *timelineWidget)
     , m_ruler(new Ruler)
     , m_playHead(new PlayHead(m_ruler))
     , m_selectionRect(new SelectionRect(m_ruler))
-    , m_rowMover(new RowMover)
+    , m_rowMover(new RowMover(this))
     , m_widgetTimeline(timelineWidget)
     , m_widgetRoot(new QGraphicsWidget)
     , m_rowManager(new RowManager(this, m_layoutTree, m_layoutTimeline))
@@ -276,19 +276,6 @@ void TimelineGraphicsScene::commitMoveRows()
     // updating the UI happens in TimelineWidget.onChildAdded()
 }
 
-RowTree *TimelineGraphicsScene::getNextSiblingRow(RowTree *row) const
-{
-    if (row && m_layoutTree->count() > 1) {
-        for (int i = row->indexInLayout() + 1; i < m_layoutTree->count(); ++i) {
-            RowTree *row_i = static_cast<RowTree *>(m_layoutTree->itemAt(i)->graphicsItem());
-            if (row_i->depth() <= row->depth())
-                return row_i;
-        }
-    }
-
-    return nullptr;
-}
-
 // TODO: not used, remove
 bool TimelineGraphicsScene::lastRowInAParent(RowTree *rowAtIndex, int index)
 {
@@ -305,25 +292,6 @@ int TimelineGraphicsScene::nextRowDepth(int index) {
     return static_cast<RowTree *>(m_layoutTree->itemAt(index)->graphicsItem())->depth();
 }
 
-bool TimelineGraphicsScene::validLayerMove(RowTree *rowAtIndex, RowTree *nextRowAtIndex)
-{
-    // we don't care about non-layers in this method
-    if (m_rowMover->sourceRow()->rowType() != OBJTYPE_LAYER)
-        return true;
-
-    if (rowAtIndex->rowType() == OBJTYPE_SCENE)
-        return true;
-
-    if (rowAtIndex->rowType() == OBJTYPE_LAYER)
-       return rowAtIndex->empty() || !rowAtIndex->expanded();
-
-    if (nextRowAtIndex == nullptr || (nextRowAtIndex->depth() <= rowAtIndex->depth()
-                                      && nextRowAtIndex->depth() == 2))
-        return true;
-
-    return false;
-}
-
 void TimelineGraphicsScene::updateTreeWidth(double treeWidth)
 {
     if (m_treeWidth != treeWidth) {
@@ -487,107 +455,7 @@ void TimelineGraphicsScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
             // moving rows vertically (reorder/reparent)
             // collapse all properties so correctIndex() counts correctly
             m_rowManager->collapseAllPropertyRows();
-            int indexRaw = qRound(event->scenePos().y() / TimelineConstants::ROW_H) - 1;
-            int indexInLayout = indexRaw;
-            m_rowManager->correctIndex(indexInLayout);
-            bool valid = indexInLayout != -1;
-
-            RowTree *rowAtIndex;
-            RowTree *nextRowAtIndex;
-
-            if (valid) { // valid row index
-                rowAtIndex = static_cast<RowTree *>(m_layoutTree->itemAt(indexInLayout)
-                                                    ->graphicsItem());
-                nextRowAtIndex = indexInLayout > m_layoutTree->count() - 2 ? nullptr :
-                             static_cast<RowTree *>(m_layoutTree->itemAt(indexInLayout + 1)
-                                                    ->graphicsItem());
-
-                if (!rowAtIndex->expanded())
-                    nextRowAtIndex = getNextSiblingRow(rowAtIndex);
-
-                        // not moving an ancestor into a decendent
-                valid = !rowAtIndex->isDecendentOf(m_rowMover->sourceRow())
-
-                        // not inserting as a first child of self
-                        && !(rowAtIndex == m_rowMover->sourceRow() && !rowAtIndex->empty())
-
-                        // not inserting non-layer at root level
-                        && !(m_rowMover->sourceRow()->rowType() != OBJTYPE_LAYER
-                             && rowAtIndex->rowType() == OBJTYPE_SCENE)
-
-                        // Layer cases
-                        && validLayerMove(rowAtIndex, nextRowAtIndex)
-
-                        // Not inserting into a component
-                        && rowAtIndex->rowType() != OBJTYPE_COMPONENT;
-            }
-
-            if (valid) {
-                // if dragging over a property or a parent of a property, move to the first row
-                // after the property
-                if (rowAtIndex->isProperty())
-                    indexRaw = rowAtIndex->parentRow()->childProps().last()->indexInLayout();
-                else if (rowAtIndex->hasPropertyChildren() && rowAtIndex->expanded())
-                    indexRaw = rowAtIndex->childProps().last()->indexInLayout();
-
-                // calc insertion depth
-                int depth;
-                if (m_rowMover->sourceRow()->rowType() == OBJTYPE_LAYER) {
-                    depth = 2; // layers can only be moved on depth 2
-                } else {
-                    int depthMin = nextRowAtIndex ? nextRowAtIndex->depth() : 3;
-                    int depthMax = rowAtIndex->depth();
-
-                    if (rowAtIndex->isContainer() && rowAtIndex->expanded()
-                            && rowAtIndex != m_rowMover->sourceRow()) {
-                        depthMax++; // Container: allow insertion as a child
-                    } else if (rowAtIndex->isPropertyOrMaterial()
-                              && !rowAtIndex->parentRow()->isContainer()) {
-                         depthMax--; // non-container with properties and/or a material
-                    }
-
-                    depth = (event->scenePos().x() - 20) / 15;
-                    depth = qBound(depthMin, depth, depthMax);
-                }
-
-                // calc insertion parent
-                RowTree *insertParent = rowAtIndex;
-                for (int i = rowAtIndex->depth(); i >= depth; --i)
-                    insertParent = insertParent->parentRow();
-                m_rowMover->resetInsertionParent(insertParent);
-
-                if (m_rowMover->sourceRow()->rowType() == OBJTYPE_MATERIAL
-                        && m_rowMover->sourceRow()->parentRow()
-                        != m_rowMover->insertionParent()) {
-                    valid = false; // not moving a material row outside its parent
-                }
-
-                if (valid) {
-                    // calc insertion index
-                    int index = rowAtIndex->index() + 1;
-                    if ((rowAtIndex->isProperty() && depth == rowAtIndex->depth())
-                            || rowAtIndex == insertParent) {
-                        index = 0;
-                    } else if (depth < rowAtIndex->depth()) {
-                        RowTree *row = rowAtIndex;
-                        for (int i = depth; i < rowAtIndex->depth(); ++i)
-                            row = row->parentRow();
-                        index = row->index() + 1;
-                    }
-
-                    if (insertParent == m_rowMover->sourceRow()->parentRow()
-                            && index > m_rowMover->sourceRow()->index()) {
-                        index--;
-                    }
-
-                    m_rowMover->updateState(index, depth, indexRaw);
-                }
-            }
-
-            if (!valid) {
-                m_rowMover->setVisible(false);
-                m_rowMover->resetInsertionParent();
-            }
+            m_rowMover->updateTargetRow(event->scenePos().x(), event->scenePos().y());
         } else if (m_keyframePressed) { // moving selected keyframes
             double newX = event->scenePos().x() - m_ruler->x() - m_pressPosInKeyframe;
 
@@ -948,3 +816,4 @@ QGraphicsWidget       *TimelineGraphicsScene::widgetRoot()      const { return m
 KeyframeManager       *TimelineGraphicsScene::keyframeManager() const { return m_keyframeManager; }
 QGraphicsLinearLayout *TimelineGraphicsScene::layoutTree()      const { return m_layoutTree;      }
 QGraphicsLinearLayout *TimelineGraphicsScene::layoutTimeline()  const { return m_layoutTimeline;  }
+TimelineWidget        *TimelineGraphicsScene::widgetTimeline()  const { return m_widgetTimeline;  }
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.h b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.h
index 5271a3f6..ad46b87b 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.h
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineGraphicsScene.h
@@ -76,6 +76,7 @@ public:
     QGraphicsLinearLayout *layoutTimeline() const;
     TreeHeader *treeHeader() const;
     double treeWidth() const;
+    TimelineWidget *widgetTimeline() const;
     void updateTreeWidth(double x);
     void setMouseCursor(CMouseCursor::Qt3DSMouseCursor cursor);
     void resetMouseCursor();
@@ -100,8 +101,6 @@ private:
     void snap(double &value, bool snapToPlayHead = true);
     int nextRowDepth(int index);
     bool lastRowInAParent(RowTree *rowAtIndex, int index);
-    bool validLayerMove(RowTree *rowAtIndex, RowTree *nextRowAtIndex);
-    RowTree *getNextSiblingRow(RowTree *row) const;
     QGraphicsItem *getItemBelowType(TimelineItem::ItemType type,
                                     QGraphicsItem *item,
                                     const QPointF &scenePos);
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.cpp b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.cpp
index 6757f136..94b3977a 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.cpp
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.cpp
@@ -53,6 +53,8 @@
 #include "Bindings/Qt3DSDMTimelineItemProperty.h"
 #include "TimeEditDlg.h"
 #include "IDocumentEditor.h"
+#include "Control.h"
+#include "TimelineDropTarget.h"
 
 #include <QtGui/qevent.h>
 #include <QtWidgets/qgraphicslinearlayout.h>
@@ -134,6 +136,8 @@ TimelineWidget::TimelineWidget(QWidget *parent)
     , m_viewTimelineContent(new QGraphicsView(this))
     , m_graphicsScene(new TimelineGraphicsScene(this))
 {
+    // Mahmoud_TODO: CTimelineTranslationManager should be eventually removed or cleaned. Already
+    // most of its functionality is implemented in this class
     m_translationManager = new CTimelineTranslationManager();
 
     setWindowTitle(tr("Timeline", "Title of timeline view"));
@@ -443,6 +447,7 @@ void TimelineWidget::onSelectionChange(Q3DStudio::SSelectedValue inNewSelectable
     if (theInstances.size() > 0) {
         for (size_t idx = 0, end = theInstances.size(); idx < end; ++idx) {
             qt3dsdm::Qt3DSDMInstanceHandle theInstance(theInstances[idx]);
+
             if (g_StudioApp.GetCore()->GetDoc()->GetStudioSystem()->IsInstance(theInstance)) {
                 auto *binding = getBindingForHandle(theInstance, m_binding);
                 if (binding)
@@ -641,6 +646,85 @@ void TimelineWidget::onChildMoved(int inParent, int inChild, long inOldIndex,
     }
 }
 
+void TimelineWidget::OnDraw(CRenderer *inRenderer, CRct &inDirtyRect, bool inIgnoreValidation)
+{
+
+}
+
+void TimelineWidget::Draw(CRenderer *inRenderer)
+{
+
+}
+
+void TimelineWidget::OnGainFocus()
+{
+
+}
+
+CDropTarget *TimelineWidget::FindDropCandidate(CPt &inMousePoint, Qt::KeyboardModifiers inFlags)
+{
+    CTimeLineDropTarget *theTarget = new CTimeLineDropTarget();
+
+    int mouseY = inMousePoint.y - m_navigationBar->height()
+                 + viewTreeContent()->verticalScrollBar()->value()
+                 - viewTreeContent()->verticalScrollBar()->minimum();
+    RowMover *mover = m_graphicsScene->rowMover();
+    mover->updateTargetRow(inMousePoint.x, mouseY);
+
+    if (mover->insertionParent()) {
+        RowTree *targetRow = mover->insertionParent()->getChildAt(mover->targetIndex()-1);
+
+        if (targetRow) {
+            theTarget->SetDestination(EDROPDESTINATION_BELOW);
+            targetRow->getBinding()->SetDropTarget(theTarget);
+        } else {
+            if (mover->insertionParent()->childRows().empty()) {
+                theTarget->SetDestination(EDROPDESTINATION_ON);
+                mover->insertionParent()->getBinding()->SetDropTarget(theTarget);
+            } else {
+                theTarget->SetDestination(EDROPDESTINATION_ABOVE);
+                mover->insertionParent()->getChildAt(0)->getBinding()->SetDropTarget(theTarget);
+            }
+        }
+    }
+
+    return theTarget;
+}
+
+bool TimelineWidget::OnMouseHover(CPt inPoint, Qt::KeyboardModifiers inFlags)
+{
+    return true;
+}
+
+void TimelineWidget::OnMouseOut(CPt inPoint, Qt::KeyboardModifiers inFlags)
+{
+}
+
+void TimelineWidget::OnMouseUp(CPt inPoint, Qt::KeyboardModifiers inFlags)
+{
+}
+
+CPt TimelineWidget::GetPreferredSize()
+{
+    return CPt();
+}
+
+void TimelineWidget::SetSize(long inX, long inY)
+{
+    setFixedSize(inX, inY);
+}
+
+// If views are interactive they block the DnD. If we could think of a way to make them do not block
+// DnD, then this method can be removed (and it's callers)
+void TimelineWidget::enableDnD(bool b)
+{
+    m_viewTreeHeader->setInteractive(!b);
+    m_viewTreeContent->setInteractive(!b);
+
+    if (!b)
+        m_graphicsScene->rowMover()->end(true);
+}
+
 Qt3DSDMTimelineItemBinding *TimelineWidget::getBindingForHandle(int handle,
                                                 Qt3DSDMTimelineItemBinding *binding) const
 {
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.h b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.h
index 85d6e3a6..9a90ea63 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.h
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/TimelineWidget.h
@@ -39,6 +39,7 @@
 #include "TreeHeaderView.h"
 #include "Bindings/Qt3DSDMTimeline.h"
 #include "NavigationBar.h"
+#include "Control.h"
 
 class RowTree;
 class TimelineToolbar;
@@ -52,7 +53,8 @@ QT_FORWARD_DECLARE_CLASS(QGraphicsView)
 
 class TimelineWidget : public QWidget,
                        public CPresentationChangeListener,
-                       public CClientPlayChangeListener
+                       public CClientPlayChangeListener,
+                       public CControl
 {
     Q_OBJECT
 
@@ -64,10 +66,10 @@ public:
     QGraphicsView *viewTimelineContent() const;
     QGraphicsView *viewTreeContent() const;
     QVector<RowTree *> selectedRows() const;
-
     void openBarColorDialog();
     void onTimeBarColorChanged(const QColor &color);
     void setSelectedTimeBarsColor(const QColor &color, bool preview);
+    void enableDnD(bool b = true);
 
     // Presentation Change Listener
     void OnNewPresentation() override;
@@ -78,6 +80,17 @@ public:
     void OnTimeChanged(long inTime) override;
     bool hasSelectedKeyframes() const;
 
+    // CControl
+    void OnDraw(CRenderer *inRenderer, CRct &inDirtyRect, bool inIgnoreValidation = false) override;
+    void Draw(CRenderer *inRenderer) override;
+    void OnGainFocus() override;
+    CDropTarget *FindDropCandidate(CPt &inMousePoint, Qt::KeyboardModifiers inFlags) override;
+    bool OnMouseHover(CPt inPoint, Qt::KeyboardModifiers inFlags) override;
+    void OnMouseOut(CPt inPoint, Qt::KeyboardModifiers inFlags) override;
+    void OnMouseUp(CPt inPoint, Qt::KeyboardModifiers inFlags) override;
+    CPt GetPreferredSize() override;
+    void SetSize(long inX, long inY) override;
+
 protected:
     // DataModel callbacks
     virtual void onActiveSlide(const qt3dsdm::Qt3DSDMSlideHandle &inMaster, int inIndex,
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.cpp b/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.cpp
index 0882474f..9d4159d3 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.cpp
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.cpp
@@ -538,6 +538,14 @@ int RowTree::addChildToLayout(RowTree *child, int indexInLayout)
     return indexInLayout;
 }
 
+RowTree *RowTree::getChildAt(int index) const
+{
+    if (index < 0 || index > m_childRows.count() - 1)
+        return nullptr;
+
+    return m_childRows.at(index);
+}
+
 // TODO: so far not used, delete if end up not used
 void RowTree::moveChild(int from, int to)
 {
@@ -799,8 +807,12 @@ void RowTree::setMoveSourceRecursive(bool value)
 
 bool RowTree::isContainer() const
 {
-    return !m_isProperty && m_rowType != OBJTYPE_ALIAS && m_rowType != OBJTYPE_MATERIAL
-            && m_rowType != OBJTYPE_IMAGE && m_rowType != OBJTYPE_TEXT;
+    return !m_isProperty
+            && m_rowType != OBJTYPE_ALIAS
+            && m_rowType != OBJTYPE_MATERIAL
+            && m_rowType != OBJTYPE_IMAGE
+            && m_rowType != OBJTYPE_TEXT
+            && m_rowType != OBJTYPE_COMPONENT;
 }
 
 bool RowTree::isProperty() const
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.h b/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.h
index e1f83641..ccafcdf0 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.h
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/RowTree.h
@@ -104,6 +104,7 @@ public:
     int treeWidth() const;
     EStudioObjectType rowType() const;
     QString propertyType() const;
+    RowTree *getChildAt(int index) const;
     RowTree *parentRow() const;
     RowTree *getPropertyRow(const QString &type) const;
     QList<RowTree *> childRows() const;
diff --git a/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/TimelineToolbar.cpp b/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/TimelineToolbar.cpp
index e80d4b22..755913a6 100644
--- a/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/TimelineToolbar.cpp
+++ b/src/Authoring/Studio/Palettes/TimelineGraphicsView/ui/TimelineToolbar.cpp
@@ -394,12 +394,13 @@ void TimelineToolbar::updateTimelineTitleColor(bool controlled)
 {
     QString styleString;
     if (controlled) {
-        styleString= "QDockWidget { color: "
+        styleString = "QDockWidget { color: "
                 + QString(CStudioPreferences::dataInputColor().name()) + "; }";
     } else {
         styleString = "QDockWidget { color: "
                 + QString(CStudioPreferences::textColor().name()) + "; }";
     }
-    QWidget *timelineDock = parentWidget()->parentWidget();
+
+    QWidget *timelineDock = parentWidget()->parentWidget()->parentWidget()->parentWidget();
     timelineDock->setStyleSheet(styleString);
 }
diff --git a/src/Authoring/Studio/_Win/Palettes/PaletteManager.cpp b/src/Authoring/Studio/_Win/Palettes/PaletteManager.cpp
index be98cdac..03def618 100644
--- a/src/Authoring/Studio/_Win/Palettes/PaletteManager.cpp
+++ b/src/Authoring/Studio/_Win/Palettes/PaletteManager.cpp
@@ -108,11 +108,23 @@ CPaletteManager::CPaletteManager(CMainFrame *inMainFrame)
     inMainFrame->tabifyDockWidget(m_basicObjectsDock, m_slideDock);
     m_ControlList.insert(std::make_pair(CONTROLTYPE_BASICOBJECTS, m_basicObjectsDock));
 
-    m_timelineGVDock = new QDockWidget(QObject::tr("Timeline GV"), inMainFrame);
+    m_timelineGVDock = new QDockWidget(QObject::tr("Timeline GV"));
     m_timelineGVDock->setObjectName("timeline GV.");
     m_timelineGVDock->setAllowedAreas(Qt::BottomDockWidgetArea);
-    m_timelineWidget = new TimelineWidget(m_timelineGVDock);
-    m_timelineGVDock->setWidget(m_timelineWidget);
+
+    m_timelineWidget = new TimelineWidget();
+    WidgetControl *timeLineWidgetControl = new WidgetControl(m_timelineWidget, m_timelineGVDock);
+    timeLineWidgetControl->RegisterForDnd(timeLineWidgetControl);
+    timeLineWidgetControl->AddMainFlavor(QT3DS_FLAVOR_LISTBOX);
+    timeLineWidgetControl->AddMainFlavor(QT3DS_FLAVOR_FILE);
+    timeLineWidgetControl->AddMainFlavor(QT3DS_FLAVOR_ASSET_UICFILE);
+    timeLineWidgetControl->AddMainFlavor(QT3DS_FLAVOR_ASSET_LIB);
+    timeLineWidgetControl->AddMainFlavor(QT3DS_FLAVOR_ASSET_TL);
+    timeLineWidgetControl->AddMainFlavor(QT3DS_FLAVOR_BASIC_OBJECTS);
+
+    m_timelineWidget->setParent(timeLineWidgetControl);
+
+    m_timelineGVDock->setWidget(timeLineWidgetControl);
     inMainFrame->addDockWidget(Qt::BottomDockWidgetArea, m_timelineGVDock);
     m_ControlList.insert(std::make_pair(CONTROLTYPE_TIMELINE, m_timelineGVDock));