Focus lower video track on project opening, correctly scroll view when active track changes

src/timeline2/model/timelineitemmodel.cpp

@@ -394,6 +394,20 @@ QVariant TimelineItemModel::getTrackProperty(int tid, const QString &name) const
     return getTrackById_const(tid)->getProperty(name);
 }
 
+int TimelineItemModel::getFirstVideoTrackIndex() const
+{
+    int trackId;
+    auto it = m_allTracks.cbegin();
+    while (it != m_allTracks.cend()) {
+        trackId = getTrackMltIndex((*it)->getId());
+        if ((*it)->getProperty("kdenlive:audio_track").toInt() != 1) {
+            break;
+        }
+        ++it;
+    }
+    return trackId;
+}
+
 const QString TimelineItemModel::getTrackFullName(int tid) const
 {
     QString tag = getTrackTagById(tid);

src/timeline2/model/timelineitemmodel.hpp

@@ -81,6 +81,9 @@ public:
     QModelIndex parent(const QModelIndex &index) const override;
     Q_INVOKABLE void setTrackProperty(int tid, const QString &name, const QString &value);
     Q_INVOKABLE QVariant getTrackProperty(int tid, const QString &name) const;
+    /** @brief returns the lower video track index in timeline.
+     **/
+    int getFirstVideoTrackIndex() const;
     const QString getTrackFullName(int tid) const;
     void notifyChange(const QModelIndex &topleft, const QModelIndex &bottomright, bool start, bool duration, bool updateThumb) override;
     void notifyChange(const QModelIndex &topleft, const QModelIndex &bottomright, const QVector<int> &roles) override;

src/timeline2/view/qml/timeline.qml

@@ -131,6 +131,7 @@ Rectangle {
     property int copiedClip: -1
     property var dragList: []
     property int zoomOnMouse: -1
+    property int viewActiveTrack: timeline.activeTrack
 
     //onCurrentTrackChanged: timeline.selection = []
     onTimeScaleChanged: {
@@ -144,6 +145,15 @@ Rectangle {
         ruler.adjustStepSize()
     }
 
+    onViewActiveTrackChanged: {
+        var tk = Logic.getTrackById(timeline.activeTrack)
+        if (tk.y < scrollView.flickableItem.contentY) {
+            scrollView.flickableItem.contentY = Math.max(0, tk.y - scrollView.height / 3)
+        } else if (tk.y + tk.height > scrollView.flickableItem.contentY + scrollView.viewport.height) {
+            scrollView.flickableItem.contentY = Math.min(scrollView.flickableItem.height, tk.y - scrollView.height / 3)
+        }
+    }
+
     onTimelineSelectionChanged: {
         if (root.timelineSelection.length == 0) {
             root.dragList = []

src/timeline2/view/timelinewidget.cpp

@@ -92,7 +92,7 @@ void TimelineWidget::setModel(std::shared_ptr<TimelineItemModel> model)
     m_proxy->setRoot(rootObject());
     setVisible(true);
     loading = false;
-    m_proxy->setActiveTrack(model->getTrackIndexFromPosition(model->getTracksCount() - 1));
+    m_proxy->setActiveTrack(model->getFirstVideoTrackIndex());
     m_proxy->checkDuration();
 }