moved some timelineview functions into a timelineviewbase for reusing

Later classes will feature similar functionality to the TimelineView, moving
them to a base class that can be easily reused seems like a good idea.

app/widget/timelinewidget/view/timelineviewbase.cpp

@@ -0,0 +1,80 @@
+#include "timelineviewbase.h"
+
+#include <QGraphicsRectItem>
+#include <QMouseEvent>
+
+#include "common/timecodefunctions.h"
+
+TimelineViewBase::TimelineViewBase(QWidget *parent) :
+  QGraphicsView(parent),
+  playhead_(0),
+  playhead_scene_left_(-1),
+  playhead_scene_right_(-1)
+{
+}
+
+void TimelineViewBase::SetTimebase(const rational &timebase)
+{
+  SetTimebaseInternal(timebase);
+
+  // Timebase influences position/visibility of playhead
+  viewport()->update();
+}
+
+void TimelineViewBase::SetTime(const int64_t time)
+{
+  playhead_ = time;
+
+  // Force redraw for playhead
+  viewport()->update();
+}
+
+void TimelineViewBase::drawForeground(QPainter *painter, const QRectF &rect)
+{
+  QGraphicsView::drawForeground(painter, rect);
+
+  if (!timebase().isNull()) {
+    double width = TimeToScene(timebase());
+
+    playhead_scene_left_ = TimeToScene(rational(playhead_ * timebase().numerator(), timebase().denominator()));
+    playhead_scene_right_ = playhead_scene_left_ + width;
+
+    playhead_style_.Draw(painter, QRectF(playhead_scene_left_, rect.top(), width, rect.height()));
+  }
+}
+
+rational TimelineViewBase::GetPlayheadTime()
+{
+  return rational(playhead_ * timebase().numerator(), timebase().denominator());
+}
+
+bool TimelineViewBase::PlayheadPress(QMouseEvent *event)
+{
+  QPointF scene_pos = mapToScene(event->pos());
+
+  dragging_playhead_ = (scene_pos.x() >= playhead_scene_left_ && scene_pos.x() < playhead_scene_right_);
+
+  return dragging_playhead_;
+}
+
+bool TimelineViewBase::PlayheadMove(QMouseEvent *event)
+{
+  if (!dragging_playhead_) {
+    return false;
+  }
+
+  QPointF scene_pos = mapToScene(event->pos());
+  rational mouse_time = SceneToTime(scene_pos.x());
+
+  int64_t target_ts = olive::time_to_timestamp(mouse_time, timebase());
+
+  SetTime(target_ts);
+  emit TimeChanged(target_ts);
+
+  return true;
+}
+
+bool TimelineViewBase::PlayheadRelease(QMouseEvent *event)
+{
+  return dragging_playhead_;
+}