moved timeline playhead line to its own class

app/widget/timelineview/timelineviewrect.cpp

@@ -0,0 +1,32 @@
+#include "timelineviewrect.h"
+
+TimelineViewRect::TimelineViewRect(QGraphicsItem* parent) :
+  QGraphicsRectItem(parent),
+  scale_(1.0)
+{
+
+}
+
+void TimelineViewRect::SetTimebase(const rational &timebase)
+{
+  timebase_ = timebase;
+  timebase_dbl_ = timebase_.ToDouble();
+
+  UpdateRect();
+}
+
+void TimelineViewRect::SetScale(const double &scale)
+{
+  scale_ = scale;
+  UpdateRect();
+}
+
+bool TimelineViewRect::TimebaseIsValid()
+{
+  return timebase_.denominator() != 0;
+}
+
+double TimelineViewRect::TimeToScreenCoord(const rational &time)
+{
+  return time.ToDouble() / timebase_dbl_ * scale_;
+}