Fixes bug with pasting of TCOs (#5840) (#5847)

* Fixes bug with pasting of TCOs (#5840)

	TimePos::quantize works for negative values, but ends
up snapping the TCO to the opposite direction. This is because the
snapping happens in the direction of the origin, which is left for
positive values and right for negative values.
	That wasn't accounted for in the pasteSelection method
and we ended up with wrong positions when pasting before the
TCO(s) we copied.
	This PR fixes the issue by ensuring that we snap in the same direction when halfway through an interval, regardless of negative or positive offset.

* Fixes a calculation on TimePos::quantize

	Since we are working with integers, using "offset /
(interval/2)" would be problematic if interval was odd. We instead
multiply both sides by two and use "(2 * offset) / interval" to obtain
the result for snapUp.

src/core/TimePos.cpp

@@ -72,7 +72,12 @@ TimePos TimePos::quantize(float bars) const
 	//Offset from the lower position
 	int offset = m_ticks % interval;
 	//1 if we should snap up, 0 if we shouldn't
-	int snapUp = offset / (interval / 2);
+	// Ternary expression is making sure that the snap happens in the direction to
+	// the right even if m_ticks is negative and the offset is exactly half-way
+	// More details on issue #5840 and PR #5847
+	int snapUp = ((2 * offset) == -interval)
+		? 0
+		: (2 * offset) / interval;
 
 	return (lowPos + snapUp) * interval;
 }

src/gui/widgets/TrackContentWidget.cpp

@@ -477,7 +477,7 @@ bool TrackContentWidget::pasteSelection( TimePos tcoPos, const QMimeData * md, b
 	// All patterns should be offset the same amount as the grabbed pattern
 	TimePos offset = TimePos(tcoPos - grabbedTCOPos);
 	// Users expect clips to "fall" backwards, so bias the offset
-	offset = offset - TimePos::ticksPerBar() * snapSize / 2;
+	offset -= TimePos::ticksPerBar() * snapSize / 2;
 	// The offset is quantized (rather than the positions) to preserve fine adjustments
 	offset = offset.quantize(snapSize);