Adding custom bezier easing curves to QEasingCurve

I added the possibilty to define Bezier/TCB splines and use them
as custom easing curves.

Note:
Splines have a parametric definition. This means we have a
function/polynom of t that evalutes to x and y. x/y = f(t).

For our purpose we actually need the function y = f(x).
So as a first step we have to solve the solution x = f(t) for a given
t and then in a second step we evaluate y = f(t).

f(t) is a cubic polynom so we use cardanos formula to solve this equation
directly.

For the casus irreducibilis we need 3 functions that are a combination of
arcos and cos. Instead of evaluating arcos and cos we approximate these
functions directly.

TCB splines are converted into the corresponding cubic bezier spline.

Change-Id: Id2afc15efac92e494d6358dc2e11f94e8c524da1
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/corelib/tools/qeasingcurve.h b/src/corelib/tools/qeasingcurve.h
index 2deda2cd1e..a1c11ceba4 100644
--- a/src/corelib/tools/qeasingcurve.h
+++ b/src/corelib/tools/qeasingcurve.h
@@ -52,6 +52,7 @@ QT_BEGIN_NAMESPACE
 QT_MODULE(Core)
 
 class QEasingCurvePrivate;
+class QPointF;
 class Q_CORE_EXPORT QEasingCurve
 {
     Q_GADGET
@@ -70,7 +71,7 @@ public:
         InBack, OutBack, InOutBack, OutInBack,
         InBounce, OutBounce, InOutBounce, OutInBounce,
         InCurve, OutCurve, SineCurve, CosineCurve,
-        Custom, NCurveTypes
+        BezierSpline, TCBSpline, Custom, NCurveTypes
     };
 
     QEasingCurve(Type type = Linear);
@@ -91,6 +92,9 @@ public:
     qreal overshoot() const;
     void setOvershoot(qreal overshoot);
 
+    void addCubicBezierSegment(const QPointF & c1, const QPointF & c2, const QPointF & endPoint);
+    void addTCBSegment(const QPointF &nextPoint, qreal t, qreal c, qreal b);
+
     Type type() const;
     void setType(Type type);
     typedef qreal (*EasingFunction)(qreal progress);