Revert "ecore/animator: fix the bezier cubic compuation."

This reverts commit 2e1032e28f.

This patch is wrong. On reviewing the origin implementation.

src/lib/ecore/ecore_anim.c

@@ -307,19 +307,70 @@ _pos_map_spring(double pos,
    return _pos_map_sin((M_PI / 2.0) + (p2 * len)) * decay;
 }
 
+static double
+_cubic_bezier_a (double a1, double a2)
+{
+    return 1.0 - 3.0 * a2 + 3.0 * a1;
+}
+
+static double
+_cubic_bezier_b (double a1, double a2)
+{
+    return 3.0 * a2 - 6.0 * a1;
+}
+
+static double
+_cubic_bezier_c(double a1)
+{
+    return 3.0 * a1;
+}
+
+static double
+_cubic_bezier_calc(double t,
+                   double a1,
+                   double a2)
+{
+    return ((_cubic_bezier_a(a1, a2) * t +
+             _cubic_bezier_b(a1, a2)) * t +
+            _cubic_bezier_c(a1)) * t;
+}
+
+static double
+_cubic_bezier_slope_get(double t,
+                        double a1,
+                        double a2)
+{
+    return 3.0 * _cubic_bezier_a(a1, a2) * t * t +
+           2.0 * _cubic_bezier_b(a1, a2) * t +
+           _cubic_bezier_c(a1);
+}
+
+static double
+_cubic_bezier_t_get(double a,
+                        double x1,
+                        double x2)
+{
+    double guess_t = a;
+    for (int i = 0; i < 4; ++i)
+    {
+        double current_slope = _cubic_bezier_slope_get(a, x1, x2);
+        if (current_slope == 0.0)
+            return guess_t;
+        double current_x = _cubic_bezier_calc(guess_t, x1, x2) - a;
+        guess_t -= current_x / current_slope;
+    }
+    return guess_t;
+}
+
 static double
 _pos_map_cubic_bezier(double pos,
-                      double x1 EINA_UNUSED,
+                      double x1,
                       double y1,
-                      double x2 EINA_UNUSED,
+                      double x2,
                       double y2)
 {
     if (x1 == y1 && x2 == y2) return pos;
-
-    /* Bezier Cubic formula:
-		 y(t) = (1 - t)^3 + 3t(1 - t)^2 + 3t^2(1 - t) + t^3 */
-    return (pow((1 - pos), 3) * 0) + (3 * pos * pow((1 - pos), 2) * y1) +
-           (3 * pow(pos, 2) * (1 - pos) * y2) + (pow(pos, 3) * 1);
+    return _cubic_bezier_calc(_cubic_bezier_t_get(pos, x1, x2), y1, y2);
 }
 
 #define DBL_TO(Fp) eina_f32p32_double_to(Fp)