@Override
            void onControlPoint1Moved(float cx1, float cy1) {
                cx1Label.setText("ControlX: " + String.format("%.2f", cx1));
                cy1Label.setText("ControlY: " + String.format("%.2f", cy1));
            }
Creates a quadratic PathInterpolator, whose control point values can be changed
by the user dragging that handle around in the UI.
AnimationsInterpolatorPlayground/app/src/main/java/com/example/android/interpolatorplayground/MainActivity.java