Libgdx pinch zoom + pan listener

gistfile1.java

    private EventListener dragListener = new ActorGestureListener() {

        private float initialScale;
        private float iX;
        private float iY;

        @Override
        public void touchDown(InputEvent event, float x, float y, int pointer, int button) {
            if (event.getTarget() != stage.getRoot())
                return;
            initialScale = root.getScaleX();
            iX = root.getX();
            iY = root.getY();
        }

        @Override
        public void pan(InputEvent event, float x, float y, float deltaX, float deltaY) {
            if (event.getTarget() != stage.getRoot())
                return;
            root.setPosition(root.getX() + deltaX, root.getY() + deltaY);
        }

        @Override
        public void touchUp(InputEvent event, float x, float y, int pointer, int button) {
            if (event.getTarget() != stage.getRoot())
                return;
            if (Math.abs(iX - root.getX()) > 10 || Math.abs(iY - root.getY()) > 10)
                return;
            int worldX = (int) ((x - root.getX()) / (CELL_SIZE * root.getScaleX()));
            int worldY = (int) ((y - root.getY()) / (CELL_SIZE * root.getScaleY()));
            WorldViewEvent viewEvent = world.dispatcher.obtain(WorldViewEvent.class);
            viewEvent.init(worldX, worldY);
            world.dispatcher.dispatch(WorldViewEvent.ON_TAP, viewEvent);
        }

        @Override
        public void pinch(InputEvent event, Vector2 initialPointer1, Vector2 initialPointer2, Vector2 pointer1, Vector2 pointer2) {
            float initialDistance = initialPointer1.dst(initialPointer2);
            float distance = pointer1.dst(pointer2);
            float pointerScale = distance / initialDistance;
            float targetScale = initialScale * pointerScale;
            root.setScale(targetScale);
            float icx = (initialPointer1.x + initialPointer2.x) / 2;
            float icy = (initialPointer1.y + initialPointer2.y) / 2;

            float tcx = (pointer1.x + pointer2.x) / 2;
            float tcy = (pointer1.y + pointer2.y) / 2;

            float d = (float) Math.sqrt(iX * iX + iY * iY);

            //initial x == 0 -> 0
            root.setPosition(
                iX + (tcx - (icx) * pointerScale) - iX * (initialScale - targetScale) / initialScale,
                iY + (tcy - (icy) * pointerScale) - iY * (initialScale - targetScale) / initialScale
            );
        }
    };