How to use heart animation using Animation Buidler Widget

heart_animation.dart

    body: Center(
        child:
        AnimatedBuilder(animation: _myAnimation,
            builder: (ctx, ch) =>  Container(
              width: _myAnimation.value.width,
              height: _myAnimation.value.height,

              decoration: BoxDecoration(
                  image: new DecorationImage(
                      image: new AssetImage(
                        'assets/images/heart.png',
                      )
                  )
              ),
            )
        )
    ),