View 大小动画

class MainActivity : AppCompatActivity() {

    private lateinit var mBinding: ActivityMainBinding;
    lateinit var objectAnimator: ObjectAnimator;

    @SuppressLint("ObjectAnimatorBinding")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        mBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
        val viewWrapper = ViewWrapper(mBinding.vc)
        objectAnimator = ObjectAnimator.ofInt(viewWrapper, "trueHeight", dp2px(500f), dp2px(400f)).setDuration(1000)

        objectAnimator.addListener(object : AnimatorListenerAdapter() {
            override fun onAnimationEnd(animation: Animator) {
                super.onAnimationEnd(animation)
            }

            override fun onAnimationStart(animation: Animator?) {
                super.onAnimationStart(animation)
            }
        })
        mBinding.vc?.setOnClickListener {

            objectAnimator.start()
        }

    }

    private fun dp2px(dpValue: Float): Int {
        val scale: Float = resources.displayMetrics.density
        return (dpValue * scale + 0.5f).toInt()
    }

    fun pxToDp( px: Int): Int {
        val displayMetrics: DisplayMetrics = resources.displayMetrics
        return (px / (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT)).roundToInt()
    }


    private class ViewWrapper(view: View) {
        private val mTarget: View = view
        var trueHeight: Int
            get() = mTarget.layoutParams.height
            set(height) {
                mTarget.layoutParams.height = height
                mTarget.requestLayout()
            }
    }
}