allprojects {
  repositories {
   ...
   maven { url 'https://jitpack.io' }
  }
 }
    
    
     dependencies {
         implementation 'com.github.tuanhav95:DragView:1.1.0'
 }

   <com.tuanhav95.drag.DragView
        android:id="@+id/dragView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:height_when_max="300dp"
        app:height_when_min="80dp"
        app:margin_bottom_when_min="8dp"
        app:margin_edge_when_min="8dp"
        app:percent_when_middle="0.9"
        app:state="MIN" />

        dragView.setDragListener(object : DragView.DragListener {
            override fun onChangeState(state: DragView.State) {
            }

            override fun onChangePercent(percent: Float) {
                alpha.alpha = 1 - percent
            }

        })

        supportFragmentManager.beginTransaction().add(R.id.frameFirst, TopFragment()).commit() // add frame top
        supportFragmentManager.beginTransaction().add(R.id.frameSecond, BottomFragment()).commit() // add frame bottom

        btnMax.setOnClickListener { dragView.maximize() }
        btnMin.setOnClickListener { dragView.minimize() }
        btnClose.setOnClickListener { dragView.close() }

        class DragSource @JvmOverloads constructor(
         context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
 ) : DragView(context, attrs, defStyleAttr) {

     var mWidthWhenMax = 0

     var mWidthWhenMiddle = 0

     var mWidthWhenMin = 0

     init {
  getFrameFirst().addView(inflate(R.layout.layout_top))
  getFrameSecond().addView(inflate(R.layout.layout_bottom))
     }

     override fun initFrame() {
  mWidthWhenMax = width

  mWidthWhenMiddle = (width - mPercentWhenMiddle * mMarginEdgeWhenMin).toInt()

  mWidthWhenMin = mHeightWhenMin * 22 / 9

  super.initFrame()
     }

     override fun refreshFrameFirst() {
  super.refreshFrameFirst()

  val width = if (mCurrentPercent < mPercentWhenMiddle) {
      (mWidthWhenMax - (mWidthWhenMax - mWidthWhenMiddle) * mCurrentPercent)
  } else {
      (mWidthWhenMiddle - (mWidthWhenMiddle - mWidthWhenMin) * (mCurrentPercent - mPercentWhenMiddle) / (1 - mPercentWhenMiddle))
  }

  frameTop.reWidth(width.toInt())
     }
 }

   <com.tuanhav95.example.custom.DragSource
        android:id="@+id/dragView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:height_when_max="300dp"
        app:height_when_min="58dp"
        app:state="MIN" />

        dragView.setDragListener(object : DragView.DragListener {
            override fun onChangeState(state: DragView.State) {
            }

            override fun onChangePercent(percent: Float) {
                alpha.alpha = 1 - percent
                shadow.alpha = percent
            }

        })

        supportFragmentManager.beginTransaction().add(R.id.frameTop, TopFragment()).commit()
        supportFragmentManager.beginTransaction().add(R.id.frameBottom, BottomFragment()).commit()

        btnMax.setOnClickListener { dragView.maximize() }
        btnMin.setOnClickListener { dragView.minimize() }
        btnClose.setOnClickListener { dragView.close() }