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fun transform(fab: FloatingActionButton) {
        if (fab.isVisible) {
            fab.hide(object : FloatingActionButton.OnVisibilityChangedListener() {
                override fun onHidden(fab: FloatingActionButton?) {
                    super.onHidden(fab)
                    ValueAnimator.ofFloat(materialShapeDrawable.interpolation, 0F).apply {
                        addUpdateListener { materialShapeDrawable.interpolation = it.animatedValue as Float }
                        start()
                    }
                }

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ValueAnimator.ofFloat(materialShapeDrawable.interpolation, finishState).apply {
                addUpdateListener { materialShapeDrawable.interpolation = it.animatedValue as Float }
                doOnEnd { fab.show() }
                start()
            }

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<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.vadmax.fabbottomnavigationview.FabBottomNavigationView
        android:id="@+id/bottomNavigationView"

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<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:icon="@drawable/ic_android"
        android:title="@null" />

    <item
        android:icon="@drawable/ic_android"
        android:title="@null" />

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<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
  
  <com.vadmax.fabbottomnavigationview.FabBottomNavigationView
        android:id="@+id/bottomNavigationView"

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val materialShapeDrawable = MaterialShapeDrawable(shapePathModel).apply {
            setTint(ContextCompat.getColor(context, R.color.bottom_bar))
            shadowElevation = 4
            shadowRadius = 16
            isShadowEnabled = true
            paintStyle = Paint.Style.FILL_AND_STROKE
        }
background = materialShapeDrawable

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val shapePathModel = ShapePathModel().apply {
            topEdge = topCurvedEdgeTreatment
        }

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val topCurvedEdgeTreatment =TopCurvedEdgeTreatment(fabCradleMargin, fabCradleRoundedCornerRadius, cradleVerticalOffset).apply {
                fabDiameter = fabSize
            }

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

init {
      //There will be magic
    }
}

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import com.google.android.material.shape.EdgeTreatment
import com.google.android.material.shape.ShapePath

class TopCurvedEdgeTreatment(
    var fabCradleMargin: Float,
    var fabCradleRoundedCornerRadius: Float,
    var cradleVerticalOffset: Float
) : EdgeTreatment() {

    var fabDiameter: Float = 0F