AlertDialog like DoalogFragment with blur background. Works with BlurKit (https://github.com/CameraKit/blurkit-android) and Anko (https://github.com/Kotlin/anko)

BlurAlertDialog.kt

// TODO: add package info here

import android.annotation.SuppressLint
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.view.accessibility.AccessibilityNodeInfo
import androidx.annotation.StringRes
import androidx.annotation.StyleRes
import androidx.appcompat.app.AppCompatActivity
import androidx.cardview.widget.CardView
import androidx.coordinatorlayout.widget.CoordinatorLayout
import androidx.core.view.AccessibilityDelegateCompat
import androidx.core.view.ViewCompat
import androidx.core.view.accessibility.AccessibilityNodeInfoCompat
import androidx.fragment.app.DialogFragment
import io.alterac.blurkit.BlurLayout
import kotlinx.android.synthetic.main.design_blur_alert_dialog.*
import org.jetbrains.anko.find
import org.jetbrains.anko.sdk27.coroutines.onClick

/**
 * Prem's creation, on 18/03/19
 */
class BlurAlertDialog : DialogFragment() {

    private lateinit var alertDialog: CardView
    private lateinit var blurLayout: BlurLayout
    var isHideable: Boolean = true

    @StyleRes
    var styleRes: Int = -1
    @StringRes
    var title: String? = null
    @StringRes
    var message: String? = null
    @StringRes
    var positiveText: Int = -1
    @StringRes
    var negativeText: Int = -1
    private var positiveClickListener: OnClickListener? = null
    private var negativeClickListener: OnClickListener? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setStyle(DialogFragment.STYLE_NORMAL, styleRes)
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
        wrapInBottomSheet()

    override fun onStart() {
        super.onStart()
        blurLayout.beginBlur()
        validateAndAddLayout()
        setListeners()
    }

    override fun onStop() {
        blurLayout.pauseBlur()
        super.onStop()
    }

    override fun dismiss() {
        alertDialog.zoomOut()?.then { super.dismiss() }
    }

    private fun initWith(builder: Builder) {
        this.styleRes = builder.styleRes
        this.title = builder.title
        this.message = builder.message
        this.positiveText = builder.positiveText
        this.negativeText = builder.negativeText
        this.positiveClickListener = builder.positiveClickListener
        this.negativeClickListener = builder.negativeClickListener
    }

    private fun wrapInBottomSheet(): View? {
        val rootLayout = View.inflate(context, R.layout.design_blur_alert_dialog, null)
        val coordinatorLayout = rootLayout.find<CoordinatorLayout>(R.id.coordinator)
        blurLayout = coordinatorLayout.find(R.id.touch_outside_blur_layout)
        alertDialog = coordinatorLayout.find(R.id.alert_dialog)

        alertDialog.zoomIn()
        return rootLayout
    }

    private fun validateAndAddLayout() {
        title_text.text = title
        message_text.text = message

        if (positiveText != -1) {
            positive_btn.makeVisible()
            positive_btn.setText(positiveText)
            positive_btn.onClick { positiveClickListener?.onClick(this@BlurAlertDialog) }
        } else {
            positive_btn.makeGone()
        }
        if (negativeText != -1) {
            negative_btn.makeVisible()
            negative_btn.setText(negativeText)
            negative_btn.onClick { negativeClickListener?.onClick(this@BlurAlertDialog) }
        } else {
            negative_btn.makeGone()
        }
    }

    override fun getTheme(): Int = styleRes

    @SuppressLint("ClickableViewAccessibility")
    private fun setListeners() {
        blurLayout.onClick {
            if (isAdded && isHideable) {
                dismiss()
            }
        }
        ViewCompat.setAccessibilityDelegate(alertDialog, object : AccessibilityDelegateCompat() {

            override fun onInitializeAccessibilityNodeInfo(host: View?, info: AccessibilityNodeInfoCompat?) {
                super.onInitializeAccessibilityNodeInfo(host, info)
                if (isHideable) {
                    info?.addAction(AccessibilityNodeInfo.ACTION_DISMISS)
                    info?.isDismissable = true
                } else {
                    info?.isDismissable = false
                }
            }

            override fun performAccessibilityAction(host: View?, action: Int, args: Bundle?): Boolean {
                return if (action == AccessibilityNodeInfo.ACTION_DISMISS && isHideable) {
                    dismiss()
                    true
                } else super.performAccessibilityAction(host, action, args)
            }
        })
        alertDialog.setOnTouchListener { _, _ -> true }
    }

    class Builder(private val activity: AppCompatActivity) {

        @StyleRes
        var styleRes: Int = R.style.BlurDialog
        @StringRes
        var title: String? = null
        @StringRes
        var message: String? = null
        @StringRes
        var positiveText: Int = -1
        @StringRes
        var negativeText: Int = -1
        var positiveClickListener: OnClickListener? = null
        var negativeClickListener: OnClickListener? = null

        fun setStyle(@StyleRes styleRes: Int) = apply { this.styleRes = styleRes }

        fun setTitle(@StringRes title: Int) = apply { this.title = activity.getString(title) }

        fun setMessage(@StringRes message: Int) = apply { this.message = activity.getString(message) }

        fun setTitle(title: String?) = apply { this.title = title }

        fun setMessage(message: String?) = apply { this.message = message }

        fun setPositiveButton(@StringRes positiveText: Int, onClickListener: (BlurAlertDialog) -> Unit) = apply {
            positiveText(positiveText)
            positiveClickListener(object : BlurAlertDialog.OnClickListener {
                override fun onClick(dialog: BlurAlertDialog) {
                    onClickListener(dialog)
                }
            })
        }

        fun setNegativeButton(@StringRes negativeText: Int, onClickListener: (BlurAlertDialog) -> Unit) = apply {
            negativeText(negativeText)
            negativeClickListener(object : BlurAlertDialog.OnClickListener {
                override fun onClick(dialog: BlurAlertDialog) {
                    onClickListener(dialog)
                }
            })
        }

        private fun positiveText(@StringRes positiveText: Int) {
            this.positiveText = positiveText
        }

        private fun negativeText(@StringRes negativeText: Int) {
            this.negativeText = negativeText
        }

        private fun positiveClickListener(positiveClickListener: OnClickListener) {
            this.positiveClickListener = positiveClickListener
        }

        private fun negativeClickListener(negativeClickListener: OnClickListener?) {
            this.negativeClickListener = negativeClickListener
        }

        fun show() {
            val blurAlertDialog = BlurAlertDialog()
            blurAlertDialog.initWith(this)
            blurAlertDialog.show(activity.supportFragmentManager, "$title - $message")
        }
    }

    interface OnClickListener {
        fun onClick(dialog: BlurAlertDialog)
    }
}

design_blur_alert_dialog.xml

<?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"
    android:id="@+id/coordinator"
    style="@style/MatchWidthMatchHeight"
    android:fitsSystemWindows="true">

    <io.alterac.blurkit.BlurLayout
        android:id="@+id/touch_outside_blur_layout"
        style="@style/BlurLayoutFullScreen"
        android:importantForAccessibility="no"
        android:soundEffectsEnabled="false" />

    <View
        style="@style/MatchWidthMatchHeight"
        android:background="@color/color_light_black_blur_background"
        android:importantForAccessibility="no"
        android:soundEffectsEnabled="false" />

    <androidx.cardview.widget.CardView
        android:id="@+id/alert_dialog"
        style="@style/DefaultCard.WrapHeight"
        android:layout_gravity="center"
        app:cardElevation="@dimen/dimen20dp">

        <RelativeLayout
            style="?attr/bottomSheetStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center">

            <TextView
                android:id="@+id/title_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/dimen16dp"
                android:textColor="@color/black_text"
                android:textSize="@dimen/text18sp"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/message_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/title_text"
                android:layout_marginStart="@dimen/dimen16dp"
                android:layout_marginEnd="@dimen/dimen16dp" />

            <Button
                android:id="@+id/positive_btn"
                style="@style/Widget.AppCompat.Button.Borderless"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/message_text"
                android:layout_alignParentEnd="true"
                android:layout_marginTop="@dimen/dimen8dp"
                android:layout_marginEnd="@dimen/dimen16dp"
                android:text="@string/confirm"
                android:textColor="@color/pumpkin_orange" />

            <Button
                android:id="@+id/negative_btn"
                style="@style/Widget.AppCompat.Button.Borderless"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@+id/message_text"
                android:layout_marginTop="@dimen/dimen8dp"
                android:layout_marginEnd="@dimen/dimen8dp"
                android:layout_toStartOf="@+id/positive_btn"
                android:text="@string/cancel"
                android:textColor="@color/torch_red" />

        </RelativeLayout>
    </androidx.cardview.widget.CardView>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

styles.xml

    <style name="MatchWidthMatchHeight">
        <item name="android:layout_width">match_parent</item>
        <item name="android:layout_height">match_parent</item>
    </style>

    <style name="BlurLayoutFullScreen">
        <item name="android:layout_width">match_parent</item>
        <item name="android:layout_height">match_parent</item>
        <item name="android:visibility">invisible</item>
        <item name="blk_blurRadius">2</item>
        <item name="blk_downscaleFactor">0.12</item>
        <item name="blk_fps">0</item>
    </style>

    <style name="DefaultCard" parent="CardView.Light">
        <item name="cardCornerRadius">@dimen/dimen8dp</item>
        <item name="cardElevation">4dp</item>
        <item name="cardUseCompatPadding">true</item>
    </style>

    <style name="DefaultCard.WrapHeight">
        <item name="android:layout_width">match_parent</item>
        <item name="android:layout_height">wrap_content</item>
        <item name="android:layout_marginStart">@dimen/dimen8dp</item>
        <item name="android:layout_marginEnd">@dimen/dimen8dp</item>
    </style>

    <style name="BlurDialog" parent="Theme.AppCompat.Light.Dialog">
        <item name="android:windowNoTitle">true</item>
        <item name="android:windowIsFloating">false</item>
        <item name="bottomSheetStyle">@style/AppModalStyle</item>
        <item name="android:windowBackground">@android:color/transparent</item>
        <item name="android:statusBarColor">@color/colorPrimaryDark</item>
    </style>

UtilAnim.kt

package com.gdn.offline.events.base.util

import android.animation.Animator
import android.view.View
import android.view.ViewPropertyAnimator
import android.view.animation.AccelerateInterpolator
import android.view.animation.Animation
import android.view.animation.AnimationUtils
import androidx.annotation.AnimRes
import com.gdn.offline.events.R

/**
 * Prem's creation, on 18/03/19
 */
fun BlurLayout.beginBlur() {
    postDelayed({
        visibility = View.VISIBLE
        startBlur()
    }, 150)
}

fun Animation.then(action: () -> Unit) {
    setAnimationListener(object : Animation.AnimationListener {
        override fun onAnimationRepeat(animation: Animation?) {}
        override fun onAnimationStart(animation: Animation?) {}
        override fun onAnimationEnd(animation: Animation?) {
            action()
        }
    })
}

fun ViewPropertyAnimator.then(action: () -> Unit) {
    setListener(object : Animator.AnimatorListener {
        override fun onAnimationRepeat(animation: Animator?) {}
        override fun onAnimationCancel(animation: Animator?) {}
        override fun onAnimationStart(animation: Animator?) {}
        override fun onAnimationEnd(animation: Animator?) {
            action()
        }
    })
}

fun View.zoomIn(): Animation? = animate(R.anim.zoom_in)

fun View.zoomOut(): ViewPropertyAnimator? {
    val anim = animate()
        .scaleX(0f)
        .scaleY(0f)
        .alpha(0f)
        .setInterpolator(AccelerateInterpolator())
        .setDuration(150)
    anim.start()
    return anim
}

zoom_in.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <scale
        android:duration="200"
        android:fromXScale="0%"
        android:fromYScale="0%"
        android:interpolator="@android:anim/decelerate_interpolator"
        android:pivotX="50%"
        android:pivotY="50%"
        android:toXScale="102%"
        android:toYScale="102%" />

    <scale
        android:duration="100"
        android:fromXScale="102%"
        android:fromYScale="102%"
        android:interpolator="@android:anim/decelerate_interpolator"
        android:pivotX="50%"
        android:pivotY="50%"
        android:startOffset="200"
        android:toXScale="98%"
        android:toYScale="98%" />

    <scale
        android:duration="150"
        android:fromXScale="98%"
        android:fromYScale="98%"
        android:interpolator="@android:anim/decelerate_interpolator"
        android:pivotX="50%"
        android:pivotY="50%"
        android:startOffset="300"
        android:toXScale="100%"
        android:toYScale="100%" />

    <alpha
        android:duration="50"
        android:fromAlpha="0"
        android:startOffset="100"
        android:toAlpha="1" />
</set>