supported preview in DivVideo

client/android/div-video/src/main/java/com/yandex/div/video/ExoDivPlayer.kt

@@ -48,13 +48,13 @@ class ExoDivPlayer(
         }
 
         override fun onPlaybackStateChanged(state: Int) {
-            if (state != Player.STATE_BUFFERING && state != Player.STATE_ENDED) return
             if (state == Player.STATE_ENDED) needToRenderFrameExplicitly = true
 
             observers.forEach {
                 when (state) {
                     Player.STATE_BUFFERING -> it.onBuffering()
                     Player.STATE_ENDED -> it.onEnd()
+                    Player.STATE_READY -> it.onReady()
                     else -> Unit
                 }
             }

client/android/div/src/main/java/com/yandex/div/core/player/DivPlayer.kt

@@ -10,6 +10,11 @@ interface DivPlayer {
          */
         fun onPlay() = Unit
 
+        /**
+         * Called when player video is ready to show.
+         */
+        fun onReady() = Unit
+
         /**
          * Called when playback has been paused by an action.
          */

client/android/div/src/main/java/com/yandex/div/core/view2/divs/DivVideoBinder.kt

@@ -1,5 +1,13 @@
 package com.yandex.div.core.view2.divs
 
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.graphics.Color
+import android.util.Base64
+import android.view.View
+import android.view.ViewGroup
+import android.widget.FrameLayout
+import android.widget.ImageView
 import com.yandex.div.core.DivActionHandler
 import com.yandex.div.core.dagger.DivScope
 import com.yandex.div.core.expression.variables.TwoWayIntegerVariableBinder
@@ -45,7 +53,20 @@ internal class DivVideoBinder @Inject constructor(
         )
 
         val playerView = divView.div2Component.divVideoFactory.makePlayerView(view.context)
+        val preview = div.createPreview(resolver)
+        val previewImageView: ImageView = ImageView(view.context).apply {
+            layoutParams = FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)
+            scaleType = ImageView.ScaleType.FIT_CENTER
+            if (preview != null) {
+                visibility = View.VISIBLE
+                setImageBitmap(preview)
+            } else {
+                visibility = View.INVISIBLE
+            }
+            setBackgroundColor(Color.TRANSPARENT)
+        }
         view.addView(playerView)
+        view.addView(previewImageView)
 
         playerView.attach(player)
 
@@ -70,6 +91,10 @@ internal class DivVideoBinder @Inject constructor(
                     divView.let { divActionHandler.handleAction(divAction, it) }
                 }
             }
+
+            override fun onReady() {
+                previewImageView.visibility = View.INVISIBLE
+            }
         }
         player.addObserver(playerListener)
 
@@ -120,3 +145,9 @@ fun DivVideo.createSource(resolver: ExpressionResolver): List<DivVideoSource> {
         )
     }
 }
+
+fun DivVideo.createPreview(resolver: ExpressionResolver): Bitmap? {
+    val base64String = preview?.evaluate(resolver) ?: return null
+    val imageBytes = Base64.decode(base64String, Base64.DEFAULT)
+    return BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.size)
+}

client/android/div/src/main/java/com/yandex/div/core/view2/divs/widgets/DivVideoView.kt

@@ -97,8 +97,8 @@ internal class DivVideoView @JvmOverloads constructor(
     }
 
     fun getPlayerView(): DivPlayerView? {
-        if (this.childCount > 1) {
-            KAssert.fail { "More than one player view inside DivVideo" }
+        if (this.childCount > 2) {
+            KAssert.fail { "Too many children in DivVideo" }
         }
         this.getChildAt(0)?.let {
             if (it !is DivPlayerView) {