reuse the built in fade animations

app/src/main/kotlin/com/simplemobiletools/gallery/fragments/VideoFragment.kt

@@ -172,16 +172,19 @@ class VideoFragment : ViewPagerFragment(), View.OnClickListener, SurfaceHolder.C
     }
 
     private fun checkFullscreen() {
-        var anim = R.anim.fade_in
+        var anim = android.R.anim.fade_in
         if (mIsFullscreen) {
-            anim = R.anim.fade_out
+            anim = android.R.anim.fade_out
             mSeekBar!!.setOnSeekBarChangeListener(null)
         } else {
             mSeekBar!!.setOnSeekBarChangeListener(this)
         }
 
-        val animation = AnimationUtils.loadAnimation(context, anim)
-        mTimeHolder!!.startAnimation(animation)
+        AnimationUtils.loadAnimation(context, anim).apply {
+            duration = 150
+            fillAfter = true
+            mTimeHolder!!.startAnimation(this)
+        }
     }
 
     private fun togglePlayPause() {

app/src/main/res/anim/fade_in.xml

@@ -1,7 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<alpha xmlns:android="http://schemas.android.com/apk/res/android"
-       android:duration="150"
-       android:fillAfter="true"
-       android:fromAlpha="0.0"
-       android:interpolator="@android:anim/accelerate_interpolator"
-       android:toAlpha="1.0"/>

app/src/main/res/anim/fade_out.xml

@@ -1,7 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<alpha xmlns:android="http://schemas.android.com/apk/res/android"
-       android:duration="150"
-       android:fillAfter="true"
-       android:fromAlpha="1.0"
-       android:interpolator="@android:anim/accelerate_interpolator"
-       android:toAlpha="0.0"/>