ShimmerLayout animation logic ignores parent visibility and detached from window state

[alexandrvj]

There are at least two problem cases with ShimmerLayout animation logic.

1. If the ShimmerLayout has parent view/container and you hide parent view, animation logic inside ShimmerLayout doesn't stop. For example, we have some xml

<androidx.cardview.widget.CardView
android:id="@+id/cardView"
android:layout_width="match_parent"
android:layout_height="48dp"
android:layout_margin="8dp"
android:visibility="gone">

<io.supercharge.shimmerlayout.ShimmerLayout
    android:id="@+id/shimmer"
    app:shimmer_auto_start="true"
    style="@style/ShimmerLayout">

    <View
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:layout_gravity="center_vertical|start"
        android:layout_marginLeft="16dp"
        android:background="@color/n7"/>

    <View
        android:layout_width="match_parent"
        android:layout_height="16dp"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="64dp"
        android:layout_marginRight="32dp"
        android:background="@color/n7"/>
</io.supercharge.shimmerlayout.ShimmerLayout>

</androidx.cardview.widget.CardView>

then our ShimmerLayout will run recursivelly in startShimmerAnimation method, although we have not even shown it to the user.

2. More than that it leads to memory leak when using Activity#recreate method:
   a) ShimmerLayout#startShimmerAnimation subscribes to ViewTreeObserver#onPreDraw to detect own width;
   b) ShimmerLayout don't stop animation logic when parent view becomes hidden or the ShimmerLayout is detached from the window.;

• com.example.app.MyFragment has leaked:
• static WindowManagerGlobal.sDefaultWindowManager
• ↳ WindowManagerGlobal.mRoots
• ↳ ArrayList.elementData
• ↳ array Object[].[0]
• ↳ ViewRootImpl.!(mAttachInfo)!
• ↳ View$AttachInfo.!(mTreeObserver)!
• ↳ ViewTreeObserver.!(mOnPreDrawListeners)!
• ↳ ViewTreeObserver$CopyOnWriteArray.!(mData)!
• ↳ ArrayList.!(elementData)!
• ↳ array Object[].!([1])!
• ↳ ShimmerLayout$1.!(this$0)! (anonymous implementation of android.view.ViewTreeObserver$OnPreDrawListener)
• ↳ ShimmerLayout.mContext
• ↳ MainActivity.navigationController
• ↳ DefaultBottomBarController.adapter
• ↳ CachePagerAdapter.mCurrentPrimaryItem
• ↳ MyFragment

[alexandrvj]

Up!

[veghtomi]

@alexandrvj

1. issue: I believe the answer to this is very obvious. If you animate a View with built-in classes like ObjectAnimator and the animated View becomes hidden, then the animation will continue regardless. With this library, it is the same.

2. issue: good finding. I could reproduce the memory leak, a fix will come.

[matheuspontoporto]

@veghtomi any updates on this fix for the leak, to stop the previous animations ?