IssueTracker

Component used: androidx.leanback:leanback

Version used: 1.1.0-rc01

The DetailsSupportFragmentBackgroundController class no longer works correctly.

https://developer.android.com/reference/androidx/leanback/app/DetailsSupportFragmentBackgroundController

When following the documentation linked above, it seems to work fine. The cover bitmap appears. However, when you navigate to another screen (for example using the AndroidX Navigation component), and then go back again, the cover bitmap does not appear. In my app it shows just a grey background. So for some reason the background is not set.

I looked into this bug and it seems that it was introduced when fixing memory leaks here: https://android.googlesource.com/platform/frameworks/support/+/2f2fa284ef504e466c21b91820b7bb3a18ddea30%5E%21/#F3

Specifically, it is caused by setting mBackgroundDrawable to null in onDestroyView. So when you navigate to another fragment, and then back again, mBackgroundDrawable is null which was not the case before.

The DetailsSupportFragment automatically uses mBackgroundDrawable in onCreateView to configure the background: https://android.googlesource.com/platform/frameworks/support/+/2f2fa284ef504e466c21b91820b7bb3a18ddea30/leanback/leanback/src/main/java/androidx/leanback/app/DetailsSupportFragment.java#477. But as this value is now set to null this does not work anymore.

The fix is to not set mBackgroundDrawable to null in onDestroyView. As far as I know that cannot cause a leak as the drawable does not reference any views.

A workaround which I am using at the moment is the following class:

package androidx.leanback.app

abstract class DetailsSupportFragmentFix : DetailsSupportFragment() {

    override fun onDestroyView() {
        // Background drawable should not be cleared in onDestroyView.
        val drawable = mBackgroundDrawable
        super.onDestroyView()
        mBackgroundDrawable = drawable
    }
}