Fitssystemwindows Effect Gone for Fragments Added via Fragmenttransaction

fitsSystemWindows effect gone for fragments added via FragmentTransaction

When you use <fragment>, the layout returned in your Fragment's onCreateView is directly attached in place of the <fragment> tag (you'll never actually see a <fragment> tag if you look at your View hierarchy.

Therefore in the <fragment> case, you have

DrawerLayout
  CoordinatorLayout
    AppBarLayout
    ...
  NavigationView

Similar to how cheesesquare works. This works because, as explained in this blog post, DrawerLayout and CoordinatorLayout both have different rules on how fitsSystemWindows applies to them - they both use it to inset their child Views, but also call dispatchApplyWindowInsets() on each child, allowing them access to the fitsSystemWindows="true" property.

This is a difference from the default behavior with layouts such as FrameLayout where when you use fitsSystemWindows="true" is consumes all insets, blindly applying padding without informing any child views (that's the 'depth first' part of the blog post).

So when you replace the <fragment> tag with a FrameLayout and FragmentTransactions, your view hierarchy becomes:

DrawerLayout
  FrameLayout
    CoordinatorLayout
      AppBarLayout
      ...
  NavigationView

as the Fragment's view is inserted into the FrameLayout. That View doesn't know anything about passing fitsSystemWindows to child views, so your CoordinatorLayout never gets to see that flag or do its custom behavior.

Fixing the problem is actually fairly simple: replace your FrameLayout with another CoordinatorLayout. This ensures the fitsSystemWindows="true" gets passed onto the newly inflated CoordinatorLayout from the Fragment.

Alternate and equally valid solutions would be to make a custom subclass of FrameLayout and override onApplyWindowInsets() to dispatch to each child (in your case just the one) or use the ViewCompat.setOnApplyWindowInsetsListener() method to intercept the call in code and dispatch from there (no subclass required). Less code is usually the easiest to maintain, so I wouldn't necessarily recommend going these routes over the CoordinatorLayout solution unless you feel strongly about it.

Android fitsSystemWindows not working when replacing fragments

Your FrameLayout is not aware of window inset sizes, because it's parent - LinearLayout hasn't dispatched it any. As a workaround, you can subclass LinearLayout and pass insets to children on your own:

@TargetApi(Build.VERSION_CODES.KITKAT_WATCH)
@Override
public WindowInsets onApplyWindowInsets(WindowInsets insets) {
    int childCount = getChildCount();
    for (int index = 0; index < childCount; index++)
        getChildAt(index).dispatchApplyWindowInsets(insets); // let children know about WindowInsets

    return insets;
}

You can have a look to my this answer, which will explain detailed how this works, and also how to use ViewCompat.setOnApplyWindowInsetsListener API.

Change toolbar from fragment

It's been a wild ride, but I finally found a solution. For the issue number 1, this is due to the way Android manages the fitsSystemWindows property propagation. For this to work correctly, I made a few changes to my layouts. I created a custom FitSystemWindowLinearLayout, which is simply a class extending the standard LinearLayout and overriding onApplyWindowInsets like this:

  @Override
  public WindowInsets onApplyWindowInsets(WindowInsets insets) {
    int childCount = getChildCount();
    for (int index = 0; index < childCount; ++index) {
      getChildAt(index).dispatchApplyWindowInsets(insets);
    }

    return insets;
  }

My main activity now looks like this:

+-- CoordinatorLayout, fitsSystemWindows=false
    +-- FitSystemWindowLinearLayout, fitsSystemWindows="false"
        +-- Toolbar
        +-- NavHostFragment, fitsSystemWindows="false"
        +-- BottomNavigationView, fitsSystemWindows="false"

For the second issue, namely the transition being ugly, I mitigated that by adding a shared element to the transition.

All in all, I think it's easier to use a new activity for this kind of things, the NavigationUI falls a bit short for now.

Here are some resources that helped me:

• https://medium.com/androiddevelopers/why-would-i-want-to-fitssystemwindows-4e26d9ce1eec
• Android fitsSystemWindows not working when replacing fragments
• Collapsing Toolbar problems with Status Bar and Bottom Bar. Fitssystemwindows="true" not working
• fitsSystemWindows effect gone for fragments added via FragmentTransaction
• https://www.reddit.com/r/androiddev/comments/aryxvu/fitssystemwindows_misbehaves_with_navigation/
  -https://medium.com/androiddevelopers/why-would-i-want-to-fitssystemwindows-4e26d9ce1eec

Android 4.4 — Translucent status/navigation bars — fitsSystemWindows/clipToPadding don't work through fragment transactions

I solved the issue by using the library I use the set the color of my translucent status bar.

The SystemBarConfig class of SystemBarTint (as seen here https://github.com/jgilfelt/SystemBarTint#systembarconfig) lets you get insets which I set as the padding to the list in every fragment, along with the use of clipToPadding="false" on the list.

I have details of what I've done on this post: http://mindofaandroiddev.wordpress.com/2013/12/28/making-the-status-bar-and-navigation-bar-transparent-with-a-listview-on-android-4-4-kitkat/

How to correctly implement view content behind statusbar when using fragments

Ok the problem was the content_main.xml it's always replaced so I thought it wasn't necessary to have the android:fitsSystemWindows attribute but i was wrong, adding android:fitsSystemWindows="true" solved the problem.

snippet content_main:

    <?xml version="1.0" encoding="utf-8"?>
    <android.support.design.widget.CoordinatorLayout
    android:id="@+id/fragment_container"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"/>

Important: if like me after that you find a bug in viewPager when coordinatorLayout has android:fitsSystemWindows="true" take a look here: CoordinatorLayout status bar padding disappears from ViewPager 2nd page

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