Need to disable expand on CollapsingToolbarLayout for certain fragments

Question

I have a AppCompatActivity that controls replacing many fragments. Here is my layout for it.

activity_main.xml

Answer 1

You can lock appbarlayout expansion by resetting collapsing toolbar height to toolbar height

toolbarHeight = toolbar.getLayoutParams().height;

if (expand) {
    collapsingToolbar.getLayoutParams().height = getResources().getDimensionPixelOffset(R.dimen.collapsingToolbarDefaultHeight);
    appBarLayout.setExpanded(true, true);
} else {
    //collapse
    //** it is important you do this before resetting **
    appBarLayout.setExpanded(false, true);
    appBarLayout.postDelayed(new Runnable() {
        @Override
        public void run() {
            collapsingToolbar.getLayoutParams().height = toolbarHeight;
        }
     }, 700/* 600 is default animation time to collapse */);
}

Answer 2

I have found a workaround solution that works with activity and various fragments. You implement the CollapsingToolbarLayout with AppBar etc in your activity and then each time you call a new fragment you can call these 2 functions.

• When I want my appbar to keep collapsed:

  public void lockAppBarClosed() {
      mAppBarLayout.setExpanded(false, false);
      mAppBarLayout.setActivated(false);
      CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams)mAppBarLayout.getLayoutParams();
      lp.height = (int) getResources().getDimension(R.dimen.toolbar_height);
  }
  

• When I want my appbar to be expanded and scrollable again

  public void unlockAppBarOpen() {
      mAppBarLayout.setExpanded(true, false);
      mAppBarLayout.setActivated(true);
      CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams)mAppBarLayout.getLayoutParams();
      lp.height = (int) getResources().getDimension(R.dimen.toolbar_expand_height);
  }
  

---

You can call thoses functions from your fragments by implementing an interface. Here's a quick example, for your case (toolbar expands only in homeFragment)

public interface CustomListener() {
    void unlockAppBarOpen();
    void lockAppBarClosed()
}

public class MainActivity extends BaseActivity implements CustomListener {

    @Override
    public void unlockAppBarOpen() {
        mAppBarLayout.setExpanded(true, false);
        mAppBarLayout.setActivated(true);
        CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams)mAppBarLayout.getLayoutParams();
        lp.height = (int) getResources().getDimension(R.dimen.toolbar_expand_height);
    }

    @Override
    public void lockAppBarClosed() {
        mAppBarLayout.setExpanded(false, false);
        mAppBarLayout.setActivated(false);
        CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams)mAppBarLayout.getLayoutParams();
        lp.height = (int) getResources().getDimension(R.dimen.toolbar_height);
    }
}

public class MainFragment extends BaseFragment {

    @Override
    public void onResume() {
        super.onPause();
        ((MainActivity) getContext()).unlockAppBarOpen();
    }
}

public class SecondFragment extends BaseFragment {

    @Override
    public void onResume() {
        super.onPause();
        ((MainActivity) getContext()).lockAppBarClosed();
    }
}

With this example:

• each time the MainFragment will be displayed -> it will extends the toolbar and make it collapsable and expandable

• each time the SecondFragment is displayed -> il will collapsed the toolbar to a standard size and prevent it to expand again

Hope it will help you !