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

All you have to do is replace CoordinatorLayout with custom implementation of CoordinatorLayout which will cheat that nested scrolling has been handled.

MyCoordinatorLayout implementation:

public class MyCoordinatorLayout extends CoordinatorLayout {

    private boolean allowForScroll = false;

    public MyCoordinatorLayout(Context context) {
        super(context);
    }

    public MyCoordinatorLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
        return allowForScroll && super.onStartNestedScroll(child, target, nestedScrollAxes);
    }

    public boolean isAllowForScroll() {
        return allowForScroll;
    }

    public void setAllowForScroll(boolean allowForScroll) {
        this.allowForScroll = allowForScroll;
    }
}

activity view xml:

I encourage you to use custom AppBarLayout implementation with helper methods to collapse/expand toolbar. On this gist you can find one.

Ok, now it's time to configure our toolbar in activity.

public class ToolbarAppcompatActivity extends AppCompatActivity
        implements AppBarLayout.OnOffsetChangedListener {

    protected Toolbar toolbar;
    protected MyCoordinatorLayout coordinator;
    protected ControllableAppBarLayout appbar;

    @Override protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        configureToolbar();
    switchFragment(new FooFragment(), "FOO", true);
    }

    protected void configureToolbar() {
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        coordinator = (MyCoordinatorLayout) findViewById(R.id.coordinator);
        appbar = (ControllableAppBarLayout) findViewById(R.id.appbar);
        appbar.addOnOffsetChangedListener(this);
        getDelegate().setSupportActionBar(toolbar);
    }

    public void switchToFragment(Fragment fragment, String tag, boolean expandToolbar){
        FragmentManager fragmentManager = getSupportFragmentManager();

        Fragment currentFragment = fragmentManager.findFragmentByTag(currentFragmentTag);

        if(currentFragment == null || !TextUtils.equals(tag, currentFragmentTag) ){
            currentFragmentTag = tag;
            fragmentManager
                    .beginTransaction()
                    .replace(R.id.flContent, fragment, currentFragmentTag)
                    .commit();

            if(expandToolbar){
                expandToolbar();
            }else{
                collapseToolbar();
            }
        }
    }

    protected void addFragment(Fragment fragment, String tag, boolean expandToolbar) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        currentFragmentTag = tag;
        fragmentManager
                .beginTransaction()
                .add(R.id.flContent, fragment, currentFragmentTag)
                .addToBackStack(tag)
                .commit();

        if(expandToolbar){
            expandToolbar();
        }else{
            collapseToolbar();
        }
    }

   protected void collapseToolbar(){
        appbar.collapseToolbar();
        coordinator.setAllowForScroll(false);
    }

    public void expandToolbar(){
        appbar.expandToolbar();
        coordinator.setAllowForScroll(true);
    }

}

Every time you want to switch fragment and collapse/expand toolbar just call method switchFragment/addFragment with proper boolean parameter.

Just one last note. Make sure you use latest support libraries.

dependencies {

    // android support
    compile 'com.android.support:appcompat-v7:22.2.1'
    compile 'com.android.support:recyclerview-v7:22.2.1'
    compile 'com.android.support:design:22.2.1'

}

Do not use include tag in AppBarLayout. It does not work