How to block CollapsingToolbarLayout from Android Support Library

Question

I use an Activity class with (usually) a single fragment as content. In Activity, I use CollapsingToolbarLayoutas a kind of header for some information, and everything works fine. But in some cases (when some fragments are attached) I do not want to show this information, I do not want to CollapsingToolbarLayoutopen in the scroll.

What I want to achieve is to block CollapsingToolbarLayoutso that it does not open from the fragment. I reset it programmatically withappBarLayout.setExpanded(false, true);

Answer 1

, . ViewCompat.setNestedScrollingEnabled(recyclerView, expanded);

backstack, , backstack . , NestedScrollView . :

getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            NestedScrollView nestedScrollView = (NestedScrollView)findViewById(R.id.nested_scroll_view);
            int size = getSupportFragmentManager().getBackStackEntryCount();
            if (size >= 1 && nestedScrollView != null) {
                if (getSupportFragmentManager().getBackStackEntryAt(size - 1).getName().equals("SpotDetailsFragment")) {
                    Log.d(LOG_TAG, "Enabling collapsible toolbar.");
                    ViewCompat.setNestedScrollingEnabled(nestedScrollView, true);
                } else {
                    Log.d(LOG_TAG, "Disabling collapsible toolbar.");
                    ViewCompat.setNestedScrollingEnabled(nestedScrollView, false);
                }
            }
        }
    });

, : CollapsingToolbarLayout

Answer 2

, NestedScrollView. .

"Utils". , , , , .

,

public static void LockToolbar(boolean locked, final AppBarLayout appbar, final CollapsingToolbarLayout toolbar) {

    if (locked) {
        // We want to lock so add the listener and collapse the toolbar
        appbar.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {

            @Override
            public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
                if (toolbar.getHeight() + verticalOffset < 2 * ViewCompat.getMinimumHeight(toolbar)) {
                    // Now fully expanded again so remove the listener
                    appbar.removeOnOffsetChangedListener(this);
                } else {
                    // Fully collapsed so set the flags to lock the toolbar
                    AppBarLayout.LayoutParams lp = (AppBarLayout.LayoutParams) toolbar.getLayoutParams();
                    lp.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_ENTER_ALWAYS_COLLAPSED);
                }
            }
        });
        appbar.setExpanded(false, true);
    } else {
        // Unlock by restoring the flags and then expand 
        AppBarLayout.LayoutParams lp = (AppBarLayout.LayoutParams) toolbar.getLayoutParams();
        lp.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL | AppBarLayout.LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED);
        appbar.setExpanded(true, true);
    }

}