android - How to disable scrolling of NestedScrollView&CollapsingToolbarLayout, for example when there is no more content below?

Question

Background

I try to add the same functionality as shown on many apps, where the upper area of the screen shrinks&expands according to the scrolled content.

For this, I use Google's design library, as shown on the CheeseSquare sample.

The problem

Thing is, no matter how much content there is in the NestedScrollView , it lets me scroll way below the last view of the content, just to let me see the final state of the actionbar, having the minimal size of itself.

In short, this is what I see when scrolling to the bottom (modified content of CheeseSquare sample):

while this is what I'd like to have when scrolling to the bottom (taken from contacts app) :

I'm also trying to fix a bug on ThreePhasesBottomSheet sample that scrolling in the bottom sheet content is possible even when it's in peek-state. To reproduce, start scrolling horizontally (which doesn't do anything, as there is nothing to scroll this way) and then vertically, which would somehow trigger scrolling of the content of the bottom-sheet.

Therefore, I need to disable there the scrolling in "transformView()" method, in the case that "translation

This is how it works using normal usage:

And this is how it behaves with the bug of not blocking the scrolling:

What I've tried

I've tried to play with the "layout_scrollFlags" flags, to change the height to wrap_content, and to remove the clipToPadding and fitsSystemWindows attributes.

Here's the sample XML file, which I've modified to include only a single cardView instead of many:

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/detail_backdrop_height"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        android:fitsSystemWindows="true">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginStart="48dp"
            app:expandedTitleMarginEnd="64dp">

            <ImageView
                android:id="@+id/backdrop"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="centerCrop"
                android:fitsSystemWindows="true"
                app:layout_collapseMode="parallax" />

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
                app:layout_collapseMode="pin" />

        </android.support.design.widget.CollapsingToolbarLayout>

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:paddingTop="24dp">

            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/card_margin">

                <LinearLayout
                    style="@style/Widget.CardContent"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="Info"
                        android:textAppearance="@style/TextAppearance.AppCompat.Title" />

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="@string/cheese_ipsum" />

                </LinearLayout>

            </android.support.v7.widget.CardView>

        </LinearLayout>

    </android.support.v4.widget.NestedScrollView>

    <android.support.design.widget.FloatingActionButton
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        app:layout_anchor="@id/appbar"
        app:layout_anchorGravity="bottom|right|end"
        android:src="@drawable/ic_discuss"
        android:layout_margin="@dimen/fab_margin"
        android:clickable="true"/>

</android.support.design.widget.CoordinatorLayout>

I've tried the next code too :

((AppBarLayout.LayoutParams) collapsingToolbar.getLayoutParams()).setScrollFlags(0);

but this still allowed scrolling of the NestedScrollView itself in the CheeseSquare example, and also allowed flinging in the ThreePhasesBottomSheet sample .

The questions

1. What can I do in order to make the scrolling stop when there is no more content to show at the bottom?

2. In addition, what can be done to disable scrolling of the NestedScrollView in any time I wish ( for the ThreePhasesBottomSheet sample) ? Something like "setEnableScrolling(...)" ?

   I've tried to extend NestedScrollView and also extend from ScrollingViewBehavior, but failed to find what can be done to disable the scrolling.

It's probably a very simple thing to change, but I can't find out what...

EDIT: if needed, this is what I currently use for the design&support library

compile 'com.android.support:appcompat-v7:23.1.0'
compile 'com.android.support:design:23.1.0'

---

EDIT: for #2, I've found a workaround from within the BottomSheetLayout.java file, to disable all that's related to the variable "sheetViewOwnsTouch", as if it's always set to "false". This will allow stealing touch events on the bottom sheet. However, this is just a workaround, and only for this case. It also causes some touch events that should have been handled by other views. I still wish to know how to block the scrolling programmatically, and also in the other case of enough-space-to-show-content.

Answer 1

What can I do in order to make the scrolling stop when there is no more content to show at the bottom?

Firstly, as I have commented below, the scrolling you said in your question is not of the NestedScrollView. It belongs to the CollapsingToolbarLayout. The NestedScrollView's scroll event only happens when CollapsingToolbarLayout fully collapsed, and of course it will stop scrolling when when there is no more content inside it (bottom reached). For the CollapsingToolbarLayout, it will collapse to its Toolbar's layout_height (as in the xml file, you will find "?attr/actionBarSize"). The following image will demonstrate that, pay attention to the red rectangular that is the toolbar (I set its background)

So to have a solution for your #1, you need to calculate the height of NestedScrollView, then if it's smaller than screen height, we fix the toolbar's height.

In short, you can update activity_detail.xml as the following:

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/detail_backdrop_height"
        android:fitsSystemWindows="true"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <ImageView
                android:id="@+id/backdrop"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:fitsSystemWindows="false"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax" />

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

        </android.support.design.widget.CollapsingToolbarLayout>

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"            
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <LinearLayout
            android:id="@+id/linearLayout1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/card_margin">

                <LinearLayout
                    style="@style/Widget.CardContent"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="Info"
                        android:textAppearance="@style/TextAppearance.AppCompat.Title" />

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="@string/cheese_ipsum" />

                </LinearLayout>

            </android.support.v7.widget.CardView>

        </LinearLayout>

    </android.support.v4.widget.NestedScrollView>

</android.support.design.widget.CoordinatorLayout>

And CheeseDetailActivity.java:

public class CheeseDetailActivity extends AppCompatActivity {

    public static final String EXTRA_NAME = "cheese_name";
    private final Context mContext = this;
    private int screenHeight;
    private int linearLayoutHeight;
    private int toolbarHeight_org;
    private int toolbarHeight;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);

        Intent intent = getIntent();
        final String cheeseName = intent.getStringExtra(EXTRA_NAME);

        screenHeight = getScreenHeight(this);

        TypedValue typedValue = new TypedValue();
        getTheme().resolveAttribute(R.attr.colorPrimary, typedValue, true);
        final int colorPrimary = typedValue.data;

        final Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        AppBarLayout appbar = (AppBarLayout) findViewById(R.id.appbar);
        final CoordinatorLayout.LayoutParams appbarLayoutParams = (CoordinatorLayout.LayoutParams)appbar.getLayoutParams();

        final ViewGroup.LayoutParams toolbarLayoutParams = toolbar.getLayoutParams();
        if (toolbarLayoutParams != null) {
            toolbarHeight_org = toolbarLayoutParams.height;
            toolbarHeight = toolbarLayoutParams.height;
        }

        final CollapsingToolbarLayout collapsingToolbar =
                (CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
        collapsingToolbar.setTitle(cheeseName);

        collapsingToolbar.setContentScrimColor(colorPrimary);
        collapsingToolbar.setExpandedTitleTextAppearance(R.style.ExpandedTitleTextAppearance);
        //collapsingToolbar.setCollapsedTitleTextAppearance(R.style.CollapsedTitleTextAppearance);

        final LinearLayout linearLayout = (LinearLayout) findViewById(R.id.linearLayout1);
        ViewTreeObserver observer = linearLayout.getViewTreeObserver();
        observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                linearLayoutHeight = linearLayout.getHeight();
                if (linearLayoutHeight + toolbarHeight < screenHeight) {
                    if (toolbarLayoutParams != null) {
                        toolbarLayoutParams.height = screenHeight - linearLayoutHeight - 20;
                        if (toolbarLayoutParams.height < toolbarHeight_org) {
                            toolbarLayoutParams.height = toolbarHeight_org;
                        }

                        int extended_text_size = (int) getResources().getDimension(R.dimen.expanded_text_size);

                        if (appbarLayoutParams.height - toolbarLayoutParams.height <= extended_text_size) {
                            int value = appbarLayoutParams.height - toolbarLayoutParams.height;
                            if (value < 0) {
                                appbarLayoutParams.height = toolbarLayoutParams.height - value + extended_text_size * 3;
                            } else {
                                appbarLayoutParams.height = toolbarLayoutParams.height + extended_text_size * 3;
                            }
                            if (appbarLayoutParams.height >= screenHeight) {
                                appbarLayoutParams.height = screenHeight;
                            }
                        }

                        // collapsingToolbar.setContentScrimColor(getResources().getColor(android.R.color.transparent));
                        if (toolbarLayoutParams.height > toolbarHeight_org) {
                            collapsingToolbar.setContentScrimColor(ContextCompat.getColor(mContext, android.R.color.transparent));
                        }
                    }
                }
                // Removes the listener if possible
                ViewTreeObserver viewTreeObserver = linearLayout.getViewTreeObserver();
                if (viewTreeObserver.isAlive()) {
                    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
                        linearLayout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                    } else {
                        linearLayout.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                    }
                }
            }
        });

        loadBackdrop();
        appbar.setExpanded(true);
    }

    private int getScreenHeight(Context context) {
        int measuredHeight;
        Point size = new Point();
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
            wm.getDefaultDisplay().getSize(size);
            measuredHeight = size.y;
        } else {
            Display d = wm.getDefaultDisplay();
            measuredHeight = d.getHeight();
        }

        return measuredHeight;
    }

    private void loadBackdrop() {
        final ImageView imageView = (ImageView) findViewById(R.id.backdrop);
        Glide.with(this).load(Cheeses.getRandomCheeseDrawable()).centerCrop().into(imageView);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.sample_actions, menu);
        return true;
    }
}

Here's the result:

With Cheesesquare sample, I have customized this project and uploaded to My GitHub. I agree that it still has some problems, however, at least it can be a solution for your 1st issue.

Please take a look. Hope it helps!