[android-developers] Scrolling to view in CoordinatorLayout shows only partially the view

[simonsysarbejder]

I have made an Android app containing a CoordinatorLayout with a AppBar and 
a NestedScrollView. 


In my NestedScrollView I have a list of items, and a button which scroll to 
an item in my NestedScrollView.

When clicking the button, the Android app scroll down to the item, but 
doesn't show the whole item, only partially: 
http://i.stack.imgur.com/8kuq0.png

I expected something like the following: http://i.stack.imgur.com/k0A5N.png


It seems like the amount the app needs to scroll is about the same size as 
the AppBar, in order to show the whole view. If I remove the scroll flag in 
my layout file below, I get the expected behavior.

I'm in doubt if View.requestRectangleOnScreen() is the right method to 
call, or if I should use a different layout then NestedScrollView? What do 
I do wrong?


My activity is coded as follows:


package com.example.sij.coordinatorlayoutbug;

import android.graphics.Rect;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    TextView itemToNavigateTo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        itemToNavigateTo = (TextView)findViewById(R.id.itemToNavigateTo);
        Button navigatorButton = (Button) findViewById(R.id.navigator_button
);
        navigatorButton.setOnClickListener(navigateToItemListener());
    }

    View.OnClickListener navigateToItemListener() {
        return new View.OnClickListener() {
            @Override
            public void onClick(final View v) {
                new Handler(Looper.getMainLooper()).post(new Runnable() {
                    @Override
                    public void run() {
                        itemToNavigateTo.requestRectangleOnScreen(new Rect(
                            0, 
                            0, 
                            itemToNavigateTo.getWidth(), 
                            itemToNavigateTo.getHeight()));
                    }
                });
            }
        };
    }
}


And the layout:
<?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:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways" />

    </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">

            <Button
                android:id="@+id/navigator_button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/scroll_to_item" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/item1"/>
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/lorem_ipsum"
                android:paddingBottom="20dp"/>

            <!-- Items 2 to 5 omitted for brevity -->
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/item6"/>
            <TextView
                android:id="@+id/itemToNavigateTo"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/lorem_ipsum"
                android:paddingBottom="20dp"/> 
        </LinearLayout>
    </android.support.v4.widget.NestedScrollView>
</android.support.design.widget.CoordinatorLayout>


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