<!-- layout_collapseMode(折叠模式)-有两个值:
                 1.parallax:在内容滚动时，CollapsingToolbarLayout中的View（比如ImageView)也可以同时滚动，
                 实现视差滚动效果，通常和layout_collapseParallaxMultiplier(设置视差因子)搭配使用。
                 2.pin - 当CollapsingToolbarLayout完全收缩后，Toolbar还可以固定在屏幕上。
          -->

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    tools:context="fanggao.qf.collapsingtoolbarlayout.MainActivity">
   <!-- android:fitsSystemWindow = "true" 表示整个布局展示是整个屏幕出去状态栏,标题栏和导航栏剩下的区域-->
    <android.support.design.widget.AppBarLayout
        android:id="@+id/layout_appbar"
        android:layout_width="match_parent"
        android:layout_height = "wrap_content"
       >
        <!--
         app:expandedTitleMarginStart="10dp"
        设置扩张时候(还没有收缩时)title离屏幕左边的距离

         app:contentScrim="?attr/colorPrimary"
        设置当完全CollapsingToolbarLayout折叠(收缩)后的背景颜色
        -->
        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/ctb"
            android:layout_width="match_parent"
            android:layout_height="250dp"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginStart="10dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">
       
        <ImageView
            android:id="@+id/image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="centerCrop"
            app:layout_collapseMode="parallax"
            android:src = "@drawable/cat"
            />
        <!--标题-->
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            app:layout_collapseMode="pin"
            app:title="Toolbar"/>
        </android.support.design.widget.CollapsingToolbarLayout>
        <!--选项卡-->
        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabIndicatorColor="@color/colorAccent"
            app:tabMode="scrollable"
            app:tabSelectedTextColor="@color/colorAccent"
            app:tabTextColor="@android:color/black"/>

    </android.support.design.widget.AppBarLayout>
    <android.support.v4.widget.NestedScrollView
        android:id="@+id/nestedScrollView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <android.support.v4.view.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </android.support.v4.widget.NestedScrollView>

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

public class MainActivity extends AppCompatActivity {
    private Toolbar toolbar;
    private ImageView image;
    private ViewPager viewpager;
    private TabLayout tabLayout;
    private CollapsingToolbarLayout collapsingToolbarLayout;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        initData();
    }
    private void initData() {
        toolbar.setLogo(R.mipmap.ic_launcher);
        setSupportActionBar(toolbar);
        //设置返回按钮
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        //设置收缩展开toolbar字体颜色
        collapsingToolbarLayout.setExpandedTitleColor(Color.WHITE);
        collapsingToolbarLayout.setCollapsedTitleTextColor(Color.BLACK);

        //设置tablayout与viewPager
        viewpager.setAdapter(new TestViewPageAdapter());
        tabLayout.setupWithViewPager(viewpager);
    }
    private void initView() {
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        image = (ImageView) findViewById(R.id.image);
        viewpager = (ViewPager) findViewById(R.id.viewPager);
       tabLayout = (TabLayout) findViewById(R.id.tabLayout);
       collapsingToolbarLayout = (CollapsingToolbarLayout) findViewById(R.id.ctb);
    }
    class TestViewPageAdapter extends PagerAdapter{
        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            TextView textView = new TextView(MainActivity.this);
            textView.setGravity(Gravity.CENTER);
            textView.setText("pager "+(position+1));
            textView.setTextSize(30);
            textView.setTextColor(Color.BLUE);
            container.addView(textView);
            return textView;
        }
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView((View)object);
        }
        @Override
        public int getCount() {
            return 5;
        }
        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }
/*获得标题*/
        /*该方法必须写,不然tablayout不能显示标题*/
        @Override
        public CharSequence getPageTitle(int position) {
            return "TAB"+(position+1);
        }
    }
}