android - 使用 coordinatorlayout 折叠全屏 ImageView 并将其替换为带标题的 viewpager

Question

我开始尝试使用 coordinatoralyout 并尝试在附加图像上实现行为，我希望背景图像为全屏大小，并且在滚动时我希望一些 TextView 消失，一些 TextView 作为部分粘贴viewpager(而不是工具栏布局)关于如何实现此目的的任何指导？

Answer 1

您可以使用layout_behavior 来处理您希望在滚动时消失的字符串。使用 CoordinatorLayout.Behavior

自定义您的 View 行为

ViewBehavior.java

public class ViewBehavior extends CoordinatorLayout.Behavior<RelativeLayout> {

private Context mContext;

public ViewBehavior(Context context, AttributeSet attrs) {
    mContext = context;
}

@Override
public boolean layoutDependsOn(CoordinatorLayout parent, RelativeLayout child, View dependency) {
    return dependency instanceof AppBarLayout;
}

@Override
public boolean onDependentViewChanged(CoordinatorLayout parent, RelativeLayout child, View dependency) {
    child.measure(View.MeasureSpec.makeMeasureSpec(parent.getWidth(), View.MeasureSpec.EXACTLY), View.MeasureSpec.makeMeasureSpec(parent.getHeight(), View.MeasureSpec.AT_MOST));
    int maxScroll = ((AppBarLayout) dependency).getTotalScrollRange();
    float percentage = Math.abs(dependency.getY()) / (float) maxScroll;
    float childPosition = dependency.getHeight()
            + dependency.getY()
            - child.getMeasuredHeight()
            - (getToolbarHeight() - child.getMeasuredHeight()) * percentage / 2;

    CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) child.getLayoutParams();
    child.setLayoutParams(lp);

    child.setY(childPosition);
    return true;
}

public int getToolbarHeight() {
    int result = 0;
    TypedValue tv = new TypedValue();
    if (mContext.getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true)) {
        result = TypedValue.complexToDimensionPixelSize(tv.data, mContext.getResources().getDisplayMetrics());
    }
    return result;
}
}

在布局 xml 中，将您的自定义 View 行为设置为您要处理的 View 中的 app:layout_behavior。

activity_main.xml

<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/coordinator_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">

<android.support.design.widget.AppBarLayout
    android:id="@+id/app_bar_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    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/image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:layout_collapseMode="parallax" />

    </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"
    android:fillViewport="true"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

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

        <com.astuetz.PagerSlidingTabStrip
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="48dp"
            android:textColor="@color/red"
            app:pstsShouldExpand="true"
            app:pstsTextAllCaps="true" />

        <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@android:color/white" />
    </LinearLayout>
</android.support.v4.widget.NestedScrollView>

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="com.stacktest.ViewBehavior">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_marginBottom="20dp"
        android:layout_marginLeft="36dp"
        android:layout_marginTop="20dp"
        android:text="Text-1" />

    <TextView
        android:id="@+id/txt2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_marginBottom="20dp"
        android:layout_marginRight="36dp"
        android:layout_marginTop="20dp"
        android:text="Text-2" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@id/txt2"
        android:layout_marginBottom="20dp"
        android:layout_marginLeft="36dp"
        android:paddingRight="20dp"
        android:text="Text-3" />

    <TextView
        android:id="@+id/txt4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_below="@id/txt2"
        android:layout_marginBottom="20dp"
        android:layout_marginRight="36dp"
        android:text="Text-4" />
</RelativeLayout>
</android.support.design.widget.CoordinatorLayout>

最后，使用布局并在 Activity 类中创建 ViewPager 和 Tabs。

MainActivity.java

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ((CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar)).setTitle(" ");

    ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
    viewPager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));

    PagerSlidingTabStrip tabsStrip = (PagerSlidingTabStrip) findViewById(R.id.tabs);
    tabsStrip.setViewPager(viewPager);
}

public class MyPagerAdapter extends FragmentPagerAdapter {
    final int PAGE_COUNT = 2;
    private String tabTitles[] = new String[] { "Tab1", "Tab2" };

    public MyPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public int getCount() {
        return PAGE_COUNT;
    }

    @Override
    public Fragment getItem(int position) {
        return TestFragment.newInstance(position + 1);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return tabTitles[position];
    }
}
}

在 build.gradle 中添加以下额外依赖项以及 appcompat 和支持库。

• com.android.support:design:23.2.1
• com.astuetz:pagerslidingtabstrip:1.0.1(用于 ViewPager 标签)