使用coordinatorlayout折叠全屏图像视图,并将其替换为带有标题的viewpager

Question

我开始玩Coordinatoralyout并且我正在尝试实现附加图像上的行为,我想要一个背景图像在全屏尺寸上和滚动时我希望一些文本视图消失,一些粘贴作为viewpager的一部分(而不是一个toolbarlayout)关于如何实现这一目标的任何指导？

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自定义视图行为

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，将自定义视图行为设置为要处理的视图中的app:layout_behavior 。

活动主文件

<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 和选项卡。

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:设计:23.2.1
• com.astuetz:pagerslidingtabstrip:1.0.1（用于 ViewPager 选项卡）