单击更多按钮时图像消失了？

Question

我创建了一个ScrollView并在一个大的LinearLayout中添加了两个LinearLayout并为这些提供了权重。问题是它在初始状态下显示我的图像滑块图像，一旦我点击了更多图像消失，除了点当我按下读数时，再次显示图像滑块的图像。下面给出了两个截图和代码。我该如何解决？

FragmentSL.xml

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">


<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:weightSum="10">


<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="4.5"
    android:orientation="vertical">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

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

        <LinearLayout
            android:id="@+id/SliderDots"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:gravity="center_horizontal"
            android:layout_marginBottom="20dp"
            android:orientation="horizontal"/>


    </RelativeLayout>
</LinearLayout>

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="5.5"
    android:gravity="center_horizontal">

    <TextView
        android:id="@+id/aboutsltext"
        android:maxLines="3"
        android:textSize="22sp"
        android:textColor="@color/colorPrimary"
        android:text="Sri Lanka (formerly Ceylon) is an island nation south of India in the Indian Ocean. Its diverse landscapes range from rainforest and arid plains to highlands and sandy beaches. It’s famed for its ancient Buddhist ruins, including the 5th-century citadel Sigiriya, with its palace and frescoes. The city of Anuradhapura, Sri Lanka's ancient capital, has many ruins dating back more than 2,000 years. Sri Lanka (formerly Ceylon) is an island nation south of India in the Indian Ocean. Its diverse landscapes range from rainforest and arid plains to highlands and sandy beaches. It’s famed for its ancient Buddhist ruins, including the 5th-century citadel Sigiriya, with its palace and frescoes. The city of Anuradhapura, Sri Lanka's ancient capital, has many ruins dating back more than 2,000 years. "
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/readmorebtn"
        android:layout_width="wrap_content"
        android:text="Read More"
        android:textAllCaps="false"
        android:textColor="@color/colorPrimary"
        android:background="@drawable/readmorebtn"
        android:layout_height="wrap_content" />


</LinearLayout>




</LinearLayout>
</ScrollView>

FragmentClass.java

public class aboutSLFragment扩展了Fragment {

ViewPager viewPager;
LinearLayout sliderDotspanel;
private int dotscount;
private ImageView[] dots;
TextView aboutsltext;
Button readmorebtn;

public aboutSLFragment() {
    // Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_about_sl, container, false);
    viewPager = (ViewPager) rootView .findViewById(R.id.viewPager);

    sliderDotspanel = (LinearLayout)rootView.findViewById(R.id.SliderDots);

    ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(getContext());

    viewPager.setAdapter(viewPagerAdapter);

    dotscount = viewPagerAdapter.getCount();
    dots = new ImageView[dotscount];

    for(int i = 0; i < dotscount; i++){

        dots[i] = new ImageView(getContext());
        dots[i].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.non_active_dot));

        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);

        params.setMargins(8, 0, 8, 0);

        sliderDotspanel.addView(dots[i], params);

    }

    dots[0].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.active_dot));

    viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {

            for(int i = 0; i< dotscount; i++){
                dots[i].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.non_active_dot));
            }

            dots[position].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.active_dot));

        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });

    aboutsltext=(TextView)rootView.findViewById(R.id.aboutsltext);
    readmorebtn=(Button)rootView.findViewById(R.id.readmorebtn);
    readmorebtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if (readmorebtn.getText().toString().equalsIgnoreCase("Read More"))
            {
                aboutsltext.setMaxLines(Integer.MAX_VALUE);//your TextView
                readmorebtn.setText("Read Less");
            }
            else
            {
                aboutsltext.setMaxLines(3);//your TextView
                readmorebtn.setText("Read More");
            }
        }
    });

    // Inflate the layout for this fragment
    return rootView;
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    //you can set the title for your toolbar here for different fragments different titles
    getActivity().setTitle("About Sri Lanka");
}

}

点击之前点击 before read more button is clicked

后 after clicked

计算代码

   final View rootView = inflater.inflate(R.layout.fragment_about_sl, container, false);
    viewPager = (ViewPager) rootView .findViewById(R.id.viewPager);

    ViewTreeObserver vto =(ViewTreeObserver) rootView.findViewById(R.id.aboutslscrollview).getViewTreeObserver();
    vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            rootView.findViewById(R.id.aboutslscrollview).getViewTreeObserver().removeOnGlobalLayoutListener(this);

            int scrollViewHeightInPixels = rootView.findViewById(R.id.aboutslscrollview).getMeasuredHeight();

            //This is equal with %45 weight you tried before
            int height = (scrollViewHeightInPixels * 45) / 100;
            ViewGroup.LayoutParams pagerParams = viewPager.getLayoutParams();
            pagerParams.height = height;
        }
    });


    final View view = rootView.findViewById(R.id.aboutslscrollview);
    ViewTreeObserver vto = view.getViewTreeObserver();
    vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            view.getViewTreeObserver().removeOnGlobalLayoutListener(this);

            int scrollViewHeightInPixels = view.getMeasuredHeight();

            //This is equal with %45 weight you tried before
            int height = (scrollViewHeightInPixels * 45) / 100;
            ViewGroup.LayoutParams pagerParams = viewPager.getLayoutParams();
            pagerParams.height = height;
        }
    });

Answer 1

正如我之前评论的那样，你的逻辑将无法正常工作，因为在ScrollView内提供垂直权重会导致计算问题。

因此，您不应使用任何权重来调整ViewPager内容宽度。

如果您有一定的宽高比，请按以下方式以编程方式调整大小。在findViewById之后将这些行写在 onCreate（）中：

  

UPDATE 您可以像这样获取scrollView高度：

viewPager = (ViewPager) rootView.findViewById(R.id.viewPager);

ViewTreeObserver vto = scrollView.getViewTreeObserver(); 
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() { 
    @Override 
    public void onGlobalLayout() { 
   scrollView.getViewTreeObserver().removeOnGlobalLayoutListener(this);

        int scrollViewHeightInPixels = layout.getMeasuredHeight(); 

        //This is equal with %45 weight you tried before
        int height = (scrollViewHeightInPixels * 45) / 100;
        ViewGroup.LayoutParams pagerParams = viewPager.getLayoutParams();
        pagerParams.height = height;
    } 
});

然后删除不必要的布局并更改您的布局，如下所示：

  

viewPager高度为200 dp，启动时为固定高度，wrap_content和match_parent有时会导致问题

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


        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.v4.view.ViewPager
                android:id="@+id/viewPager"
                android:layout_width="match_parent"
                android:layout_height="200dp" />

            <LinearLayout
                android:id="@+id/SliderDots"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_alignBottom="@id/viewPager"
                android:layout_marginBottom="20dp"
                android:gravity="center_horizontal"
                android:orientation="horizontal" />


        </RelativeLayout>


        <TextView
            android:id="@+id/aboutsltext"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:maxLines="3"
            android:text="Sri Lanka (formerly Ceylon) is an island nation south of India in the Indian Ocean. Its diverse landscapes range from rainforest and arid plains to highlands and sandy beaches. It’s famed for its ancient Buddhist ruins, including the 5th-century citadel Sigiriya, with its palace and frescoes. The city of Anuradhapura, Sri Lanka's ancient capital, has many ruins dating back more than 2,000 years. Sri Lanka (formerly Ceylon) is an island nation south of India in the Indian Ocean. Its diverse landscapes range from rainforest and arid plains to highlands and sandy beaches. It’s famed for its ancient Buddhist ruins, including the 5th-century citadel Sigiriya, with its palace and frescoes. The city of Anuradhapura, Sri Lanka's ancient capital, has many ruins dating back more than 2,000 years. "
            android:textColor="@color/colorPrimary"
            android:textSize="22sp" />

        <Button
            android:id="@+id/readmorebtn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:background="@drawable/readmorebtn"
            android:text="Read More"
            android:textAllCaps="false"
            android:textColor="@color/colorPrimary" />

    </LinearLayout>
</ScrollView>