ScrollView inside ViewPager, scrolls to middle aut

问题:

I have a ViewPager that contains several instances of the same fragment, this fragment contains an article. The Article view hierarchy is quite simple, a Title, a Banner image, a subtitle and a body; everything but the title is wrapped in a scrollview.

The problem is, when you swipe to a new page, the fragment is presented with the Views at the top, and then it immediately scrolls to the middle of the container. (As a matter of fact it scrolls to the beginning of the TextView with id: article_content)

I have posted the layout at the bottom of the question.

Now, the ViewPager is set with a simple implementation of a FragmentStatePagerAdapter, here's the code:

class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {

    Bundle args;
    int count;

    public ScreenSlidePagerAdapter(FragmentManager fm) {
        super(fm);
        this.count = 8;
    }

    @Override
    public Fragment getItem(int position) {
        ArticleFragment mPrimaryFragment = new ArticleFragment();
        args = new Bundle();
        args.putString(ArticleFragment.KEY_ARTICLE_URL, mCurArticleLink);
        mPrimaryFragment.setArguments(args);
        return mPrimaryFragment;            
    }

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

The Fragment itself is pretty simple too. First, I check during onCreate to see if we have the article cached, the I call on onCreateView

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

    View view = inflater.inflate(R.layout.apk_article_view, null);

    mTitle = (TextView) view.findViewById(R.id.article_title);
    mBanner = (ImageView) view.findViewById(R.id.article_banner);
    mSubTitle = (TextView) view.findViewById(R.id.article_subtitle);
    mContent = (TextView) view.findViewById(R.id.article_content);

    if (isArticleCached) {
        Constants.logMessage("Article is cached, loading from database");
        setApkArticleContent();
    }
    else {
        Constants.logMessage("Article isn't cached, downloading");
        HtmlHelper.setApkArticleContent(mContext, mUrl, mTitle, mSubTitle, mContent, mBanner);
        setRefreshing(true);
    }

    return view;
}

It is worth noting that setApkArticleContent is a simple set of Texts, nothing fancy:

private void setApkArticleContent() {
    mTitle.setText(Html.fromHtml(mCursor.getString(mCursor.getColumnIndex(DbOpenHelper.TITLE))));
    mSubTitle.setText(Html.fromHtml(mCursor.getString(mCursor.getColumnIndex(DbOpenHelper.SUBTITLE))));
    mContent.setText(Html.fromHtml(mCursor.getString(mCursor.getColumnIndex(DbOpenHelper.BODY))));
    UrlImageViewHelper.setUrlDrawable(mBanner, mCursor.getString(mCursor.getColumnIndex(DbOpenHelper.BANNER)));     
}

Also, please know that I did not have a pager before, the fragment was only loaded to an empty activity, and it worked without scrolling to the middle of the scrollview.

I am really not sure what is triggering the scroll, and yes, I know I can programatically set it to scroll back to the top after loading, but then again, that'd be two scroll movements when the fragment is loaded and it would be quite noticeable for the user.

Do you guys have any ideas why it would behave like this? Any ideas on how I can stop that unintentional scroll?

Thanks,

Below is the layout for the ArticleFragment:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/article_title"
    style="@style/headerTextBoldNoUnderline"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="left|center_vertical"
    android:text="" />

<ScrollView
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    >

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

        <ImageView
            android:id="@+id/article_banner"
            android:layout_gravity="center_vertical|center_horizontal"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="12dp" />

        <TextView
            android:id="@+id/article_subtitle"
            style="@style/HeaderTextItalicNoUnderline"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="left|center_vertical" />

        <View
            android:layout_width="fill_parent"
            android:layout_height="1dp"
            android:background="?android:attr/dividerVertical" />

        <TextView
            android:id="@+id/article_content"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="sans-serif-light"
            android:gravity="left|center_vertical"
            android:padding="8dp"
            android:textColor="?android:attr/textColorSecondary"
            android:textIsSelectable="true"
            android:textSize="16sp" />
    </LinearLayout>
</ScrollView>

</LinearLayout>

回答1:

This is likely caused by android:textIsSelectable. You may try adding the following to the ScrollView:

android:focusable="true"
android:focusableInTouchMode="true"
android:descendantFocusability="beforeDescendants"

回答2:

Add this attribute value android:descendantFocusability="blocksDescendants" to the child of ScrollView, according to this question: How to prevent a scrollview from scrolling to a webview after data is loaded?

回答3:

I also had this problem. I solved it with setting android:focusable="true" and android:focusableInTouchMode="true" to the first element in the ScrollView's LinearLayout.

回答4:

I tried solution:

android:focusable=true

android:focusableInTouchMode=true

android:descendantFocusability=beforeDescendants

And i dont know why but I cant do this with my RelativeLayout which is parent view (this does not work).

I had to wrap my TextView inside FrameLayout and now everything is ok. Maybe this helps somebody.

  <FrameLayout
        android:id="@+id/detail_description_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/detail_parameters_container"
        android:layout_centerInParent="true"
        android:descendantFocusability="beforeDescendants"
        android:focusable="true"
        android:focusableInTouchMode="true" >

        <TextView
            android:id="@+id/detail_descritpion"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:autoLink="all"
            android:padding="10dp"
            android:textIsSelectable="true" />
    </FrameLayout>

回答5:

ScrollView inside ViewPager scrolls automatically but does not scrolls in middle.. Check out this.

pager.setOnPageChangeListener(new OnPageChangeListener() {

                @Override
                public void onPageSelected(int position) {
                    // TODO Auto-generated method stub
                    int x=iv.getLeft();
                    int y=iv.getTop();
                    scroll.scrollTo(x, y);
                }

pager is ViewPager's object and scroll is ScrollView and iv is any View say TextView or ImageView.

When we change page in viewpager, scrollbar automatically scrolls but to the left. If you would have find solution to middle please let me know.. :)

回答6:

i try to add

    android:focusable="true"
    android:focusableInTouchMode="true"
    android:descendantFocusability="beforeDescendants"

in the root viewGroup . it's work's well. like below.

 <RelativeLayout 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:focusable="true"
    android:focusableInTouchMode="true"
    android:descendantFocusability="beforeDescendants"
    android:background="@color/normal_bg">

    <ScrollView
        android:id="@+id/scroll"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/rl_enter"
        android:scrollbars="none">
        </ScrollView>
    </RelativeLayout>