ViewPager inside a ScrollView does not scroll correclty

Question

I have a 'page' that has a number of components on it, and who's content is longer than the height of the device. Fine, just put all of the layout (the entire page) inside a ScrollView, no problem.

One of the components is a ViewPager. This renders correctly, but the response to a swipe/fling is not performing correctly, it is jittery and doesn't always work. It seems to be getting 'confused' with the ScrollView, so only works 100% when you fling in an exact horizontal line.

If I remove the ScrollView, the ViewPager responds perfectly.

I've had a search around and have not found this as a known defect. Has anyone else experienced this?

• Platform Version: 1.6
• Compatibility Library v4.
• Device: HTC Incredible S

Below is some example code for you to test with, comment out ScrollView to see it working correctly.

Activity:

package com.ss.activities;  import com.ss.R;  import android.app.Activity; import android.content.Context; import android.graphics.Color; import android.os.Bundle; import android.os.Parcelable; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.view.View; import android.widget.TextView;  public class PagerInsideScollViewActivity extends Activity {     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);          ViewPager vp = (ViewPager) findViewById(R.id.viewpager);         vp.setAdapter(new MyPagerAdapter(this));     } }  class MyPagerAdapter extends PagerAdapter {      private Context ctx;      public MyPagerAdapter(Context context) {         ctx = context;     }      @Override     public int getCount() {         return 2;     }      @Override     public Object instantiateItem(View collection, int position) {          TextView tv =  new TextView(ctx);         tv.setTextSize(50);         tv.setTextColor(Color.WHITE);         tv.setText("SMILE DUDE, SMILE DUDE, SMILE DUDE, SMILE DUDE, SMILE DUDE, " +                 "SMILE DUDE, SMILE DUDE, SMILE DUDE, SMILE DUDE, SMILE DUDE, " +                 "SMILE DUDE, SMILE DUDE, SMILE DUDE, SMILE DUDE, SMILE DUDE, " +                 "SMILE DUDE, SMILE DUDE, SMILE DUDE");          ((ViewPager) collection).addView(tv);          return tv;      }      @Override     public void destroyItem(View collection, int position, Object view) {          ((ViewPager) collection).removeView((View) view);     }      @Override     public boolean isViewFromObject(View view, Object object) {         return view == object;     }      @Override     public Parcelable saveState() {         return null;     }      @Override     public void restoreState(Parcelable arg0, ClassLoader arg1) {     }      @Override     public void startUpdate(View arg0) {     }      @Override     public void finishUpdate(View arg0) {     } } 

Layout:

<?xml version="1.0" encoding="utf-8"?>     <ScrollView          xmlns:android="http://schemas.android.com/apk/res/android"         android:layout_width="fill_parent"         android:layout_height="fill_parent" >          <LinearLayout             android:layout_width="fill_parent"             android:layout_height="fill_parent"             android:orientation="vertical" >              <android.support.v4.view.ViewPager                 android:id="@+id/viewpager"                 android:layout_width="fill_parent"                 android:layout_height="300dp" />          </LinearLayout>      </ScrollView> 

Answer 1

I had the same problem. My solution was to call requestDisallowInterceptTouchEvent when the ViewPager scroll started.

Here is my code:

pager.setOnTouchListener(new View.OnTouchListener() {     @Override     public boolean onTouch(View v, MotionEvent event) {         v.getParent().requestDisallowInterceptTouchEvent(true);         return false;     } });  pager.setOnPageChangeListener(new SimpleOnPageChangeListener() {     @Override     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {         pager.getParent().requestDisallowInterceptTouchEvent(true);     } });