Reputation: 1499
I have a ScrollView which hosts a ViewPager which hosts Fragments of dynamic height. Since a ScrollView and ViewPager don't go well together due to the scroll handling, I used one of the custom solution from here. But I am currently getting really abnormal results. The first fragment in the ViewPager always gets a height of 0. Also sometimes the fragments don't show their content but when I scroll back and forth and come back to that fragment, content might show up.
Some code for you to look at :
The custom ViewPager :
import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
/**
* Created by Narayan Acharya on 12/07/2016.
*/
public class DynamicHeightWrappingViewPager extends ViewPager {
private View mCurrentView;
public DynamicHeightWrappingViewPager(Context context) {
super(context);
}
public DynamicHeightWrappingViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (mCurrentView == null) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
return;
}
int height = 0;
mCurrentView.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
int h = mCurrentView.getMeasuredHeight();
if (h > height) height = h;
heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
Log.d("ViewPager Measure", h + ":" + heightMeasureSpec);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
public void measureCurrentView(View currentView) {
mCurrentView = currentView;
requestLayout();
}
}
The custom ScrollView :
import android.content.Context;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ScrollView;
/**
* Created by Narayan Acharya on 12/07/2016.
*/
public class ChildrenHeightAdaptingScrollView extends ScrollView {
private GestureDetector mGestureDetector;
public ChildrenHeightAdaptingScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
mGestureDetector = new GestureDetector(context, new YScrollDetector());
setFadingEdgeLength(0);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return super.onInterceptTouchEvent(ev)
&& mGestureDetector.onTouchEvent(ev);
}
// Return false if we're scrolling in the x direction
class YScrollDetector extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
return (Math.abs(distanceY) > Math.abs(distanceX));
}
}
}
The PagerAdapter :
import android.app.Fragment;
import android.app.FragmentManager;
import android.support.v13.app.FragmentPagerAdapter;
import android.util.Log;
import android.view.ViewGroup;
/.. Some more project specific imports here../
/**
* Created by Narayan Acharya on 22/06/2016.
*/
public class EventsPagerAdapter extends FragmentPagerAdapter {
private Event event;
private int PAGE_COUNT = 2;
private int mCurrentPosition = -1;
private String tabTitles[] = new String[]{"INFO", "FAQs"};
public EventsPagerAdapter(FragmentManager fm, Event event) {
super(fm);
this.event = event;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return EventInfoFragment.getInstance(event);
case 1:
return EventFAQsFragment.getInstance(event);
default:
return null;
}
}
@Override
public int getCount() {
return PAGE_COUNT;
}
@Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
@Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
super.setPrimaryItem(container, position, object);
if (position != mCurrentPosition) {
Fragment fragment = (Fragment) object;
DynamicHeightWrappingViewPager pager = (DynamicHeightWrappingViewPager) container;
if (fragment != null && fragment.getView() != null) {
mCurrentPosition = position;
pager.measureCurrentView(fragment.getView());
Log.d("Requested Measure for", position + " " + fragment.getClass().getSimpleName());
}
}
}
}
As per my observations, the only difference I could spot in the code from the link I mentioned above and the one I am using is that the link uses FragmentPagerAdapter from support library v4 while I am using from the v13(Cannot change this to v4, due to some other restrictions). What are the major differences between the two versions of support library for how I am using it?
Upvotes: 3
Views: 3200
Reputation: 1499
This might seem like really stupid and I am not sure why this works exactly! If anyone knows why, please do answer.
The problem with the ViewPager
collapsing was that it simply contained a WebView
in each Fragment
. I toiled hard trying to find solutions and writing more custom ViewPagers
and ScrollViews
. Just when I was about to give up I wrapped the WebView
in a LinearLayout
and the Fragment
at position 0
did not collapse. It works smoothly now.
So if anyone is getting blank pages while trying this or similar solutions please try to wrap it in a LinearLayout
or something.
Hope this helps someone!
Upvotes: 4