Develop Reference

How to disable ViewPager scrolling on diagonal swipes in Android?

I have an Activity with a ViewPager, which hosts several pages, each containing a RecyclerView. Horizontal and vertical swipes are working as expected: Horizontal changes the page, vertical scrolls the RecyclerView.
When the user makes a diagonal swipe, the page changes.
How can I prevent this? Diagonal swipes should only scroll the RecyclerView.
<?xml version="1.0" encoding="utf-8"?>
<androidx.viewpager2.widget.ViewPager2
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/page"
android:layout_width="match_parent"
android:layout_height="match_parent" />
I already tried this:
binding.page.setOnTouchListener(object : View.OnTouchListener {
override fun onTouch(v: View?, event: MotionEvent?): Boolean {
when (event?.action) {
MotionEvent.ACTION_DOWN -> binding.page.isUserInputEnabled = false
}
return v?.onTouchEvent(event) ?: true
}
})

I just tested out the behavior you described. In my opinion ViewPager2 and RecyclerView work together flawlessly:
On a diagonal swipe with less than 45°, the ViewPager2 gets scrolled.
On diagonal swipes with more than 45°, the RecyclerView gets scrolled.
However, this seems only true when the Activity is newly created. It also seems to depend a little bit on the prior scroll gesture.
When you first make a vertical swipe (RecyclerView gets scrolled), after that, diagonal scrolls again will scroll the RecyclerView.
When you just made a horizontal swipe (ViewPager2 gets scrolled), then diagonal scrolls tend to scroll the ViewPager2.
Maybe this is the intended behavior. To provide a more intuitive user experience,
I'd probably keep it as is, as I had to test quite some time to reproduce your described behavior.
Actually, all the scrolling felt very intuitive the way it is.
And keep in mind: If you really only want to allow exactly 0° horizontal swipes to scroll the ViewPager2, you're giving your users a very hard time.
It would be practically impossible to scroll the ViewPager2.

Swipe-to-remove on a nested RecyclerView disables scrolling

I'm sure there is a simple solution of which I'm just not aware. I have a nested RecyclerView like this.
The outer RecyclerView has vertical scrolling with an attached ItemTouchHelper so that swiping left triggers swipe-to-delete behavior. The inner RecyclerView has horizontal scrolling.
Problem: swiping behavior in the ViewHolder, including trying to scroll the RecyclerView therein, triggers the swiping behavior.
Solution?: disable swipe-to-delete behavior for part of the ViewHolder. In this case, it would be disabled if the RecyclerView is scrolled/swiped. Conversely, it can only be enabled if a view inside the ViewHolder is swiped, like the header.
Any ideas?

Conflict between recyclerview scroll and viewpager swipe

In my app I have a ViewPager that has four fragments. All the fragments are composed of RecyclerView which can be scrolled vertically. My problem is that when I try to navigate to other fragments and swipe left or right, the RecyclerView's scroll is detected first (mostly) and instead of going to other fragments the RecyclerView gets scrolled.
To be more clear, if I scroll the recyclerView, then suddenly swipe left or right, the viewpager never swipes.
What should I do?

When you scroll your RecyclerView vertically and cross a threshold to trigger scrolling, it consumes the TouchEvent. This means the default behavior is until you release your finger from the screen, the ViewPager will not be able to trigger a horizontal scroll. This is default behavior for how scrolling views interact with each other. You could attempt to override touch handling by extending RecyclerView and ViewPager or having a coordinating view that dispatches all TouchEvents to both views. However, either of these approaches could present a number of issues.
If you were to look at the Play Store for reference, its touch handling works the same as what you are seeing here.

Nested RecyclerView and ViewPager content wrapping and scrolling don't play nice together

I have nested ViewPagers and RecyclerViews as depicted in the image:
Requirements:
The first level ViewPager1 swipes from left to right. It uses FragmentStatePagerAdapter.
The first level RecyclerView1 scrolls vertically.
The second level ViewPager2 does not swipe - the swipe motion is controlled by a TabLayout. It uses a custom PagerAdapter that returns a View as a page.
The second level RecyclerView does not scroll - it simply wraps a list of dynamic items
What I have working so far:
The first level ViewPager1 and RecyclerView1 works as intended.
The ViewPager2 does not show because its height is defined as "wrap_content"
The ViewPager2/RecyclerView2 prevents RecyclerView1 to scroll up/down.
What I have tried:
Setting RecyclerView1.setNestedScrollingEnabled(false) stops it from passing the onTouch event to its children, but because the ViewPager2/RecyclerView2 wraps its content, it does not know what the size it needs to scroll.
Setting the ViewPager2 to a fixed height solves the scrolling problem. But because it is a fixed height, the content of RecyclerView2 is cut off.
Overriding OnMeasure as described here makes ViewPager2's content wrap, perfectly, but the scrolling no longer work again. I assume it is because OnMeasure is called "after" the View has already been attached?
So basically I need help on how to get the content to wrap but in such a way that RecyclerView 1 knows what the height is so that it can scroll.
EDIT
It turns out I was totally off base with point 3. The OnMeasure workaround DOES work as intended and the scrolling problem is NOT caused by recyclerView not knowing the height. It in fact does. The reason why it doesn't scroll is due to multiple nested scrollable view groups. I found this out by putting Log.i on onTouchEvent() and onInterceptTouchEvent() on all the scrollable view groups. Some surface of the views work, but if the surface has another scrollable child, it starts to cause problems.
Setting RecyclerView2.setNestedScrollingEnabled(false) fixed the vertical scrolling. However, now, the ViewPager2's touch behaviour is interfering with ViewPager1's
On closer inspection, ViewPager1 intercepts touch event when hitting non-scrollable surface, causing the ViewPager1 to call its onTouchEvent() to scroll left and right. However, if I start the touch event over a the ViewPager2's surface, ViewPager1 never intercept and it never handles the swipe left to right.
Unlike a RecyclerView, there is no simple method to disable nestedScrolling. So I tried disabling ViewPager2, but that didn't work and caused the inside views such as buttons not clickable.
I tried to return false in ViewPager2's OnTouchEvent so that it bubbles up the chain, but still, the ViewPager1's OnTouchEvent is never fired.
So I'm stuck again, how do I pass the touch event to the parent when the parent did not intercept the event when it should have. Again, I'm assuming, and again I might be off-base, that ViewPager1 might not intercept because ViewPager2 has requested a disallowInterceptTouchEvent() somewhere in its code? I just don't know where or how to begin to fix this problem.

Recyclerview - how to disable vertical scrolling on item swipe (fling)

Simple question - how to disable recyclerview scrolling while swiping its item? I created OnTouchListener inside recyclerView item view holder, but it catches swipe events only if user makes straight horizontal line. Otherwise recycler list is scrolling. Any ideas?

I am not using ItemTouchHelper because it doesnt quite do what I want. I solved this by checking the source to it and finding the call to:
getParent().requestDisallowInterceptTouchEvent(true)
Call that when you determine the user has started swiping (i.e., moved more than a few pixels). Then don't forget it to call it again with false when the swipe is done.

I'm facing the opposite problem. If you are using the ItemTouchHelper, do this
mItemTouchHelper.startSwipe(myViewHolder);
This would force the swipe instead of the scroll.