Collapse header on scrolling without using CollapsingToolbarLayout

Collapse header on scrolling without using CollapsingToolbarLayout - android

I'm trying to implement the same behaviour than the CollapsingToolbarLayout for a view above my recyclerview that collapses to a minimum height on downscrolling and restores to its normal height when the scroll reaches the top. This header is not a Toolbar, hence the custom view.
I managed to do it, but when scrolling up it restores the height but the whole view starts flickering.
This is the header layout, I am trying to make the Textview disappear while keeping the inner linear layout visible at all times:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center">
<TextView
android:id="#+id/welcome_message"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="12dp"
android:text="welcome"/>
<LinearLayout
android:id="#+id/always_show"
android:layout_width="match_parent"
android:layout_height="36dp"
android:orientation="horizontal"
android:gravity="center_vertical"
android:layout_margin="12dp">
...
</LinearLayout>
</LinearLayout>
And this is the code
var maxHeight: Int = 0
var initialSize = false
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
...
header.getViewTreeObserver().addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
if (initialSize)
return
initialSize = true
maxHeight = header.measuredHeight
}
})
recyclerView.addOnScrollListener(object: RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView?, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
if (dy > 0) {
//scroll down
val params = header.layoutParams as LinearLayout.LayoutParams
params.topMargin = Math.max(params.topMargin-dy, -maxHeight/2)
header.layoutParams = params
} else if (layoutManager.findFirstCompletelyVisibleItemPosition() == 0) {
//top
val params = header.layoutParams as LinearLayout.LayoutParams
params.topMargin = 0
header.layoutParams = params
}
}
})
}
Any ideas on how to make this animation more natural, closest to the CollapsingToolbarLayout behaviour.

Related

Android: RelativeLayout measures child width incorrectly

What I want to do:
My idea is simple:
I have RecyclerView in RelativeLayout
When data loaded I set first item's text to TextView for pinned message
On scroll I take first visible item and set this item's text to header (TextView)
So I have:
RelativeLayout + RecyclerView + TextView for pinned message + TextView for header
I update header on scroll, it looks like sticky header for list.
It is my layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/pin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#ebebeb"
android:gravity="center"
android:padding="24dp"/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#+id/pin"/>
<androidx.appcompat.widget.AppCompatTextView
android:id="#+id/header"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="#id/list"
android:layout_alignEnd="#id/list"
android:background="#33ff0000"
android:gravity="center"
android:padding="24dp"/>
</RelativeLayout>
And it is my Activity:
class CustomAdapter() :
RecyclerView.Adapter<CustomAdapter.ViewHolder>() {
var data: List<UUID> = listOf()
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val textView: TextView
init {
textView = view.findViewById(R.id.text)
}
}
override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(viewGroup.context)
.inflate(R.layout.list_item, viewGroup, false)
return ViewHolder(view)
}
override fun onBindViewHolder(viewHolder: ViewHolder, position: Int) {
viewHolder.textView.text = data[position].toString()
}
override fun getItemCount() = data.size
}
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val adapter = CustomAdapter()
val header = findViewById<TextView>(R.id.header)
findViewById<RecyclerView>(R.id.list).apply {
this.adapter = adapter
layoutManager = LinearLayoutManager(this#MainActivity, LinearLayoutManager.VERTICAL, false)
addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
val position = recyclerView.topChildPosition() ?: return
if (position >= 0) {
header.text = adapter.data[position].toString().substring(0, 10)
Log.w("MainActivity", header.text.toString())
} else {
header.text = null
}
}
})
}
/**
* SIMULATE DATA LOADING
*/
Handler(Looper.getMainLooper()).postDelayed({
adapter.data = List(100) {
UUID.randomUUID()
}
findViewById<TextView>(R.id.pin).text = adapter.data[0].toString()
adapter.notifyDataSetChanged()
}, 1000L)
}
private fun RecyclerView.topChildPosition(): Int? {
layoutManager.let { layoutManager ->
if (layoutManager != null && layoutManager is LinearLayoutManager) {
return if (!layoutManager.reverseLayout) layoutManager.findFirstVisibleItemPosition()
else layoutManager.findLastVisibleItemPosition()
} else {
val topChild: View = getChildAt(0) ?: return null
return getChildAdapterPosition(topChild)
}
}
}
}
And what I have:
RelativeLayout measured views, header has text = null, so header's width = padding only
Data loaded (see "SIMULATE DATA LOADING" in the activity code), I call notifyDataSetChanged and I set text to header. Header (TextView) calls requestLayout() on set text, but RelativeLayout doesn't measured new width (actually, RelativeLayout calls header's onMeasure with widthMode == MeasureSpec.EXACTLY and pass old width)
When I scroll RecyclerView header remeasured successfully.
I can reproduce it on Android 26-33
What I can do with this.
I can change layout:
from this:
<androidx.appcompat.widget.AppCompatTextView
android:id="#+id/header"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="#id/list"
android:layout_alignEnd="#id/list"
android:background="#33ff0000"
android:gravity="center"
android:padding="24dp"/>
to this:
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignTop="#id/list"
android:layout_alignEnd="#id/list">
<androidx.appcompat.widget.AppCompatTextView
android:id="#+id/header"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end"
android:background="#33ff0000"
android:gravity="center"
android:padding="24dp"/>
</FrameLayout>
But actually I can't, because really my TextView in custom view extends from TextView and it is part of library. I don't know how it will be used in layouts.
I can call requestLayout() after data loading like this:
adapter.notifyDataSetChanged()
header.doOnNextLayout { header.post { header.requestLayout() } }
But it is ugly.
So, finally my questions:
Do you know how to fix it without layout changing?
Do you know bug or some documented RelativeLayout behavior
Thanks for any help!

Different width of each horizontal RecyclerViews items

I get a problem with my horizontal RecyclerView. I need to create RecyclerView with different width of each item. I use wrap_content for this:
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
android:id="#+id/recyclerItemLayout"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:cardPreventCornerOverlap="false"
app:cardCornerRadius="#dimen/_10sdp"
android:layout_marginStart="5dp"
android:layout_marginEnd="5dp"
app:cardElevation="0dp"
app:cardBackgroundColor="#android:color/darker_gray"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp">
<TextView
android:id="#+id/recyclerItemText"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:gravity="center"
android:textSize="#dimen/_17sdp"
android:text="test"
android:textColor="#color/colorKeyboardRecyclerViewItemText"
android:layout_marginStart="5dp"
android:layout_marginEnd="5dp"
android:layout_marginTop="7dp"
android:layout_marginBottom="7dp"/>
</androidx.cardview.widget.CardView>
But when I scroll recyclerview and get to the first element I got this:
I think it is because the adapter redraws items every time. Here is code of my adapter:
class KeyboardAdapter(private val fontsNames: FontsData, private val fontButtonCallback: (Int) -> Unit): RecyclerView.Adapter<KeyboardAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val v = LayoutInflater.from(parent.context).inflate(R.layout.keyboard_recyclerview_item, parent, false)
return ViewHolder(v)
}
override fun getItemCount(): Int {
return fontsNames.fontsArrayEn.count()
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.itemText.text = fontsNames.fontsArrayEn[position].name
val selectedColor = holder.itemLayout.context.resources.getColor(R.color.colorKeyboardRecyclerViewSelectedItem)
val backgroundColor = holder.itemLayout.context.resources.getColor(android.R.color.transparent)
holder.itemLayout.setOnClickListener{
fontButtonCallback(position)
changeIsSelectedState(position)
fontsNames.fontsArrayEn[position].isSelected = true
notifyDataSetChanged()
}
/* holder.itemLayout.post{ val itemHeight = holder.itemLayout.height.toFloat()
val itemRadius = itemHeight /2.5
holder.itemLayout.radius = Utils().intToDp(holder.itemLayout.context, itemRadius.toFloat())} */
if (fontsNames.fontsArrayEn[position].isSelected)
holder.itemLayout.setCardBackgroundColor(selectedColor)
else
holder.itemLayout.setCardBackgroundColor(backgroundColor)
}
class ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView){
val itemLayout = itemView.findViewById<CardView>(R.id.recyclerItemLayout)!!
val itemText = itemView.findViewById<TextView>(R.id.recyclerItemText)!!
}
private fun changeIsSelectedState(position: Int){
for (i in 0 until fontsNames.fontsArrayEn.count()){
fontsNames.fontsArrayEn[i].isSelected = i == position
}
}
}
And i have one more question. How I can set cardCornerRadius dynamically depends of item height ?
Thanks in advance!

The TextView inside the card is the problem.
The text view is match_parent
android:layout_width="match_parent"
android:layout_height="match_parent"
But the parent is wrap_content.
Change the TextView to wrap_content and then every word is gonna be the size of the TextView and the CardView will have the size of the child.

Viewpager2 inside Nestedscrollview consist two Fragment with Recyclerview having problem

I made a viewpager2 which has two Fragments, inside each Fragment there is a Recyclerview. The viewpager itself is inside a Nestedscrollview in order to hide the toolbar when scroll up. Here is my code:
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
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:orientation="vertical"
>
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/appbarlayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#color/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways">
</androidx.appcompat.widget.Toolbar>
<com.google.android.material.tabs.TabLayout
android:id="#+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAlignment="center"
app:tabGravity="fill"
app:tabMode="fixed"/>
</com.google.android.material.appbar.AppBarLayout>
<androidx.core.widget.NestedScrollView
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.viewpager2.widget.ViewPager2
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"/>
</LinearLayout>
</androidx.core.widget.NestedScrollView>
<include layout="#layout/material_design_floating_action_menu" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
As I said the viewPager2 have two fragment each of them have a recyclerview. Here problem is, fragment 2 recyclerView take the same height of fragment 1 recyclerView though both recyclerView have different list items and their height should be depends on the list items. I mean, I am expecting these recyclerViews height should act separately based on the list. How can I solve this issue? Please let me know if you need fragment code.
Edit:
Activity code which holds the viewPager2
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initToolbar();
init();
viewPager.setAdapter(createCardAdapter());
new TabLayoutMediator(tabLayout, viewPager,
new TabLayoutMediator.TabConfigurationStrategy() {
#Override public void onConfigureTab(#NonNull TabLayout.Tab tab, int position) {
//tab.setText("Tab " + (position + 1));
if(position == 0){
tab.setText("Home");
}else if(position == 1){
tab.setText("Events");
}
}
}).attach();
RunnTimePermissions.requestForAllRuntimePermissions(this);
showNotifyDialog();
}
ViewPager Adapter Code:
public class ViewPagerAdapter extends FragmentStateAdapter {
private static final int CARD_ITEM_SIZE = 2;
public ViewPagerAdapter(#NonNull FragmentActivity fragmentActivity) {
super(fragmentActivity);
}
#NonNull #Override public Fragment createFragment(int position) {
switch (position){
case 0:
return HomeFragment.newInstance("abc","abc");
// break;
case 1:
return EventListFragment.newInstance("abc","abc");
// break;
}
return HomeFragment.newInstance("abc","abc");
}
#Override public int getItemCount() {
return CARD_ITEM_SIZE;
}
}
Fragment 1 layout:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".fragment.EventListFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_event_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:layout_marginTop="16dp"
/>
</FrameLayout>
Fragment 2 layout
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".fragment.MedicineListFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_medicine_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:layout_marginTop="16dp"
/>
</FrameLayout>

Alright buddy. I did it! I have the solution to this issue.
First off, here's the official response from Google after I opened an issue.
https://issuetracker.google.com/issues/188474850?pli=1
Anyway, on to the fix. Replace the NestedScrollView with this class:
https://gist.github.com/AfzalivE/fdce03eeee8e16203bcc37ba26d7abf3
The idea is to basically create a very light-weight version of NestedScrollView. Instead of messing with child heights, we listen to the children's scroll and either let them scroll, or forward the scrolling to the BottomSheetBehavior. For example when the RecyclerView has been scrolled all the way to the top, then it doesn't consume any of the scrolling, so we can forward that to the bottom sheet so it can scroll. And we only allow the RecyclerView to scroll when the Bottom sheet is expanded.
Also, I must add that this scenario works out of the box with Jetpack Compose + Accompanist-pager so just do that if you really need perfect functionality.
class BottomSheetScrollView(context: Context, attrs: AttributeSet?) : FrameLayout(context, attrs),
NestedScrollingParent2 {
private val TAG = "NestedScroll3"
private val childHelper = NestedScrollingChildHelper(this).apply {
isNestedScrollingEnabled = true
}
private var behavior: BottomSheetBehavior<*>? = null
var started = false
var canScroll = false
var pendingCanScroll = false
var dyPreScroll = 0
init {
ViewCompat.setNestedScrollingEnabled(this, true)
}
private val bottomSheetCallback = object : BottomSheetBehavior.BottomSheetCallback() {
override fun onStateChanged(bottomSheet: View, newState: Int) {
onNextScrollStop(newState == BottomSheetBehavior.STATE_EXPANDED)
Log.d(
"BottomSheet",
"Can scroll CHANGED to: $canScroll, because bottom sheet state is ${
getBottomSheetStateString(newState)
}"
)
}
override fun onSlide(bottomSheet: View, slideOffset: Float) = Unit
}
fun onNextScrollStop(canScroll: Boolean) {
pendingCanScroll = canScroll
}
override fun onStartNestedScroll(child: View, target: View, axes: Int, type: Int): Boolean {
// ViewPager2's RecyclerView does not participate in this nested scrolling.
// This allows it to show it's overscroll indicator.
if (target is RecyclerView) {
val layoutManager = target.layoutManager as LinearLayoutManager
if (layoutManager.orientation == LinearLayoutManager.HORIZONTAL) {
target.isNestedScrollingEnabled = false
}
}
if (!started) {
Log.d(TAG, "started nested scroll from $target")
childHelper.startNestedScroll(axes, type)
started = true
}
return true
}
override fun onNestedScrollAccepted(child: View, target: View, axes: Int, type: Int) {
Log.d(TAG, "accepted nested scroll from $target")
}
override fun onStopNestedScroll(target: View, type: Int) {
if (started) {
childHelper.stopNestedScroll(type)
started = false
Log.d(
TAG,
"stopped nested scroll from $target, changing canScroll from $canScroll to $pendingCanScroll"
)
canScroll = pendingCanScroll
}
}
override fun onNestedScroll(
target: View,
dxConsumed: Int,
dyConsumed: Int,
dxUnconsumed: Int,
dyUnconsumed: Int,
type: Int
) {
Log.d(
TAG,
"onNestedScroll: dxC: $dxConsumed, dyC: $dyConsumed, dxU: $dxUnconsumed, dyU: $dyUnconsumed"
)
if (dyUnconsumed == dyPreScroll && dyPreScroll < 0) {
canScroll = false
Log.d(TAG, "Can scroll CHANGED to: $canScroll, because scrolled to the top of the list")
}
}
override fun onNestedPreScroll(target: View, dx: Int, dy: Int, consumed: IntArray, type: Int) {
Log.d(
TAG,
"onNestedPreScroll: dx: $dx, dy: $dy, consumed: [ ${consumed.joinToString(", ")} ]"
)
if (!canScroll) {
childHelper.dispatchNestedPreScroll(dx, dy, consumed, null, type)
// Ensure all dy is consumed to prevent premature scrolling when not allowed.
consumed[1] = dy
} else {
dyPreScroll = dy
}
}
override fun onAttachedToWindow() {
super.onAttachedToWindow()
behavior = findBottomSheetBehaviorParent(parent) as BottomSheetBehavior<*>?
behavior?.addBottomSheetCallback(bottomSheetCallback)
}
override fun onDetachedFromWindow() {
super.onDetachedFromWindow()
behavior?.removeBottomSheetCallback(bottomSheetCallback)
}
private fun findBottomSheetBehaviorParent(parent: ViewParent?): CoordinatorLayout.Behavior<*>? {
if (parent !is View) {
throw IllegalArgumentException(
"None of this view's ancestors are associated with BottomSheetBehavior"
)
}
val layoutParams = parent.layoutParams
return if (layoutParams is CoordinatorLayout.LayoutParams && layoutParams.behavior != null) {
layoutParams.behavior
} else {
findBottomSheetBehaviorParent((parent as View).parent)
}
}
private fun getBottomSheetStateString(state: Int): String {
return when (state) {
1 -> "STATE_DRAGGING"
2 -> "STATE_SETTLING"
3 -> "STATE_EXPANDED"
4 -> "STATE_COLLAPSED"
5 -> "STATE_HIDDEN"
6 -> "STATE_HALF_EXPANDED"
else -> "0"
}
}
}

I do not understand why you have recyclerview inside FrameLayout .
Here problem is, fragment 2 recyclerView take the same height of
fragment 1 recyclerView though both recyclerView have different list
items and their height should be depends on the list items
RecyclerView generally always depends on the item_layout until we have not fixed its height n width to match_parent.
In your case you have fixed RecyclerView android:layout_width and android:layout_width to match_parent in both the Fragment .
Try this:
Fragment 1
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".fragment.EventListFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_event_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
/>
</FrameLayout>
Fragment 2
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".fragment.MedicineListFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_medicine_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
/>
</FrameLayout>
P.S: assuming each reacyclerView's item_layout would be having height as wrap_content

Adding a hideable headerview to recyclerview

I want to add a headerview that hides when user scrolls to down and shows again when user scrolls to up.
Example: https://imgur.com/a/tTq70B0
As you can see in the link "You are writing as..." pharase is showing only when user scrolls to top. Is there something like that in Android sdk?
How can i achive the same thing?

Obtaining the scroll event is just the first step to achieving this. Animations is required to achieve the effect. I recreated a simple version of the gif example you posted.
Layout for the main activity, activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:animateLayoutChanges="true"> <!-- Note the last line-->
<TextView
android:id="#+id/textview_hello"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="8dp"
android:text="Hello Stack Overflow!"/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerview_main"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
Below is the code for the main activity where we populate the RecyclerView and use the addOnScrollListener to provide animations to the TextView. Do note the commented out lines these will provide a default fade-out or fade-in animation due to the noted line in the xml layout above. The method slideAnimation() is an example of creating a custom animation. This link proved useful for creating the animations.
class MainActivity : AppCompatActivity() {
private lateinit var viewAdapter: RecyclerView.Adapter<*>
private lateinit var viewManager: LinearLayoutManager
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Some data for the RecyclerView
val data: List<String> = (1..100).toList().map { it.toString() }
viewManager = LinearLayoutManager(this)
viewAdapter = TextAdapter(data)
findViewById<RecyclerView>(R.id.recyclerview_main).apply {
setHasFixedSize(true)
layoutManager = viewManager
adapter = viewAdapter
addOnScrollListener(
object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
val pastVisibleItems = viewManager.findFirstCompletelyVisibleItemPosition()
if (pastVisibleItems == 0) {
slideAnimation(0f, 1f, View.VISIBLE)
//textview_hello.visibility = View.VISIBLE
} else if (textview_hello.visibility != View.GONE) {
slideAnimation(-150f, 0f, View.GONE)
//textview_hello.visibility = View.GONE
}
}
}
)
}
... // SlideAnimation function
}
}
The slideAnimation function
private fun slideAnimation(translationY: Float, alpha: Float, viewVisibility: Int) {
textview_hello.visibility = View.VISIBLE
textview_hello.clearAnimation()
textview_hello
.animate()
.translationY(translationY)
.alpha(alpha)
.setListener(object : AnimatorListenerAdapter() {
override fun onAnimationEnd(animation: Animator) {
super.onAnimationEnd(animation)
textview_hello.clearAnimation()
textview_hello.visibility = viewVisibility
}
})
.duration = 500
}
The adapter for the RecycleView:
class TextAdapter(private val textList: List<String>) :
RecyclerView.Adapter<TextAdapter.TextViewHolder>() {
class TextViewHolder(val textView: TextView) : RecyclerView.ViewHolder(textView)
override fun onCreateViewHolder(
parent: ViewGroup,
viewType: Int
): TextViewHolder {
val textView = LayoutInflater.from(parent.context)
.inflate(R.layout.item_text_view, parent, false) as TextView
return TextViewHolder(textView)
}
override fun onBindViewHolder(holder: TextViewHolder, position: Int) {
holder.textView.text = textList[position]
}
override fun getItemCount() = textList.size
}
Item to display in the RecyclerView, item_text_view.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="wrap_content"
android:layout_margin="8dp"
android:padding="16dp"
android:textAlignment="center"
android:background="#android:color/darker_gray">
</TextView>

AppBarLayout extend scroll range

I have a problem with scrolling, AppBarLayout not fully scrolls to out of screen.
How can i to continue scroll to statusbar height?
But if i set to root layout (CoordinatorLayout) fitsSystemWIndows=false, no problem with scroll, but status bar becomes without alpha channel.
<androidx.coordinatorlayout.widget.CoordinatorLayout
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:fitsSystemWindows="true">
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/search_appbar"
android:layout_width="match_parent"
android:layout_height="50dp">
<com.google.android.material.appbar.CollapsingToolbarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_scrollFlags="scroll|enterAlways">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
...
other layouts here
...
</LinearLayout>
</com.google.android.material.appbar.CollapsingToolbarLayout>
</com.google.android.material.appbar.AppBarLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Add Scrolling behaviour to your Toolbar which is inside AppbarLayout.
app:layout_scrollFlags="scroll|enterAlways"
EDIT:- Replace scrolling behaviour of CollapsingToolbarLayout with below code.
app:layout_scrollFlags="scroll|exitUntilCollapsed"

I found solution.
Maybe someone it helps.
create package: com.google.android.material.appbar
create class which extend AppBarLayout.Behavior
Result in the image
package com.google.android.material.appbar
import ...
class OffsetBehavior(c: Context, a: AttributeSet) : AppBarLayout.Behavior(c, a)
{
private var mOffset = 0
fun setOffset(value: Int) {
mOffset = value
}
// completely copy the method onNestedPreScroll from AppBarLaout.Behavior
// and add some changes
override fun onNestedPreScroll(coordinatorLayout: CoordinatorLayout, child: AppBarLayout, target: View, dx: Int, dy: Int, consumed: IntArray, type: Int)
{
if (dy != 0) {
val min: Int
val max: Int
// scroll down
if (dy < 0) {
min = -(child.totalScrollRange + mOffset)
max = min + child.downNestedPreScrollRange + mOffset
}
// scroll up
else {
min = -(child.upNestedPreScrollRange + mOffset)
max = 0
}
if (min != max) {
consumed[1] = scroll(coordinatorLayout, child, dy, min, max)
}
}
if (child.isLiftOnScroll) {
child.setLiftedState(child.shouldLift(target))
}
}
}
and then set it to AppBarLayout in XML
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/search_appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_behavior="com.google.android.material.appbar.OffsetBehavior">
...
</com.google.android.material.appbar.AppBarLayout>
in the Activity:
(1) add fun
// getting statusbar height
// my phone with Android9 = 96px
// my phone with Android7 = 72px
fun getStatusBarHeight(): Int {
val id = resources.getIdentifier("status_bar_height", "dimen", "android")
return if (id > 0) {
resources.getDimensionPixelSize(id)
} else {
0
}
}
(2) in onCreate()
val lp = search_appbar?.layoutParams as? CoordinatorLayout.LayoutParams
val bh = lp?.behavior as? com.google.android.material.appbar.OffsetBehavior
bh?.setOffset(getStatusBarHeight())
Result:
https://i.stack.imgur.com/pNeze.gif

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

Collapse header on scrolling without using CollapsingToolbarLayout - android

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