Develop Reference

View container visibility based on the visibility of views contained in it

I have several views inside another view.
I need to show the container view if at least one view is visible. So, if none of the view's visibility is VISIBLE, then the container should itself hide.
It could be done by using constraintlayout group or any other ways in fragment.
But I am using Data Binding and I needed to handle it in ViewModel with LiveData. So I tried using MediatorLiveData. And it is not working as expected.
Here is how my code looks like:
class MyViewModel: ViewModel() {
val firstViewVisibility: LiveData<Int> = checkVisibility(firstView)
val secondViewVisibility: LiveData<Int> = checkVisibility(secondView)
val thirdViewVisibility: LiveData<Int> = checkVisibility(thirdView)
// and so on
val viewContainerVisibility = MediatorLiveData<Int>.apply {
fun update(visibility: Int) {
value = visibility
}
addSource(firstViewVisibility) {
update(it)
}
addSource(secondViewVisibility) {
update(it)
}
addSource(thirdViewVisibility) {
update(it)
}
// and so on
}
}
CheckVisibility function:
private fun checkVisibility(viewType: String) =
Transformations.map(myLiveData) { value ->
if(some logic involving value returns true) View.VISIBLE
else View.GONE
}
This is not working as the parent view's visibility depends upon the visibility added by last addSource in MediatorLiveData. So, if the last view's visibility is VISIBLE then the parent will be Visible and if it is GONE, the parent will be gone even though other view's visibility are VISIBLE.
Is MediatorLiveData not best fit here? OR I mis-utilized it?
What could be the best solution for my case?

Currently, when you update Visibility of the container, if the latest update of any view out of three is invisible, it set value as invisible even though previously any of three was visible. SO you need to update the Update() method. Something similar like this
val viewContainerVisibility = MediatorLiveData<Int>.apply {
fun update() {
if(firstViewVisibility.value == View.Visible || secondViewVisibility.value == View.Visible || thirdViewVisibility.value == View.Visible)
{View.Visible}
else{
View.GONE //or INVISIBLE as required}
}
addSource(firstViewVisibility) {
update()
}
addSource(secondViewVisibility) {
update()
}
addSource(thirdViewVisibility) {
update()
}
// and so on
}

Android RecycleView how to disable manual scroll but allow item clicked

I am working on an idea, which is make a RecyclerView auto scrolling but allow user to click item without stop scrolling.
First, I create a custom LayoutManager to disable manual scroll, also change the speed of scroll to a certain position
class CustomLayoutManager(context: Context, countOfColumns: Int) :
GridLayoutManager(context, countOfColumns) {
// Custom smooth scroller
private val smoothScroller = object : LinearSmoothScroller(context) {
override fun calculateSpeedPerPixel(displayMetrics: DisplayMetrics): Float =
500f / displayMetrics.densityDpi
}
// Disable manual scroll
override fun canScrollVertically(): Boolean = false
// Using custom smooth scroller to control the duration of smooth scroll to a certain position
override fun smoothScrollToPosition(
recyclerView: RecyclerView,
state: RecyclerView.State?,
position: Int
) {
smoothScroller.targetPosition = position
startSmoothScroll(smoothScroller)
}
}
Then I do the initial work for the RecyclerView and start smooth scroll after 1 sec
viewBinding.list.apply {
// initial recycler view
setHasFixedSize(true)
customLayoutManager = CustomLayoutManager(context = context, countOfColumns = 2)
layoutManager = customLayoutManager
// data list
val dataList = mutableListOf<TestModel>()
repeat(times = 100) { dataList.add(TestModel(position = it, clicked = false)) }
// adapter
testAdapter =
TestAdapter(clickListener = { testAdapter.changeVhColorByPosition(position = it) })
adapter = testAdapter
testAdapter.submitList(dataList)
// automatically scroll after 1 sec
postDelayed({ smoothScrollToPosition(dataList.lastIndex) }, 1000)
}
Everything goes as my expected until I found that the auto scrolling stopped when I clicked on any item on the RecycelerView, the function when clickListener triggered just change background color of the view holder in TestAdapter
fun changeVhColor(position: Int) {
position
.takeIf { it in 0..itemCount }
?.also { getItem(it).clicked = true }
?.also { notifyItemChanged(it) }
}
here is the screen recording screen recording
issues I encounter
auto scrolling stopped when I tap any item on the ReycelerView
first tap make scrolling stopped, second tap trigger clickListener, but I expect to trigger clickListener by one tap
Can anybody to tell me how to resolve this? Thanks in advance.

There is a lot going on here. You should suspect the touch handling of the RecyclerView and, maybe, the call to notifyItemChanged(it), but I believe that the RecyclerView is behaving correctly. You can look into overriding the touch code in the RecyclerView to make it do what you want - assuming you can get to it and override it.
An alternative would be to overlay the RecyclerView with another view that is transparent and capture all touches on the transparent view. You can then write code for the transparent view that interacts with the RecyclerView in the way that meets your objectives. This will also be tricky and you will have to make changes to the RecyclerView as it is constantly layout out views as scrolling occurs. Since you have your own layout manager, this might be easier if you queue changes to occur pre-layout as scrolling occurs.

After tried several ways, found that the key of keep recycler view scrolling automatically is override onInterceptTouchEvent
Example
class MyRecyclerView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyle: Int = 0
) : RecyclerView(context, attrs, defStyle) {
override fun onInterceptTouchEvent(e: MotionEvent?): Boolean = false
}
that will make the custom RecyclerView ignore all touch event

How to update data of a RecyclerView that is inside a composable function?

I have a RecyclerView that is created and added to my compose layout through the AndroidView function.
#Composable
fun MyView(data: State<List<Item>>) {
...
AndroidView(factory = { context ->
RecyclerView(context).apply {
layoutParams = ViewGroup.LayoutParams(MATCH_PARENT, WRAP_CONTENT)
layoutManager = LinearLayoutManager(context)
adapter = ItemListAdapter().also { it.submitList(data.value) }
}
})
}
I used RecyclerView instead of LazyColumn because I want to have add and remove animations which is not yet supported by LazyColumn and I achieve that with the RecyclerView through the use of DiffUtil
Now, every time my data changes, the view is recomposed, thus the RecyclerView is recreated and the animations are not showed.
What is the best way in which I can achieve this? Should I just pass a LiveData then observe it on the RecyclerView's Adapter?
Thanks

Use update callback, it gets called on each recomposition:
AndroidView(
factory = { context ->
RecyclerView(context).apply {
layoutParams = ViewGroup.LayoutParams(MATCH_PARENT, WRAP_CONTENT)
layoutManager = LinearLayoutManager(context)
adapter = ItemListAdapter().also { it.submitList().value }
}
},
update = { recyclerView ->
}
)
Not sure why you're saying that "RecyclerView is recreated" on each recomposition, it shouldn't be like that. I've tested and only update = { gets called on recomposition

android bottomSheet can not update child size programmatically

it's hard to me to explain this problem, but you can see the below layout code,
First i have the layout look like this:
yeah, this is the call screen using webrtc, when i have the video, put it into main_render, the change the size when i have delegate for video size:
main_render.setScalingType(RendererCommon.ScalingType.SCALE_ASPECT_FIT)
main_render.init(rootEglBase.eglBaseContext, object : RendererCommon.RendererEvents{
override fun onFirstFrameRendered() {
Log.e(TAG, "onFirstFrameRendered")
}
override fun onFrameResolutionChanged(i: Int, i1: Int, i2: Int) {
Log.e(TAG, "onFrameResolutionChanged: $i - $i1")
runOnUiThread {
val newParams = main_render.layoutParams as FrameLayout.LayoutParams
newParams.width = dm.widthPixels
newParams.height = i1 * dm.widthPixels / i
main_render.layoutParams = newParams
main_render.requestLayout()
main_layout.updateViewLayout(main_render, newParams)
main_layout.requestLayout()
}
}
})
But the problem is the size does not changed, i have to press to hide sheet, press again to show sheet then now the size is change ( i have onclick to hide and show collapse sheet)
Can someone help me know this problem, when remove sheet and using main_layout it's work normally, but when using sheet the size can not changed immediately

Try to set state of BottomSheet after update viewlayout if it helps:
val behavior = bottomSheetDialog.behavior
behavior.state = BottomSheetBehavior.STATE_EXPANDED

OnBindViewHolder does not apply after notifyitemmoved () in Android Recyclerview

The code above is the RecyclerViewAdapter, which changes color only when it is the first item, as shown below.
class TestAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
private val textColor1 = Color.BLACK
private val textColor2 = Color.YELLOW
private val items = ArrayList<String>()
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
val textColor = if(position==0) textColor1 else textColor2
holder.itemView.textView.setTextColor(textColor)
holder.itemView.textView.text = items[position]
}
fun move(from:Int,to:Int){
val item = items[from]
items.remove(item)
items.add(to,item)
notifyItemMoved(from,to)
}
}
In this state I would like to move Value 3 to the first position using the move function. The results I want are shown below.
But in fact, it shows the following results
When using notifyDataSetChanged, I can not see the animation transition effect,
Running the onBindViewHolder manually using findViewHolderForAdapterPosition results in what I wanted, but it is very unstable. (Causing other parts of the error that I did not fix)
fun move(from:Int,to:Int){
val item = items[from]
val originTopHolder = recyclerView.findViewHolderForAdapterPosition(0)
val afterTopHolder = recyclerView.findViewHolderForAdapterPosition(from)
items.remove(item)
items.add(to,item)
notifyItemMoved(from,to)
if(to==0){
onBindViewHolder(originTopHolder,1)
onBindViewHolder(afterTopHolder,0)
}
}
Is there any other way to solve this?

Using the various notifyItemFoo() methods, like moved/inserted/removed, doesn't re-bind views. This is by design. You could call
if (from == 0 || to == 0) {
notifyItemChanged(from, Boolean.FALSE);
notifyItemChanged(to, Boolean.FALSE);
}
in order to re-bind the views that moved.

notifyItemMoved will not update it. According to documentation:
https://developer.android.com/reference/android/support/v7/widget/RecyclerView.Adapter
This is a structural change event. Representations of other existing items in the data set are still considered up to date and will not be rebound, though their positions may be altered.
What you're seeing is expected.
Might want to look into using notifyItemChanged, or dig through the documentation and see what works best for you.