I want to animate appearance of only last item of a recyclerview. Every time scroll is done to end, view should be shown with animation.
Applying Item Animator animates when item is removed, added, deleted. But i did not get option to animate in on scroll.
I applied animation in onBindView, but onBindView is not always called and animation is not started. Moreover, in cases onBindView is called and user is performing slow scroll operation, animation had already started when view is actually visible to user.
What can be suitable way to apply this animation?
Thanks
Vibhor
I have tested this solution and It's working like a charm.
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
LinearLayoutManager layoutManager = LinearLayoutManager.class.cast(recyclerView.getLayoutManager());
int lastItem=adapter.getItemCount()-1;
tryAnimation(layoutManager.findViewByPosition(lastItem));
}
});
public void tryAnimation(View view) {
Animation animation = AnimationUtils.loadAnimation(this, android.R.anim.slide_in_left);
if (view != null)
view.startAnimation(animation);
}
this solution can be optimized by taking advantage of dy
Background:
I'm developing a tournament management software and I want to show the current contenders classification on a screen that is feed by an android device.
The number of contenders exceeds the vertical size of the screen, so I would like to show it using a nice vertical animate smoth scroll from bottom to top that would be endless (when the list shows the last element it would start showing the first as it would be a loop.
Approach:
After some research (sorry I don't have the all the references) I come up with the following implementation:
I'm using a recyclerview with an adapter on a fragment. In order to automatically scroll it up I have added a timer that would scroll the recycleview on fixed itervals:
CountUpTimer recyclerViewAutoScroll = new CountUpTimer(1) {
public void onTick(long millis) {
recyclerView.scrollBy(0, mSpeed * 2);
if (!recyclerView.canScrollVertically(1)) {
recyclerView.scrollToPosition(0);
}
}
};
This timer is being created and launched on a global layout listener:
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
layoutListener = () -> {
recyclerView.post(() -> recyclerViewAutoScroll.start());
recyclerView.getViewTreeObserver().addOnGlobalLayoutListener(layoutListener);
}
The CountUpTimer class is just an "infinite" timer implemented using an android CountDowntimer.
With this piece of code I can scroll up at regular times, the problem is that is not smoth at all. There are two parameters to play with: the timer tick time, and the amount of vertical scroll that is made each time the timer "ticks". The only way to make it "smooth" is to reducing so much the scroll movement that it ended being very very very slow for the user.
Just for completeness, to achieve the endless scroll efect I added an scroll listener to the recycler view:
recyclerView.addOnScrollListener(new EndlessRecyclerOnScrollListener(5) {
#Override
public void onLoadMore(int currentPage) {
Timber.d("new Page " + currentPage);
recyclerView.post(() ->
{
itemAdapter.addModel(currentClassificationList);
if (currentPage > 2)
itemAdapter.removeModelRange(0, currentClassificationList.size());
});
}
What I do there is just add twice the classificationList to have enough space on the bottom to show the top of the list after the last element, and I keep adding the list to the bottom and removing from the top every time the recyclerview is about to reach the end of the list.
So my question is: How can I implement a really smoth scroll animation of the recyclerview? As I said this is being shown WITHOUT any user interaction, just on a screen where the classification is continuously being shown and scrolled.
UPDATE
After one comment suggestion I substituted the count timer by a TimeAnimator class this way:
timeAnimator.setTimeListener(new TimeAnimator.TimeListener() {
#Override
public void onTimeUpdate(TimeAnimator timeAnimator, long l, long l1) {
Timber.d("elapsed: " + l1);
recyclerView.scrollBy(0, (int)(l1/ mSpeed));
if (!recyclerView.canScrollVertically(1)) {
recyclerView.scrollToPosition(0);
}
}
});
Also I removed the post calls as they are not needed.
Now the smoothness has improved, but is not perfect, it still hessitate a bit when a new item is about to appear from the bottom.
I'm looking now to the itemadapter to improve any calculation made there and any image loading (I added Picasso for image loading also) But still it is not perfect, they are some flickering there.
I basically have to smooth scroll a listview and update a row at the same time.
I do it with a simple approach for now:
mListViewWeeks.post(new Runnable() {
#Override
public void run() {
// update the row concerned
updateItemAtPosition(rowIndex);
int duration = 200;
mListView.smoothScrollToPositionFromTop(rowIndex, 0, duration);
}
});
with the updateItemAtPosition() function:
private void updateItemAtPosition(int position) {
int visiblePosition = mListView.getFirstVisiblePosition();
View view = mListView.getChildAt(position - visiblePosition);
mListView.getAdapter().getView(position, view, mListView);
}
It's working well at a reasonable scroll speed, but when going faster (calling the first block above at a high rate) it can get a bit laggy. Is there anything that I can do to improve updating a row while scrolling smoothly?
You should'nt acces the iew dirrectly like this. Instead you should update your model object displayed by the list and call notifyDataSetChanged() in your adapter.
Well, I'm really late in the game. It looks like one of the reason why RecyclerView was introduced. I'm gonna try to use this component from now on.
A combination of layoutManager.scrollToPosition(position);
and adapter.notifyItemChanged(position); does the job. Everything runs smoothly!!
I'm using basic RecyclerView with GridLayoutManager. I observed that nor smoothScrollToPosition nor scrollToPosition works properly.
a) when using smoothScrollToPosition I often receive error from RecyclerView
"RecyclerView﹕ Passed over target position while smooth scrolling."
and RecyclerView is not scrolled properly (often it misses the targeted row). This is observed mostly when I'm trying to scroll to the 1st item of some row
b) when using scrollToPosition it seems to work quite ok but most of the time I can see only the 1st item of the row and the rest are not displayed.
Can you give me some hints how to make work properly at least one of the methods?
Thanks a lot!
Finally I was able to make it work! LinearLayoutManager.scrollToPositionWithOffset(int, int) did the trick.
I also have same issue, but managed to fix the issue by Customizing SmoothScroller
let Custom LayoutManager as below
public class CustomLayoutManager extends LinearLayoutManager {
private static final float MILLISECONDS_PER_INCH = 50f;
private Context mContext;
public CustomLayoutManager(Context context) {
super(context);
mContext = context;
}
#Override
public void smoothScrollToPosition(RecyclerView recyclerView,
RecyclerView.State state, final int position) {
LinearSmoothScroller smoothScroller =
new LinearSmoothScroller(mContext) {
//This controls the direction in which smoothScroll looks
//for your view
#Override
public PointF computeScrollVectorForPosition
(int targetPosition) {
return CustomLayoutManager.this
.computeScrollVectorForPosition(targetPosition);
}
//This returns the milliseconds it takes to
//scroll one pixel.
#Override
protected float calculateSpeedPerPixel
(DisplayMetrics displayMetrics) {
return MILLISECONDS_PER_INCH/displayMetrics.densityDpi;
}
};
smoothScroller.setTargetPosition(position);
startSmoothScroll(smoothScroller);
}
}
(documentation commented inside the code given above)Please set the above LayoutManager
to the recyerview
CustomLayoutManagerlayoutManager = new CustomLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.smoothScrollToPosition(position);
by using the custom Layout manager
scrollToPosition
also working well in my case u can use
recyclerView.scrollToPosition(position)
also if you want to adjust the speed of smoothScrollToPosition please override the
private static final float MILLISECONDS_PER_INCH = 50f;
in CustomLayoutManager.
So if we put the value as 1f the smoothScrollToPosition will be faster like scrollToPosition.increasing value make delay and decreasing will make the speed of scroll.
Hope this will useful.
In My case,
mRecyclerView.scrollToPosition(10);
also did not work.
But
mRecyclerView.smoothScrollToPosition(10);
works fine for me...
To scroll down smoothly to bottom from any position in the RecyclerView on clicking EditText.
edittext.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
rv_commentList.postDelayed(new Runnable() {
#Override
public void run() {
rv_commentList.scrollToPosition(rv_commentList.getAdapter().getItemCount() - 1);
}
}, 1000);
}
});
Another reason why any of the before mentioned solutions may not work is if your RecyclerView is embedded in a NestedScrollView. In this case you have to call the scroll action on the NestedScrollView.
for example:
nestedScrollview.smoothScrollTo(0,0)
This extension is so useful, try please.
fun RecyclerView.smoothSnapToPosition(position: Int, snapMode: Int = LinearSmoothScroller.SNAP_TO_START) {
val smoothScroller = object : LinearSmoothScroller(this.context) {
override fun getVerticalSnapPreference(): Int = snapMode
override fun getHorizontalSnapPreference(): Int = snapMode
}
smoothScroller.targetPosition = position
layoutManager?.startSmoothScroll(smoothScroller)
}
I was facing a weird issue wherein smoothScrollToPosition only worked occasionally.
After putting the smoothScrollToPosition inside Handler Post
Delayed with 1 second delay, it worked fine.
Refer to the following Kotlin example:
Handler().postDelayed({
recyclerViewObject.smoothScrollToPosition(0) // mention the position in place of 0
}, 1000) // 1000 indicates the 1 second delay.
recyclerView.getLayoutManager().smoothScrollToPosition(recyclerView,new RecyclerView.State(),currentPosition);
Try measuring item width or height and call smoothScrollBy(int dx, int dy).
How to perform smooth scrolling and save RecyclerView vertical position after device rotating:
This is the method that works for my case,
public class MainFragment extends Fragment { //OR activity it's //fragment in my case
....
#Override
public void onLoadFinished(#NonNull Loader<List<Report>> loader, List<Report> objects) { // or other method of your choice, in my case it's a Loader
RecyclerView recyclerViewRv = findViewById(........;
.....
recyclerViewRv.setAdapter(.....Your adapter);
recyclerViewRv.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(#NonNull RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
}
#Override
public void onScrolled(#NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
recyclerScrollY = recyclerViewRv. computeVerticalScrollOffset();
}
});
//Apply smooth vertical scroll
recyclerViewRv.smoothScrollBy(0,recyclerScrollY);
}
//Save vertical scroll position before rotating devices
#Override
public void onSaveInstanceState(#NonNull Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("recyclerScrollY",recyclerScrollY);
}
//BackUp vertical scroll position after rotating devices
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState != null) {
recyclerScrollY = savedInstanceState.getInt("recyclerScrollY");
}
}
//If you want to perform the same operation for horizontal scrolling just add a variable called recyclerScrollX = recyclerScrollY = recyclerViewRv. computeHorizontalScrollOffset(); then save in bundle
Calling the recyclerView smoothScroll isn't effective, as the recyclerView itself doesn't handle its layout.
What you should do is calling the layout manager scroll method instead.
This should look something like this
mRecyclerView.getLayoutManager().scrollToPosition(desiredPosition);
If you are trying to do a quick scroll to a position at the top of the RecyclerView, just use LinearLayoutManager.scrollToPositionWithOffset with 0 as the offset.
Example:
mLinearLayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(mLinearLayoutManager);
mLinearLayoutManager.scrollToPositionWithOffset(myPosition, 0);
smoothScrollToPosition is very slow. If you want something fast go with scrollToPositionWithOffset.
when you use scrollToPosition it will show it on top of the recycler view.
But if you use smoothScrollToPosition it will scroll till it come in to Window Visible. that's why while smoothScrool to item below, it will show it on bottom
Actually, if you have a RecyclerView inside a NestedScrollView, you must use both of these lines every time you want to go to the beginning of the RecyclerView:
nestedScrollView.smoothScrollTo(0, 0);
layoutManager.scrollToPositionWithOffset(0, 0);
This completely works for me.
this worked for me
Handler().postDelayed({
(recyclerView.getLayoutManager() as LinearLayoutManager).scrollToPositionWithOffset( 0, 0)
}, 100)
None of these answers worked for me. I needed to smoothScrollToPosition but #Ramz answer didn't work. I was finding it would consistently overscroll but only in one direction. I discovered that it seemed to be the item decorators throwing it off. I had a horizontal layout and I wanted to add a space after every item except the last and it didn't like that asymmetry. As soon as I included a space after every item, it worked!
nestedScroll.smoothScrollTo(0, recycler.top)
So i was looking for a solution to get back to the top with a recyclerview inside another layout that has a view on top of it (in my case I had a LinearLayout with a TextView and my recyclerview inside). Because of that the smoothscroll would go only to half the way to the first item.
Here's what I did which works really well (Kotlin solution):
back_to_top.setOnClickListener {
GlobalScope.launch(Dispatchers.Main) {
GlobalScope.launch(Dispatchers.Main) {
recyclerview.layoutManager?.smoothScrollToPosition(recyclerview, RecyclerView.State(), 0)
delay((recyclerview.layoutManager as LinearLayoutManager).findLastVisibleItemPosition() * 100L)
}.join()
recyclerview.scrollToPosition(0)
}
back_to_top.visibility = View.GONE
}
}
Here what I do is I smoothscroll to the first element and delay the scroll by 100ms times the last item visible and then call the scrollToPosition(0) (which goes to the top.correctly)
I'm using
<ExpandableListView
android:id="#+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</ExpandableListView>
i want add animation slide for child when onclick parent . So How can i do ?
Final Update
It's been quite a while since I wrote this answer. Since then a lot has changed. The biggest change is with the introduction of RecyclerView that makes animating a list or grid easy. I highly recommend switching over to RecyclerViews if you can. For those who can't I will see what I can do regarding fixing the bugs for my library.
Original answer
I actually do not like the popular implementation of an animated ExpandableListView that simply uses a ListView with an expand animation because in my use case, each of my groups had a lot of children, therefore it was not feasible to use a normal ListView as the child views will not be recycled and the memory usage will be huge with poor performance. Instead, I went with a much more difficult but more scalable and flexible approach.
I extended the ExpandableListView class and overrode the onCollapse and onExpand functions, I also created a subclass of a BaseExpandableListAdapter called AnimatedExpandableListAdapter. Inside the adapter, I overrode the getChildView function and made the function final so that the function cannot be overrode again. Instead I provided another function called getRealChildView for subclasses to override to provide a real child view. I then added an animation flag to the class and made getChildView return a dummy view if the animation flag was set and the real view if the flag was not set. Now with the stage set I do the following for onExpand:
Set the animation flag in the adapter and tell the adapter which group is expanding.
Call notifyDataSetChanged() (forces the adapter to call getChildView() for all views on screen).
The adapter (in animation mode) will then create a dummy view for the expanding group that has initial height 0. The adapter will then get the real child views and pass these views to the dummy view.
The dummy view will then start to draw the real child views within it's own onDraw() function.
The adapter will kick off an animation loop that will expand the dummy view until it is of the right size. It will also set an animation listener so that it can clear the animation flag once the animation completes and will call notifyDataSetChanged() as well.
Finally with all of this done, I was able to not only get the desired animation effect but also the desired performance as this method will work with group with over 100 children.
For the collapsing animation, a little more work needs to be done to get this all setup and running. In particular, when you override onCollapse, you do not want to call the parent's function as it will collapse the group immediately leaving you no chance to play an animation. Instead you want to call super.onCollapse at the end of the collapse animation.
UPDATE:
I spent some time this weekend to rewrite my implementation of this AnimatedExpandableListView and I'm releasing the source with an example usage here:
https://github.com/idunnololz/AnimatedExpandableListView/
animateLayoutChanges adds auto-animation
<ExpandableListView
android:animateLayoutChanges="true"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
#idunnololz solution works great. however i would like to add some code to collapse previously expanded group.
private int previousGroup=-1;
listView.setOnGroupClickListener(new OnGroupClickListener() {
#Override
public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
// We call collapseGroupWithAnimation(int) and
// expandGroupWithAnimation(int) to animate group
// expansion/collapse.
if (listView.isGroupExpanded(groupPosition)) {
listView.collapseGroupWithAnimation(groupPosition);
previousGroup=-1;
} else {
listView.expandGroupWithAnimation(groupPosition);
if(previousGroup!=-1){
listView.collapseGroupWithAnimation(previousGroup);
}
previousGroup=groupPosition;
}
return true;
}
});
#idunnololz solution is working great, but I experienced weird behavior with my custom layout for group. The expand operation was not executed properly, the collapse however worked perfect. I imported his test project and it worked just fine, so I realized the problem is with my custom layout. However when I was not able to locate the problem after some investigation, I decided to uncomment these lines of code in his AnimatedExpandListView:
if (lastGroup && Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
return expandGroup(groupPos, true);
}
which caused the problem (my app is aimed for Android 4.0+).
Found this snnipet not remebering where here in Stack Overflow. Have two basic static methods: expand(View v) and collapse(View v).
You only have to pass the view you want to hide show.
Note: I Don't recomend pass a view having wrap_content as height. May not work fine.
public class expand {
public static void expand(View view) {
view.setVisibility(View.VISIBLE);
final int widthSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
final int heightSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
view.measure(widthSpec, heightSpec);
ValueAnimator mAnimator = slideAnimator(view, 0, view.getMeasuredHeight());
mAnimator.start();
}
public static void collapse(final View view) {
int finalHeight = view.getHeight();
ValueAnimator mAnimator = slideAnimator(view, finalHeight, 0);
mAnimator.addListener(new Animator.AnimatorListener() {
#Override
public void onAnimationEnd(Animator animator) {
view.setVisibility(View.GONE);
}
#Override
public void onAnimationStart(Animator animation) {
}
#Override
public void onAnimationCancel(Animator animation) {
}
#Override
public void onAnimationRepeat(Animator animation) {
}
});
mAnimator.start();
}
private static ValueAnimator slideAnimator(final View v, int start, int end) {
ValueAnimator animator = ValueAnimator.ofInt(start, end);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
int value = (Integer) valueAnimator.getAnimatedValue();
ViewGroup.LayoutParams layoutParams = v.getLayoutParams();
layoutParams.height = value;
v.setLayoutParams(layoutParams);
}
});
return animator;
}
}