I want to get the current position of the visible view of my PagerAdapter
I didn't see an obvious function like getPosition() and I want one.
I want to add an object into its arraylist at that position, but I need to know it first
You would use:
int position = mViewPager.getCurrentItem()
I had this problem and could not get the getCurrentItem() methode.
I ended up getting the position from the ViewPager and not from the PageAdapter. The onPageSelected(int currentPage) methode is getting the currently displayed page.
//custom PageAdapter implementation
mAdapter = new AwesomePagerAdapter();
//Our custom view pager that extends from ViewPager
mPager = (CustomViewPager) findViewById(R.id.preview_gallery);
mPager.setAdapter(mAdapter);
// get the item that we should be showing from the intent
mCurrentPage = extra.getInt("currentIndex");
// show the item the user picked
mPager.setCurrentItem(mCurrentPage);
// listen for page changes so we can track the current index
mPager.setOnPageChangeListener(new OnPageChangeListener() {
public void onPageScrollStateChanged(int arg0) {
}
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
public void onPageSelected(int currentPage) {
//currentPage is the position that is currently displayed.
}
});
Doing it in the PageAdaper didn't work for me as I want to preload images that are not visible. The position that is passed instantiateItem(View collection, int position) of the PageAdapter` is the position of the next item initialized. This has nothing to do with the item that is displayed.
https://github.com/Shereef/ViewPagerPlusExpandableList/blob/master/src/net/shereef/vewpagerplusexpandablelistexample/ViewPagerPlusExpandableListActivity.java#L204
if i write after that line
Log.i("pager",myPager.getCurrentItem()+"");
it will show in the logcat the current item page while the oncreate is being run which is always 0
noteice i have used the object for the viewpager it self not the adapter.
Here's an updated solution that I used myself. Since setOnPageChangeListener is now deprecated you must use addOnPageChangeListener.
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
int counterPosition;
if (position == 0 || position <= currentInventory.size()){
counterPosition = position + 1;
} else {
counterPosition = position;
}
viewPagerHeader.setText("Prize " + counterPosition + " of " + currentInventory.size());
}
#Override
public void onPageSelected(int position) {
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
The implementation above displays the correct index in my TextView so that positions 0 and the last item in the listcurrentInventory.size() display correctly.
Hope this helps someone looking for an updated solution.
Try this:
imageSlider.addOnPageChangeListener(object: ViewPager.OnPageChangeListener{
override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {}
override fun onPageSelected(position: Int) {Log.d(TAG, "Page No.: $position")}
override fun onPageScrollStateChanged(state: Int) {}
})
I just faced this problem yesterday. I needed to start playing an animation in each page when the page is visible to the user and not before.
My adapter inherits from PagerAdapter and I found out that there is a function setPrimaryItem() which is triggered every time a page is shown to the user as the current page.
Called to inform the adapter of which item is currently considered to be the "primary", that is the one show to the user as the current page. This method will not be invoked when the adapter contains no items.
Not only you have a callback for when the page is visible but this callback also provides the position of the current page.
class MyAdapter extends PagerAdapter {
#Override
public int getCount() {
...
}
#Override
public boolean isViewFromObject(#NonNull #NotNull View view, #NonNull #NotNull Object object) {
...
}
#Override
public void setPrimaryItem(#NonNull #NotNull ViewGroup container, int position, #NonNull #NotNull Object object) {
super.setPrimaryItem(container, position, object);
// `position` gives you the position of the current page
// And this is how I managed to play the animation (Lottie library) when the page is visible to the user
LottieAnimationView animation = ((ViewGroup) object).findViewById(R.id.my_animation_view);
animation.playAnimation();
}
}
Related
I used an external library called "Swipe Cards by Diolor" and I attached it to an Array Adapter. Within each card I also need to make a View Pager with bars showing which image the user is currently looking at. The issue I am having is that when I set an OnPageChangeListeneron the View Pager it calls methodonPageSelected and executed all the code within it. This involves a call to createBars (included below). However, everything in createBars is executed including the barHolder.removeAllView except for the li.inflate statements. I also tried using addView but a similar problem occurs. Please advise a method to work around this and if possible the resoan why it's happening. I have included code from the Array Adapter code for the createBars and getView methods. Let me know if some other piece of code would be helpful.
private void createBars(int position, int numItems, LinearLayout barHolder) {
barHolder.removeAllViews();
Log.i("View pager listner", "method called");
for (int i = 0; i < numItems; i++) {
if (i == position) {
li.inflate(R.layout.white_rectangle, barHolder);
} else {
li.inflate(R.layout.transparent_white_rectangle, barHolder);
}
}
}
public View getView(int position, View itemView, ViewGroup parent) {
// all views required for a card
final ProgressBar homeProgressBar;
final TextView homeTimeLeft;
TextView homeTitle;
CardView homeItemHolder;
HomeItem item = getItem(position);
final int numItems = item.getItemImages().length;
if (itemView == null) {
itemView = li.inflate(R.layout.home_item, parent, false);
}
homeProgressBar = itemView.findViewById(R.id.home_progressbar);
homeTimeLeft = itemView.findViewById(R.id.home_time_text);
homeTitle = itemView.findViewById(R.id.home_card_title);
homeViewPager = itemView.findViewById(R.id.home_view_pager);
homeViewPager.setOffscreenPageLimit(6);
timeLeftItem = item.getTimeLeftMiliseconds();
homeTitle.setText(item.getTitle());
HomeImageHolder viewPagerAdapter = new HomeImageHolder(context, item.getItemImages());
homeViewPager.setAdapter(viewPagerAdapter);
final LinearLayout barHolder = itemView.findViewById(R.id.home_bars);
createBars(0, item.getItemImages().length, barHolder);
homeViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
Log.i("view pager listner", "it listned");
createBars(position, numItems, barHolder);
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
countDownTimer = new CountDownTimer(timeLeftItem, milisecondsInHours) {
#Override
public void onTick(long millisUntilFinished) {
homeTimeLeft.setText(HelperMethods.milisecondsToDays(millisUntilFinished) + " Days "
+ HelperMethods.milisecondsToHours(millisUntilFinished) + " Hours");
homeProgressBar.setProgress(updateProgressBar(millisUntilFinished));
}
#Override
public void onFinish() {
homeTimeLeft.setText("0 Days 0 Hours");
homeProgressBar.setProgress(updateProgressBar(0));
}
};
countDownTimer.start();
return itemView;
}
The inflator works when it's called outside the listener but not when it is called inside it. What would be the reasoning being this?
EDIT: I figured out that the class to which the array adapter is added, (Diolor's swipe cards) calls getView 4 times on the future objects in the array. Could this be a potential issue. I know that the reference to bar holder within the listener does not change for a given card. I used Logs and toString methods to confirm that the LinearLayout passed into the listner coincided with the barHolder that corresponds to the current card.
I have a gallery/slideshow activity that allows user to swipe between Photos. Each "Page" is just a TouchImageView. There is a pagination logic in there, and I can see that it is calling the API accordingly. However, I am not able to swipe further even after notifyDataSetChanged has been called. Here's the code:
Activity {
ViewPager vp;
CustomPagerAdapter pagerAdapter;
onCreate() {
//api callback
pagerAdapter = new CustomPagerAdapter();
vp.setAdapter(pagerAdapter);
}
}
CustomPagerAdapter() {
TouchImageView imageView;
List<Photos> photos;
int getCount() {
return photos == null ? 0 : photos.size();
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
View itemView = mLayoutInflater.inflate(R.layout.pager_image, container, false);
imageView = (TouchImageView) itemView.findViewById(R.id.photo);
Glide.with(context)
.load(photos.get(position).getUrl())
.into(imageView);
container.addView(itemView);
if (position == photos.size()-1) {
loadMorePhotos();
}
return itemView;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((RelativeLayout) object);
}
void loadMorePhotos() {
//call api and stuff
void onResponse(Call call, Response<List<Photo>> response) {
photos.addAll(response.body);
notifyDataSetChanged();
}
}
}
And this is the result:
http://imgur.com/nA1TzfI
I have no idea what is going on for 2 days. Please help!
This may not be ideal, but where you call notifyDatasetChanged() you could instead try calling vp.setAdapter(pagerAdapter);
(i.e. actually re-set the adapter). A downside of this is that the pager will probably go back to having the first page selected. To avoid this, you'd need to save the latest page somewhere and restore it afterwards.
As I say, not ideal, but it may help.
You dont have to load more photos from adapter class, in your activity class you can use onPageScrolled and call the api when the last item is scrolled and set adapter again also save state of view pager before calling api to retain it when adapter is set again.
private boolean isLastPageSwiped;
private int counterPageScroll;
private OnPageChangeListener mListener = new OnPageChangeListener() {
#Override
public void onPageSelected(int arg0) {
// TODO Auto-generated method stub
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
if (position == 6 && positionOffset == 0 && !isLastPageSwiped){
if(counterPageScroll != 0){
isLastPageSwiped=true;
//call api
}
counterPageScroll++;
}else{
counterPageScroll=0;
}
}
#Override
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
};
and use this listener
vp.setOnPageChangeListener(mListener);
We can use this approach for doing pagination on ViewPager (with fragment)
load new page data but not append to the adapter
make sure the page is not scrolling, then append new page data into the adapter (ViewPager.OnPageChangeListener#onPageScrolled's positionOffsetPixels == 0).
update current item for view pager with offset = new page data's size (let's call it newPosition)
rebind data to 3 fragments: newPosition - 1, newPosition, newPosition + 1
For getting current fragment, we can use fragment manager
private fun getFragment(position: Int): PageFragment? =
supportFragmentManager.fragments.firstOrNull {
(it as? PageFragment)?.position == position // always pass possition value into the fragment
} as? PageFragment
We need to append data when not scrolling (step 2) to have a better UX to users. If we append data immediately when it comes and if user is scrolling, view pager's setCurrentItem will make a strange move.
I create a simple version here https://github.com/tuanchauict/DemoPaginationViewPager. Please take a look
In my app I use a ViewPager in conjunction with PageTransformer to display some data list as a card deck. That list is sometimes refreshed and it contains plenty of items in a common case, so I use FragmentStatePagerAdapter with needed page limit:
public class PlaceListPagerAdapter extends FragmentStatePagerAdapter {
private List<PlaceListData> items;
public PlaceListPagerAdapter (FragmentManager manager) {
super (manager);
items = new ArrayList<>();
}
#Override
public Fragment getItem(int position) {
String id = items.get(position).getId();
String name = items.get(position).getName();
String address = items.get(position).getAddress();
return PlaceFragment.newInstance(id, name, address);
}
#Override
public int getCount() {
return items.size();
}
#Override
public int getItemPosition(Object object) {
PlaceFragment frag = (PlaceFragment) object;
String id = frag.getDataId();
for (PlaceListData data : items) {
if (id != null && id.equals(data.getId())) {
return POSITION_UNCHANGED;
}
}
return POSITION_NONE;
}
public void addItems(List<PlaceListData> items) {
this.items.addAll(items);
notifyDataSetChanged();
}
public void replaceItems(List<PlaceListData> items) {
this.items.clear();
addItems(items);
}
public void clearItems () {
this.items.clear();
notifyDataSetChanged();
}
}
Nothing unusual - list of pojos, overriden getItemPosition() and add/clear methods with notifyDataSetChanged(). The problem is when I try to add/replace items over network, method transformPage(View view, float position) of my transformer is called with 0.0 position for all new views and they are placed one over another (transformation is broken).
After debugging ViewPager class I noticed that transformPage(View view, float position) is invoked only in one place in onPageScrolled(..) method of ViewPager and the latter is invoked in onLayout(..) after the first layout pass.
notifyDataSetChanged() invokes onPageScrolled(..) (and transformPage(View view, float position) respectively) and requestLayout() after that. The problem is that first invocation of transformPage(View view, float position) happens before layout pass and position parameter depends on View.left() which returns 0 as child views are not layouted. In onLayout(..) which follows the requestLayout() my transformPage(View view, float position) is not called at all because yeap, views are layouted now, but it is not the first layout pass.
The problem is cured by resetting adapter (it sets mFirstLayout flag in ViewPager to "true") or by calling any public method of ViewPager which invokes transformPage(View view, float position) in it's code such as scrollTo, fakeDrag etc, but I'd like to know - is all that a feature of ViewPager or is it a bug or am I doing something very very wrong?
Sorry for my bad English and thanks in advance!
I am using two Viewpager in my app,
1) First Viewpager displays images only
2) I am displaying price
now the issue is i have 4 images displaying in my viewpager1, and in second pager i have price as per selected product. first time it does not show anything, but when i scroll image and goes to next, it shows price..
pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
Picasso.with(ProductLandingActivity.this) .load(categorylist.get(position).getProductLanding_packLink())
.error(R.drawable.nopreview )
.placeholder(R.drawable.progress_animation)
.into(selectedImage);
System.out.println("Selected is"+position);
selectedname.setText(categorylist.get(position).getProductLanding_packDesc());
for (int i = 0; i < categorylist.get(position).getItems().size(); i++) {
System.out.println("ProductPack_ID : " + categorylist.get(position).getItems().get(i).getPackSize_sellingPrice());
}
temp = categorylist.get(position).getItems();
packadapter = new MyPacksPagerAdapter(ProductLandingActivity.this,categorylist);
pagerpacks.setAdapter(packadapter);
}
#Override
public void onPageSelected(int position) {
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
adapter
private class MyPacksPagerAdapter extends PagerAdapter {
Context context;
ArrayList<PackListModel> packsizedata ;
public MyPacksPagerAdapter(Context context,ArrayList<PackListModel> packsizedata) {
this.context = context;
this.packsizedata = packsizedata;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
final OneActor oneActor;
View view;
LayoutInflater infl = ((Activity)context).getLayoutInflater();
view = infl.inflate(R.layout.list_item_pagerpacktitles, container,false);
oneActor = new OneActor();
// oneActor.avatar = (ImageView) view.findViewById(R.id.image);
oneActor.name = (TextView) view.findViewById(R.id.product_landing_packsname);
oneActor.cmtCount = (TextView) view.findViewById(R.id.product_landing_packsprice);
view.setTag(oneActor);
oneActor.name.setText(temp.get(position).getPackSize_packSize());
oneActor.cmtCount.setText(temp.get(position).getPackSize_sellingPrice());
((ViewGroup) container).addView(view);
return view;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View)object);
}
#Override
public int getCount() {
return packsizedata.size();
}
#Override
public boolean isViewFromObject(View view, Object object) {
return (view == object);
}
class OneActor{
// ImageView avatar;
TextView name,cmtCount;
}
}
By defaulat when i run the app it shows like this,in second pager it is not showing product price,
But when i scroll image it shows price
My Expected output is
This is my json response
http://pastebin.com/fbJang2B
First, as mentioned by #NotobharatKumar, you're loading the second adapter on a wrong event of the parent adapter, ie in onPageScrolled method. Second, you're setting a new adapter each time on that specific event, it seems useless. Finally, you are setting datas in an event, (I'm not sure why you're doing this but) I'd prefer to set it in a separate adapter and let the events listener for specific behaviors.
For me, it seems that you have two separate adapters, but one datas list shared by both. Assuming that, you have to set them both at start with their datas respectly, and on the event onPageSelected of the top adapter, you just have to automatically scroll the second. And if they have the same position in the list, onPageSelected should do the work correctly.
So, these modifications should solve your issue:
Your code in onScrollChanged, when you set the image and the text, seems really weird to me. I'd use a first adapter where I'll set all the datas like these two for the first ViewPager:
#Override
public void onCreate(Bundle savedInstansteState) {
...
// set a simple adapter for the first ViewPager
FirstPagerAdapter imageadapter =
new FirstPagerAdapter(ProductLandingActivity.this, categorylist);
pagerimages.setAdapter(imageadapter);
...
}
Then, as usual, set your datas in the FirstPagerAdapter:
#Override
public View getView(int position, View view, ViewGroup container) {
...
// set the content
Picasso.with(ProductLandingActivity.this)
.load(categorylist.get(position).getProductLanding_packLink())
.error(R.drawable.nopreview )
.placeholder(R.drawable.progress_animation)
.into(selectedImage);
selectedname.setText(
categorylist.get(position).getProductLanding_packDesc());
...
}
Then no need to (re)load the image or the text when an event is triggered, since they will be holding by the adapter.
You only use getPackSize_packSize() and getPackSize_sellingPrice() in the second adapter, so you should create a separate list to only fill with these datas but outside the swiping event. Start by initializing the second list and the adapters:
// get the Items to fill the pack items list (like you did for `temp`)
ArrayList<Items> packItems = new ArrayList<>();
for (int i = 0; i < categorylist.size(); i++) {
packItems.add(categorylist.get(position).getItems());
}
// fill the first adapter with your list of products (ie categorylist)
...
pagerimages.setAdapter(imageadapter);
...
// fill the second adapter with the pack items list
packadapter = new MyPacksPagerAdapter(ProductLandingActivity.this, packItems);
pagerpacks.setAdapter(packadapter);
You have to do this when categorylist is created and populated. So place this above code for example in your callback, when you retrieve the datas from your server.
Since the second list packItems is filling in the same order than categorylist, there will be no weird behavior by changing the both positions.
Now, in the second adapter, it's preferable to use the local list packsizedata, as follows:
#Override
public Object instantiateItem(ViewGroup container, int position) {
...
oneActor.name.setText(
packsizedata.get(position).getPackSize_packSize());
oneActor.cmtCount.setText(
packsizedata.get(position).getPackSize_sellingPrice());
...
}
Finally, control the bottom ViewPager by using onPageSelected event of the first:
pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels) { }
#Override
public void onPageSelected(int position) {
// set the second current page regarding the position of the first
pagerpacks.setCurrentItem(position);
}
#Override
public void onPageScrollStateChanged(int state) { }
});
Hope this will be helpful.
You should implement code for action at onPageSelected method because after page changed of your ViewPager then onPageSelected will be called.
I would like to keep a list of 3 views at all times. The app starts at position 1 (out of positions 0,1,2). When someone scrolls to position 0, I would like to remove view 2, and create a view before position 0. This way, it appears to the user, that there are unlimited views. In the same way, when someone scrolls to position 2, I would like to remove the view at position 0 and add one at the end.
However I'm having problems with both adding and removing views. When I get to position 0, nothing changes unless I try scrolling past position 0 (to position -1, i.e. the boundary is hit). At that point, I can see that it is the boundary of my views, but then setCurrentItem(1,false) is triggered and I'm brought back to the middle of the views. When I scroll to position 2 I see that position 2 has been updated. However position 0 and 1 remain the same.
When I scroll to position 2, nothing happens. However if I try and scroll to the boundary, for some reason, position 0 gets updated and setCurrentItem(1,false) is triggered.
I have no idea why its happening like this. Can anyone shed some light on this?
Here is my code:
public class MainActivity extends Activity {
ArrayList<Integer> showThree = new ArrayList<Integer>();
int focusedPage = 0;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
showThree.add(0,5); //adding integers 5,6,7 for positions 0,1,2
showThree.add(1,6);
showThree.add(2,7);
final MyPagerAdapter adapter = new MyPagerAdapter(getApplicationContext(),showThree);
final ViewPager myPager = (ViewPager) findViewById(R.id.mypanelpager);
myPager.setAdapter(adapter);
myPager.setCurrentItem(1);
myPager.setOnPageChangeListener(new OnPageChangeListener(){
#Override
public void onPageScrollStateChanged(int state) {
if (state == ViewPager.SCROLL_STATE_IDLE) {
//when position= 0, change the 3 views from 5,6,7 to 4,5,6.
if (focusedPage == 0) {
showThreeMonths.set(0,4);
showThreeMonths.set(1,5);
showThreeMonths.set(2,6);
adapter.notifyDataSetChanged();
adapter.startUpdate(myPager);
}
else if (focusedPage ==2){
//ignore, just testing focusPage=0 for now }
}
//set current page to the middle of the 3 new views, which would be
//the same view at position 0 of the old 3 views.
//Thus user doesn't experience the views changing despite being 3 new views.
myPager.setCurrentItem(1,false);
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
// TODO Auto-generated method stub
}
#Override
public void onPageSelected(int position) {
focusedPage = position;
}
});
}
PagerAdapter
public class MyPagerAdapter extends PagerAdapter {
private ArrayList<Integer> showThreeMonths;
private Context ctx;
public MyPagerAdapter (Context ctx, ArrayList<Integer> showThree){
this.ctx = ctx ;
this.showThree = showThree;
}
#Override
public int getCount() {
return showThree.size();
}
public Object instantiateItem(ViewGroup collection, int position ){
//NewCustomView is a class I made that takes parameters context and an integer and creates a view based on the integer
NewCustomView MyOwnView = new NewCustomView(ctx, showThree.get(position));
View customViewLayout = MyOwnView.newLayout; //part of the class object
collection.addView(customViewLayout);
return customViewLayout;
}
#Override
public void destroyItem(ViewGroup collection, int position, Object arg2) {
((ViewPager) collection).removeView((ViewGroup) arg2);}
#Override
public Parcelable saveState() {
return null;}
#Override
public boolean isViewFromObject(View view, Object arg1) {
return view==arg1;}
#Override
public void startUpdate(ViewGroup collection) {}
#Override
public void finishUpdate(ViewGroup collection) {}
}
The instantiateItem() method creates the 2 view pages in the memory by default. Therefore when you swipe to the second page then 0 page is recreated as it's outside the range of the 2 pages saved in the memory. Please try to use
myViewPager.setOffscreenPageLimit(numberOfPages)
method that receives an integer as a parameter and declares how many pages it should be keeping before recycling them.