I have a vertical RecyclerView hosted in a CoordinatorLayout featuring a collapsing toolbar layout. The ViewHolder for this RecyclerView contains yet another RecyclerView with a GridLayoutManager.
The reason for this nesting is that the inner RecyclerView displays a collection of pictures that can have anywhere between 1 - 20 pictures. I don't know how many pictures there will be, but the span of the Grid must always be 3. Every time I bind the ViewHolder I adjust the layout params of the RecyclerView to just accommodate the contents.
This works great if there is no CollapsingToolBarLayout. However, if there is a collapsing ToolBar, scrolling with my finger on the inner RecyclerView does not scroll the Collapsing toolbar, scrolling on another Item however does.
To reemphasize, in the bound ViewHolder, if I begin to scroll on any other item besides the nested RecyclerView, scrolling works fine. However, If I begin the scroll on the nested RecyclerView, then it breaks.
Is it possible to prevent scrolling interception on the inner RecyclerView and let only the Parent scroll? I would like the inner RecyclerView to still handle clicks however.
Here's a YouTube link for the phenomenon: https://youtu.be/fzj7HmqskzU
Here is the XML for the parent RecyclerView:
<android.support.design.widget.CoordinatorLayout 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=".MainActivityFragment">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
<android.support.design.widget.AppBarLayout
android:id="@+id/app_bar_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="4dp"
app:contentScrim="?attr/colorPrimary"
app:layout_collapseParallaxMultiplier="0.7"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<View
android:id="@+id/header_view"
android:layout_width="match_parent"
android:layout_height="192dp"
android:animateLayoutChanges="true"
android:background="@color/primary" />
<android.support.v7.widget.Toolbar
android:id="@+id/action_bar"
android:layout_width="match_parent"
android:layout_height="@dimen/abc_action_bar_default_height_material"
android:elevation="4dp"
app:layout_collapseMode="pin"
app:popupTheme="@style/Theme.AppCompat.NoActionBar"
app:theme="@style/Theme.AppCompat.NoActionBar" />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
Here's the primary ViewHolder that hosts the nested RecyclerView:
public class SimpleAdapter extends RecyclerView.Adapter<SimpleAdapter.ViewHolder> {
private static final int MODEL_OBJECT = 1;
private List<ModelObject> modelObjects;
private Context context;
private int imageSize;
public SimpleAdapter(List<ModelObject> modelObjects) {
this.modelObjects = modelObjects;
setHasStableIds(true);
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
context = viewGroup.getContext();
int screenWidth= context.getResources().getDisplayMetrics().widthPixels;
imageSize = screenWidth / 3;
final LayoutInflater inflater = LayoutInflater.from(context);
View itemView;
itemView = inflater.inflate(R.layout.fragment_main_row, viewGroup, false);
return new ViewHolder(itemView, viewType);
}
@Override
public void onBindViewHolder(ViewHolder viewHolder, final int position) {
final ModelObject modelObject = modelObjects.get(position);
// set text
modelObject.setPosition(position + 1);
viewHolder.titleTextView.setText(modelObject.getTitle());
viewHolder.positionTextView.setText("" + (position + 1));
adjustsizes(viewHolder.recyclerView, modelObject, imageSize);
final NestedAdapter nestedAdapter = new NestedAdapter(modelObject.getPhotos());
// Create and set GridLayoutManager for RecyclerView
final GridLayoutManager recylerViewGridLayoutManager = new GridLayoutManager(context, 3);
recylerViewGridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
return 1;
}
});
viewHolder.recyclerView.setAdapter(nestedAdapter);
viewHolder.recyclerView.setLayoutManager(recylerViewGridLayoutManager);
}
@Override
public int getItemViewType(int position) {
return MODEL_OBJECT;
}
@Override
public int getItemCount() {
return modelObjects.size();
}
@Override
public long getItemId(int position) {
return modelObjects.get(position).hashCode();
}
private void adjustsizes(RecyclerView recyclerView, ModelObject modelObject, int imageSize) {
LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) recyclerView.getLayoutParams();
if (modelObject.getPhotos() != null) {
Double numberOfRowsDouble = modelObject.getPhotos().size() / 3.0;
int numberOfRowsInt = (numberOfRowsDouble.intValue() < numberOfRowsDouble)
? numberOfRowsDouble.intValue() + 1
: numberOfRowsDouble.intValue();
params.height = imageSize * numberOfRowsInt;
}
}
public static class ViewHolder extends RecyclerView.ViewHolder {
public int viewType;
public ViewGroup mContainer;
public View mDragHandle;
public TextView titleTextView;
public TextView positionTextView;
public RecyclerView recyclerView;
public ViewHolder(View itemView, int viewType) {
super(itemView);
this.viewType = viewType;
mContainer = (ViewGroup) itemView.findViewById(R.id.container);
mDragHandle = itemView.findViewById(R.id.drag_handle);
titleTextView = (TextView) itemView.findViewById(R.id.title);
positionTextView = (TextView) itemView.findViewById(R.id.position);
recyclerView = (RecyclerView) itemView.findViewById(R.id.recycler_view);
}
}
}
Finally, here's the adapter for the nested child with the picture:
public class NestedAdapter extends RecyclerView.Adapter<NestedAdapter.PhotoViewHolder> {
private static final int PHOTO = 1;
private Context context;
ArrayList<String> photos;
/**
* Default constructor, takes no data as nothing has been recieved from the API
*/
public NestedAdapter(ArrayList<String> photos) {
this.photos = photos;
}
@Override
public PhotoViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
this.context = viewGroup.getContext();
View itemView;
switch (viewType) {
default: // Load default Message layout as bucketLists all have the same layout
itemView = LayoutInflater.from(context).inflate(R.layout.fragment_photo_row, viewGroup, false);
break;
}
return new PhotoViewHolder(itemView, viewType);
}
@Override
public void onBindViewHolder(PhotoViewHolder viewHolder, final int position) {
// Switch depending on the kind of View
switch (getItemViewType(position)) {
case PHOTO: // Subtract 1, padding has taken up a space
final String photo = photos.get(position);
Picasso.with(context)
.load(photo)
.placeholder(R.drawable.rocks) // Must use place holder or fit won't work!
.fit()
.centerCrop()
.into(viewHolder.photo);
break;
}
}
@Override
public int getItemViewType(int position) {
return PHOTO;
}
@Override
public int getItemCount() {
return photos.size();
}
// ViewHolder for actual content
public final static class PhotoViewHolder extends RecyclerView.ViewHolder {
public int viewType; // Used to specify the view type.
public ImageView photo;
public PhotoViewHolder(View itemView, int ViewType) {
super(itemView);
switch (ViewType) {
case PHOTO:
viewType = PHOTO;
photo = (ImageView) itemView.findViewById(R.id.photo);
break;
}
}
}
}
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