I have a viewpager with 3 pages and each of the pages may or may not contain a recyclerview. The count of items in recyclerview vary from users to users. I have made a custom view pager following this question:
How to wrap the height of a ViewPager to the height of its current Fragment?.
The issues that I face now are 2 things:
1. While switching tabs, requestLayout() is called for each of the fragments. So when recyclerview contains a lot of items, there is a lag while switching because It is measuring the tabs again and again. And the items in the recyclerview are dynamic meaning it has a load more item on scroll behavior.
2. When the recyclerview have no items, a textview is shown to indicate the absence of items. Because the viewpager wraps the content, It seems that I cannot center the textview in the fragment. So when there are no recyclerview, I need the viewpager to fill the whole height.
Here is my CustomViewPager code:
public class CustomViewPager extends ViewPager {
private int currentPagePosition = 0;
Context context;
public CustomViewPager(@NonNull Context context) {
super(context);
this.context = context;
}
public CustomViewPager(@NonNull Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
this.context = context;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
View child = getChildAt(currentPagePosition);
if(child != null) {
child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
int h = child.getMeasuredHeight();
heightMeasureSpec = MeasureSpec.makeMeasureSpec(h, MeasureSpec.EXACTLY);
}
if(heightMeasureSpec != 0) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
public void measureCurrentView(int position) {
currentPagePosition = position;
requestLayout();
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return false;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
return false;
}
}
Here is my viewpager layout file:
<?xml version="1.0" encoding="utf-8"?>
<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="0dp"
android:layout_height="250dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:background="#F8F8F8"
android:id="@+id/header"/>
<com.google.android.material.tabs.TabLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/header"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:id="@+id/tabs">
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="1ST"
/>
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="2ND"
/>
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="3RD"
/>
</com.google.android.material.tabs.TabLayout>
<com.example.smilee.adapters.CustomViewPager
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/items"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="@id/tabs"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
And this is the layout for each of the fragments:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
android:background="@android:color/white">
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/recyclerview"
android:nestedScrollingEnabled="false"
android:visibility="gone"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:text="No items to show."
android:fontFamily="@font/medium"
android:textColor="#777"
android:textSize="15dp"
android:gravity="center"
android:id="@+id/noItemText"
android:includeFontPadding="false"
android:visibility="visible"/>
</androidx.constraintlayout.widget.ConstraintLayout>
How to achieve this?
How can I switch between tabs so fast irrespective of count of items in recyclerview and How can I center the textview by filling the whole height if the recyclerview is not available? Hope you can help. Regards.
