The question was asked more than two years ago, but unfortunately the problem persists.
I finally got a solution to keep the call to the addView and removeView functions in a BottomSheet, while having animateLayoutChanges="true".
BottomSheetBehavior cannot calculate the correct height when it changes, so the height must remain the same. To do this, I set the height of the BottomSheet to match_parent and divide it into two children: the content and a Space that changes height according to the height of the content.
To best mimic the true behavior of a BottomSheet, you also need to add a TouchToDismiss view that darkens the background when the BottomSheet is extended but also to close the BottomSheet when the user presses outside the content.
Here's the code:
activity.xml
<androidx.coordinatorlayout.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=".MainActivity">
<Button
android:id="@+id/show_bottom_sheet"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Show bottom sheet"/>
<View
android:id="@+id/touch_to_dismiss"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clickable="true"
android:background="#9000"/>
<LinearLayout
android:id="@+id/bottom_sheet"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior">
<Space
android:id="@+id/space"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="1"/>
<LinearLayout
android:id="@+id/bottom_sheet_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:animateLayoutChanges="true">
<Button
android:id="@+id/add_or_remove_another_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Add another view"/>
<TextView
android:id="@+id/another_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Another view"/>
</LinearLayout>
</LinearLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
activity.java
BottomSheetBehavior bottomSheetBehavior;
View touchToDismiss;
LinearLayout bottomSheet;
Button showBottomSheet;
Space space;
LinearLayout bottomSheetContent;
Button addOrRemoveAnotherView;
TextView anotherView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
touchToDismiss = findViewById(R.id.touch_to_dismiss);
touchToDismiss.setVisibility(View.GONE);
touchToDismiss.setOnClickListener(this);
bottomSheet = findViewById(R.id.bottom_sheet);
bottomSheetBehavior = BottomSheetBehavior.from(bottomSheet);
bottomSheetBehavior.setPeekHeight(0);
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);
bottomSheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
@Override
public void onStateChanged(@NonNull View bottomSheet, int newState) {
if (newState == BottomSheetBehavior.STATE_HIDDEN || newState == BottomSheetBehavior.STATE_COLLAPSED) {
touchToDismiss.setVisibility(View.GONE);
}else {
touchToDismiss.setVisibility(View.VISIBLE);
}
}
@Override
public void onSlide(@NonNull View bottomSheet, float slideOffset) {
touchToDismiss.setAlpha(getRealOffset());
}
});
showBottomSheet = findViewById(R.id.show_bottom_sheet);
showBottomSheet.setOnClickListener(this);
space = findViewById(R.id.space);
bottomSheetContent = findViewById(R.id.bottom_sheet_content);
addOrRemoveAnotherView = findViewById(R.id.add_or_remove_another_view);
addOrRemoveAnotherView.setOnClickListener(this);
anotherView = findViewById(R.id.another_view);
bottomSheetContent.removeView(anotherView);
}
@Override
public void onClick(View v) {
if (v == showBottomSheet)
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_EXPANDED);
else if (v == addOrRemoveAnotherView) {
if (anotherView.getParent() == null)
bottomSheetContent.addView(anotherView);
else
bottomSheetContent.removeView(anotherView);
}
else if (v == touchToDismiss)
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
}
/**
* Since the height does not change and remains at match_parent, it is required to calculate the true offset.
* @return Real offset of the BottomSheet content.
*/
public float getRealOffset() {
float num = (space.getHeight() + bottomSheetContent.getHeight()) - (bottomSheet.getY() + space.getHeight());
float den = bottomSheetContent.getHeight();
return (num / den);
}
This is the result obtained with this code:
Hopefully it will be useful to someone since the problem is still there!
