databinding: Add an adapter for the KeyedObservableList
This adapter actually finally implements stable IDs correctly. Signed-off-by: Samuel Holland <samuel@sholland.org>
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package com.wireguard.android.databinding;
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import android.content.Context;
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import android.databinding.DataBindingUtil;
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import android.databinding.ObservableList;
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import android.databinding.ViewDataBinding;
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import android.view.LayoutInflater;
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import android.view.View;
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import android.view.ViewGroup;
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import android.widget.BaseAdapter;
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import com.wireguard.android.BR;
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import com.wireguard.android.util.Keyed;
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import com.wireguard.android.util.KeyedObservableList;
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import java.lang.ref.WeakReference;
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/**
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* A generic {@code ListAdapter} backed by a {@code KeyedObservableList}.
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*/
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class KeyedObservableListAdapter<K, E extends Keyed<? extends K>> extends BaseAdapter {
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private final OnListChangedCallback<E> callback = new OnListChangedCallback<>(this);
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private final int layoutId;
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private final LayoutInflater layoutInflater;
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private KeyedObservableList<K, E> list;
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KeyedObservableListAdapter(final Context context, final int layoutId,
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final KeyedObservableList<K, E> list) {
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this.layoutId = layoutId;
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layoutInflater = LayoutInflater.from(context);
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setList(list);
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}
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@Override
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public int getCount() {
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return list != null ? list.size() : 0;
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}
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@Override
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public E getItem(final int position) {
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if (list == null || position < 0 || position >= list.size())
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return null;
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return list.get(position);
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}
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@Override
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public long getItemId(final int position) {
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final K key = getKey(position);
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return key != null ? key.hashCode() : -1;
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}
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private K getKey(final int position) {
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final E item = getItem(position);
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return item != null ? item.getKey() : null;
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}
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@Override
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public View getView(final int position, final View convertView, final ViewGroup parent) {
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ViewDataBinding binding = DataBindingUtil.getBinding(convertView);
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if (binding == null)
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binding = DataBindingUtil.inflate(layoutInflater, layoutId, parent, false);
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binding.setVariable(BR.collection, list);
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binding.setVariable(BR.key, getKey(position));
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binding.setVariable(BR.item, getItem(position));
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binding.executePendingBindings();
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return binding.getRoot();
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}
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@Override
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public boolean hasStableIds() {
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return true;
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}
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void setList(final KeyedObservableList<K, E> newList) {
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if (list != null)
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list.removeOnListChangedCallback(callback);
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list = newList;
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if (list != null) {
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list.addOnListChangedCallback(callback);
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}
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notifyDataSetChanged();
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}
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private static final class OnListChangedCallback<E extends Keyed<?>>
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extends ObservableList.OnListChangedCallback<ObservableList<E>> {
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private final WeakReference<KeyedObservableListAdapter<?, E>> weakAdapter;
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private OnListChangedCallback(final KeyedObservableListAdapter<?, E> adapter) {
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weakAdapter = new WeakReference<>(adapter);
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}
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@Override
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public void onChanged(final ObservableList<E> sender) {
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final KeyedObservableListAdapter adapter = weakAdapter.get();
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if (adapter != null)
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adapter.notifyDataSetChanged();
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else
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sender.removeOnListChangedCallback(this);
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}
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@Override
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public void onItemRangeChanged(final ObservableList<E> sender, final int positionStart,
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final int itemCount) {
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onChanged(sender);
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}
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@Override
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public void onItemRangeInserted(final ObservableList<E> sender, final int positionStart,
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final int itemCount) {
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onChanged(sender);
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}
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@Override
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public void onItemRangeMoved(final ObservableList<E> sender, final int fromPosition,
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final int toPosition, final int itemCount) {
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onChanged(sender);
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}
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@Override
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public void onItemRangeRemoved(final ObservableList<E> sender, final int positionStart,
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final int itemCount) {
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onChanged(sender);
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}
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}
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}
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