Add an adapter for binding an ObservableList to a LinearLayout

EditTexts do not work in ListViews.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/BindingAdapters.java

@@ -1,10 +1,11 @@
 package com.wireguard.android;
 
 import android.databinding.BindingAdapter;
-import android.databinding.ObservableArrayMap;
 import android.databinding.ObservableList;
+import android.databinding.adapters.ListenerUtil;
 import android.graphics.Typeface;
 import android.text.InputFilter;
+import android.widget.LinearLayout;
 import android.widget.ListView;
 import android.widget.TextView;
 
@@ -15,11 +16,34 @@ import android.widget.TextView;
 @SuppressWarnings("unused")
 public final class BindingAdapters {
     @BindingAdapter({"items", "layout"})
-    public static <T> void listBinding(final ListView view,
-                                       final ObservableList<T> oldList, final int oldLayoutId,
-                                       final ObservableList<T> newList, final int newLayoutId) {
-        // Remove any existing binding when there is no new list.
-        if (newList == null) {
+    public static <T> void setItems(final LinearLayout view,
+                                    final ObservableList<T> oldList, final int oldLayoutId,
+                                    final ObservableList<T> newList, final int newLayoutId) {
+        if (oldList == newList && oldLayoutId == newLayoutId)
+            return;
+        ItemChangeListener<T> listener = ListenerUtil.getListener(view, R.id.item_change_listener);
+        // If the layout changes, any existing listener must be replaced.
+        if (listener != null && oldList != null && oldLayoutId != newLayoutId) {
+            listener.setList(null);
+            listener = null;
+        }
+        // Avoid adding a listener when there is no new list or layout.
+        if (newList == null || newLayoutId == 0)
+            return;
+        if (listener == null) {
+            listener = new ItemChangeListener<>(view, newLayoutId);
+            ListenerUtil.trackListener(view, listener, R.id.item_change_listener);
+        }
+        // Either the list changed, or this is an entirely new listener because the layout changed.
+        listener.setList(newList);
+    }
+
+    @BindingAdapter({"items", "layout"})
+    public static <T> void setItems(final ListView view,
+                                    final ObservableList<T> oldList, final int oldLayoutId,
+                                    final ObservableList<T> newList, final int newLayoutId) {
+        // Remove any existing binding when there is no new list or layout.
+        if (newList == null || newLayoutId == 0) {
             view.setAdapter(null);
             return;
         }
@@ -39,11 +63,12 @@ public final class BindingAdapters {
     }
 
     @BindingAdapter({"items", "layout"})
-    public static <K extends Comparable<K>, V> void sortedMapBinding(
-            final ListView view, final ObservableSortedMap<K, V> oldMap, final int oldLayoutId,
+    public static <K extends Comparable<K>, V> void setItems(
+            final ListView view,
+            final ObservableSortedMap<K, V> oldMap, final int oldLayoutId,
             final ObservableSortedMap<K, V> newMap, final int newLayoutId) {
-        // Remove any existing binding when there is no new map.
-        if (newMap == null) {
+        // Remove any existing binding when there is no new map or layout.
+        if (newMap == null || newLayoutId == 0) {
             view.setAdapter(null);
             return;
         }

app/src/main/java/com/wireguard/android/ItemChangeListener.java

@@ -0,0 +1,126 @@
+package com.wireguard.android;
+
+import android.databinding.DataBindingUtil;
+import android.databinding.ObservableList;
+import android.databinding.ViewDataBinding;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import java.lang.ref.WeakReference;
+
+/**
+ * Helper class for binding an ObservableList to the children of a ViewGroup.
+ */
+
+class ItemChangeListener<T> {
+    private final OnListChangedCallback<T> callback = new OnListChangedCallback<>(this);
+    private final ViewGroup container;
+    private final int layoutId;
+    private final LayoutInflater layoutInflater;
+    private ObservableList<T> list;
+
+    ItemChangeListener(final ViewGroup container, final int layoutId) {
+        this.container = container;
+        this.layoutId = layoutId;
+        layoutInflater = LayoutInflater.from(container.getContext());
+    }
+
+    private View getView(final int position, final View convertView) {
+        ViewDataBinding binding = DataBindingUtil.getBinding(convertView);
+        if (binding == null)
+            binding = DataBindingUtil.inflate(layoutInflater, layoutId, container, false);
+        binding.setVariable(BR.item, list.get(position));
+        binding.executePendingBindings();
+        return binding.getRoot();
+    }
+
+    public void setList(final ObservableList<T> newList) {
+        if (list != null)
+            list.removeOnListChangedCallback(callback);
+        list = newList;
+        if (list != null) {
+            list.addOnListChangedCallback(callback);
+            callback.onChanged(list);
+        } else {
+            container.removeAllViews();
+        }
+    }
+
+    private static class OnListChangedCallback<T>
+            extends ObservableList.OnListChangedCallback<ObservableList<T>> {
+
+        private final WeakReference<ItemChangeListener<T>> weakListener;
+
+        private OnListChangedCallback(final ItemChangeListener<T> listener) {
+            weakListener = new WeakReference<>(listener);
+        }
+
+        @Override
+        public void onChanged(final ObservableList<T> sender) {
+            final ItemChangeListener<T> listener = weakListener.get();
+            if (listener != null) {
+                // TODO: recycle views
+                listener.container.removeAllViews();
+                for (int i = 0; i < sender.size(); ++i)
+                    listener.container.addView(listener.getView(i, null));
+            } else {
+                sender.removeOnListChangedCallback(this);
+            }
+        }
+
+        @Override
+        public void onItemRangeChanged(final ObservableList<T> sender, final int positionStart,
+                                       final int itemCount) {
+            final ItemChangeListener<T> listener = weakListener.get();
+            if (listener != null) {
+                for (int i = positionStart; i < positionStart + itemCount; ++i) {
+                    final View child = listener.container.getChildAt(i);
+                    listener.container.removeViewAt(i);
+                    listener.container.addView(listener.getView(i, child));
+                }
+            } else {
+                sender.removeOnListChangedCallback(this);
+            }
+        }
+
+        @Override
+        public void onItemRangeInserted(final ObservableList<T> sender, final int positionStart,
+                                        final int itemCount) {
+            final ItemChangeListener<T> listener = weakListener.get();
+            if (listener != null) {
+                for (int i = positionStart; i < positionStart + itemCount; ++i)
+                    listener.container.addView(listener.getView(i, null));
+            } else {
+                sender.removeOnListChangedCallback(this);
+            }
+        }
+
+        @Override
+        public void onItemRangeMoved(final ObservableList<T> sender, final int fromPosition,
+                                     final int toPosition, final int itemCount) {
+            final ItemChangeListener<T> listener = weakListener.get();
+            if (listener != null) {
+                final View[] views = new View[itemCount];
+                for (int i = 0; i < itemCount; ++i)
+                    views[i] = listener.container.getChildAt(fromPosition + i);
+                listener.container.removeViews(fromPosition, itemCount);
+                for (int i = 0; i < itemCount; ++i)
+                    listener.container.addView(views[i], toPosition + i);
+            } else {
+                sender.removeOnListChangedCallback(this);
+            }
+        }
+
+        @Override
+        public void onItemRangeRemoved(final ObservableList<T> sender, final int positionStart,
+                                       final int itemCount) {
+            final ItemChangeListener<T> listener = weakListener.get();
+            if (listener != null) {
+                listener.container.removeViews(positionStart, itemCount);
+            } else {
+                sender.removeOnListChangedCallback(this);
+            }
+        }
+    }
+}

app/src/main/java/com/wireguard/android/ObservableListAdapter.java

@@ -17,14 +17,14 @@ import java.lang.ref.WeakReference;
  */
 
 class ObservableListAdapter<T> extends BaseAdapter implements ListAdapter {
+    private final OnListChangedCallback<T> callback = new OnListChangedCallback<>(this);
     private final int layoutId;
     private final LayoutInflater layoutInflater;
     private ObservableList<T> list;
-    private final OnListChangedCallback<T> callback = new OnListChangedCallback<>(this);
 
     ObservableListAdapter(final Context context, final int layoutId, final ObservableList<T> list) {
-        layoutInflater = LayoutInflater.from(context);
         this.layoutId = layoutId;
+        layoutInflater = LayoutInflater.from(context);
         setList(list);
     }
 

app/src/main/java/com/wireguard/android/ObservableMapAdapter.java

@@ -19,16 +19,16 @@ import java.util.Collections;
  */
 
 class ObservableMapAdapter<K extends Comparable<K>, V> extends BaseAdapter implements ListAdapter {
+    private final OnMapChangedCallback<K, V> callback = new OnMapChangedCallback<>(this);
     private ArrayList<K> keys;
     private final int layoutId;
     private final LayoutInflater layoutInflater;
     private ObservableSortedMap<K, V> map;
-    private final OnMapChangedCallback<K, V> callback = new OnMapChangedCallback<>(this);
 
     ObservableMapAdapter(final Context context, final int layoutId,
                          final ObservableSortedMap<K, V> map) {
-        layoutInflater = LayoutInflater.from(context);
         this.layoutId = layoutId;
+        layoutInflater = LayoutInflater.from(context);
         setMap(map);
     }
 

app/src/main/res/values/ids.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <item name="item_change_listener" type="id" />
+</resources>