| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package android.databinding.adapters; |
| |
| import android.os.Build.VERSION; |
| import android.os.Build.VERSION_CODES; |
| import android.util.SparseArray; |
| import android.view.View; |
| |
| import java.lang.ref.WeakReference; |
| import java.util.WeakHashMap; |
| |
| public class ListenerUtil { |
| private static SparseArray<WeakHashMap<View, WeakReference<?>>> sListeners = |
| new SparseArray<WeakHashMap<View, WeakReference<?>>>(); |
| |
| /** |
| * This method tracks listeners for a View. Only one listener per listenerResourceId |
| * can be tracked at a time. This is useful for add*Listener and remove*Listener methods |
| * when used with BindingAdapters. This guarantees not to leak the listener or the View, |
| * so will not keep a strong reference to either. |
| * |
| * Example usage: |
| *<pre><code>@BindingAdapter("onFoo") |
| * public static void addFooListener(MyView view, OnFooListener listener) { |
| * OnFooListener oldValue = ListenerUtil.trackListener(view, listener, R.id.fooListener); |
| * if (oldValue != null) { |
| * view.removeOnFooListener(oldValue); |
| * } |
| * if (listener != null) { |
| * view.addOnFooListener(listener); |
| * } |
| * }</code></pre> |
| * |
| * @param view The View that will have this listener |
| * @param listener The listener to keep track of. May be null if the listener is being removed. |
| * @param listenerResourceId A unique resource ID associated with the listener type. |
| * @return The previously tracked listener. This will be null if the View did not have |
| * a previously-tracked listener. |
| */ |
| @SuppressWarnings("unchecked") |
| public static <T> T trackListener(View view, T listener, int listenerResourceId) { |
| if (VERSION.SDK_INT >= VERSION_CODES.ICE_CREAM_SANDWICH) { |
| final T oldValue = (T) view.getTag(listenerResourceId); |
| view.setTag(listenerResourceId, listener); |
| return oldValue; |
| } else { |
| synchronized (sListeners) { |
| WeakHashMap<View, WeakReference<?>> listeners = sListeners.get(listenerResourceId); |
| if (listeners == null) { |
| listeners = new WeakHashMap<View, WeakReference<?>>(); |
| sListeners.put(listenerResourceId, listeners); |
| } |
| final WeakReference<T> oldValue; |
| if (listener == null) { |
| oldValue = (WeakReference<T>) listeners.remove(view); |
| } else { |
| oldValue = (WeakReference<T>) listeners.put(view, new WeakReference(listener)); |
| } |
| if (oldValue == null) { |
| return null; |
| } else { |
| return oldValue.get(); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Returns the previous value for a listener if one was stored previously with |
| * {@link #trackListener(View, Object, int)} |
| * @param view The View to check for a listener previously stored with |
| * {@link #trackListener(View, Object, int)} |
| * @param listenerResourceId A unique resource ID associated with the listener type. |
| * @return The previously tracked listener. This will be null if the View did not have |
| * a previously-tracked listener. |
| */ |
| public static <T> T getListener(View view, int listenerResourceId) { |
| if (VERSION.SDK_INT >= VERSION_CODES.ICE_CREAM_SANDWICH) { |
| return (T) view.getTag(listenerResourceId); |
| } else { |
| synchronized (sListeners) { |
| WeakHashMap<View, WeakReference<?>> listeners = sListeners.get(listenerResourceId); |
| if (listeners == null) { |
| return null; |
| } |
| final WeakReference<T> oldValue = (WeakReference<T>) listeners.get(view); |
| if (oldValue == null) { |
| return null; |
| } else { |
| return oldValue.get(); |
| } |
| } |
| } |
| } |
| } |