/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.camera.settings;
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import com.android.camera.async.Observable;
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import com.android.camera.async.SafeCloseable;
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import java.util.concurrent.Executor;
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import javax.annotation.CheckReturnValue;
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import javax.annotation.Nonnull;
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import javax.annotation.concurrent.ThreadSafe;
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/**
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* Wraps a {@link SettingsManager} setting with thread-safe interfaces for
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* observing changes.
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*/
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@ThreadSafe
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public final class SettingObserver<T> implements Observable<T> {
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private class Listener implements SettingsManager.OnSettingChangedListener, SafeCloseable {
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private final Runnable mRunnable;
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private final Executor mExecutor;
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private Listener(Runnable runnable, Executor executor) {
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mRunnable = runnable;
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mExecutor = executor;
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}
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@Override
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public void onSettingChanged(SettingsManager settingsManager, String key) {
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mExecutor.execute(mRunnable);
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}
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@Override
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public void close() {
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mSettingsManager.removeListener(this);
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}
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}
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private final SettingsManager mSettingsManager;
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private final String mScope;
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private final String mKey;
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private final Class<T> mTClass;
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private SettingObserver(SettingsManager manager, String scope, String key, Class<T> tClass) {
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mSettingsManager = manager;
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mScope = scope;
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mKey = key;
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mTClass = tClass;
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}
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public static SettingObserver<Integer> ofInteger(SettingsManager manager,
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String scope, String key) {
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return new SettingObserver<>(manager, scope, key,
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Integer.class);
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}
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public static SettingObserver<String> ofString(SettingsManager manager,
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String scope, String key) {
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return new SettingObserver<>(manager, scope, key,
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String.class);
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}
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public static SettingObserver<Boolean> ofBoolean(SettingsManager manager,
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String scope, String key) {
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return new SettingObserver<>(manager, scope, key,
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Boolean.class);
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}
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@CheckReturnValue
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@Nonnull
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@Override
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public SafeCloseable addCallback(@Nonnull Runnable callback, @Nonnull Executor executor) {
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Listener listener = new Listener(callback, executor);
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mSettingsManager.addListener(listener);
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return listener;
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}
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@Nonnull
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@Override
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@SuppressWarnings("unchecked")
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public T get() {
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if (mTClass.equals(Integer.class)) {
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return (T) Integer.valueOf(mSettingsManager.getInteger(mScope, mKey));
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} else if (mTClass.equals(String.class)) {
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Object string = mSettingsManager.getString(mScope, mKey);
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if (string == null) {
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return null;
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} else {
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return (T) string;
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}
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} else if (mTClass.equals(Boolean.class)) {
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return (T) Boolean.valueOf(mSettingsManager.getBoolean(mScope, mKey));
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} else {
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// Impossible branch
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throw new IllegalStateException("T must be one of {Integer, Boolean, String}");
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}
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}
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}
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