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/*
* 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 com.android.camera.settings;
import com.android.camera.async.Observable;
import com.android.camera.async.SafeCloseable;
import java.util.concurrent.Executor;
import javax.annotation.CheckReturnValue;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.ThreadSafe;
/**
* Wraps a {@link SettingsManager} setting with thread-safe interfaces for
* observing changes.
*/
@ThreadSafe
public final class SettingObserver<T> implements Observable<T> {
private class Listener implements SettingsManager.OnSettingChangedListener, SafeCloseable {
private final Runnable mRunnable;
private final Executor mExecutor;
private Listener(Runnable runnable, Executor executor) {
mRunnable = runnable;
mExecutor = executor;
}
@Override
public void onSettingChanged(SettingsManager settingsManager, String key) {
mExecutor.execute(mRunnable);
}
@Override
public void close() {
mSettingsManager.removeListener(this);
}
}
private final SettingsManager mSettingsManager;
private final String mScope;
private final String mKey;
private final Class<T> mTClass;
private SettingObserver(SettingsManager manager, String scope, String key, Class<T> tClass) {
mSettingsManager = manager;
mScope = scope;
mKey = key;
mTClass = tClass;
}
public static SettingObserver<Integer> ofInteger(SettingsManager manager,
String scope, String key) {
return new SettingObserver<>(manager, scope, key,
Integer.class);
}
public static SettingObserver<String> ofString(SettingsManager manager,
String scope, String key) {
return new SettingObserver<>(manager, scope, key,
String.class);
}
public static SettingObserver<Boolean> ofBoolean(SettingsManager manager,
String scope, String key) {
return new SettingObserver<>(manager, scope, key,
Boolean.class);
}
@CheckReturnValue
@Nonnull
@Override
public SafeCloseable addCallback(@Nonnull Runnable callback, @Nonnull Executor executor) {
Listener listener = new Listener(callback, executor);
mSettingsManager.addListener(listener);
return listener;
}
@Nonnull
@Override
@SuppressWarnings("unchecked")
public T get() {
if (mTClass.equals(Integer.class)) {
return (T) Integer.valueOf(mSettingsManager.getInteger(mScope, mKey));
} else if (mTClass.equals(String.class)) {
Object string = mSettingsManager.getString(mScope, mKey);
if (string == null) {
return null;
} else {
return (T) string;
}
} else if (mTClass.equals(Boolean.class)) {
return (T) Boolean.valueOf(mSettingsManager.getBoolean(mScope, mKey));
} else {
// Impossible branch
throw new IllegalStateException("T must be one of {Integer, Boolean, String}");
}
}
}
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