/*
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* Copyright (C) 2016 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 android.print;
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import android.annotation.NonNull;
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import android.content.Context;
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import android.content.Loader;
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import android.os.Handler;
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import android.os.Message;
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import android.printservice.PrintServiceInfo;
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import com.android.internal.util.Preconditions;
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import java.util.List;
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/**
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* Loader for the list of print services. Can be parametrized to select a subset.
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*
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* @hide
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*/
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public class PrintServicesLoader extends Loader<List<PrintServiceInfo>> {
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/** What type of services to load. */
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private final int mSelectionFlags;
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/** The print manager to be used by this object */
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private final @NonNull PrintManager mPrintManager;
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/** Handler to sequentialize the delivery of the results to the main thread */
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private final @NonNull Handler mHandler;
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/** Listens for updates to the data from the platform */
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private PrintManager.PrintServicesChangeListener mListener;
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/**
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* Create a new PrintServicesLoader.
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*
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* @param printManager The print manager supplying the data
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* @param context Context of the using object
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* @param selectionFlags What type of services to load.
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*/
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public PrintServicesLoader(@NonNull PrintManager printManager, @NonNull Context context,
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int selectionFlags) {
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super(Preconditions.checkNotNull(context));
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mHandler = new MyHandler();
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mPrintManager = Preconditions.checkNotNull(printManager);
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mSelectionFlags = Preconditions.checkFlagsArgument(selectionFlags,
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PrintManager.ALL_SERVICES);
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}
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@Override
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protected void onForceLoad() {
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queueNewResult();
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}
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/**
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* Read the print services and queue it to be delivered on the main thread.
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*/
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private void queueNewResult() {
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Message m = mHandler.obtainMessage(0);
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m.obj = mPrintManager.getPrintServices(mSelectionFlags);
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mHandler.sendMessage(m);
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}
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@Override
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protected void onStartLoading() {
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mListener = new PrintManager.PrintServicesChangeListener() {
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@Override public void onPrintServicesChanged() {
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queueNewResult();
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}
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};
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mPrintManager.addPrintServicesChangeListener(mListener, null);
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// Immediately deliver a result
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deliverResult(mPrintManager.getPrintServices(mSelectionFlags));
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}
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@Override
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protected void onStopLoading() {
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if (mListener != null) {
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mPrintManager.removePrintServicesChangeListener(mListener);
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mListener = null;
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}
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mHandler.removeMessages(0);
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}
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@Override
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protected void onReset() {
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onStopLoading();
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}
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/**
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* Handler to sequentialize all the updates to the main thread.
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*/
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private class MyHandler extends Handler {
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/**
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* Create a new handler on the main thread.
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*/
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public MyHandler() {
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super(getContext().getMainLooper());
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}
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@Override
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public void handleMessage(Message msg) {
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if (isStarted()) {
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deliverResult((List<PrintServiceInfo>) msg.obj);
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}
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}
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}
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}
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