1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * Copyright (C) 2016 Mopria Alliance, Inc. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package com.android.bips; 19 20 import android.print.PrintJobId; 21 22 import java.util.ArrayList; 23 import java.util.List; 24 25 /** Manages a job queue, ensuring only one job is printed at a time */ 26 class JobQueue { 27 private final List<LocalPrintJob> mJobs = new ArrayList<>(); 28 private LocalPrintJob mCurrent; 29 30 /** Queue a print job for printing at the next available opportunity */ print(LocalPrintJob job)31 void print(LocalPrintJob job) { 32 mJobs.add(job); 33 startNextJob(); 34 } 35 36 /** Cancel a previously queued job */ cancel(PrintJobId id)37 void cancel(PrintJobId id) { 38 // If a job hasn't started, kill it instantly. 39 for (LocalPrintJob job : mJobs) { 40 if (job.getPrintJobId().equals(id)) { 41 mJobs.remove(job); 42 job.getPrintJob().cancel(); 43 return; 44 } 45 } 46 47 if (mCurrent.getPrintJobId().equals(id)) { 48 mCurrent.cancel(); 49 } 50 } 51 52 /** Launch the next job if possible */ startNextJob()53 private void startNextJob() { 54 if (mJobs.isEmpty() || mCurrent != null) return; 55 56 mCurrent = mJobs.remove(0); 57 mCurrent.start(job -> { 58 mCurrent = null; 59 startNextJob(); 60 }); 61 } 62 }