1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
/*
* Copyright (C) 2016 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.print;
import android.annotation.NonNull;
import android.content.Context;
import android.content.Loader;
import android.os.Handler;
import android.os.Message;
import android.printservice.PrintServiceInfo;
import com.android.internal.util.Preconditions;
import java.util.List;
/**
* Loader for the list of print services. Can be parametrized to select a subset.
*
* @hide
*/
public class PrintServicesLoader extends Loader<List<PrintServiceInfo>> {
/** What type of services to load. */
private final int mSelectionFlags;
/** The print manager to be used by this object */
private final @NonNull PrintManager mPrintManager;
/** Handler to sequentialize the delivery of the results to the main thread */
private final @NonNull Handler mHandler;
/** Listens for updates to the data from the platform */
private PrintManager.PrintServicesChangeListener mListener;
/**
* Create a new PrintServicesLoader.
*
* @param printManager The print manager supplying the data
* @param context Context of the using object
* @param selectionFlags What type of services to load.
*/
public PrintServicesLoader(@NonNull PrintManager printManager, @NonNull Context context,
int selectionFlags) {
super(Preconditions.checkNotNull(context));
mHandler = new MyHandler();
mPrintManager = Preconditions.checkNotNull(printManager);
mSelectionFlags = Preconditions.checkFlagsArgument(selectionFlags,
PrintManager.ALL_SERVICES);
}
@Override
protected void onForceLoad() {
queueNewResult();
}
/**
* Read the print services and queue it to be delivered on the main thread.
*/
private void queueNewResult() {
Message m = mHandler.obtainMessage(0);
m.obj = mPrintManager.getPrintServices(mSelectionFlags);
mHandler.sendMessage(m);
}
@Override
protected void onStartLoading() {
mListener = new PrintManager.PrintServicesChangeListener() {
@Override public void onPrintServicesChanged() {
queueNewResult();
}
};
mPrintManager.addPrintServicesChangeListener(mListener, null);
// Immediately deliver a result
deliverResult(mPrintManager.getPrintServices(mSelectionFlags));
}
@Override
protected void onStopLoading() {
if (mListener != null) {
mPrintManager.removePrintServicesChangeListener(mListener);
mListener = null;
}
mHandler.removeMessages(0);
}
@Override
protected void onReset() {
onStopLoading();
}
/**
* Handler to sequentialize all the updates to the main thread.
*/
private class MyHandler extends Handler {
/**
* Create a new handler on the main thread.
*/
public MyHandler() {
super(getContext().getMainLooper());
}
@Override
public void handleMessage(Message msg) {
if (isStarted()) {
deliverResult((List<PrintServiceInfo>) msg.obj);
}
}
}
}
|
