1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.view;
18
19import android.os.Parcel;
20import android.os.Parcelable;
21import android.util.Slog;
22
23/**
24 * An input channel specifies the file descriptors used to send input events to
25 * a window in another process.  It is Parcelable so that it can be sent
26 * to the process that is to receive events.  Only one thread should be reading
27 * from an InputChannel at a time.
28 * @hide
29 */
30public final class InputChannel implements Parcelable {
31    private static final String TAG = "InputChannel";
32
33    private static final boolean DEBUG = false;
34
35    public static final Parcelable.Creator<InputChannel> CREATOR
36            = new Parcelable.Creator<InputChannel>() {
37        public InputChannel createFromParcel(Parcel source) {
38            InputChannel result = new InputChannel();
39            result.readFromParcel(source);
40            return result;
41        }
42
43        public InputChannel[] newArray(int size) {
44            return new InputChannel[size];
45        }
46    };
47
48    @SuppressWarnings("unused")
49    private int mPtr; // used by native code
50
51    private static native InputChannel[] nativeOpenInputChannelPair(String name);
52
53    private native void nativeDispose(boolean finalized);
54    private native void nativeTransferTo(InputChannel other);
55    private native void nativeReadFromParcel(Parcel parcel);
56    private native void nativeWriteToParcel(Parcel parcel);
57
58    private native String nativeGetName();
59
60    /**
61     * Creates an uninitialized input channel.
62     * It can be initialized by reading from a Parcel or by transferring the state of
63     * another input channel into this one.
64     */
65    public InputChannel() {
66    }
67
68    @Override
69    protected void finalize() throws Throwable {
70        try {
71            nativeDispose(true);
72        } finally {
73            super.finalize();
74        }
75    }
76
77    /**
78     * Creates a new input channel pair.  One channel should be provided to the input
79     * dispatcher and the other to the application's input queue.
80     * @param name The descriptive (non-unique) name of the channel pair.
81     * @return A pair of input channels.  They are symmetric and indistinguishable.
82     */
83    public static InputChannel[] openInputChannelPair(String name) {
84        if (name == null) {
85            throw new IllegalArgumentException("name must not be null");
86        }
87
88        if (DEBUG) {
89            Slog.d(TAG, "Opening input channel pair '" + name + "'");
90        }
91        return nativeOpenInputChannelPair(name);
92    }
93
94    /**
95     * Gets the name of the input channel.
96     * @return The input channel name.
97     */
98    public String getName() {
99        String name = nativeGetName();
100        return name != null ? name : "uninitialized";
101    }
102
103    /**
104     * Disposes the input channel.
105     * Explicitly releases the reference this object is holding on the input channel.
106     * When all references are released, the input channel will be closed.
107     */
108    public void dispose() {
109        nativeDispose(false);
110    }
111
112    /**
113     * Transfers ownership of the internal state of the input channel to another
114     * instance and invalidates this instance.  This is used to pass an input channel
115     * as an out parameter in a binder call.
116     * @param other The other input channel instance.
117     */
118    public void transferTo(InputChannel outParameter) {
119        if (outParameter == null) {
120            throw new IllegalArgumentException("outParameter must not be null");
121        }
122
123        nativeTransferTo(outParameter);
124    }
125
126    public int describeContents() {
127        return Parcelable.CONTENTS_FILE_DESCRIPTOR;
128    }
129
130    public void readFromParcel(Parcel in) {
131        if (in == null) {
132            throw new IllegalArgumentException("in must not be null");
133        }
134
135        nativeReadFromParcel(in);
136    }
137
138    public void writeToParcel(Parcel out, int flags) {
139        if (out == null) {
140            throw new IllegalArgumentException("out must not be null");
141        }
142
143        nativeWriteToParcel(out);
144
145        if ((flags & PARCELABLE_WRITE_RETURN_VALUE) != 0) {
146            dispose();
147        }
148    }
149
150    @Override
151    public String toString() {
152        return getName();
153    }
154}
155