1/*
2 * Copyright (C) 2011 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 dalvik.system.CloseGuard;
20
21import android.os.Looper;
22import android.os.MessageQueue;
23import android.util.Log;
24
25import java.lang.ref.WeakReference;
26
27/**
28 * Provides a low-level mechanism for an application to receive display events
29 * such as vertical sync.
30 *
31 * The display event receive is NOT thread safe.  Moreover, its methods must only
32 * be called on the Looper thread to which it is attached.
33 *
34 * @hide
35 */
36public abstract class DisplayEventReceiver {
37    private static final String TAG = "DisplayEventReceiver";
38
39    private final CloseGuard mCloseGuard = CloseGuard.get();
40
41    private long mReceiverPtr;
42
43    // We keep a reference message queue object here so that it is not
44    // GC'd while the native peer of the receiver is using them.
45    private MessageQueue mMessageQueue;
46
47    private static native long nativeInit(WeakReference<DisplayEventReceiver> receiver,
48            MessageQueue messageQueue);
49    private static native void nativeDispose(long receiverPtr);
50    private static native void nativeScheduleVsync(long receiverPtr);
51
52    /**
53     * Creates a display event receiver.
54     *
55     * @param looper The looper to use when invoking callbacks.
56     */
57    public DisplayEventReceiver(Looper looper) {
58        if (looper == null) {
59            throw new IllegalArgumentException("looper must not be null");
60        }
61
62        mMessageQueue = looper.getQueue();
63        mReceiverPtr = nativeInit(new WeakReference<DisplayEventReceiver>(this), mMessageQueue);
64
65        mCloseGuard.open("dispose");
66    }
67
68    @Override
69    protected void finalize() throws Throwable {
70        try {
71            dispose(true);
72        } finally {
73            super.finalize();
74        }
75    }
76
77    /**
78     * Disposes the receiver.
79     */
80    public void dispose() {
81        dispose(false);
82    }
83
84    private void dispose(boolean finalized) {
85        if (mCloseGuard != null) {
86            if (finalized) {
87                mCloseGuard.warnIfOpen();
88            }
89            mCloseGuard.close();
90        }
91
92        if (mReceiverPtr != 0) {
93            nativeDispose(mReceiverPtr);
94            mReceiverPtr = 0;
95        }
96        mMessageQueue = null;
97    }
98
99    /**
100     * Called when a vertical sync pulse is received.
101     * The recipient should render a frame and then call {@link #scheduleVsync}
102     * to schedule the next vertical sync pulse.
103     *
104     * @param timestampNanos The timestamp of the pulse, in the {@link System#nanoTime()}
105     * timebase.
106     * @param builtInDisplayId The surface flinger built-in display id such as
107     * {@link SurfaceControl#BUILT_IN_DISPLAY_ID_MAIN}.
108     * @param frame The frame number.  Increases by one for each vertical sync interval.
109     */
110    public void onVsync(long timestampNanos, int builtInDisplayId, int frame) {
111    }
112
113    /**
114     * Called when a display hotplug event is received.
115     *
116     * @param timestampNanos The timestamp of the event, in the {@link System#nanoTime()}
117     * timebase.
118     * @param builtInDisplayId The surface flinger built-in display id such as
119     * {@link SurfaceControl#BUILT_IN_DISPLAY_ID_HDMI}.
120     * @param connected True if the display is connected, false if it disconnected.
121     */
122    public void onHotplug(long timestampNanos, int builtInDisplayId, boolean connected) {
123    }
124
125    /**
126     * Schedules a single vertical sync pulse to be delivered when the next
127     * display frame begins.
128     */
129    public void scheduleVsync() {
130        if (mReceiverPtr == 0) {
131            Log.w(TAG, "Attempted to schedule a vertical sync pulse but the display event "
132                    + "receiver has already been disposed.");
133        } else {
134            nativeScheduleVsync(mReceiverPtr);
135        }
136    }
137
138    // Called from native code.
139    @SuppressWarnings("unused")
140    private void dispatchVsync(long timestampNanos, int builtInDisplayId, int frame) {
141        onVsync(timestampNanos, builtInDisplayId, frame);
142    }
143
144    // Called from native code.
145    @SuppressWarnings("unused")
146    private void dispatchHotplug(long timestampNanos, int builtInDisplayId, boolean connected) {
147        onHotplug(timestampNanos, builtInDisplayId, connected);
148    }
149}
150