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