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 android.os.Looper;
20import android.os.MessageQueue;
21import android.util.Log;
22
23import dalvik.annotation.optimization.FastNative;
24import dalvik.system.CloseGuard;
25
26import java.lang.ref.WeakReference;
27
28/**
29 * Provides a low-level mechanism for an application to receive display events
30 * such as vertical sync.
31 *
32 * The display event receive is NOT thread safe.  Moreover, its methods must only
33 * be called on the Looper thread to which it is attached.
34 *
35 * @hide
36 */
37public abstract class DisplayEventReceiver {
38
39    /**
40     * When retrieving vsync events, this specifies that the vsync event should happen at the normal
41     * vsync-app tick.
42     * <p>
43     * Needs to be kept in sync with frameworks/native/include/gui/ISurfaceComposer.h
44     */
45    public static final int VSYNC_SOURCE_APP = 0;
46
47    /**
48     * When retrieving vsync events, this specifies that the vsync event should happen whenever
49     * Surface Flinger is processing a frame.
50     * <p>
51     * Needs to be kept in sync with frameworks/native/include/gui/ISurfaceComposer.h
52     */
53    public static final int VSYNC_SOURCE_SURFACE_FLINGER = 1;
54
55    private static final String TAG = "DisplayEventReceiver";
56
57    private final CloseGuard mCloseGuard = CloseGuard.get();
58
59    private long mReceiverPtr;
60
61    // We keep a reference message queue object here so that it is not
62    // GC'd while the native peer of the receiver is using them.
63    private MessageQueue mMessageQueue;
64
65    private static native long nativeInit(WeakReference<DisplayEventReceiver> receiver,
66            MessageQueue messageQueue, int vsyncSource);
67    private static native void nativeDispose(long receiverPtr);
68    @FastNative
69    private static native void nativeScheduleVsync(long receiverPtr);
70
71    /**
72     * Creates a display event receiver.
73     *
74     * @param looper The looper to use when invoking callbacks.
75     */
76    public DisplayEventReceiver(Looper looper) {
77        this(looper, VSYNC_SOURCE_APP);
78    }
79
80    /**
81     * Creates a display event receiver.
82     *
83     * @param looper The looper to use when invoking callbacks.
84     * @param vsyncSource The source of the vsync tick. Must be on of the VSYNC_SOURCE_* values.
85     */
86    public DisplayEventReceiver(Looper looper, int vsyncSource) {
87        if (looper == null) {
88            throw new IllegalArgumentException("looper must not be null");
89        }
90
91        mMessageQueue = looper.getQueue();
92        mReceiverPtr = nativeInit(new WeakReference<DisplayEventReceiver>(this), mMessageQueue,
93                vsyncSource);
94
95        mCloseGuard.open("dispose");
96    }
97
98    @Override
99    protected void finalize() throws Throwable {
100        try {
101            dispose(true);
102        } finally {
103            super.finalize();
104        }
105    }
106
107    /**
108     * Disposes the receiver.
109     */
110    public void dispose() {
111        dispose(false);
112    }
113
114    private void dispose(boolean finalized) {
115        if (mCloseGuard != null) {
116            if (finalized) {
117                mCloseGuard.warnIfOpen();
118            }
119            mCloseGuard.close();
120        }
121
122        if (mReceiverPtr != 0) {
123            nativeDispose(mReceiverPtr);
124            mReceiverPtr = 0;
125        }
126        mMessageQueue = null;
127    }
128
129    /**
130     * Called when a vertical sync pulse is received.
131     * The recipient should render a frame and then call {@link #scheduleVsync}
132     * to schedule the next vertical sync pulse.
133     *
134     * @param timestampNanos The timestamp of the pulse, in the {@link System#nanoTime()}
135     * timebase.
136     * @param builtInDisplayId The surface flinger built-in display id such as
137     * {@link SurfaceControl#BUILT_IN_DISPLAY_ID_MAIN}.
138     * @param frame The frame number.  Increases by one for each vertical sync interval.
139     */
140    public void onVsync(long timestampNanos, int builtInDisplayId, int frame) {
141    }
142
143    /**
144     * Called when a display hotplug event is received.
145     *
146     * @param timestampNanos The timestamp of the event, in the {@link System#nanoTime()}
147     * timebase.
148     * @param builtInDisplayId The surface flinger built-in display id such as
149     * {@link SurfaceControl#BUILT_IN_DISPLAY_ID_HDMI}.
150     * @param connected True if the display is connected, false if it disconnected.
151     */
152    public void onHotplug(long timestampNanos, int builtInDisplayId, boolean connected) {
153    }
154
155    /**
156     * Schedules a single vertical sync pulse to be delivered when the next
157     * display frame begins.
158     */
159    public void scheduleVsync() {
160        if (mReceiverPtr == 0) {
161            Log.w(TAG, "Attempted to schedule a vertical sync pulse but the display event "
162                    + "receiver has already been disposed.");
163        } else {
164            nativeScheduleVsync(mReceiverPtr);
165        }
166    }
167
168    // Called from native code.
169    @SuppressWarnings("unused")
170    private void dispatchVsync(long timestampNanos, int builtInDisplayId, int frame) {
171        onVsync(timestampNanos, builtInDisplayId, frame);
172    }
173
174    // Called from native code.
175    @SuppressWarnings("unused")
176    private void dispatchHotplug(long timestampNanos, int builtInDisplayId, boolean connected) {
177        onHotplug(timestampNanos, builtInDisplayId, connected);
178    }
179}
180