/*
 * Copyright (C) 2011 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.view;

import android.os.Looper;
import android.os.MessageQueue;
import android.util.Log;

import dalvik.annotation.optimization.FastNative;
import dalvik.system.CloseGuard;

import java.lang.ref.WeakReference;

Provides a low-level mechanism for an application to receive display events
such as vertical sync.
The display event receive is NOT thread safe.  Moreover, its methods must only
be called on the Looper thread to which it is attached.
@hide
/**
 * Provides a low-level mechanism for an application to receive display events
 * such as vertical sync.
 *
 * The display event receive is NOT thread safe.  Moreover, its methods must only
 * be called on the Looper thread to which it is attached.
 *
 * @hide
 */
public abstract class DisplayEventReceiver {

    
When retrieving vsync events, this specifies that the vsync event should happen at the normal
vsync-app tick.

Needs to be kept in sync with frameworks/native/include/gui/ISurfaceComposer.h
/**
     * When retrieving vsync events, this specifies that the vsync event should happen at the normal
     * vsync-app tick.
     * <p>
     * Needs to be kept in sync with frameworks/native/include/gui/ISurfaceComposer.h
     */
    public static final int VSYNC_SOURCE_APP = 0;

    
When retrieving vsync events, this specifies that the vsync event should happen whenever
Surface Flinger is processing a frame.

Needs to be kept in sync with frameworks/native/include/gui/ISurfaceComposer.h
/**
     * When retrieving vsync events, this specifies that the vsync event should happen whenever
     * Surface Flinger is processing a frame.
     * <p>
     * Needs to be kept in sync with frameworks/native/include/gui/ISurfaceComposer.h
     */
    public static final int VSYNC_SOURCE_SURFACE_FLINGER = 1;

    private static final String TAG = "DisplayEventReceiver";

    private final CloseGuard mCloseGuard = CloseGuard.get();

    private long mReceiverPtr;

    // We keep a reference message queue object here so that it is not
    // GC'd while the native peer of the receiver is using them.
    private MessageQueue mMessageQueue;

    private static native long nativeInit(WeakReference<DisplayEventReceiver> receiver,
            MessageQueue messageQueue, int vsyncSource);
    private static native void nativeDispose(long receiverPtr);
    @FastNative
    private static native void nativeScheduleVsync(long receiverPtr);

    
Creates a display event receiver.
Params:
looper – The looper to use when invoking callbacks./**
     * Creates a display event receiver.
     *
     * @param looper The looper to use when invoking callbacks.
     */
    public DisplayEventReceiver(Looper looper) {
        this(looper, VSYNC_SOURCE_APP);
    }

    
Creates a display event receiver.
Params:
looper – The looper to use when invoking callbacks.
vsyncSource – The source of the vsync tick. Must be on of the VSYNC_SOURCE_* values./**
     * Creates a display event receiver.
     *
     * @param looper The looper to use when invoking callbacks.
     * @param vsyncSource The source of the vsync tick. Must be on of the VSYNC_SOURCE_* values.
     */
    public DisplayEventReceiver(Looper looper, int vsyncSource) {
        if (looper == null) {
            throw new IllegalArgumentException("looper must not be null");
        }

        mMessageQueue = looper.getQueue();
        mReceiverPtr = nativeInit(new WeakReference<DisplayEventReceiver>(this), mMessageQueue,
                vsyncSource);

        mCloseGuard.open("dispose");
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            dispose(true);
        } finally {
            super.finalize();
        }
    }

    
Disposes the receiver.
/**
     * Disposes the receiver.
     */
    public void dispose() {
        dispose(false);
    }

    private void dispose(boolean finalized) {
        if (mCloseGuard != null) {
            if (finalized) {
                mCloseGuard.warnIfOpen();
            }
            mCloseGuard.close();
        }

        if (mReceiverPtr != 0) {
            nativeDispose(mReceiverPtr);
            mReceiverPtr = 0;
        }
        mMessageQueue = null;
    }

    
Called when a vertical sync pulse is received. The recipient should render a frame and then call scheduleVsync to schedule the next vertical sync pulse. 
Params:
timestampNanos – The timestamp of the pulse, in the System.nanoTime() timebase.
builtInDisplayId – The surface flinger built-in display id such as SurfaceControl.BUILT_IN_DISPLAY_ID_MAIN.
frame – The frame number.  Increases by one for each vertical sync interval./**
     * Called when a vertical sync pulse is received.
     * The recipient should render a frame and then call {@link #scheduleVsync}
     * to schedule the next vertical sync pulse.
     *
     * @param timestampNanos The timestamp of the pulse, in the {@link System#nanoTime()}
     * timebase.
     * @param builtInDisplayId The surface flinger built-in display id such as
     * {@link SurfaceControl#BUILT_IN_DISPLAY_ID_MAIN}.
     * @param frame The frame number.  Increases by one for each vertical sync interval.
     */
    public void onVsync(long timestampNanos, int builtInDisplayId, int frame) {
    }

    
Called when a display hotplug event is received.
Params:
timestampNanos – The timestamp of the event, in the System.nanoTime() timebase.
builtInDisplayId – The surface flinger built-in display id such as SurfaceControl.BUILT_IN_DISPLAY_ID_HDMI.
connected – True if the display is connected, false if it disconnected./**
     * Called when a display hotplug event is received.
     *
     * @param timestampNanos The timestamp of the event, in the {@link System#nanoTime()}
     * timebase.
     * @param builtInDisplayId The surface flinger built-in display id such as
     * {@link SurfaceControl#BUILT_IN_DISPLAY_ID_HDMI}.
     * @param connected True if the display is connected, false if it disconnected.
     */
    public void onHotplug(long timestampNanos, int builtInDisplayId, boolean connected) {
    }

    
Schedules a single vertical sync pulse to be delivered when the next
display frame begins.
/**
     * Schedules a single vertical sync pulse to be delivered when the next
     * display frame begins.
     */
    public void scheduleVsync() {
        if (mReceiverPtr == 0) {
            Log.w(TAG, "Attempted to schedule a vertical sync pulse but the display event "
                    + "receiver has already been disposed.");
        } else {
            nativeScheduleVsync(mReceiverPtr);
        }
    }

    // Called from native code.
    @SuppressWarnings("unused")
    private void dispatchVsync(long timestampNanos, int builtInDisplayId, int frame) {
        onVsync(timestampNanos, builtInDisplayId, frame);
    }

    // Called from native code.
    @SuppressWarnings("unused")
    private void dispatchHotplug(long timestampNanos, int builtInDisplayId, boolean connected) {
        onHotplug(timestampNanos, builtInDisplayId, connected);
    }
}