AnimationThread.java

/*
 * Copyright (C) 2010 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.animation;

import com.android.ide.common.rendering.api.IAnimationListener;
import com.android.ide.common.rendering.api.RenderSession;
import com.android.ide.common.rendering.api.Result;
import com.android.ide.common.rendering.api.Result.Status;
import com.android.layoutlib.bridge.Bridge;
import com.android.layoutlib.bridge.impl.RenderSessionImpl;

import android.os.Handler;
import android.os.Handler_Delegate;
import android.os.Handler_Delegate.IHandlerCallback;
import android.os.Message;

import java.util.PriorityQueue;
import java.util.Queue;

/**
 * Abstract animation thread.
 * <p/>
 * This does not actually start an animation, instead it fakes a looper that will play whatever
 * animation is sending messages to its own {@link Handler}.
 * <p/>
 * Classes should implement {@link #preAnimation()} and {@link #postAnimation()}.
 * <p/>
 * If {@link #preAnimation()} does not start an animation somehow then the thread doesn't do
 * anything.
 *
 */
public abstract class AnimationThread extends Thread {

    private static class MessageBundle implements Comparable<MessageBundle> {
        final Handler mTarget;
        final Message mMessage;
        final long mUptimeMillis;

        MessageBundle(Handler target, Message message, long uptimeMillis) {
            mTarget = target;
            mMessage = message;
            mUptimeMillis = uptimeMillis;
        }

        @Override
        public int compareTo(MessageBundle bundle) {
            if (mUptimeMillis < bundle.mUptimeMillis) {
                return -1;
            }
            return 1;
        }
    }

    private final RenderSessionImpl mSession;

    private Queue<MessageBundle> mQueue = new PriorityQueue<MessageBundle>();
    private final IAnimationListener mListener;

    public AnimationThread(RenderSessionImpl scene, String threadName,
            IAnimationListener listener) {
        super(threadName);
        mSession = scene;
        mListener = listener;
    }

    public abstract Result preAnimation();
    public abstract void postAnimation();

    @Override
    public void run() {
        Bridge.prepareThread();
        try {
            /* FIXME: The ANIMATION_FRAME message no longer exists.  Instead, the
             * animation timing loop is completely based on a Choreographer objects
             * that schedules animation and drawing frames.  The animation handler is
             * no longer even a handler; it is just a Runnable enqueued on the Choreographer.
            Handler_Delegate.setCallback(new IHandlerCallback() {
                @Override
                public void sendMessageAtTime(Handler handler, Message msg, long uptimeMillis) {
                    if (msg.what == ValueAnimator.ANIMATION_START ||
                            msg.what == ValueAnimator.ANIMATION_FRAME) {
                        mQueue.add(new MessageBundle(handler, msg, uptimeMillis));
                    } else {
                        // just ignore.
                    }
                }
            });
            */

            // call out to the pre-animation work, which should start an animation or more.
            Result result = preAnimation();
            if (result.isSuccess() == false) {
                mListener.done(result);
            }

            // loop the animation
            RenderSession session = mSession.getSession();
            do {
                // check early.
                if (mListener.isCanceled()) {
                    break;
                }

                // get the next message.
                MessageBundle bundle = mQueue.poll();
                if (bundle == null) {
                    break;
                }

                // sleep enough for this bundle to be on time
                long currentTime = System.currentTimeMillis();
                if (currentTime < bundle.mUptimeMillis) {
                    try {
                        sleep(bundle.mUptimeMillis - currentTime);
                    } catch (InterruptedException e) {
                        // FIXME log/do something/sleep again?
                        e.printStackTrace();
                    }
                }

                // check after sleeping.
                if (mListener.isCanceled()) {
                    break;
                }

                // ready to do the work, acquire the scene.
                result = mSession.acquire(250);
                if (result.isSuccess() == false) {
                    mListener.done(result);
                    return;
                }

                // process the bundle. If the animation is not finished, this will enqueue
                // the next message, so mQueue will have another one.
                try {
                    // check after acquiring in case it took a while.
                    if (mListener.isCanceled()) {
                        break;
                    }

                    bundle.mTarget.handleMessage(bundle.mMessage);
                    if (mSession.render(false /*freshRender*/).isSuccess()) {
                        mListener.onNewFrame(session);
                    }
                } finally {
                    mSession.release();
                }
            } while (mListener.isCanceled() == false && mQueue.size() > 0);

            mListener.done(Status.SUCCESS.createResult());

        } catch (Throwable throwable) {
            // can't use Bridge.getLog() as the exception might be thrown outside
            // of an acquire/release block.
            mListener.done(Status.ERROR_UNKNOWN.createResult("Error playing animation", throwable));

        } finally {
            postAnimation();
            Handler_Delegate.setCallback(null);
            Bridge.cleanupThread();
        }
    }
}