/*
 * 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 android.view.animation.AnimationUtils;

This class provides a simple callback mechanism to listeners that is synchronized with all
other animators in the system. There is no duration, interpolation, or object value-setting
with this Animator. Instead, it is simply started, after which it proceeds to send out events
on every animation frame to its TimeListener (if set), with information about this animator,
the total elapsed time, and the elapsed time since the previous animation frame.
/**
 * This class provides a simple callback mechanism to listeners that is synchronized with all
 * other animators in the system. There is no duration, interpolation, or object value-setting
 * with this Animator. Instead, it is simply started, after which it proceeds to send out events
 * on every animation frame to its TimeListener (if set), with information about this animator,
 * the total elapsed time, and the elapsed time since the previous animation frame.
 */
public class TimeAnimator extends ValueAnimator {

    private TimeListener mListener;
    private long mPreviousTime = -1;

    @Override
    public void start() {
        mPreviousTime = -1;
        super.start();
    }

    @Override
    boolean animateBasedOnTime(long currentTime) {
        if (mListener != null) {
            long totalTime = currentTime - mStartTime;
            long deltaTime = (mPreviousTime < 0) ? 0 : (currentTime - mPreviousTime);
            mPreviousTime = currentTime;
            mListener.onTimeUpdate(this, totalTime, deltaTime);
        }
        return false;
    }

    @Override
    public void setCurrentPlayTime(long playTime) {
        long currentTime = AnimationUtils.currentAnimationTimeMillis();
        mStartTime = Math.max(mStartTime, currentTime - playTime);
        mStartTimeCommitted = true; // do not allow start time to be compensated for jank
        animateBasedOnTime(currentTime);
    }

    
Sets a listener that is sent update events throughout the life of
an animation.
Params:
listener – the listener to be set./**
     * Sets a listener that is sent update events throughout the life of
     * an animation.
     *
     * @param listener the listener to be set.
     */
    public void setTimeListener(TimeListener listener) {
        mListener = listener;
    }

    @Override
    void animateValue(float fraction) {
        // Noop
    }

    @Override
    void initAnimation() {
        // noop
    }

    
Implementors of this interface can set themselves as update listeners
to a TimeAnimator instance to receive callbacks on every animation frame to receive the total time since the animator started and the delta time since the last frame. The first time the listener is called, deltaTime will be zero. The same is true for totalTime, unless the animator was set to a specific currentPlayTime prior to starting. /**
     * Implementors of this interface can set themselves as update listeners
     * to a <code>TimeAnimator</code> instance to receive callbacks on every animation
     * frame to receive the total time since the animator started and the delta time
     * since the last frame. The first time the listener is called,
     * deltaTime will be zero. The same is true for totalTime, unless the animator was
     * set to a specific {@link ValueAnimator#setCurrentPlayTime(long) currentPlayTime}
     * prior to starting.
     */
    public static interface TimeListener {
        
Notifies listeners of the occurrence of another frame of the animation,
along with information about the elapsed time.
Params:
animation – The animator sending out the notification.
totalTime – The total time elapsed since the animator started, in milliseconds.
deltaTime – The time elapsed since the previous frame, in milliseconds./**
         * <p>Notifies listeners of the occurrence of another frame of the animation,
         * along with information about the elapsed time.</p>
         *
         * @param animation The animator sending out the notification.
         * @param totalTime The total time elapsed since the animator started, in milliseconds.
         * @param deltaTime The time elapsed since the previous frame, in milliseconds.
         */
        void onTimeUpdate(TimeAnimator animation, long totalTime, long deltaTime);

    }
}