/*
 * Copyright (C) 2014 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.support.v17.leanback.app;

import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.animation.Animator;
import android.animation.AnimatorInflater;
import android.animation.TimeInterpolator;
import android.animation.ValueAnimator;
import android.view.InputEvent;
import android.view.animation.AccelerateInterpolator;
import android.animation.ValueAnimator.AnimatorUpdateListener;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.widget.RecyclerView;
import android.support.v17.leanback.R;
import android.support.v17.leanback.animation.LogAccelerateInterpolator;
import android.support.v17.leanback.animation.LogDecelerateInterpolator;
import android.support.v17.leanback.widget.Presenter;
import android.support.v17.leanback.widget.ItemBridgeAdapter;
import android.support.v17.leanback.widget.ObjectAdapter;
import android.support.v17.leanback.widget.ObjectAdapter.DataObserver;
import android.support.v17.leanback.widget.VerticalGridView;
import android.support.v17.leanback.widget.PlaybackControlsRowPresenter;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;

/**
 * A fragment for displaying playback controls and related content.
 * The {@link android.support.v17.leanback.widget.PlaybackControlsRow} is expected to be
 * at position 0 in the adapter.
 */
public class PlaybackOverlayFragment extends DetailsFragment {

    /**
     * No background.
     */
    public static final int BG_NONE = 0;

    /**
     * A dark translucent background.
     */
    public static final int BG_DARK = 1;

    /**
     * A light translucent background.
     */
    public static final int BG_LIGHT = 2;

    public static class OnFadeCompleteListener {
        public void onFadeInComplete() {
        }
        public void onFadeOutComplete() {
        }
    }

    public interface InputEventHandler {
        /**
         * Called when an {@link InputEvent} is received.
         *
         * @return If the event should be consumed, return true. To allow the event to
         * continue on to the next handler, return false.
         */
        public boolean handleInputEvent(InputEvent event);
    }

    private static final String TAG = "PlaybackOverlayFragment";
    private static final boolean DEBUG = false;
    private static final int ANIMATION_MULTIPLIER = 1;

    private static int START_FADE_OUT = 1;

    // Fading status
    private static final int IDLE = 0;
    private static final int IN = 1;
    private static final int OUT = 2;

    private int mAlignPosition;
    private int mPaddingBottom;
    private View mRootView;
    private int mBackgroundType = BG_DARK;
    private int mBgDarkColor;
    private int mBgLightColor;
    private int mShowTimeMs;
    private int mMajorFadeTranslateY, mMinorFadeTranslateY;
    private int mAnimationTranslateY;
    private OnFadeCompleteListener mFadeCompleteListener;
    private InputEventHandler mInputEventHandler;
    private boolean mFadingEnabled = true;
    private int mFadingStatus = IDLE;
    private int mBgAlpha;
    private ValueAnimator mBgFadeInAnimator, mBgFadeOutAnimator;
    private ValueAnimator mControlRowFadeInAnimator, mControlRowFadeOutAnimator;
    private ValueAnimator mDescriptionFadeInAnimator, mDescriptionFadeOutAnimator;
    private ValueAnimator mOtherRowFadeInAnimator, mOtherRowFadeOutAnimator;
    private boolean mTranslateAnimationEnabled;
    private boolean mResetControlsToPrimaryActionsPending;
    private RecyclerView.ItemAnimator mItemAnimator;

    private final Animator.AnimatorListener mFadeListener =
            new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animation) {
            enableVerticalGridAnimations(false);
        }
        @Override
        public void onAnimationRepeat(Animator animation) {
        }
        @Override
        public void onAnimationCancel(Animator animation) {
        }
        @Override
        public void onAnimationEnd(Animator animation) {
            if (DEBUG) Log.v(TAG, "onAnimationEnd " + mBgAlpha);
            if (mBgAlpha > 0) {
                enableVerticalGridAnimations(true);
                startFadeTimer();
                if (mFadeCompleteListener != null) {
                    mFadeCompleteListener.onFadeInComplete();
                }
            } else {
                if (getVerticalGridView() != null) {
                    // Reset focus to the controls row
                    getVerticalGridView().setSelectedPosition(0);
                    resetControlsToPrimaryActions(null);
                }
                if (mFadeCompleteListener != null) {
                    mFadeCompleteListener.onFadeOutComplete();
                }
            }
            mFadingStatus = IDLE;
        }
    };

    private final Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message message) {
            if (message.what == START_FADE_OUT && mFadingEnabled) {
                fade(false);
            }
        }
    };

    private final VerticalGridView.OnTouchInterceptListener mOnTouchInterceptListener =
            new VerticalGridView.OnTouchInterceptListener() {
        public boolean onInterceptTouchEvent(MotionEvent event) {
            return onInterceptInputEvent(event);
        }
    };

    private final VerticalGridView.OnKeyInterceptListener mOnKeyInterceptListener =
            new VerticalGridView.OnKeyInterceptListener() {
        public boolean onInterceptKeyEvent(KeyEvent event) {
            return onInterceptInputEvent(event);
        }
    };

    private void setBgAlpha(int alpha) {
        mBgAlpha = alpha;
        if (mRootView != null) {
            mRootView.getBackground().setAlpha(alpha);
        }
    }

    private void enableVerticalGridAnimations(boolean enable) {
        if (getVerticalGridView() != null) {
            getVerticalGridView().setAnimateChildLayout(enable);
        }
    }

    private void resetControlsToPrimaryActions(ItemBridgeAdapter.ViewHolder vh) {
        if (vh == null && getVerticalGridView() != null) {
            vh = (ItemBridgeAdapter.ViewHolder) getVerticalGridView().findViewHolderForPosition(0);
        }
        if (vh == null) {
            mResetControlsToPrimaryActionsPending = true;
        } else if (vh.getPresenter() instanceof PlaybackControlsRowPresenter) {
            mResetControlsToPrimaryActionsPending = false;
            ((PlaybackControlsRowPresenter) vh.getPresenter()).showPrimaryActions(
                    (PlaybackControlsRowPresenter.ViewHolder) vh.getViewHolder());
            vh.getViewHolder().view.clearFocus();
        }
    }

    /**
     * Enables or disables view fading.  If enabled,
     * the view will be faded in when the fragment starts,
     * and will fade out after a time period.  The timeout
     * period is reset each time {@link #tickle} is called.
     *
     */
    public void setFadingEnabled(boolean enabled) {
        if (DEBUG) Log.v(TAG, "setFadingEnabled " + enabled);
        if (enabled != mFadingEnabled) {
            mFadingEnabled = enabled;
            if (mFadingEnabled) {
                if (isResumed() && mFadingStatus == IDLE
                        && !mHandler.hasMessages(START_FADE_OUT)) {
                    startFadeTimer();
                }
            } else {
                // Ensure fully opaque
                mHandler.removeMessages(START_FADE_OUT);
                fade(true);
            }
        }
    }

    /**
     * Returns true if view fading is enabled.
     */
    public boolean isFadingEnabled() {
        return mFadingEnabled;
    }

    /**
     * Sets the listener to be called when fade in or out has completed.
     */
    public void setFadeCompleteListener(OnFadeCompleteListener listener) {
        mFadeCompleteListener = listener;
    }

    /**
     * Returns the listener to be called when fade in or out has completed.
     */
    public OnFadeCompleteListener getFadeCompleteListener() {
        return mFadeCompleteListener;
    }

    /**
     * Sets the input event handler.
     */
    public final void setInputEventHandler(InputEventHandler handler) {
        mInputEventHandler = handler;
    }

    /**
     * Returns the input event handler.
     */
    public final InputEventHandler getInputEventHandler() {
        return mInputEventHandler;
    }

    /**
     * Tickles the playback controls.  Fades in the view if it was faded out,
     * otherwise resets the fade out timer.  Tickling on input events is handled
     * by the fragment.
     */
    public void tickle() {
        if (DEBUG) Log.v(TAG, "tickle enabled " + mFadingEnabled + " isResumed " + isResumed());
        if (!mFadingEnabled || !isResumed()) {
            return;
        }
        if (mHandler.hasMessages(START_FADE_OUT)) {
            // Restart the timer
            startFadeTimer();
        } else {
            fade(true);
        }
    }

    private static boolean isConsumableKey(KeyEvent keyEvent) {
        if (keyEvent.isSystem()) {
            return false;
        }
        return true;
    }

    private boolean onInterceptInputEvent(InputEvent event) {
        if (DEBUG) Log.v(TAG, "onInterceptInputEvent status " + mFadingStatus +
                " mBgAlpha " + mBgAlpha + " event " + event);
        final boolean controlsHidden = (mFadingStatus == IDLE && mBgAlpha == 0);
        boolean consumeEvent = controlsHidden;
        int keyCode = KeyEvent.KEYCODE_UNKNOWN;

        if (event instanceof KeyEvent) {
            if (consumeEvent) {
                consumeEvent = isConsumableKey((KeyEvent) event);
            }
            keyCode = ((KeyEvent) event).getKeyCode();
        }
        if (!consumeEvent && mInputEventHandler != null) {
            consumeEvent = mInputEventHandler.handleInputEvent(event);
        }
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            // If fading enabled and controls are not hidden, back will be consumed to fade
            // them out (even if the key was consumed by the handler).
            if (mFadingEnabled && !controlsHidden) {
                consumeEvent = true;
                mHandler.removeMessages(START_FADE_OUT);
                fade(false);
            } else if (consumeEvent) {
                tickle();
            }
        } else {
            // Any other key will show the controls
            tickle();
        }
        return consumeEvent;
    }

    @Override
    public void onResume() {
        super.onResume();
        if (mFadingEnabled) {
            setBgAlpha(0);
            fade(true);
        }
        getVerticalGridView().setOnTouchInterceptListener(mOnTouchInterceptListener);
        getVerticalGridView().setOnKeyInterceptListener(mOnKeyInterceptListener);
    }

    private void startFadeTimer() {
        if (mHandler != null) {
            mHandler.removeMessages(START_FADE_OUT);
            mHandler.sendEmptyMessageDelayed(START_FADE_OUT, mShowTimeMs);
        }
    }

    private static ValueAnimator loadAnimator(Context context, int resId) {
        ValueAnimator animator = (ValueAnimator) AnimatorInflater.loadAnimator(context, resId);
        animator.setDuration(animator.getDuration() * ANIMATION_MULTIPLIER);
        return animator;
    }

    private void loadBgAnimator() {
        AnimatorUpdateListener listener = new AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator arg0) {
                setBgAlpha((Integer) arg0.getAnimatedValue());
            }
        };

        mBgFadeInAnimator = loadAnimator(getActivity(), R.animator.lb_playback_bg_fade_in);
        mBgFadeInAnimator.addUpdateListener(listener);
        mBgFadeInAnimator.addListener(mFadeListener);

        mBgFadeOutAnimator = loadAnimator(getActivity(), R.animator.lb_playback_bg_fade_out);
        mBgFadeOutAnimator.addUpdateListener(listener);
        mBgFadeOutAnimator.addListener(mFadeListener);
    }

    private TimeInterpolator mLogDecelerateInterpolator = new LogDecelerateInterpolator(100,0);
    private TimeInterpolator mLogAccelerateInterpolator = new LogAccelerateInterpolator(100,0);

    private View getControlRowView() {
        if (getVerticalGridView() == null) {
            return null;
        }
        RecyclerView.ViewHolder vh = getVerticalGridView().findViewHolderForPosition(0);
        if (vh == null) {
            return null;
        }
        return vh.itemView;
    }

    private void loadControlRowAnimator() {
        final AnimatorListener listener = new AnimatorListener() {
            @Override
            void getViews(ArrayList<View> views) {
                View view = getControlRowView();
                if (view != null) {
                    views.add(view);
                }
            }
        };
        final AnimatorUpdateListener updateListener = new AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator arg0) {
                View view = getControlRowView();
                if (view != null) {
                    final float fraction = (Float) arg0.getAnimatedValue();
                    if (DEBUG) Log.v(TAG, "fraction " + fraction);
                    view.setAlpha(fraction);
                    view.setTranslationY((float) mAnimationTranslateY * (1f - fraction));
                }
            }
        };

        mControlRowFadeInAnimator = loadAnimator(
                getActivity(), R.animator.lb_playback_controls_fade_in);
        mControlRowFadeInAnimator.addUpdateListener(updateListener);
        mControlRowFadeInAnimator.addListener(listener);
        mControlRowFadeInAnimator.setInterpolator(mLogDecelerateInterpolator);

        mControlRowFadeOutAnimator = loadAnimator(
                getActivity(), R.animator.lb_playback_controls_fade_out);
        mControlRowFadeOutAnimator.addUpdateListener(updateListener);
        mControlRowFadeOutAnimator.addListener(listener);
        mControlRowFadeOutAnimator.setInterpolator(mLogAccelerateInterpolator);
    }

    private void loadOtherRowAnimator() {
        final AnimatorListener listener = new AnimatorListener() {
            @Override
            void getViews(ArrayList<View> views) {
                if (getVerticalGridView() == null) {
                    return;
                }
                final int count = getVerticalGridView().getChildCount();
                for (int i = 0; i < count; i++) {
                    View view = getVerticalGridView().getChildAt(i);
                    if (view != null) {
                        views.add(view);
                    }
                }
            }
        };
        final AnimatorUpdateListener updateListener = new AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator arg0) {
                if (getVerticalGridView() == null) {
                    return;
                }
                final float fraction = (Float) arg0.getAnimatedValue();
                for (View view : listener.mViews) {
                    if (getVerticalGridView().getChildPosition(view) > 0) {
                        view.setAlpha(fraction);
                        view.setTranslationY((float) mAnimationTranslateY * (1f - fraction));
                    }
                }
            }
        };

        mOtherRowFadeInAnimator = loadAnimator(
                getActivity(), R.animator.lb_playback_controls_fade_in);
        mOtherRowFadeInAnimator.addListener(listener);
        mOtherRowFadeInAnimator.addUpdateListener(updateListener);
        mOtherRowFadeInAnimator.setInterpolator(mLogDecelerateInterpolator);

        mOtherRowFadeOutAnimator = loadAnimator(
                getActivity(), R.animator.lb_playback_controls_fade_out);
        mOtherRowFadeOutAnimator.addListener(listener);
        mOtherRowFadeOutAnimator.addUpdateListener(updateListener);
        mOtherRowFadeOutAnimator.setInterpolator(new AccelerateInterpolator());
    }

    private void loadDescriptionAnimator() {
        AnimatorUpdateListener listener = new AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator arg0) {
                if (getVerticalGridView() == null) {
                    return;
                }
                ItemBridgeAdapter.ViewHolder adapterVh = (ItemBridgeAdapter.ViewHolder)
                        getVerticalGridView().findViewHolderForPosition(0);
                if (adapterVh != null && adapterVh.getViewHolder()
                        instanceof PlaybackControlsRowPresenter.ViewHolder) {
                    final Presenter.ViewHolder vh = ((PlaybackControlsRowPresenter.ViewHolder)
                            adapterVh.getViewHolder()).mDescriptionViewHolder;
                    if (vh != null) {
                        vh.view.setAlpha((Float) arg0.getAnimatedValue());
                    }
                }
            }
        };

        mDescriptionFadeInAnimator = loadAnimator(
                getActivity(), R.animator.lb_playback_description_fade_in);
        mDescriptionFadeInAnimator.addUpdateListener(listener);
        mDescriptionFadeInAnimator.setInterpolator(mLogDecelerateInterpolator);

        mDescriptionFadeOutAnimator = loadAnimator(
                getActivity(), R.animator.lb_playback_description_fade_out);
        mDescriptionFadeOutAnimator.addUpdateListener(listener);
    }

    private void fade(boolean fadeIn) {
        if (DEBUG) Log.v(TAG, "fade " + fadeIn);
        if (getView() == null) {
            return;
        }
        if ((fadeIn && mFadingStatus == IN) || (!fadeIn && mFadingStatus == OUT)) {
            if (DEBUG) Log.v(TAG, "requested fade in progress");
            return;
        }
        if ((fadeIn && mBgAlpha == 255) || (!fadeIn && mBgAlpha == 0)) {
            if (DEBUG) Log.v(TAG, "fade is no-op");
            return;
        }

        mAnimationTranslateY = getVerticalGridView().getSelectedPosition() == 0 ?
                mMajorFadeTranslateY : mMinorFadeTranslateY;

        if (mFadingStatus == IDLE) {
            if (fadeIn) {
                mBgFadeInAnimator.start();
                mControlRowFadeInAnimator.start();
                mOtherRowFadeInAnimator.start();
                mDescriptionFadeInAnimator.start();
            } else {
                mBgFadeOutAnimator.start();
                mControlRowFadeOutAnimator.start();
                mOtherRowFadeOutAnimator.start();
                mDescriptionFadeOutAnimator.start();
            }
        } else {
            if (fadeIn) {
                mBgFadeOutAnimator.reverse();
                mControlRowFadeOutAnimator.reverse();
                mOtherRowFadeOutAnimator.reverse();
                mDescriptionFadeOutAnimator.reverse();
            } else {
                mBgFadeInAnimator.reverse();
                mControlRowFadeInAnimator.reverse();
                mOtherRowFadeInAnimator.reverse();
                mDescriptionFadeInAnimator.reverse();
            }
        }

        // If fading in while control row is focused, set initial translationY so
        // views slide in from below.
        if (fadeIn && mFadingStatus == IDLE) {
            final int count = getVerticalGridView().getChildCount();
            for (int i = 0; i < count; i++) {
                getVerticalGridView().getChildAt(i).setTranslationY(mAnimationTranslateY);
            }
        }

        mFadingStatus = fadeIn ? IN : OUT;
    }

    /**
     * Sets the list of rows for the fragment.
     */
    @Override
    public void setAdapter(ObjectAdapter adapter) {
        if (getAdapter() != null) {
            getAdapter().unregisterObserver(mObserver);
        }
        super.setAdapter(adapter);
        if (adapter != null) {
            adapter.registerObserver(mObserver);
        }
    }

    @Override
    void setVerticalGridViewLayout(VerticalGridView listview) {
        if (listview == null) {
            return;
        }
        // Padding affects alignment when last row is focused
        // (last is first when there's only one row).
        setBottomPadding(listview, mPaddingBottom);

        // Item alignment affects focused row that isn't the last.
        listview.setItemAlignmentOffset(mAlignPosition);
        listview.setItemAlignmentOffsetPercent(100);

        // Push rows to the bottom.
        listview.setWindowAlignmentOffset(0);
        listview.setWindowAlignmentOffsetPercent(100);
        listview.setWindowAlignment(VerticalGridView.WINDOW_ALIGN_HIGH_EDGE);
    }

    private static void setBottomPadding(View view, int padding) {
        view.setPadding(view.getPaddingLeft(), view.getPaddingTop(),
                view.getPaddingRight(), padding);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mAlignPosition =
                getResources().getDimensionPixelSize(R.dimen.lb_playback_controls_align_bottom);
        mPaddingBottom =
                getResources().getDimensionPixelSize(R.dimen.lb_playback_controls_padding_bottom);
        mBgDarkColor =
                getResources().getColor(R.color.lb_playback_controls_background_dark);
        mBgLightColor =
                getResources().getColor(R.color.lb_playback_controls_background_light);
        mShowTimeMs =
                getResources().getInteger(R.integer.lb_playback_controls_show_time_ms);
        mMajorFadeTranslateY =
                getResources().getDimensionPixelSize(R.dimen.lb_playback_major_fade_translate_y);
        mMinorFadeTranslateY =
                getResources().getDimensionPixelSize(R.dimen.lb_playback_minor_fade_translate_y);

        loadBgAnimator();
        loadControlRowAnimator();
        loadOtherRowAnimator();
        loadDescriptionAnimator();
    }

    /**
     * Sets the background type.
     *
     * @param type One of BG_LIGHT, BG_DARK, or BG_NONE.
     */
    public void setBackgroundType(int type) {
        switch (type) {
        case BG_LIGHT:
        case BG_DARK:
        case BG_NONE:
            if (type != mBackgroundType) {
                mBackgroundType = type;
                updateBackground();
            }
            break;
        default:
            throw new IllegalArgumentException("Invalid background type");
        }
    }

    /**
     * Returns the background type.
     */
    public int getBackgroundType() {
        return mBackgroundType;
    }

    private void updateBackground() {
        if (mRootView != null) {
            int color = mBgDarkColor;
            switch (mBackgroundType) {
                case BG_DARK: break;
                case BG_LIGHT: color = mBgLightColor; break;
                case BG_NONE: color = Color.TRANSPARENT; break;
            }
            mRootView.setBackground(new ColorDrawable(color));
        }
    }

    private void updateControlsBottomSpace(ItemBridgeAdapter.ViewHolder vh) {
        // Add extra space between rows 0 and 1
        if (vh == null && getVerticalGridView() != null) {
            vh = (ItemBridgeAdapter.ViewHolder)
                    getVerticalGridView().findViewHolderForPosition(0);
        }
        if (vh != null && vh.getPresenter() instanceof PlaybackControlsRowPresenter) {
            final int adapterSize = getAdapter() == null ? 0 : getAdapter().size();
            ((PlaybackControlsRowPresenter) vh.getPresenter()).showBottomSpace(
                    (PlaybackControlsRowPresenter.ViewHolder) vh.getViewHolder(),
                    adapterSize > 1);
        }
    }

    private final ItemBridgeAdapter.AdapterListener mAdapterListener =
            new ItemBridgeAdapter.AdapterListener() {
        @Override
        public void onAttachedToWindow(ItemBridgeAdapter.ViewHolder vh) {
            if (DEBUG) Log.v(TAG, "onAttachedToWindow " + vh.getViewHolder().view);
            if ((mFadingStatus == IDLE && mBgAlpha == 0) || mFadingStatus == OUT) {
                if (DEBUG) Log.v(TAG, "setting alpha to 0");
                vh.getViewHolder().view.setAlpha(0);
            }
            if (vh.getPosition() == 0 && mResetControlsToPrimaryActionsPending) {
                resetControlsToPrimaryActions(vh);
            }
        }
        @Override
        public void onDetachedFromWindow(ItemBridgeAdapter.ViewHolder vh) {
            if (DEBUG) Log.v(TAG, "onDetachedFromWindow " + vh.getViewHolder().view);
            // Reset animation state
            vh.getViewHolder().view.setAlpha(1f);
            vh.getViewHolder().view.setTranslationY(0);
            if (vh.getViewHolder() instanceof PlaybackControlsRowPresenter.ViewHolder) {
                Presenter.ViewHolder descriptionVh = ((PlaybackControlsRowPresenter.ViewHolder)
                        vh.getViewHolder()).mDescriptionViewHolder;
                if (descriptionVh != null) {
                    descriptionVh.view.setAlpha(1f);
                }
            }
        }
        @Override
        public void onBind(ItemBridgeAdapter.ViewHolder vh) {
            if (vh.getPosition() == 0) {
                updateControlsBottomSpace(vh);
            }
        }
    };

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        mRootView = super.onCreateView(inflater, container, savedInstanceState);
        mBgAlpha = 255;
        updateBackground();
        getRowsFragment().setExternalAdapterListener(mAdapterListener);
        return mRootView;
    }

    @Override
    public void onDestroyView() {
        mRootView = null;
        super.onDestroyView();
    }

    private final DataObserver mObserver = new DataObserver() {
        public void onChanged() {
            updateControlsBottomSpace(null);
        }
    };

    static abstract class AnimatorListener implements Animator.AnimatorListener {
        ArrayList<View> mViews = new ArrayList<View>();
        ArrayList<Integer> mLayerType = new ArrayList<Integer>();

        public void onAnimationCancel(Animator animation) {
        }
        public void onAnimationRepeat(Animator animation) {
        }
        public void onAnimationStart(Animator animation) {
            getViews(mViews);
            for (View view : mViews) {
                mLayerType.add(view.getLayerType());
                view.setLayerType(View.LAYER_TYPE_HARDWARE, null);
            }
        }
        public void onAnimationEnd(Animator animation) {
            for (int i = 0; i < mViews.size(); i++) {
                mViews.get(i).setLayerType(mLayerType.get(i), null);
            }
            mLayerType.clear();
            mViews.clear();
        }
        abstract void getViews(ArrayList<View> views);
    };
}