/*
* Copyright (C) 2006 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 org.edx.mobile.player;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Formatter;
import java.util.List;
import java.util.Locale;
import org.edx.mobile.player.IVideo.IClosedCaption;
import org.edx.mobile.view.custom.SettingPopup;
import org.edx.mobile.view.custom.cc.CCLanguageDialogFragment;
import org.edx.mobile.view.custom.speed.SpeedDialogFragment;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.FragmentManager;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.Point;
import android.net.Uri;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.FrameLayout;
import android.widget.ImageButton;
import android.widget.ProgressBar;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;
import com.google.android.exoplayer.R;
/**
* A view containing controls for a MediaPlayer. Typically contains the
* buttons like "Play/Pause", "Rewind", "Fast Forward" and a progress
* slider. It takes care of synchronizing the controls with the state
* of the MediaPlayer.
* <p>
* The way to use this class is to instantiate it programatically.
* The MediaController will create a default set of controls
* and put them in a window floating above your application. Specifically,
* the controls will float above the view specified with setAnchorView().
* The window will disappear if left idle for three seconds and reappear
* when the user touches the anchor view.
* <p>
* Functions like show() and hide() have no effect when MediaController
* is created in an xml layout.
*
* MediaController will hide and
* show the buttons according to these rules:
* <ul>
* <li> The "previous" and "next" buttons are hidden until setPrevNextListeners()
* has been called
* <li> The "previous" and "next" buttons are visible but disabled if
* setPrevNextListeners() was called with null listeners
* <li> The "rewind" and "fastforward" buttons are shown unless requested
* otherwise by using the MediaController(Context, boolean) constructor
* with the boolean set to false
* </ul>
*/
@SuppressLint("WrongViewCast")
public class EPlayerController extends FrameLayout {
private static final String TAG = "VideoControllerView";
private IEPlayerControl mPlayer;
private Context mContext;
private ViewGroup mAnchor;
private View mRoot;
private ProgressBar mProgress;
private TextView mEndTime, mCurrentTime;
private boolean mShowing;
private boolean mDragging;
private static final int sDefaultTimeout = 3000;
private static final int FADE_OUT = 1;
private static final int SHOW_PROGRESS = 2;
private boolean mUseFastForward;
private boolean mFromXml;
private boolean mListenersSet;
private View.OnClickListener mNextListener, mPrevListener;
StringBuilder mFormatBuilder;
Formatter mFormatter;
private ImageButton mPauseButton;
private ImageButton mFfwdButton;
private ImageButton mRewButton;
private ImageButton mNextButton;
private ImageButton mPrevButton;
private ImageButton mFullscreenButton;
private ImageButton mSettingsButton;
private ImageButton mLmsButton;
private Handler mHandler = new MessageHandler(this);
// private IEventListener mEventListener;
private TextView mTitleTextView;
private SettingPopup mSettingPopup;
public EPlayerController(Context context, AttributeSet attrs) {
super(context, attrs);
mRoot = null;
mContext = context;
mUseFastForward = true;
mFromXml = true;
Log.i(TAG, TAG);
}
public EPlayerController(Context context, boolean useFastForward) {
super(context);
mContext = context;
mUseFastForward = useFastForward;
Log.i(TAG, TAG);
}
public EPlayerController(Context context) {
this(context, true);
}
@Override
public void onFinishInflate() {
if (mRoot != null)
initControllerView(mRoot);
}
public void setMediaPlayer(IEPlayerControl player) {
mPlayer = player;
updatePausePlay();
updateFullScreen();
}
/**
* Set the view that acts as the anchor for the control view.
* This can for example be a VideoView, or your Activity's main view.
* @param view The view to which to anchor the controller when it is visible.
*/
public void setAnchorView(ViewGroup view) {
mAnchor = view;
FrameLayout.LayoutParams frameParams = new FrameLayout.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT
);
removeAllViews();
View v = makeControllerView();
addView(v, frameParams);
}
/**
* Create the view that holds the widgets that control playback.
* Derived classes can override this to create their own.
* @return The controller view.
* @hide This doesn't work as advertised
*/
protected View makeControllerView() {
LayoutInflater inflate = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mRoot = inflate.inflate(R.layout.player_controller, null);
initControllerView(mRoot);
return mRoot;
}
private void initControllerView(View v) {
mPauseButton = (ImageButton) v.findViewById(R.id.pause);
if (mPauseButton != null) {
mPauseButton.requestFocus();
mPauseButton.setOnClickListener(mPauseListener);
}
mFullscreenButton = (ImageButton) v.findViewById(R.id.fullscreen);
if (mFullscreenButton != null) {
mFullscreenButton.requestFocus();
mFullscreenButton.setOnClickListener(mFullscreenListener);
}
mFfwdButton = (ImageButton) v.findViewById(R.id.ffwd);
if (mFfwdButton != null) {
mFfwdButton.setOnClickListener(mFfwdListener);
if (!mFromXml) {
mFfwdButton.setVisibility(mUseFastForward ? View.VISIBLE : View.GONE);
}
}
mRewButton = (ImageButton) v.findViewById(R.id.rew);
if (mRewButton != null) {
mRewButton.setOnClickListener(mRewListener);
if (!mFromXml) {
mRewButton.setVisibility(mUseFastForward ? View.VISIBLE : View.GONE);
}
}
// By default these are hidden. They will be enabled when setPrevNextListeners() is called
mNextButton = (ImageButton) v.findViewById(R.id.next);
if (mNextButton != null && !mFromXml && !mListenersSet) {
mNextButton.setVisibility(View.GONE);
}
mPrevButton = (ImageButton) v.findViewById(R.id.prev);
if (mPrevButton != null && !mFromXml && !mListenersSet) {
mPrevButton.setVisibility(View.GONE);
}
mProgress = (ProgressBar) v.findViewById(R.id.mediacontroller_progress);
if (mProgress != null) {
if (mProgress instanceof SeekBar) {
SeekBar seeker = (SeekBar) mProgress;
seeker.setOnSeekBarChangeListener(mSeekListener);
}
mProgress.setMax(1000);
}
mLmsButton = (ImageButton) v.findViewById(R.id.lms_btn);
if (mLmsButton != null) {
mLmsButton.requestFocus();
mLmsButton.setOnClickListener(mLinkClickListener);
}
mSettingsButton = (ImageButton) v.findViewById(R.id.settings);
if (mSettingsButton != null) {
mSettingsButton.requestFocus();
mSettingsButton.setOnClickListener(mSettingClickListener);
}
mEndTime = (TextView) v.findViewById(R.id.time);
mCurrentTime = (TextView) v.findViewById(R.id.time_current);
mFormatBuilder = new StringBuilder();
mFormatter = new Formatter(mFormatBuilder, Locale.getDefault());
installPrevNextListeners();
mTitleTextView = (TextView) v.findViewById(R.id.video_title);
}
/**
* Show the controller on screen. It will go away
* automatically after 3 seconds of inactivity.
*/
public void show() {
show(sDefaultTimeout);
}
/**
* Disable pause or seek buttons if the stream cannot be paused or seeked.
* This requires the control interface to be a IEPlayerControlExt
*/
private void disableUnsupportedButtons() {
if (mPlayer == null) {
return;
}
try {
if (mPauseButton != null) {
if (!mPlayer.canPause()) {
mPauseButton.setEnabled(false);
} else {
mPauseButton.setEnabled(true);
}
}
if (mRewButton != null) {
if (!mPlayer.canSeekBackward()) {
mRewButton.setEnabled(false);
} else {
mRewButton.setEnabled(true);
}
}
if (mFfwdButton != null) {
if ( !mPlayer.canSeekForward()) {
mFfwdButton.setEnabled(false);
} else {
mFfwdButton.setEnabled(true);
}
}
} catch (IncompatibleClassChangeError ex) {
// We were given an old version of the interface, that doesn't have
// the canPause/canSeekXYZ methods. This is OK, it just means we
// assume the media can be paused and seeked, and so we don't disable
// the buttons.
}
}
/**
* Show the controller on screen. It will go away
* automatically after 'timeout' milliseconds of inactivity.
* @param timeout The timeout in milliseconds. Use 0 to show
* the controller until hide() is called.
*/
public void show(int timeout) {
// check if autoHide is disabled
if ( !mPlayer.isControlPanelAutoHide()) {
// when timeout is zero, control panel does not hide automatically
timeout = 0;
}
if (!mShowing && mAnchor != null) {
setProgress();
if (mPauseButton != null) {
mPauseButton.requestFocus();
}
disableUnsupportedButtons();
FrameLayout.LayoutParams tlp = new FrameLayout.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT,
Gravity.BOTTOM
);
mAnchor.addView(this, tlp);
mShowing = true;
}
updatePausePlay();
updateFullScreen();
updateTitle();
// cause the progress bar to be updated even if mShowing
// was already true. This happens, for example, if we're
// paused with the progress bar showing the user hits play.
mHandler.sendEmptyMessage(SHOW_PROGRESS);
Message msg = mHandler.obtainMessage(FADE_OUT);
if (timeout != 0) {
mHandler.removeMessages(FADE_OUT);
mHandler.sendMessageDelayed(msg, timeout);
}
}
public boolean isShowing() {
return mShowing;
}
/**
* Remove the controller from the screen.
*/
public void hide() {
// remove if any popups are showing
if (mSettingPopup != null) {
mSettingPopup.dismiss();
}
if (mAnchor == null) {
return;
}
try {
mAnchor.removeView(this);
mHandler.removeMessages(SHOW_PROGRESS);
} catch (IllegalArgumentException ex) {
Log.w("MediaController", "already removed");
}
mShowing = false;
}
private String stringForTime(int timeMs) {
int totalSeconds = timeMs / 1000;
int seconds = totalSeconds % 60;
int minutes = (totalSeconds / 60) % 60;
int hours = totalSeconds / 3600;
mFormatBuilder.setLength(0);
if (hours > 0) {
return mFormatter.format("%d:%02d:%02d", hours, minutes, seconds).toString();
} else {
return mFormatter.format("%02d:%02d", minutes, seconds).toString();
}
}
private synchronized int setProgress() {
if (mPlayer == null || mDragging) {
return 0;
}
int position = mPlayer.getCurrentPosition();
int duration = mPlayer.getDuration();
if (mProgress != null) {
if (duration > 0) {
// use long to avoid overflow
long pos = 1000L * position / duration;
mProgress.setProgress( (int) pos);
}
int percent = mPlayer.getBufferPercentage();
mProgress.setSecondaryProgress(percent * 10);
}
if (mEndTime != null)
mEndTime.setText(stringForTime(duration));
if (mCurrentTime != null)
mCurrentTime.setText(stringForTime(position));
return position;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// super.onTouchEvent(event);
show(sDefaultTimeout);
return false;
}
@Override
public boolean onTrackballEvent(MotionEvent ev) {
show(sDefaultTimeout);
return false;
}
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
if (mPlayer == null) {
return true;
}
int keyCode = event.getKeyCode();
final boolean uniqueDown = event.getRepeatCount() == 0
&& event.getAction() == KeyEvent.ACTION_DOWN;
if (keyCode == KeyEvent.KEYCODE_HEADSETHOOK
|| keyCode == KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE
|| keyCode == KeyEvent.KEYCODE_SPACE) {
if (uniqueDown) {
doPauseResume();
show(sDefaultTimeout);
if (mPauseButton != null) {
mPauseButton.requestFocus();
}
}
return true;
} else if (keyCode == KeyEvent.KEYCODE_MEDIA_PLAY) {
if (uniqueDown && !mPlayer.isPlaying()) {
mPlayer.start();
updatePausePlay();
show(sDefaultTimeout);
}
return true;
} else if (keyCode == KeyEvent.KEYCODE_MEDIA_STOP
|| keyCode == KeyEvent.KEYCODE_MEDIA_PAUSE) {
if (uniqueDown && mPlayer.isPlaying()) {
mPlayer.pause();
updatePausePlay();
show(sDefaultTimeout);
}
return true;
} else if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN
|| keyCode == KeyEvent.KEYCODE_VOLUME_UP
|| keyCode == KeyEvent.KEYCODE_VOLUME_MUTE) {
// don't show the controls for volume adjustment
return super.dispatchKeyEvent(event);
} else if (keyCode == KeyEvent.KEYCODE_BACK || keyCode == KeyEvent.KEYCODE_MENU) {
if (uniqueDown) {
hide();
}
return true;
}
show(sDefaultTimeout);
return super.dispatchKeyEvent(event);
}
private View.OnClickListener mPauseListener = new View.OnClickListener() {
public void onClick(View v) {
doPauseResume();
show(sDefaultTimeout);
}
};
private View.OnClickListener mFullscreenListener = new View.OnClickListener() {
public void onClick(View v) {
doToggleFullscreen();
show(sDefaultTimeout);
}
};
private View.OnClickListener mLinkClickListener = new View.OnClickListener() {
public void onClick(View v) {
onLinkClicked();
}
};
private View.OnClickListener mSettingClickListener = new View.OnClickListener() {
public void onClick(View v) {
try{
int[] location = new int[2];
// Get the x, y location and store it in the location[] array
// location[0] = x, location[1] = y.
v.getLocationOnScreen(location);
//Initialize the Point with x, and y positions
Point p = new Point();
p.x = location[0];
p.y = location[1];
setSettingButtonActive(true);
fade();
mSettingPopup = new SettingPopup(getContext(), p) {
@Override
public void onDismiss() {
setSettingButtonActive(false);
unfade();
}
@Override
public void onCcClicked() {
if (getContext() instanceof Activity) {
CCLanguageDialogFragment langsDialog = new CCLanguageDialogFragment(getContext(), mPlayer.getVideo().getClosedCaptions(),
new CCLanguageDialogFragment.IListDialogCallback() {
@Override
public void onItemClicked(IClosedCaption lang) {
mPlayer.getVideo().setSelectedClosedCaption(lang);
}
@Override
public void onNoneClicked() {
mPlayer.getVideo().setSelectedClosedCaption(null);
}
});
langsDialog.setSelected(mPlayer.getVideo().getSelectedClosedCaption());
FragmentManager fm = ((Activity) getContext()).getFragmentManager();
langsDialog.show(fm, "languages");
dismiss();
}
}
@Override
public void onSpeedClicked() {
if (getContext() instanceof Activity) {
List<Float> speeds = new ArrayList<Float>();
speeds.add(0.5f);
speeds.add(1.f);
speeds.add(1.5f);
speeds.add(2.0f);
SpeedDialogFragment speedDialog = new SpeedDialogFragment(getContext(), speeds,
new SpeedDialogFragment.IListDialogCallback() {
@Override
public void onItemClicked(Float speed) {
mPlayer.setPlaybackSpeed(speed);
}
@Override
public void onNoneClicked() {
mPlayer.setPlaybackSpeed(1.0f);
}
});
speedDialog.setSelected(mPlayer.getPlaybackSpeed());
FragmentManager fm = ((Activity) getContext()).getFragmentManager();
speedDialog.show(fm, "speed");
dismiss();
}
}
};
}catch(Exception e){
e.printStackTrace();
}
}
};
private void updateTitle() {
mTitleTextView.setText(mPlayer.getVideo().getTitle());
}
public void updatePausePlay() {
if (mRoot == null || mPauseButton == null || mPlayer == null) {
return;
}
mPauseButton.setBackgroundColor(Color.TRANSPARENT);
if (mPlayer.isPlaying()) {
mPauseButton.setImageResource(R.drawable.ic_pause_button_selector);
} else {
mPauseButton.setImageResource(R.drawable.ic_play_button_selector);
}
}
public void updateFullScreen() {
if (mRoot == null || mFullscreenButton == null || mPlayer == null) {
return;
}
mFullscreenButton.setBackgroundColor(Color.TRANSPARENT);
if (mPlayer.isFullScreen()) {
//mFullscreenButton.setImageResource(R.drawable.ic_fullscreen_exit_selector);
mFullscreenButton.setBackgroundResource(R.drawable.ic_fullscreen_exit_selector);
} else {
//mFullscreenButton.setImageResource(R.drawable.ic_fullscreen_selector);
mFullscreenButton.setBackgroundResource(R.drawable.ic_fullscreen_selector);
}
}
private void doPauseResume() {
if (mPlayer == null) {
return;
}
if (mPlayer.isPlaying()) {
mPlayer.pause();
} else {
mPlayer.start();
}
updatePausePlay();
}
private void onLinkClicked() {
Intent i = new Intent(Intent.ACTION_VIEW);
i.addCategory(Intent.CATEGORY_BROWSABLE);
i.setData(Uri.parse(mPlayer.getVideo().getExternalLink()));
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getContext().startActivity(i);
}
/**
* Toggles player preview between landscape and portrait.
*/
private void doToggleFullscreen() {
mPlayer.toggleFullScreen();
}
// There are two scenarios that can trigger the seekbar listener to trigger:
//
// The first is the user using the touchpad to adjust the posititon of the
// seekbar's thumb. In this case onStartTrackingTouch is called followed by
// a number of onProgressChanged notifications, concluded by onStopTrackingTouch.
// We're setting the field "mDragging" to true for the duration of the dragging
// session to avoid jumps in the position in case of ongoing playback.
//
// The second scenario involves the user operating the scroll ball, in this
// case there WON'T BE onStartTrackingTouch/onStopTrackingTouch notifications,
// we will simply apply the updated position without suspending regular updates.
private OnSeekBarChangeListener mSeekListener = new OnSeekBarChangeListener() {
public void onStartTrackingTouch(SeekBar bar) {
show(3600000);
mDragging = true;
// By removing these pending progress messages we make sure
// that a) we won't update the progress while the user adjusts
// the seekbar and b) once the user is done dragging the thumb
// we will post one of these messages to the queue again and
// this ensures that there will be exactly one message queued up.
mHandler.removeMessages(SHOW_PROGRESS);
}
public synchronized void onProgressChanged(SeekBar bar, int progress, boolean fromuser) {
if (mPlayer == null) {
return;
}
if (!fromuser) {
// We're not interested in programmatically generated changes to
// the progress bar's position.
return;
}
long duration = mPlayer.getDuration();
long newposition = (duration * progress) / 1000L;
mPlayer.seekTo( (int) newposition);
if (mCurrentTime != null)
mCurrentTime.setText(stringForTime( (int) newposition));
}
public void onStopTrackingTouch(SeekBar bar) {
mDragging = false;
setProgress();
updatePausePlay();
show(sDefaultTimeout);
// Ensure that progress is properly updated in the future,
// the call to show() does not guarantee this because it is a
// no-op if we are already showing.
mHandler.sendEmptyMessage(SHOW_PROGRESS);
}
};
@Override
public void setEnabled(boolean enabled) {
if (mPauseButton != null) {
mPauseButton.setEnabled(enabled);
}
if (mFfwdButton != null) {
mFfwdButton.setEnabled(enabled);
}
if (mRewButton != null) {
mRewButton.setEnabled(enabled);
}
if (mNextButton != null) {
mNextButton.setEnabled(enabled && mNextListener != null);
}
if (mPrevButton != null) {
mPrevButton.setEnabled(enabled && mPrevListener != null);
}
if (mLmsButton != null) {
mLmsButton.setEnabled(enabled);
}
if (mProgress != null) {
mProgress.setEnabled(enabled);
}
disableUnsupportedButtons();
super.setEnabled(enabled);
}
@Override
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(event);
event.setClassName(EPlayerController.class.getName());
}
@Override
public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(info);
info.setClassName(EPlayerController.class.getName());
}
private View.OnClickListener mRewListener = new View.OnClickListener() {
public void onClick(View v) {
if (mPlayer == null) {
return;
}
int pos = mPlayer.getCurrentPosition();
// apply 30 seconds rewind
pos -= (30 * 1000); // milliseconds
mPlayer.seekTo(pos);
setProgress();
show(sDefaultTimeout);
}
};
private View.OnClickListener mFfwdListener = new View.OnClickListener() {
public void onClick(View v) {
if (mPlayer == null) {
return;
}
int pos = mPlayer.getCurrentPosition();
// apply 30 seconds forward
pos += (30 * 1000); // milliseconds
mPlayer.seekTo(pos);
setProgress();
show(sDefaultTimeout);
}
};
private void installPrevNextListeners() {
if(mNextListener!=null){
if (mNextButton != null) {
mNextButton.setOnClickListener(mNextListener);
mNextButton.setEnabled(mNextListener != null);
}
}
if(mPrevListener!=null){
if (mPrevButton != null) {
mPrevButton.setOnClickListener(mPrevListener);
mPrevButton.setEnabled(mPrevListener != null);
}
}
}
public void setPrevNextListeners(View.OnClickListener next, View.OnClickListener prev) {
mNextListener = next;
mPrevListener = prev;
mListenersSet = true;
if (mRoot != null) {
installPrevNextListeners();
if (mNextButton != null && !mFromXml) {
if(mNextListener!=null){
mNextButton.setVisibility(View.VISIBLE);
}else{
mNextButton.setVisibility(View.GONE);
}
}
if (mPrevButton != null && !mFromXml) {
if(mPrevListener!=null){
mPrevButton.setVisibility(View.VISIBLE);
}else{
mPrevButton.setVisibility(View.GONE);
}
}
}
}
private static class MessageHandler extends Handler {
private final WeakReference<EPlayerController> mView;
MessageHandler(EPlayerController view) {
mView = new WeakReference<EPlayerController>(view);
}
@Override
public void handleMessage(Message msg) {
try {
EPlayerController view = mView.get();
if (view == null || view.mPlayer == null) {
return;
}
int pos;
switch (msg.what) {
case FADE_OUT:
view.hide();
break;
case SHOW_PROGRESS:
pos = view.setProgress();
if (!view.mDragging && view.mShowing && view.mPlayer.isPlaying()) {
msg = obtainMessage(SHOW_PROGRESS);
sendMessageDelayed(msg, 1000 - (pos % 1000));
}
break;
}
} catch(Exception ex) {
ex.printStackTrace();
}
}
}
public void hideProgress() {
this.mProgress.setVisibility(View.INVISIBLE);
}
public void showProgress() {
this.mProgress.setVisibility(View.VISIBLE);
}
private void playNext() {
if (mNextListener != null
&& mNextButton != null
&& mNextButton.getVisibility() == View.VISIBLE) {
mNextListener.onClick(mNextButton);
}
}
private void playPrevious() {
if (mPrevListener != null
&& mPrevButton != null
&& mPrevButton.getVisibility() == View.VISIBLE) {
mPrevListener.onClick(mPrevButton);
}
}
private void setSettingButtonActive(boolean isActive){
if(mSettingsButton!=null){
if(isActive){
mSettingsButton.setBackgroundResource
(R.drawable.ic_media_settings_active);
}else{
mSettingsButton.setBackgroundResource
(R.drawable.ic_media_settings_inactive);
}
}
}
/**
* Fades out the preview.
*/
private void fade() {
mRoot.findViewById(R.id.preview_fader).setVisibility(View.VISIBLE);
}
/**
* Clears the fade on the preview.
*/
private void unfade() {
mRoot.findViewById(R.id.preview_fader).setVisibility(View.GONE);
}
}