MainActivity.java

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/*
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 * Copyright (C) 2015 Google Inc. All Rights Reserved.
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *      http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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package com.example.android.wearable.wear.alwayson;
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import android.app.AlarmManager;
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import android.app.PendingIntent;
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import android.content.Context;
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import android.content.Intent;
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import android.graphics.Color;
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import android.os.Bundle;
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import android.os.Handler;
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import android.os.Message;
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import android.support.wearable.activity.WearableActivity;
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import android.support.wearable.view.WatchViewStub;
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import android.util.Log;
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import android.widget.TextView;
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import java.lang.ref.WeakReference;
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import java.text.SimpleDateFormat;
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import java.util.Date;
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import java.util.Locale;
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import java.util.concurrent.TimeUnit;
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/**
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 * Demonstrates support for Ambient screens by extending WearableActivity and overriding
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 * onEnterAmbient, onUpdateAmbient, and onExitAmbient.
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 *
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 * There are two modes (Active and Ambient). To trigger future updates (data/screen), we use a
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 * custom Handler for the "Active" mode and an Alarm for the "Ambient" mode.
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 *
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 * Why don't we use just one? Handlers are generally less battery intensive and can be triggered
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 * every second. However, they can not wake up the processor (common in Ambient mode).
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 *
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 * Alarms can wake up the processor (what we need for Ambient), but they struggle with quick updates
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 * (less than one second) and are much less efficient compared to Handlers.
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 *
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 * Therefore, we use Handlers for "Active" mode (can trigger every second and are better on the
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 * battery), and we use Alarms for "Ambient" mode (only need to update once every 20 seconds and
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 * they can wake up a sleeping processor).
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 *
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 * Again, the Activity waits 20 seconds between doing any processing (getting data, updating screen
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 * etc.) while in ambient mode to conserving battery life (processor allowed to sleep). If you can
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 * hold off on updates for a full minute, you can throw away all the Alarm code and just use
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 * onUpdateAmbient() to save even more battery life.
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 *
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 * As always, you will still want to apply the performance guidelines outlined in the Watch Faces
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 * documention to your app.
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 *
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 * Finally, in ambient mode, this Activity follows the same best practices outlined in the
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 * Watch Faces API documentation, e.g., keep most pixels black, avoid large blocks of white pixels,
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 * use only black and white, and disable anti-aliasing.
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 *
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 */
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public class MainActivity extends WearableActivity {
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    private static final String TAG = "MainActivity";
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    /** Custom 'what' for Message sent to Handler. */
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    private static final int MSG_UPDATE_SCREEN = 0;
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    /** Milliseconds between updates based on state. */
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    private static final long ACTIVE_INTERVAL_MS = TimeUnit.SECONDS.toMillis(1);
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    private static final long AMBIENT_INTERVAL_MS = TimeUnit.SECONDS.toMillis(20);
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    /** Tracks latest ambient details, such as burnin offsets, etc. */
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    private Bundle mAmbientDetails;
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    private TextView mTimeTextView;
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    private TextView mTimeStampTextView;
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    private TextView mStateTextView;
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    private TextView mUpdateRateTextView;
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    private TextView mDrawCountTextView;
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    private final SimpleDateFormat sDateFormat =
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            new SimpleDateFormat("HH:mm:ss", Locale.US);
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    private volatile int mDrawCount = 0;
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    /**
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     * Since the handler (used in active mode) can't wake up the processor when the device is in
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     * ambient mode and undocked, we use an Alarm to cover ambient mode updates when we need them
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     * more frequently than every minute. Remember, if getting updates once a minute in ambient
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     * mode is enough, you can do away with the Alarm code and just rely on the onUpdateAmbient()
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     * callback.
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     */
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    private AlarmManager mAmbientStateAlarmManager;
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    private PendingIntent mAmbientStatePendingIntent;
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    /**
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     * This custom handler is used for updates in "Active" mode. We use a separate static class to
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     * help us avoid memory leaks.
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     */
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    private final Handler mActiveModeUpdateHandler = new UpdateHandler(this);
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    @Override
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    public void onCreate(Bundle savedInstanceState) {
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        Log.d(TAG, "onCreate()");
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        super.onCreate(savedInstanceState);
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        setContentView(R.layout.activity_main);
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        setAmbientEnabled();
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        mAmbientStateAlarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
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        Intent ambientStateIntent = new Intent(getApplicationContext(), MainActivity.class);
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        mAmbientStatePendingIntent = PendingIntent.getActivity(
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                getApplicationContext(),
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                0 /* requestCode */,
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                ambientStateIntent,
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                PendingIntent.FLAG_UPDATE_CURRENT);
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        /** Determines whether watch is round or square and applies proper view. **/
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        final WatchViewStub stub = (WatchViewStub) findViewById(R.id.watch_view_stub);
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        stub.setOnLayoutInflatedListener(new WatchViewStub.OnLayoutInflatedListener() {
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            @Override
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            public void onLayoutInflated(WatchViewStub stub) {
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                mTimeTextView = (TextView) stub.findViewById(R.id.time);
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                mTimeStampTextView = (TextView) stub.findViewById(R.id.time_stamp);
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                mStateTextView = (TextView) stub.findViewById(R.id.state);
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                mUpdateRateTextView = (TextView) stub.findViewById(R.id.update_rate);
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                mDrawCountTextView = (TextView) stub.findViewById(R.id.draw_count);
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                refreshDisplayAndSetNextUpdate();
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            }
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        });
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    }
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    /**
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     * This is mostly triggered by the Alarms we set in Ambient mode and informs us we need to
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     * update the screen (and process any data).
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     */
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    @Override
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    public void onNewIntent(Intent intent) {
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        Log.d(TAG, "onNewIntent(): " + intent);
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        super.onNewIntent(intent);
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        setIntent(intent);
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        refreshDisplayAndSetNextUpdate();
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    }
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    @Override
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    public void onDestroy() {
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        Log.d(TAG, "onDestroy()");
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        mActiveModeUpdateHandler.removeMessages(MSG_UPDATE_SCREEN);
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        mAmbientStateAlarmManager.cancel(mAmbientStatePendingIntent);
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        super.onDestroy();
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    }
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    /**
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     * Prepares UI for Ambient view.
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     */
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    @Override
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    public void onEnterAmbient(Bundle ambientDetails) {
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        Log.d(TAG, "onEnterAmbient()");
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        super.onEnterAmbient(ambientDetails);
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        /**
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         * In this sample, we aren't using the ambient details bundle (EXTRA_BURN_IN_PROTECTION or
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         * EXTRA_LOWBIT_AMBIENT), but if you need them, you can pull them from the local variable
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         * set here.
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         */
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        mAmbientDetails = ambientDetails;
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        /** Clears Handler queue (only needed for updates in active mode). */
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        mActiveModeUpdateHandler.removeMessages(MSG_UPDATE_SCREEN);
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        /**
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         * Following best practices outlined in WatchFaces API (keeping most pixels black,
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         * avoiding large blocks of white pixels, using only black and white,
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         * and disabling anti-aliasing anti-aliasing, etc.)
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         */
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        mStateTextView.setTextColor(Color.WHITE);
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        mUpdateRateTextView.setTextColor(Color.WHITE);
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        mDrawCountTextView.setTextColor(Color.WHITE);
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        mTimeTextView.getPaint().setAntiAlias(false);
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        mTimeStampTextView.getPaint().setAntiAlias(false);
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        mStateTextView.getPaint().setAntiAlias(false);
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        mUpdateRateTextView.getPaint().setAntiAlias(false);
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        mDrawCountTextView.getPaint().setAntiAlias(false);
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        refreshDisplayAndSetNextUpdate();
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    }
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    /**
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     * Updates UI in Ambient view (once a minute). Because we need to update UI sooner than that
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     * (every ~20 seconds), we also use an Alarm. However, since the processor is awake for this
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     * callback, we might as well call refreshDisplayAndSetNextUpdate() to update screen and reset
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     * the Alarm.
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     *
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     * If you are happy with just updating the screen once a minute in Ambient Mode (which will be
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     * the case a majority of the time), then you can just use this method and remove all
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     * references/code regarding Alarms.
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     */
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    @Override
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    public void onUpdateAmbient() {
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        Log.d(TAG, "onUpdateAmbient()");
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        super.onUpdateAmbient();
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        refreshDisplayAndSetNextUpdate();
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    }
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    /**
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     * Prepares UI for Active view (non-Ambient).
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     */
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    @Override
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    public void onExitAmbient() {
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        Log.d(TAG, "onExitAmbient()");
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        super.onExitAmbient();
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        /** Clears out Alarms since they are only used in ambient mode. */
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        mAmbientStateAlarmManager.cancel(mAmbientStatePendingIntent);
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        mStateTextView.setTextColor(Color.GREEN);
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        mUpdateRateTextView.setTextColor(Color.GREEN);
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        mDrawCountTextView.setTextColor(Color.GREEN);
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        mTimeTextView.getPaint().setAntiAlias(true);
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        mTimeStampTextView.getPaint().setAntiAlias(true);
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        mStateTextView.getPaint().setAntiAlias(true);
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        mUpdateRateTextView.getPaint().setAntiAlias(true);
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        mDrawCountTextView.getPaint().setAntiAlias(true);
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        refreshDisplayAndSetNextUpdate();
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    }
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    /**
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     * Loads data/updates screen (via method), but most importantly, sets up the next refresh
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     * (active mode = Handler and ambient mode = Alarm).
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     */
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    private void refreshDisplayAndSetNextUpdate() {
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        loadDataAndUpdateScreen();
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        long timeMs = System.currentTimeMillis();
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        if (isAmbient()) {
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            /** Calculate next trigger time (based on state). */
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            long delayMs = AMBIENT_INTERVAL_MS - (timeMs % AMBIENT_INTERVAL_MS);
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            long triggerTimeMs = timeMs + delayMs;
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            /**
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             * Note: Make sure you have set activity launchMode to singleInstance in the manifest.
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             * Otherwise, it is easy for the AlarmManager launch intent to open a new activity
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             * every time the Alarm is triggered rather than reusing this Activity.
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             */
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            mAmbientStateAlarmManager.setExact(
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                    AlarmManager.RTC_WAKEUP,
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                    triggerTimeMs,
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                    mAmbientStatePendingIntent);
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        } else {
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            /** Calculate next trigger time (based on state). */
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            long delayMs = ACTIVE_INTERVAL_MS - (timeMs % ACTIVE_INTERVAL_MS);
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            mActiveModeUpdateHandler.removeMessages(MSG_UPDATE_SCREEN);
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            mActiveModeUpdateHandler.sendEmptyMessageDelayed(MSG_UPDATE_SCREEN, delayMs);
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        }
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    }
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    /**
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     * Updates display based on Ambient state. If you need to pull data, you should do it here.
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     */
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    private void loadDataAndUpdateScreen() {
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        mDrawCount += 1;
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        long currentTimeMs = System.currentTimeMillis();
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        Log.d(TAG, "loadDataAndUpdateScreen(): " + currentTimeMs + "(" + isAmbient() + ")");
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        if (isAmbient()) {
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            mTimeTextView.setText(sDateFormat.format(new Date()));
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            mTimeStampTextView.setText(getString(R.string.timestamp_label, currentTimeMs));
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            mStateTextView.setText(getString(R.string.mode_ambient_label));
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            mUpdateRateTextView.setText(
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                    getString(R.string.update_rate_label, (AMBIENT_INTERVAL_MS / 1000)));
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            mDrawCountTextView.setText(getString(R.string.draw_count_label, mDrawCount));
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        } else {
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            mTimeTextView.setText(sDateFormat.format(new Date()));
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            mTimeStampTextView.setText(getString(R.string.timestamp_label, currentTimeMs));
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            mStateTextView.setText(getString(R.string.mode_active_label));
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            mUpdateRateTextView.setText(
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                    getString(R.string.update_rate_label, (ACTIVE_INTERVAL_MS / 1000)));
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            mDrawCountTextView.setText(getString(R.string.draw_count_label, mDrawCount));
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        }
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    }
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    /**
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     * Handler separated into static class to avoid memory leaks.
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     */
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    private static class UpdateHandler extends Handler {
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        private final WeakReference<MainActivity> mMainActivityWeakReference;
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        public UpdateHandler(MainActivity reference) {
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            mMainActivityWeakReference = new WeakReference<MainActivity>(reference);
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        }
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        @Override
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        public void handleMessage(Message message) {
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            MainActivity mainActivity = mMainActivityWeakReference.get();
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            if (mainActivity != null) {
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                switch (message.what) {
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                    case MSG_UPDATE_SCREEN:
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                        mainActivity.refreshDisplayAndSetNextUpdate();
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                        break;
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                }
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            }
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        }
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    }
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}