TextClock.java

/*
 * Copyright (C) 2014 Hippo Seven
 *
 * 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 com.hippo.widget;

import android.content.BroadcastReceiver;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.ContentObserver;
import android.net.Uri;
import android.os.Build;
import android.os.Handler;
import android.os.SystemClock;
import android.provider.Settings;
import android.text.format.DateFormat;
import android.util.AttributeSet;
import android.view.ViewDebug.ExportedProperty;
import android.widget.TextView;

import java.util.Calendar;
import java.util.TimeZone;

public class TextClock extends TextView {

    public static final CharSequence DEFAULT_FORMAT_12_HOUR = "hh:mm a";
    public static final CharSequence DEFAULT_FORMAT_24_HOUR;

    static {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR2)
            DEFAULT_FORMAT_24_HOUR = "kk:mm";
        else
            DEFAULT_FORMAT_24_HOUR = "HH:mm";
    }

    private CharSequence mFormat12;
    private CharSequence mFormat24;

    @ExportedProperty
    private CharSequence mFormat;
    @ExportedProperty
    private boolean mHasSeconds;

    private boolean mAttached;

    private Calendar mTime;
    private String mTimeZone;

    private final ContentObserver mFormatChangeObserver = new ContentObserver(new Handler()) {
        @Override
        public void onChange(boolean selfChange) {
            chooseFormat();
            onTimeChanged();
        }

        @Override
        public void onChange(boolean selfChange, Uri uri) {
            chooseFormat();
            onTimeChanged();
        }
    };

    private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (mTimeZone == null && Intent.ACTION_TIMEZONE_CHANGED.equals(intent.getAction())) {
                final String timeZone = intent.getStringExtra("time-zone");
                createTime(timeZone);
            }
            onTimeChanged();
        }
    };

    private final Runnable mTicker = new Runnable() {
        @Override
        public void run() {
            onTimeChanged();

            long now = SystemClock.uptimeMillis();
            long next = now + (1000 - now % 1000);

            getHandler().postAtTime(mTicker, next);
        }
    };

    public TextClock(Context context) {
        this(context, null);
    }

    public TextClock(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public TextClock(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        mFormat12 = DEFAULT_FORMAT_12_HOUR;
        mFormat24 = DEFAULT_FORMAT_24_HOUR;
        mTimeZone = TimeZone.getDefault().getID();

        init();
    }

    private void init() {
        createTime(mTimeZone);
        // Wait until onAttachedToWindow() to handle the ticker
        chooseFormat(false);
    }

    private void createTime(String timeZone) {
        if (timeZone != null) {
            mTime = Calendar.getInstance(TimeZone.getTimeZone(timeZone));
        } else {
            mTime = Calendar.getInstance();
        }
    }

    public CharSequence getFormat12Hour() {
        return mFormat12;
    }

    public void setFormat12Hour(CharSequence format) {
        mFormat12 = format;

        chooseFormat();
        onTimeChanged();
    }

    public CharSequence getFormat24Hour() {
        return mFormat24;
    }

    public void setFormat24Hour(CharSequence format) {
        mFormat24 = format;

        chooseFormat();
        onTimeChanged();
    }

    public boolean is24HourModeEnabled() {
        return DateFormat.is24HourFormat(getContext());
    }

    public String getTimeZone() {
        return mTimeZone;
    }

    public void setTimeZone(String timeZone) {
        mTimeZone = timeZone;

        createTime(timeZone);
        onTimeChanged();
    }

    /**
     * Selects either one of {@link #getFormat12Hour()} or {@link #getFormat24Hour()}
     * depending on whether the user has selected 24-hour format.
     *
     * Calling this method does not schedule or unschedule the time ticker.
     */
    private void chooseFormat() {
        chooseFormat(true);
    }

    public CharSequence getFormat() {
        return mFormat;
    }

    /**
     * Selects either one of {@link #getFormat12Hour()} or {@link #getFormat24Hour()}
     * depending on whether the user has selected 24-hour format.
     *
     * @param handleTicker true if calling this method should schedule/unschedule the
     *                     time ticker, false otherwise
     */
    private void chooseFormat(boolean handleTicker) {
        final boolean format24Requested = is24HourModeEnabled();

        if (format24Requested) {
            mFormat = mFormat24;
        } else {
            mFormat = mFormat12;
        }

        boolean hadSeconds = mHasSeconds;
        mHasSeconds = DateUtils.hasSeconds(mFormat);

        if (handleTicker && mAttached && hadSeconds != mHasSeconds) {
            if (hadSeconds) getHandler().removeCallbacks(mTicker);
            else mTicker.run();
        }
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();

        if (!mAttached) {
            mAttached = true;

            registerReceiver();
            registerObserver();

            createTime(mTimeZone);

            if (mHasSeconds) {
                mTicker.run();
            } else {
                onTimeChanged();
            }
        }
    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();

        if (mAttached) {
            unregisterReceiver();
            unregisterObserver();

            getHandler().removeCallbacks(mTicker);

            mAttached = false;
        }
    }

    private void registerReceiver() {
        final IntentFilter filter = new IntentFilter();

        filter.addAction(Intent.ACTION_TIME_TICK);
        filter.addAction(Intent.ACTION_TIME_CHANGED);
        filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);

        getContext().registerReceiver(mIntentReceiver, filter, null, getHandler());
    }

    private void registerObserver() {
        final ContentResolver resolver = getContext().getContentResolver();
        resolver.registerContentObserver(Settings.System.CONTENT_URI, true, mFormatChangeObserver);
    }

    private void unregisterReceiver() {
        getContext().unregisterReceiver(mIntentReceiver);
    }

    private void unregisterObserver() {
        final ContentResolver resolver = getContext().getContentResolver();
        resolver.unregisterContentObserver(mFormatChangeObserver);
    }

    private void onTimeChanged() {
        mTime.setTimeInMillis(System.currentTimeMillis());
        setText(DateFormat.format(mFormat, mTime));
    }
}