Initial commit

foudations/mogo-utils/src/main/java/com/mogo/utils/CountDownTimer.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright (C) 2008 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 com.mogo.utils;
+
+import android.os.Handler;
+import android.os.Message;
+import android.os.SystemClock;
+
+/**
+ * Schedule a countdown until a time in the future, with
+ * regular notifications on intervals along the way.
+ *
+ * Example of showing a 30 second countdown in a text field:
+ *
+ * <pre class="prettyprint">
+ * new CountDownTimer(30000, 1000) {
+ *
+ *     public void onTick(long millisUntilFinished) {
+ *         mTextField.setText("seconds remaining: " + millisUntilFinished / 1000);
+ *     }
+ *
+ *     public void onFinish() {
+ *         mTextField.setText("done!");
+ *     }
+ *  }.start();
+ * </pre>
+ *
+ * The calls to {@link #onTick(long)} are synchronized to this object so that
+ * one call to {@link #onTick(long)} won't ever occur before the previous
+ * callback is complete.  This is only relevant when the implementation of
+ * {@link #onTick(long)} takes an amount of time to execute that is significant
+ * compared to the countdown interval.
+ */
+public abstract class CountDownTimer {
+
+    /**
+     * Millis since epoch when alarm should stop.
+     */
+    private final long mMillisInFuture;
+
+    /**
+     * The interval in millis that the user receives callbacks
+     */
+    private final long mCountdownInterval;
+
+    private long mStopTimeInFuture;
+    
+    /**
+    * boolean representing if the timer was cancelled
+    */
+    private boolean mCancelled = false;
+
+    /**
+     * @param millisInFuture The number of millis in the future from the call
+     *   to {@link #start()} until the countdown is done and {@link #onFinish()}
+     *   is called.
+     * @param countDownInterval The interval along the way to receive
+     *   {@link #onTick(long)} callbacks.
+     */
+    public CountDownTimer(long millisInFuture, long countDownInterval) {
+        mMillisInFuture = millisInFuture;
+        mCountdownInterval = countDownInterval;
+    }
+
+    /**
+     * Cancel the countdown.
+     */
+    public synchronized final void cancel() {
+        mCancelled = true;
+        mHandler.removeMessages(MSG);
+    }
+
+    /**
+     * Start the countdown.
+     */
+    public synchronized final CountDownTimer start() {
+        mCancelled = false;
+        if (mMillisInFuture <= 0) {
+            onFinish();
+            return this;
+        }
+        mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;
+        mHandler.sendMessage(mHandler.obtainMessage(MSG));
+        return this;
+    }
+
+
+    /**
+     * Callback fired on regular interval.
+     * @param millisUntilFinished The amount of time until finished.
+     */
+    public abstract void onTick(long millisUntilFinished);
+
+    /**
+     * Callback fired when the time is up.
+     */
+    public abstract void onFinish();
+
+
+    private static final int MSG = 1;
+
+
+    // handles counting down
+    private Handler mHandler = new Handler() {
+
+        @Override
+        public void handleMessage( Message msg) {
+
+            synchronized (CountDownTimer.this) {
+                if (mCancelled) {
+                    return;
+                }
+
+                final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();
+
+                if (millisLeft <= 0) {
+                    onFinish();
+                } else if (millisLeft < mCountdownInterval) {
+                    // no tick, just delay until done
+                    sendMessageDelayed(obtainMessage(MSG), millisLeft);
+                } else {
+                    long lastTickStart = SystemClock.elapsedRealtime();
+                    onTick(millisLeft);
+
+                    // take into account user's onTick taking time to execute
+                    long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime();
+
+                    // special case: user's onTick took more than interval to
+                    // complete, skip to next interval
+                    while (delay < 0) delay += mCountdownInterval;
+
+                    sendMessageDelayed(obtainMessage(MSG), delay);
+                }
+            }
+        }
+    };
+}