TimerInternal.java

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// -*- mode: java; c-basic-offset: 2; -*-
// Copyright 2009-2011 Google, All Rights reserved
// Copyright 2011-2012 MIT, All rights reserved
// Released under the Apache License, Version 2.0
// http://www.apache.org/licenses/LICENSE-2.0
 
package com.google.appinventor.components.runtime.util;
 
import com.google.appinventor.components.runtime.AlarmHandler;
 
import android.os.Handler;
 
public final class TimerInternal implements Runnable {
 
  // Android message handler used as a timer
  private Handler handler;
 
  // Indicates whether the timer is running or not
  private boolean enabled;  // set in constructor
 
  // Interval between timer events in ms
  private int interval;  // set in constructor
 
  // Component that should be called by timer
  private AlarmHandler component;
 
  public TimerInternal(AlarmHandler component, boolean enabled, int interval) {
    this(component, enabled, interval, new Handler());
  }
 
  public TimerInternal(AlarmHandler component, boolean enabled, int interval, Handler handler) {
    this.handler = handler;
    this.component = component;
 
    // Set properties to default values specified by caller.
    this.enabled = enabled;
    this.interval = interval;
    if (enabled) {
      handler.postDelayed(this, interval);
    }
  }
 
  public int Interval() {
    return interval;
  }
 
  public void Interval(int interval) {
    this.interval = interval;
    if (enabled) {
      handler.removeCallbacks(this);
      handler.postDelayed(this, interval);
    }
  }
 
  public boolean Enabled() {
    return enabled;
  }
 
  public void Enabled(boolean enabled) {
    if (this.enabled) {
      handler.removeCallbacks(this);
    }
 
    this.enabled = enabled;
 
    if (enabled) {
      handler.postDelayed(this, interval);
    }
  }
 
  // Runnable implementation
 
  public void run() {
    if (enabled) {
      component.alarm();
 
      // During the call to component.alarm, the enabled field may have changed.
      // We need to make sure that enabled is still true before we call handler.postDelayed.
      if (enabled) {
        handler.postDelayed(this, interval);
      }
    }
  }
}