安卓CountDownTimer - 刻度之间的附加毫秒​​的延迟 [英] android CountDownTimer - additional milliseconds delay between ticks

问题描述

从我的观察刻度线之间的安卓CountDownTimer countDownInterval恰好是不准确，countDownInterval经常比指定的不再是几毫秒。所述countDownInterval在我的特定的应用程序是1000毫秒，只是向下计数了一定量的时间与一个第二台阶。

From my observation the android CountDownTimer countDownInterval between ticks happens to be not accurate, the countDownInterval is regularly a few milliseconds longer than specified. The countDownInterval in my specific app is 1000ms, just counting down a certain amount of time with one second steps.

由于这一长期蜱我最终有较少蜱当时就想，当在countdowntimer运行足够长的时间它搞砸了的时候显示倒计时（2第二步发生在用户界面级别时，足够的额外毫秒总结了）

Due to this prolonged ticks I end up having less ticks then wanted when the the countdowntimer runs long enough which screws up the displayed countdown of the time (a 2 second step happens on the UI level when enough additional ms have summed up)

展望CountDownTimer源似乎可以扭转它，所以它改正这种不必要的误差但我不知道是否有已经在Java / Android的世界变得更加美好CountDownTimer可用。

Looking into the source of CountDownTimer it seems possible to twist it so it corrects this unwanted inaccuracy yet I was wondering if there is already a better CountDownTimer available in the java/android world.

谢谢哥们任何指针...

Thanks buddies for any pointer ...

推荐答案

重写

正如你所说，你也注意到，在接下来的时间 onTick（）从时间计算的previous onTick（） 运行，其中介绍了的每次的勾选一个微小的错误。我改变了CountDownTimer源$ C ​​$ C调用每个 onTick（）从开始时间指定的时间间隔。

As you said, you also noticed that the next time in onTick() is calculated from the time the previous onTick() ran, which introduces a tiny error on every tick. I changed the CountDownTimer source code to call each onTick() at the specified intervals from the start time.

我建立这个于CountDownTimer框架，因此，剪切和放大器;粘贴<一href="http://grep$c$c.com/file_/repository.grep$c$c.com/java/ext/com.google.android/android/4.1.1_r1/android/os/CountDownTimer.java/?v=source">the来源$ C ​​$ C 到您的项目，并为类提供一个唯一的名称。 （我打电话给我MoreAccurateTimer）现在进行一些更改：

I build this upon the CountDownTimer framework, so cut & paste the source code into your project and give the class a unique name. (I called mine MoreAccurateTimer.) Now make a few changes:

1. 添加一个新的类变量：

1. Add a new class variable:

private long mNextTime;

修改启动（）：

public synchronized final MoreAccurateTimer start() {
    if (mMillisInFuture <= 0) {
        onFinish();
        return this;
    }

    mNextTime = SystemClock.uptimeMillis();
    mStopTimeInFuture = mNextTime + mMillisInFuture;

    mNextTime += mCountdownInterval;
    mHandler.sendMessageAtTime(mHandler.obtainMessage(MSG), mNextTime);
    return this;
}

更​​改处理程序的 handlerMessage（）：

@Override
public void handleMessage(Message msg) {
    synchronized (MoreAccurateTimer.this) {
        final long millisLeft = mStopTimeInFuture - SystemClock.uptimeMillis();

        if (millisLeft <= 0) {
            onFinish();
        } else {
            onTick(millisLeft);

            // Calculate next tick by adding the countdown interval from the original start time
            // If user's onTick() took too long, skip the intervals that were already missed
            long currentTime = SystemClock.uptimeMillis();
            do {
                mNextTime += mCountdownInterval;
            } while (currentTime > mNextTime);

            // Make sure this interval doesn't exceed the stop time
            if(mNextTime < mStopTimeInFuture)
                sendMessageAtTime(obtainMessage(MSG), mNextTime);
            else
                sendMessageAtTime(obtainMessage(MSG), mStopTimeInFuture);
        }
    }
}

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