一、随着手势定制震动
震动是很多应用中常见的交互方式，比如在游戏中提示用户任务完成、在闹钟应用中提醒用户该起床了等等。不同的震动模式可以传递不同的信息，但是Android系统默认提供的震动模式有限。那么怎么自定义一个比较独特的震动模式呢？这里我们提供一个通过手势实现震动模式定制的例子。
首先我们需要实现一个抽象基类ExtendedGestureListener，它能够处理用户的手势并返回一个数字数组，该数组可以用于定义震动模式。我们可以继承SimpleOnGestureListener并重写onDown()、onFling()和onScroll()三个方法来实现定制。
public abstract class ExtendedGestureListener extends SimpleOnGestureListener {
protected static final String TAG = "ExtendedGestureListener";
private static final int SWIPE_MIN_DISTANCE = 120;
private static final int SWIPE_THRESHOLD_VELOCITY = 200;
private static final int SCROLL_THRESHOLD_DISTANCE = 30;
private float downX;
private float downY;
@Override
public boolean onDown(MotionEvent e) {
downX = e.getX();
downY = e.getY();
return true;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return false;
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
float deltaX = e2.getX() - e1.getX();
float deltaY = e2.getY() - e1.getY();
float absDeltaX = Math.abs(deltaX);
float absDeltaY = Math.abs(deltaY);
if (absDeltaX > absDeltaY) {
if (absDeltaX > SCROLL_THRESHOLD_DISTANCE) {
if (deltaX > 0) {
// Right swipe
return onSwipeRight();
} else {
// Left swipe
return onSwipeLeft();
}
}
} else {
if (absDeltaY > SCROLL_THRESHOLD_DISTANCE) {
if (deltaY > 0) {
// Down swipe
return onSwipeDown();
} else {
// Up swipe
return onSwipeUp();
}
}
}
return false;
}
protected abstract boolean onSwipeRight();
protected abstract boolean onSwipeLeft();
protected abstract boolean onSwipeUp();
protected abstract boolean onSwipeDown();
}
然后我们实现一个类CustomVibrator，它能够接收一个数字数组，并转化为具体的震动模式。下面是它的代码片段。
public class CustomVibrator {
private Vibrator vibrator;
public CustomVibrator(Context context) {
vibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
}
/**
* @param vibration pattern represented by an array of integers. Each element
* specifies the duration of a single vibration in milliseconds.
* The array must contain an even number of elements, with the
* first element specifying the duration to wait before starting
* the vibration and every subsequent pair of elements specifying
* the duration of a vibration and the duration to wait before
* vibrating again.
*/
public void vibrate(int[] pattern) {
if (vibrator.hasVibrator()) {
vibrator.vibrate(pattern, -1);
} else {
Log.w(TAG, "No vibrator found on device");
}
}
}
最后我们来看一下如何使用上面所述的两个类。在MainActivity中我们需要实例化CustomVibrator，同时传递一个ExtendedGestureListener实例并实现相应的方法来处理用户手势输入。下面是MainActivity的代码片段。
public class MainActivity extends AppCompatActivity {
private CustomVibrator vibrator;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
vibrator = new CustomVibrator(this);
final ExtendedGestureListener gestureListener = new ExtendedGestureListener() {
private List vibrationPattern = new ArrayList();
@Override
protected boolean onSwipeRight() {
vibrationPattern.add(200);
vibrationPattern.add(200);
vibrator.vibrate(toIntArray(vibrationPattern));
return true;
}
@Override
protected boolean onSwipeLeft() {
vibrationPattern.add(300);
vibrationPattern.add(200);
vibrator.vibrate(toIntArray(vibrationPattern));
return true;
}
@Override
protected boolean onSwipeUp() {
vibrationPattern.add(400);
vibrationPattern.add(200);
vibrator.vibrate(toIntArray(vibrationPattern));
return true;
}
@Override
protected boolean onSwipeDown() {
vibrationPattern.clear();
vibrator.vibrate(new int[]{0});
return true;
}
private int[] toIntArray(List list) {
int[] array = new int[list.size()];
for (int i = 0; i < list.size(); i++) {
array[i] = list.get(i);
}
return array;
}
};
final GestureDetector gestureDetector = new GestureDetector(this, gestureListener);
View gestureView = findViewById(R.id.gesture_view);
gestureView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
});
}
}
二、根据音乐节奏震动
当你在听音乐时，你是否有过这样的体验：如果能够把手机的震动和音乐的节奏同步，那该多好啊！这里我们提供一个例子来实现这一点。
首先，我们需要读取音乐的节奏信息。这里我们可以使用Android系统提供的MediaMetadataRetriever类来获取一个媒体文件的元数据信息，包括它的时长、MIME类型以及其中的所有ID3标签和章节信息。
下面是如何使用MediaMetadataRetriever类读取音乐标签信息的示例代码。
MediaMetadataRetriever retriever = new MediaMetadataRetriever(); retriever.setDataSource(path); String duration = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION); String mimeType = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_MIMETYPE); byte[] art = retriever.getEmbeddedPicture(); int bitrate = Integer.parseInt(retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_BITRATE));
然后，我们需要根据读取到的音乐信息，计算出每一个时间片段应该持续多长时间。这里我们可以使用Android系统提供的Visualizer类。它可以用FFT计算出实时音频频谱，并提供了有用的回调函数，如onWaveFormDataCapture()和onFftDataCapture()。
public class MusicVisualizerView extends View implements Visualizer.OnDataCaptureListener {
private static final int MAX_AMPLITUDE = 32768;
private Visualizer visualizer;
private Paint paint;
private byte[] waveformBytes;
public MusicVisualizerView(Context context, AttributeSet attrs) {
super(context, attrs);
paint = new Paint();
}
public void setVisualizer(Visualizer visualizer) {
this.visualizer = visualizer;
this.visualizer.setDataCaptureListener(this,
Visualizer.getMaxCaptureRate() / 2, true, false);
}
@Override
public void onWaveFormDataCapture(Visualizer visualizer, byte[] waveform, int samplingRate) {
waveformBytes = waveform;
invalidate();
}
@Override
public void onFftDataCapture(Visualizer visualizer, byte[] fft, int samplingRate) {
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (waveformBytes == null) {
return;
}
int width = getWidth();
int height = getHeight();
paint.setStrokeWidth(1.5f);
paint.setColor(Color.BLUE);
for (int i = 0; i < waveformBytes.length - 1; i++) {
float left = width * i / (waveformBytes.length - 1);
float top = (0.5f + ((byte) (waveformBytes[i] + 128)) / (2 * MAX_AMPLITUDE)) * height;
float right = width * (i + 1) / (waveformBytes.length - 1);
float bottom = (0.5f + ((byte) (waveformBytes[i + 1] + 128)) / (2 * MAX_AMPLITUDE)) * height;
canvas.drawColor(Color.WHITE);
canvas.drawLine(left, top, right, bottom, paint);
}
}
}
最后我们将震动和的音乐节奏同步起来。为了更好地控制时间粒度，我们使用Handler来定时执行震动任务，同时音乐的节奏信息也是按照一定的时间片段来处理。代码实现如下：
final CustomVibrator vibrator = new CustomVibrator(this);
final Visualizer visualizer = new Visualizer(0);
visualizer.setEnabled(true);
final MusicVisualizerView musicVisualizerView = findViewById(R.id.music_visualizer_view);
musicVisualizerView.setVisualizer(visualizer);
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
final int size = Visualizer.getCaptureSizeRange()[1];
if (waveformBytes == null) {
return;
}
int bytesPerSecond = (waveformBytes.length * 1000 / Integer.parseInt(duration));
int millisecondsPerSample = size * 1000 / Integer.parseInt(duration);
int samplesPerSecond = size / millisecondsPerSample;
int frequencyBucketSize = (int) Math.floor((double) samplesPerSecond / 20);
int maxFrequencyVolume = 0;
for (int i = 0; i < frequencyBucketSize; i++) {
int start = i * millisecondsPerSample;
int end = start + millisecondsPerSample;
int volume = 0;
for (int j = start; j < end && j = 20) {
int durationInMillis = (int) Math.ceil((double) bytesPerSecond / frequencyBucketSize) * 10;
Log.d(TAG, "vibrate durationInMillis: " + durationInMillis);
int[] pattern = new int[2];
pattern[0] = 0;
pattern[1] = durationInMillis;
vibrator.vibrate(pattern);
}
handler.postDelayed(this, 10);
}
}, 10);
三、Android系统提供的震动模式
除了自定义震动模式，Android系统还提供了一些预定义的震动模式，比如调用某个API时产生的模式、短信、电话挂断等事件产生的模式等等。下面是一个例子，展示如何调用这些API。
private void playSystemVibrationPattern() {
// Vibrate for 500 milliseconds
vibrator.vibrate(500);
// Play a vibration pattern defined in an XML resource
vibrator.vibrate(getResources().getIntArray(R.array.fade_in_out), -1);
// Play a vibration pattern designed for notifications
vibrator.vibrate(NotificationManager.IMPORTANCE_HIGH);
// Play a vibration pattern similar to the system's low battery alert
vibrator.vibrate(NotificationManager.IMPORTANCE_LOW);
}
以上是三种不同的音乐震动模式实现例子，开发者可以根据自己的需求来进行选择和改进。
原创文章，作者：小蓝，如若转载，请注明出处：https://www.506064.com/n/200136.html
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