Android 带有悬浮计时器的录屏实现

MediaRecorder

/**
 * Used to record audio and video. The recording control is based on a
 * simple state machine (see below).
 *
 * <p><img src="{@docRoot}images/mediarecorder_state_diagram.gif" border="0" />
 * </p>
 *
 * <p>A common case of using MediaRecorder to record audio works as follows:
 *
 * <pre>MediaRecorder recorder = new MediaRecorder();
 * recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
 * recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
 * recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
 * recorder.setOutputFile(PATH_NAME);
 * recorder.prepare();
 * recorder.start();   // Recording is now started
 * ...
 * recorder.stop();
 * recorder.reset();   // You can reuse the object by going back to setAudioSource() step
 * recorder.release(); // Now the object cannot be reused
 * </pre>
 *
 * <p>Applications may want to register for informational and error
 * events in order to be informed of some internal update and possible
 * runtime errors during recording. Registration for such events is
 * done by setting the appropriate listeners (via calls
 * (to {@link #setOnInfoListener(OnInfoListener)}setOnInfoListener and/or
 * {@link #setOnErrorListener(OnErrorListener)}setOnErrorListener).
 * In order to receive the respective callback associated with these listeners,
 * applications are required to create MediaRecorder objects on threads with a
 * Looper running (the main UI thread by default alre