Android：触发 MotionEvent.ACTION_CANCEL

Question

要求：确保itemLookup 仅在按住按钮至少 1 秒时才执行。按住按钮 3 秒后停止按钮事件，因此用于查找的记录不会包含不必要的数据。

• 问题：MotionEvent.ACTION_CANCEL 从未被调用，即使调试确认 TableLayoutForIntercept 的 onInterceptTouchEvent 在调用 MainActivity 的 OnTouchListener 事件之前被调用，正如预期的那样。也许我不明白onInterceptTouchEvent 的目的？我看过其他关于这个问题的帖子，但他们都在处理滑动或拖动事件，而不是取消按钮按下。也许这无法做到？

• 代码：只显示MainActivity 的相关部分，以及完整的TableLayoutForIntercept 类，当然还有<com.company.myapplication.TableLayoutForIntercept></com.company.myapplication.TableLayoutForIntercept> 标记围绕我的xml 布局。

  public class MainActivity extends Activity {
  
      //...
  
      DateTime recordingStartedTime;
      DateTime recordingEndedTime;
      boolean buttonHeldLongEnough = false;
  
      PackageManager pm = getPackageManager();
      boolean micPresent = pm.hasSystemFeature(PackageManager.FEATURE_MICROPHONE);
  
      if (micPresent) {
          recordBtn.setOnTouchListener(new View.OnTouchListener() {
  
              @Override
              public boolean onTouch(View recordView, MotionEvent recordEvent) {
  
                  switch (recordEvent.getAction()) {
  
                      case MotionEvent.ACTION_DOWN:
                          // Try to record audio
                          try {
                              recordingOff.setVisibility(View.INVISIBLE);
                              recordingOn.setVisibility(View.VISIBLE);
  
                              recordingStartedTime = DateTime.now();
                              constructPrepareStartRecording();
                          }
                          catch (Exception ex) {
                              Log.e(MainActivity.class.getSimpleName(), "An unknown error occurred.");
                          }
                          return true;
  
                      case MotionEvent.ACTION_UP:
                          recordingOff.setVisibility(View.VISIBLE);
                          recordingOn.setVisibility(View.INVISIBLE);
  
                          recordingEndedTime = DateTime.now();
                          Seconds seconds = Seconds.secondsBetween(recordingStartedTime, recordingEndedTime);
                          int secondsButtonHeld = seconds.getSeconds();
  
                          // Button must have been held at least 1 second before running itemLookup 
                          if (secondsButtonHeld > 0 ) {
                              buttonHeldLongEnough = true;
                          }
                          else {
                              buttonHeldLongEnough = false;
                          }
  
                          // Need to release resources regardless
                          stopReleaseResetRecording();
  
                          if (buttonHeldLongEnough) {
                              itemLookup();
                          }
                          return true;
  
                      case MotionEvent.ACTION_CANCEL:
                          // I think this is the event I have to trigger to halt the button press 
                          boolean codeHasHitCancel = true;
                          return codeHasHitCancel;
  
                  }
                  return false;
              }
          });
      }
      else {
          toastTitle = "Unable To Record";
          toastMessage = "Device microphone not found.";
          toast = new GenericCustomToast();
          toast.show(toastTitle, toastMessage, MainActivity.this);
      }
  
      //...
  }
  
  public class TableLayoutForIntercept extends TableLayout {
  
      public TableLayoutForIntercept (Context context) {
          super(context);
      }
  
      public TableLayoutForIntercept (Context context, AttributeSet attrs) {
          super(context, attrs);
      }
  
      private CancelPressTask cancelPressTask = null;
      private boolean stopTouchEvent = false;
  
      @Override
      public boolean onInterceptTouchEvent (MotionEvent event) {
  
          final int action = event.getAction();
  
          switch (action) {
  
              case MotionEvent.ACTION_DOWN:
                  stopTouchEvent = false;
                  cancelPressTask = new CancelPressTask();
                  break;
  
              case MotionEvent.ACTION_CANCEL:
              case MotionEvent.ACTION_UP:
                  cancelPressTask.resetCancelPressTimer();
                  cancelPressTask.stopCancelPressTimer();
                  return stopTouchEvent;
          }
  
          return super.onInterceptTouchEvent(event);
      }
  
      @Override
      public boolean onTouchEvent (MotionEvent event) {
  
          if (!stopTouchEvent) {
          return super.onTouchEvent(event);
          }
  
          return true;
      }
  
      private class CancelPressTask {
  
          public final long CANCEL_PRESS_TIMEOUT = 3000; // 3 seconds
  
          private Handler cancelPressHandler = new Handler(){
              public void handleMessage(Message msg) {
              }
          };
  
          private Runnable cancelPressCallback = new Runnable() {
              @Override
              public void run() {
                  stopTouchEvent = true;
              }
          };
  
          public void resetCancelPressTimer(){
              cancelPressHandler.removeCallbacks(cancelPressCallback);
              cancelPressHandler.postDelayed(cancelPressCallback, CANCEL_PRESS_TIMEOUT);
          }
  
          public void stopCancelPressTimer(){
              cancelPressHandler.removeCallbacks(cancelPressCallback);
          }
      }
  }
  

Answer 1

我想出了另一种方法来解决这个问题。我没有尝试触发一个事件，而是决定窃取它！下面的代码将停止录制，然后在 3 秒后进行项目查找，无论用户尝试按住按钮多长时间。唯一的问题是对于太短（少于 1 秒）的录音，仍然需要整整 3 秒才能通过 toast 消息通知用户。但我愿意接受。

    public class Main Activity extends Activity {

        DateTime recordingStartedTime;
        DateTime recordingEndedTime = null;
        boolean buttonHeldLongEnough = false;
        LimitRecordingTask limitRecordingTask;

        PackageManager pm = getPackageManager();
        boolean micPresent = pm.hasSystemFeature(PackageManager.FEATURE_MICROPHONE);

        if (micPresent) {
            recordBtn.setOnTouchListener(new View.OnTouchListener() {
                @Override
                public boolean onTouch(View recordView, MotionEvent recordEvent) {

                    limitRecordingTask = new LimitRecordingTask();
                    switch (recordEvent.getAction()) {

                        case MotionEvent.ACTION_DOWN:
                            // Try to record audio
                            try {
                                recordBtn.setBackgroundColor(Color.DKGRAY);
                                recordingOff.setVisibility(View.INVISIBLE);
                                recordingOn.setVisibility(View.VISIBLE);

                                recordingStartedTime = DateTime.now();
                                constructPrepareStartRecording();
                                limitRecordingTask.resetRecordingTimer();
                            }
                            catch (Exception ex) {
                                Log.e(MainActivity.class.getSimpleName(), "An unknown error occurred.");
                                limitRecordingTask.stopRecordingTimer();
                            }
                            return true;

                        case MotionEvent.ACTION_UP:
                            // After 3 seconds limitRecordingTask will 'steal' this event
                            recordBtn.setBackgroundResource(R.drawable.custom_button);
                            recordingOff.setVisibility(View.VISIBLE);
                            recordingOn.setVisibility(View.INVISIBLE);

                            recordingEndedTime = DateTime.now();
                            Seconds seconds = Seconds.secondsBetween(recordingStartedTime, recordingEndedTime);
                            int secondsButtonHeld = Math.abs(seconds.getSeconds());

                            if (secondsButtonHeld > 0 ) {
                                buttonHeldLongEnough = true;
                            }
                            else {
                                buttonHeldLongEnough = false;
                            }
                            return true;
                    }
                    return false;
                }
            });
        }
        else {
            toastTitle = "Unable To Record";
            toastMessage = "Device microphone not found.";
            toast = new GenericCustomToast();
            toast.show(toastTitle, toastMessage, MainActivity.this);
        }

        private class LimitRecordingTask {

            public final long RECORDING_TIMEOUT = 3000; // 3 seconds

            private Handler limitRecordingHandler = new Handler(){
                public void handleMessage(Message msg) {
                }
            };

            private Runnable limitRecordingCallback = new Runnable() {
                @Override
                public void run() {
                    // 'Stolen' MotionEvent.ACTION_UP
                    recordBtn.setBackgroundResource(R.drawable.custom_button);
                    recordingOff.setVisibility(View.VISIBLE);
                    recordingOn.setVisibility(View.INVISIBLE);

                    if (recordingEndedTime == null) {
                        recordingEndedTime = DateTime.now();
                    }
                    Seconds seconds = Seconds.secondsBetween(recordingStartedTime, recordingEndedTime);
                    int secondsButtonHeld = Math.abs(seconds.getSeconds());

                    if (secondsButtonHeld > 0 ) {
                        buttonHeldLongEnough = true;
                    }
                    else {
                        buttonHeldLongEnough = false;
                    }

                    limitRecordingTask.stopRecordingTimer();

                    stopReleaseResetRecording();
                    itemLookup();
                }
            };

            public void resetRecordingTimer(){
                limitRecordingHandler.removeCallbacks(limitRecordingCallback);
                limitRecordingHandler.postDelayed(limitRecordingCallback, RECORDING_TIMEOUT);
            }

            public void stopRecordingTimer(){
                limitRecordingHandler.removeCallbacks(limitRecordingCallback);
            }
        }
    }