android (eight), touch event distribution

 

This article is based on android 4.2.1. Starting from the view to get the event information, first do some detection and preprocessing of the event; if the event has a problem, discard the information, otherwise start to analyze the event.

First determine whether mListenerInfo is empty and whether the onTouch event is set; if the event is set, the onTouch event is executed. When the onTouch method consumes the event, the message delivery ends; otherwise, the event is handed over to the OnTouchEvent method for processing. The event is still a long press event. If the event is not consumed, the event is thrown to the parent control or the end event (the end event if there is no parent control).

 

7226     public boolean dispatchTouchEvent(MotionEvent event) {
7227         if (mInputEventConsistencyVerifier != null) {
7228             mInputEventConsistencyVerifier.onTouchEvent(event, 0);
7229         }
7230 
7231         if (onFilterTouchEventForSecurity(event)) {
7232             //noinspection SimplifiableIfStatement
7233             ListenerInfo li = mListenerInfo;//包括onTouch，onClick和onLongClick事件
7234             if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
7235                     && li.mOnTouchListener.onTouch(this, event)) {
7236                 return true;
7237             }
7238 
7239             if (onTouchEvent(event)) {
7240                 return true;
7241             }
7242         }
7243 
7244         if (mInputEventConsistencyVerifier != null) {
7245             mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
7246         }
7247         return false;
7248     }