android onclick onLongClick ontouch dispatchTouchEvent onInterceptTouchEvent
按ACTION_DOWN -> onLongClick -> ACTION_UP -> onClick的次序发生的
onTouchevent() vs onTouch()
onTouch() is used by users of the View to get touch events while onTouchEvent() is used by derived classes of the View to get touch events.
1) Implementation:
If you want use onTouch() you have to do three things.
1- implement OnTouchListener
2- call setOnTouchListener() on the view you want to set catch the event
3- override onTouch() to handle the event
but if you want to use onTouchEvent() you don't need to do step 1 & 2 above. just you need to override onTouchEvent().
2) Working:
onTouch() works on view, viewgroup, activity. Meaning you can use onTouch() inside view, viewgroup or activity. This methods take two arguments [onTouch(View v, MotionEvent e) ]. This allows you filter events for different views in an activity or view group. Or the activity can itself handle it. onTouchEvent() takes on one argument [onTouchEvent(MotionEvent e) ]. Thus this can be used only inside the view that implements it or on the derived view.
I think, such options are part of Android's more flexible development philosophy, though it creates confusion for the learners at times.
