關於dispatchTouchEvent, onInterceptTouchEvent, onTouchEvent的分發機制淺析

 

雖說這個問題不是很難...動動手就能看出答案...但是似乎不太容易理解...幾次嘗試把這個問題說明白....但是好像感覺說不明白....(頓時想起了那句話----說不明白就是自己還不明白! 我怎麼可能不明白..so)

這裡面牽扯到Activity的dispatchTouchEvent, onTouchEvent以及ViewGroup的dispatchTouchevent, onInterceptTouchEvent, onTouchEvent還有View的dispatchTouchEvent, onTouchEvent

(別嫌我..多一嘴View沒有onInterceptTouchEvent).

前沿: 知識儲備...預設只有View的onTouchEvent返回true其它都返回false;  true意味著本View需要處理(ViewGroup也是View), false則代表不處理繼續分發.

0. 這個事件的執行順序是activity的dispatchTouchEvent先接收到down事件..然後由父往子執行....如果期間沒有視圖的onTouchEvent返回true的, 那不好意思..只能由activity的onTouchEvent執行了(自個走完down, move, up)

06-10 17:08:29.535: V/Activity(3174): dispatchTouchEvent DOWN
06-10 17:08:29.535: V/ViewGroup1(3174): onInterceptTouchEvent DOWN
06-10 17:08:29.535: V/ViewGroup2(3174): onInterceptTouchEvent DOWN
06-10 17:08:29.535: V/Activity(3174): onTouch DOWN
06-10 17:08:29.535: V/Child(3174): onTouchEvent DOWN
06-10 17:08:29.535: V/ViewGroup2(3174): onTouchEvent DOWN
06-10 17:08:29.535: V/ViewGroup1(3174): onTouchEvent DOWN
06-10 17:08:29.535: V/Activity(3174): onTouchEvent DOWN
06-10 17:08:29.565: V/Activity(3174): dispatchTouchEvent MOVE
06-10 17:08:29.565: V/Activity(3174): onTouchEvent MOVE
06-10 17:08:29.575: V/Activity(3174): dispatchTouchEvent MOVE
06-10 17:08:29.575: V/Activity(3174): onTouchEvent MOVE
06-10 17:08:29.575: V/Activity(3174): dispatchTouchEvent UP
06-10 17:08:29.575: V/Activity(3174): onTouchEvent UP

這麼多...咱就先拋開所有的dispatchTouchEvent先來分析onInterceptTouchEvent和onTouchEvent

1. 如果有哪個View的onInterceptTouchEvent返回true, 並且該View的onTouchEvent也返回true了....

本View的onInterceptTouchEvent走完down之後就跟它沒關係了.

下面是ViewGroup2的情況.

06-10 16:36:24.881: V/Activity(30631): dispatchTouchEvent DOWN
06-10 16:36:24.881: V/ViewGroup1(30631): onInterceptTouchEvent DOWN
06-10 16:36:24.881: V/ViewGroup2(30631): onInterceptTouchEvent DOWN
06-10 16:36:24.881: V/ViewGroup2(30631): onTouchEvent DOWN
06-10 16:36:24.911: V/Activity(30631): dispatchTouchEvent MOVE
06-10 16:36:24.911: V/ViewGroup1(30631): onInterceptTouchEvent MOVE
06-10 16:36:24.911: V/ViewGroup2(30631): onTouchEvent MOVE
06-10 16:36:24.921: V/Activity(30631): dispatchTouchEvent MOVE
06-10 16:36:24.921: V/ViewGroup1(30631): onInterceptTouchEvent MOVE
06-10 16:36:24.921: V/ViewGroup2(30631): onTouchEvent MOVE
06-10 16:36:24.951: V/Activity(30631): dispatchTouchEvent UP
06-10 16:36:24.951: V/ViewGroup1(30631): onInterceptTouchEvent UP
06-10 16:36:24.951: V/ViewGroup2(30631): onTouchEvent UP

2. 如果有哪個onInterceptTouchEvent返回true了, 但是onTouchEvent返回false了.遵循第0規律

06-10 16:43:50.496: V/Activity(32620): dispatchTouchEvent DOWN
06-10 16:43:50.496: V/ViewGroup1(32620): onInterceptTouchEvent DOWN
06-10 16:43:50.496: V/ViewGroup2(32620): onInterceptTouchEvent DOWN
06-10 16:43:50.496: V/ViewGroup2(32620): onTouchEvent DOWN
06-10 16:43:50.496: V/ViewGroup1(32620): onTouchEvent DOWN
06-10 16:43:50.496: V/Activity(32620): onTouchEvent DOWN
06-10 16:43:50.556: V/Activity(32620): dispatchTouchEvent MOVE
06-10 16:43:50.556: V/Activity(32620): onTouchEvent MOVE
06-10 16:43:50.576: V/Activity(32620): dispatchTouchEvent MOVE
06-10 16:43:50.576: V/Activity(32620): onTouchEvent MOVE
06-10 16:43:50.586: V/Activity(32620): dispatchTouchEvent UP
06-10 16:43:50.586: V/Activity(32620): onTouchEvent UP

3. 還有第三種嗎...第三種就是預設情況了....只走Child的onTouchEvent, 那就遵循第1條規律

06-10 16:49:04.191: V/Activity(746): dispatchTouchEvent DOWN
06-10 16:49:04.191: V/ViewGroup1(746): onInterceptTouchEvent DOWN
06-10 16:49:04.191: V/ViewGroup2(746): onInterceptTouchEvent DOWN
06-10 16:49:04.191: V/Activity(746): onTouch DOWN
06-10 16:49:04.191: V/Child(746): onTouchEvent DOWN
06-10 16:49:04.261: V/Activity(746): dispatchTouchEvent MOVE
06-10 16:49:04.261: V/ViewGroup1(746): onInterceptTouchEvent MOVE
06-10 16:49:04.261: V/ViewGroup2(746): onInterceptTouchEvent MOVE
06-10 16:49:04.261: V/Activity(746): onTouch MOVE
06-10 16:49:04.271: V/Child(746): onTouchEvent MOVE
06-10 16:49:04.271: V/Activity(746): dispatchTouchEvent UP
06-10 16:49:04.271: V/ViewGroup1(746): onInterceptTouchEvent UP
06-10 16:49:04.271: V/ViewGroup2(746): onInterceptTouchEvent UP
06-10 16:49:04.271: V/Activity(746): onTouch UP
06-10 16:49:04.271: V/Child(746): onTouchEvent UP

最後加上這個dispatchTouchEvent,這個View要是走的話...先走dispatchTouchEvent, 如果返回true的話,那就跟本View的onInterceptTouchEvent和onTouchEvent沒關係了.自己處理了, 不分發了.

下面我把ViewGroup2的dispatchTouchEvent返回true(ViewGroup1的dispatchTouchEvent注釋了.)

06-10 16:52:52.284: V/Activity(1403): dispatchTouchEvent DOWN
06-10 16:52:52.284: V/ViewGroup1(1403): onInterceptTouchEvent DOWN
06-10 16:52:52.284: V/ViewGroup2(1403): dispatchTouchEvent DOWN
06-10 16:52:52.324: V/Activity(1403): dispatchTouchEvent MOVE
06-10 16:52:52.324: V/ViewGroup1(1403): onInterceptTouchEvent MOVE
06-10 16:52:52.334: V/ViewGroup2(1403): dispatchTouchEvent MOVE
06-10 16:52:52.345: V/Activity(1403): dispatchTouchEvent MOVE
06-10 16:52:52.345: V/ViewGroup1(1403): onInterceptTouchEvent MOVE
06-10 16:52:52.345: V/ViewGroup2(1403): dispatchTouchEvent MOVE
06-10 16:52:52.365: V/Activity(1403): dispatchTouchEvent MOVE
06-10 16:52:52.365: V/ViewGroup1(1403): onInterceptTouchEvent MOVE
06-10 16:52:52.365: V/ViewGroup2(1403): dispatchTouchEvent MOVE
06-10 16:52:52.375: V/Activity(1403): dispatchTouchEvent UP
06-10 16:52:52.375: V/ViewGroup1(1403): onInterceptTouchEvent UP
06-10 16:52:52.375: V/ViewGroup2(1403): dispatchTouchEvent UP

說到底就是攔不攔截, 與攔截了處不處理的問題! 攔截處理..那好...再來一遍該來的....攔截不處理..那由裡往外再出去(期間碰到處理的, 那就跟0條一樣了.), 不攔截, 處理(有處理機會)跟攔截處理一樣..

終於寫完了...發現自己越來越懂了...要是沒明白的話...建議自己寫一下...