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1   UÿĵViewViewGroupѣÿĶonTouchҲU
     L    ĳˣøεViewGroupӦdispatchTouchEvent  ѵonTouchEvent ǳ֮ΪL
2  Down¼ еViewжĸViewҪ¼
    Move¼  ᷢViewߵ TouchTarget 

3 TouchTarget  رƵmove¼£ر죬ViewֱҵҪѵ¼