Coordinatorlayout appbarrayout recyclerview item exposure buried point misalignment analysis

Problem description

   Coordinatorlayout （ Coordinator layout ） And AppBarLayout  Realization    topbar The effect of sliding zoom ,

RecyclerView  Monitor when sliding stops The first and last visible item Report the exposure point

（findFirstVisibleItemPosition  findLastVisibleItemPosition）

However, the reported buried point data is different from what users really see item Not in conformity with , The exposure buried point is inaccurate .

Question why

The height of the user's visible field of view （768）

 

RecyclerView Calculated height of 1104

 

Analysis of the source code AppBarLayout redefined heightMeasureSpec  MeasureSpec scale size by 1653

 

The real boundary of the interface is at the bottom of the mobile screen

 

Solution

findLastVisibleItemPosition Value     Start Decrement cycle to findFirstVisibleItemPosition  , Judge again in turn item Whether it is the visual field area visible to the user

viewpager.getY（）+item.getY() An area smaller than the screen height and considered visible to the user

 

Nuclear new code ：