How to find percentage of each visible item in recycleview

Question

int findFirstVisibleItemPosition();
int findFirstCompletelyVisibleItemPosition();
int findLastVisibleItemPosition();
int findLastCompletelyVisibleItemPosition();
         


        

Answer 1

Here is more improved and less complex (more effective, less memory usage, less code) in kotlin.

No need do compare item rect with recycler view rect

recycler.addOnScrollListener(object : RecyclerView.OnScrollListener() {
    override fun onScrolled(recyclerView: RecyclerView?, dx: Int, dy: Int) {
        val layoutManager = recycler.layoutManager as LinearLayoutManager
        val firstPosition = layoutManager.findFirstVisibleItemPosition()
        val lastPosition = layoutManager.findLastVisibleItemPosition()

       val globalVisibleRect = Rect()
       recycler.getGlobalVisibleRect(globalVisibleRect)
       for (pos in firstPosition..lastPosition) {
          val view = layoutManager.findViewByPosition(pos)
          if (view != null) {
              val percentage = getVisibleHeightPercentage(view)
          }
       }
   }

    //Method to calculate how much of the view is visible
    private fun getVisibleHeightPercentage(view: View): Double {

        val itemRect = Rect()
        val isParentViewEmpty = view.getLocalVisibleRect(itemRect)

       // Find the height of the item.
       val visibleHeight = itemRect.height().toDouble()
       val height = view.getMeasuredHeight()

       val viewVisibleHeightPercentage = visibleHeight / height * 100

       if(isParentViewEmpty){
          return viewVisibleHeightPercentage
       }else{
           return 0.0
        }
     }
})