CODEWITHSUNDEEP
androidandroid-layoutandroid-recyclerviewandroid-adapterondraw
Drocchio
Drocchio

Reputation: 413

eliminate divider on top of the first item in the RecyclerView

I have a RecyclerView with an header on top( namely a title, a TextView that describe the content of the RecyclerView)

Now I combined two different ViewHolders with some logic into the Adapter to obtain this effect, but I have an unexpected result.

The recyclerView hava to have dividers, but I have a line I want to eliminate between the TextViewand the first Item of the `RecyclerView:

In other words I need to eliminate only the top divider of the RecyclerView, the first item, because I want that between the TextView on top and the list below there is not separation, the other items instead I expect they are separated as I obtained

This post shows how to eliminate the last row divider of a RV, but i need the first top line and I have no idea how I can adapt this snippet to my use case, or if I should create a new class.

Upvotes: 1

Views: 2488

Answers (1)

Cheticamp
Cheticamp

Reputation: 62841

In the RecyclerView.ItemDecoration I want to identify the first view in the RecyclerView and not draw a decoration for it. I will also want to not reserve any space for the decoration since it is not drawn. This necessitates an override of getItemOffsets().

Here is some code that applies a decoration to the bottom of all RecyclerView items except the first and the last.

    public class DividerItemDecorator extends RecyclerView.ItemDecoration {  
    private Drawable mDivider;  

    public DividerItemDecorator(Drawable divider) {  
        mDivider = divider;  
    }  

    @Override  
  public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {  
        int pos = parent.getChildAdapterPosition(view);  
        if (pos != 0 &&  
            pos != parent.getLayoutManager().getItemCount() - 1) {  
            outRect.bottom = mDivider.getIntrinsicHeight();  
        }  
    }  

    @Override  
  public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {  
        int dividerLeft = parent.getPaddingLeft();  
        int dividerRight = parent.getWidth() - parent.getPaddingRight();  

        int childCount = parent.getChildCount();  
        for (int i = 0; i < childCount; i++) {  
            View child = parent.getChildAt(i);  

            int pos = parent.getChildAdapterPosition(child);  
            if (pos != 0 &&  
                pos != parent.getLayoutManager().getItemCount() - 1) {  

                RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();  

                int dividerTop = child.getBottom() + params.bottomMargin;  
                int dividerBottom = dividerTop + mDivider.getIntrinsicHeight();  
                mDivider.setBounds(dividerLeft, dividerTop, dividerRight, dividerBottom);  
                mDivider.draw(canvas);  
            }  
        }  
    }  
}

Here is what this looks like. I have exaggerated the dividers so they would stand out.

enter image description here

Upvotes: 4

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