RecyclerView: How to simulate ListView's draw selector on top?

Question

I would like to create a RecyclerView that draws a selector on top of its items. It should be rendered on top of the items, that means I cannot simply set a StateListDrawable as item background.

I am particularly interested in the pressed state, i.e. something should be drawn if (and only if) an item is pressed.

RecyclerView.ItemDecoration is capable of drawing over items of a RecyclerView. Here is what I have tried so far:

public final class ItemPressedDecoration extends RecyclerView.ItemDecoration {
    private final Rect rect = new Rect();

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        final int count = parent.getChildCount();
        for (int index = 0; index < count; index++) {
            final View child = parent.getChildAt(index);
            if (child.isPressed()) {
                drawOverlay(c, child);
            }
        }
    }

    private void drawOverlay(Canvas c, View child) {
        c.save();
        rect.set(child.getLeft(), child.getTop(), child.getRight(), child.getBottom());
        c.clipRect(rect);
        c.drawColor(0x80ff0000);
        c.restore();
    }
}

The problem is that RecyclerView does not seem to redraw the item decoration if the drawable state of one of its children changes. So how do I get it to do that?

I have tried to add an RecyclerView.OnItemTouchListener and call recyclerView.invalidate() from its onInterceptTouchEvent() method but that did not work.

Answer 1

If you can use FrameLayout as root, and your selector is semi-transparent, below layout may useful.

android:foreground, not android:background

layout/view_listitem.xml

<FrameLayout
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:foreground="@drawable/your_selector">

  <!-- your list items -->

</FrameLayout>