When we develop, we often encounter the problem that the use of ImageView causes the click hot area to be too small. At this time, we can replace it with ImageButton and try:
<ImageButton android:id="@+id/iv_back" android:layout_width="@dimen/default_margin_45dp" android:layout_height="match_parent" android:src="@mipmap/ret" android: onClick = "onPopupClick" android:background="@null" android:scaleType="center" />